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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef VIEWS_VIEW_H_
#define VIEWS_VIEW_H_
#pragma once
#include <algorithm>
#include <map>
#include <set>
#include <string>
#include <vector>
#include "base/i18n/rtl.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "build/build_config.h"
#include "ui/base/dragdrop/os_exchange_data.h"
#include "ui/gfx/compositor/layer_delegate.h"
#include "ui/gfx/native_widget_types.h"
#include "ui/gfx/rect.h"
#include "views/accelerator.h"
#include "views/background.h"
#include "views/border.h"
using ui::OSExchangeData;
namespace gfx {
class Canvas;
class Insets;
class Path;
namespace ui {
struct AccessibleViewState;
class Compositor;
class Layer;
class Texture;
class ThemeProvider;
class Transform;
enum TouchStatus;
#if defined(OS_WIN)
class NativeViewAccessibilityWin;
namespace views {
class Background;
class Border;
class ContextMenuController;
class DragController;
class FocusManager;
class FocusTraversable;
class InputMethod;
class LayerPropertySetter;
class LayoutManager;
class ScrollView;
class TextInputClient;
class Widget;
namespace internal {
class NativeWidgetView;
class RootView;
// View class
// A View is a rectangle within the views View hierarchy. It is the base
// class for all Views.
// A View is a container of other Views (there is no such thing as a Leaf
// View - makes code simpler, reduces type conversion headaches, design
// mistakes etc)
// The View contains basic properties for sizing (bounds), layout (flex,
// orientation, etc), painting of children and event dispatch.
// The View also uses a simple Box Layout Manager similar to XUL's
// SprocketLayout system. Alternative Layout Managers implementing the
// LayoutManager interface can be used to lay out children if required.
// It is up to the subclass to implement Painting and storage of subclass -
// specific properties and functionality.
// Unless otherwise documented, views is not thread safe and should only be
// accessed from the main thread.
class VIEWS_EXPORT View : public ui::LayerDelegate,
public AcceleratorTarget {
typedef std::vector<View*> Views;
// TO BE MOVED ---------------------------------------------------------------
// TODO(beng): These methods are to be moved to other files/classes.
// TODO(beng): delete
// Set whether this view is hottracked. A disabled view cannot be hottracked.
// If flag differs from the current value, SchedulePaint is invoked.
virtual void SetHotTracked(bool flag);
// TODO(beng): delete
// Returns whether the view is hot-tracked.
virtual bool IsHotTracked() const;
// Creation and lifetime -----------------------------------------------------
virtual ~View();
// By default a View is owned by its parent unless specified otherwise here.
bool parent_owned() const { return parent_owned_; }
void set_parent_owned(bool parent_owned) { parent_owned_ = parent_owned; }
// Tree operations -----------------------------------------------------------
// Get the Widget that hosts this View, if any.
virtual const Widget* GetWidget() const;
virtual Widget* GetWidget();
// Adds |view| as a child of this view, optionally at |index|.
void AddChildView(View* view);
void AddChildViewAt(View* view, int index);
// Moves |view| to the specified |index|. A negative value for |index| moves
// the view at the end.
void ReorderChildView(View* view, int index);
// Removes |view| from this view. The view's parent will change to NULL.
void RemoveChildView(View* view);
// Removes all the children from this view. If |delete_children| is true,
// the views are deleted, unless marked as not parent owned.
void RemoveAllChildViews(bool delete_children);
// STL-style accessors.
Views::const_iterator children_begin() { return children_.begin(); }
Views::const_iterator children_end() { return children_.end(); }
Views::const_reverse_iterator children_rbegin() { return children_.rbegin(); }
Views::const_reverse_iterator children_rend() { return children_.rend(); }
int child_count() const { return static_cast<int>(children_.size()); }
bool has_children() const { return !children_.empty(); }
// Returns the child view at |index|.
const View* child_at(int index) const {
DCHECK_GE(index, 0);
DCHECK_LT(index, child_count());
return children_[index];
View* child_at(int index) {
return const_cast<View*>(const_cast<const View*>(this)->child_at(index));
// Returns the parent view.
const View* parent() const { return parent_; }
View* parent() { return parent_; }
// Returns true if |view| is contained within this View's hierarchy, even as
// an indirect descendant. Will return true if child is also this view.
bool Contains(const View* view) const;
// Returns the index of |view|, or -1 if |view| is not a child of this view.
int GetIndexOf(const View* view) const;
// Size and disposition ------------------------------------------------------
// Methods for obtaining and modifying the position and size of the view.
// Position is in the coordinate system of the view's parent.
// Position is NOT flipped for RTL. See "RTL positioning" for RTL-sensitive
// position accessors.
// Transformations are not applied on the size/position. For example, if
// bounds is (0, 0, 100, 100) and it is scaled by 0.5 along the X axis, the
// width will still be 100 (although when painted, it will be 50x50, painted
// at location (0, 0)).
void SetBounds(int x, int y, int width, int height);
void SetBoundsRect(const gfx::Rect& bounds);
void SetSize(const gfx::Size& size);
void SetPosition(const gfx::Point& position);
void SetX(int x);
void SetY(int y);
// No transformation is applied on the size or the locations.
const gfx::Rect& bounds() const { return bounds_; }
int x() const { return bounds_.x(); }
int y() const { return bounds_.y(); }
int width() const { return bounds_.width(); }
int height() const { return bounds_.height(); }
const gfx::Size& size() const { return bounds_.size(); }
// Returns the bounds of the content area of the view, i.e. the rectangle
// enclosed by the view's border.
gfx::Rect GetContentsBounds() const;
// Returns the bounds of the view in its own coordinates (i.e. position is
// 0, 0).
gfx::Rect GetLocalBounds() const;
// Returns the insets of the current border. If there is no border an empty
// insets is returned.
virtual gfx::Insets GetInsets() const;
// Returns the visible bounds of the receiver in the receivers coordinate
// system.
// When traversing the View hierarchy in order to compute the bounds, the
// function takes into account the mirroring setting and transformation for
// each View and therefore it will return the mirrored and transformed version
// of the visible bounds if need be.
gfx::Rect GetVisibleBounds() const;
// Return the bounds of the View in screen coordinate system.
gfx::Rect GetScreenBounds() const;
// Returns the baseline of this view, or -1 if this view has no baseline. The
// return value is relative to the preferred height.
virtual int GetBaseline() const;
// Get the size the View would like to be, if enough space were available.
virtual gfx::Size GetPreferredSize();
// Convenience method that sizes this view to its preferred size.
void SizeToPreferredSize();
// Gets the minimum size of the view. View's implementation invokes
// GetPreferredSize.
virtual gfx::Size GetMinimumSize();
// Return the height necessary to display this view with the provided width.
// View's implementation returns the value from
// Override if your View's preferred height depends upon the width (such
// as with Labels).
virtual int GetHeightForWidth(int w);
// Set whether the receiving view is visible. Painting is scheduled as needed
virtual void SetVisible(bool visible);
// Return whether a view is visible
virtual bool IsVisible() const;
// Return whether a view and its ancestors are visible. Returns true if the
// path from this view to the root view is visible.
virtual bool IsVisibleInRootView() const;
// Set whether this view is enabled. A disabled view does not receive keyboard
// or mouse inputs. If flag differs from the current value, SchedulePaint is
// invoked.
void SetEnabled(bool enabled);
// Returns whether the view is enabled.
virtual bool IsEnabled() const;
// This indicates that the view completely fills its bounds in an opaque
// color. This doesn't affect compositing but is a hint to the compositor to
// optimize painting.
// Note that this method does not implicitly create a layer if one does not
// already exist for the View, but is a no-op in that case.
void SetFillsBoundsOpaquely(bool fills_bounds_opaquely);
// Transformations -----------------------------------------------------------
// Methods for setting transformations for a view (e.g. rotation, scaling).
const ui::Transform& GetTransform() const;
// Clipping parameters. Clipping happens from the right and/or bottom. The
// clipping amount is in parent's coordinate system, as in, if the view is
// rotated, then the clipping will be applied after the rotation (and other
// transformations, if any).
void set_clip_x(float x) { clip_x_ = x; }
void set_clip_y(float y) { clip_y_ = y; }
void set_clip(float x, float y) { clip_x_ = x; clip_y_ = y; }
// Sets the transform to the supplied transform.
void SetTransform(const ui::Transform& transform);
// Sets whether this view paints to a layer. A view paints to a layer if
// either of the following are true:
// . the view has a non-identity transform.
// . SetPaintToLayer(true) has been invoked.
// View creates the Layer only when it exists in a Widget with a non-NULL
// Compositor.
void SetPaintToLayer(bool paint_to_layer);
// Sets the LayerPropertySetter for this view. A value of NULL resets the
// LayerPropertySetter to the default (immediate). Can only be called on a
// View that has a layer().
void SetLayerPropertySetter(LayerPropertySetter* setter);
const ui::Layer* layer() const { return layer_.get(); }
ui::Layer* layer() { return layer_.get(); }
// RTL positioning -----------------------------------------------------------
// Methods for accessing the bounds and position of the view, relative to its
// parent. The position returned is mirrored if the parent view is using a RTL
// layout.
// NOTE: in the vast majority of the cases, the mirroring implementation is
// transparent to the View subclasses and therefore you should use the
// bounds() accessor instead.
gfx::Rect GetMirroredBounds() const;
gfx::Point GetMirroredPosition() const;
int GetMirroredX() const;
// Given a rectangle specified in this View's coordinate system, the function
// computes the 'left' value for the mirrored rectangle within this View. If
// the View's UI layout is not right-to-left, then bounds.x() is returned.
// UI mirroring is transparent to most View subclasses and therefore there is
// no need to call this routine from anywhere within your subclass
// implementation.
int GetMirroredXForRect(const gfx::Rect& rect) const;
// Given the X coordinate of a point inside the View, this function returns
// the mirrored X coordinate of the point if the View's UI layout is
// right-to-left. If the layout is left-to-right, the same X coordinate is
// returned.
// Following are a few examples of the values returned by this function for
// a View with the bounds {0, 0, 100, 100} and a right-to-left layout:
// GetMirroredXCoordinateInView(0) -> 100
// GetMirroredXCoordinateInView(20) -> 80
// GetMirroredXCoordinateInView(99) -> 1
int GetMirroredXInView(int x) const;
// Given a X coordinate and a width inside the View, this function returns
// the mirrored X coordinate if the View's UI layout is right-to-left. If the
// layout is left-to-right, the same X coordinate is returned.
// Following are a few examples of the values returned by this function for
// a View with the bounds {0, 0, 100, 100} and a right-to-left layout:
// GetMirroredXCoordinateInView(0, 10) -> 90
// GetMirroredXCoordinateInView(20, 20) -> 60
int GetMirroredXWithWidthInView(int x, int w) const;
// Layout --------------------------------------------------------------------
// Lay out the child Views (set their bounds based on sizing heuristics
// specific to the current Layout Manager)
virtual void Layout();
// TODO(beng): I think we should remove this.
// Mark this view and all parents to require a relayout. This ensures the
// next call to Layout() will propagate to this view, even if the bounds of
// parent views do not change.
void InvalidateLayout();
// Gets/Sets the Layout Manager used by this view to size and place its
// children.
// The LayoutManager is owned by the View and is deleted when the view is
// deleted, or when a new LayoutManager is installed.
LayoutManager* GetLayoutManager() const;
void SetLayoutManager(LayoutManager* layout);
// Attributes ----------------------------------------------------------------
// The view class name.
static char kViewClassName[];
// Return the receiving view's class name. A view class is a string which
// uniquely identifies the view class. It is intended to be used as a way to
// find out during run time if a view can be safely casted to a specific view
// subclass. The default implementation returns kViewClassName.
virtual std::string GetClassName() const;
// Returns the first ancestor, starting at this, whose class name is |name|.
// Returns null if no ancestor has the class name |name|.
View* GetAncestorWithClassName(const std::string& name);
// Recursively descends the view tree starting at this view, and returns
// the first child that it encounters that has the given ID.
// Returns NULL if no matching child view is found.
virtual const View* GetViewByID(int id) const;
virtual View* GetViewByID(int id);
// Gets and sets the ID for this view. ID should be unique within the subtree
// that you intend to search for it. 0 is the default ID for views.
int id() const { return id_; }
void set_id(int id) { id_ = id; }
// A group id is used to tag views which are part of the same logical group.
// Focus can be moved between views with the same group using the arrow keys.
// Groups are currently used to implement radio button mutual exclusion.
// The group id is immutable once it's set.
void SetGroup(int gid);
// Returns the group id of the view, or -1 if the id is not set yet.
int GetGroup() const;
// If this returns true, the views from the same group can each be focused
// when moving focus with the Tab/Shift-Tab key. If this returns false,
// only the selected view from the group (obtained with
// GetSelectedViewForGroup()) is focused.
virtual bool IsGroupFocusTraversable() const;
// Fills |views| with all the available views which belong to the provided
// |group|.
void GetViewsInGroup(int group, Views* views);
// Returns the View that is currently selected in |group|.
// The default implementation simply returns the first View found for that
// group.
virtual View* GetSelectedViewForGroup(int group);
// Coordinate conversion -----------------------------------------------------
// Note that the utility coordinate conversions functions always operate on
// the mirrored position of the child Views if the parent View uses a
// right-to-left UI layout.
// Convert a point from source coordinate system to dst coordinate system.
// |src| and |dst| needs to be in the same widget, but doesn't need to be in
// the same view hierarchy.
// If |src| and |dst| are not in the same widget, the result is undefined.
// Source can be NULL in which case it means the screen coordinate system
static void ConvertPointToView(const View* src,
const View* dst,
gfx::Point* point);
// Convert a point from the coordinate system of a View to that of the
// Widget. This is useful for example when sizing HWND children of the
// Widget that don't know about the View hierarchy and need to be placed
// relative to the Widget that is their parent.
static void ConvertPointToWidget(const View* src, gfx::Point* point);
// Convert a point from a view Widget to a View dest
static void ConvertPointFromWidget(const View* dest, gfx::Point* p);
// Convert a point from the coordinate system of a View to that of the
// screen. This is useful for example when placing popup windows.
static void ConvertPointToScreen(const View* src, gfx::Point* point);
// Applies transformation on the rectangle, which is in the view's coordinate
// system, to convert it into the parent's coordinate system.
gfx::Rect ConvertRectToParent(const gfx::Rect& rect) const;
// Converts a rectangle from this views coordinate system to its widget
// cooridnate system.
gfx::Rect ConvertRectToWidget(const gfx::Rect& rect) const;
// Painting ------------------------------------------------------------------
// Mark all or part of the View's bounds as dirty (needing repaint).
// |r| is in the View's coordinates.
// Rectangle |r| should be in the view's coordinate system. The
// transformations are applied to it to convert it into the parent coordinate
// system before propagating SchedulePaint up the view hierarchy.
// TODO(beng): Make protected.
virtual void SchedulePaint();
virtual void SchedulePaintInRect(const gfx::Rect& r);
// Called by the framework to paint a View. Performs translation and clipping
// for View coordinates and language direction as required, allows the View
// to paint itself via the various OnPaint*() event handlers and then paints
// the hierarchy beneath it.
virtual void Paint(gfx::Canvas* canvas);
// The background object is owned by this object and may be NULL.
void set_background(Background* b) { background_.reset(b); }
const Background* background() const { return background_.get(); }
Background* background() { return background_.get(); }
// The border object is owned by this object and may be NULL.
void set_border(Border* b) { border_.reset(b); }
const Border* border() const { return border_.get(); }
Border* border() { return border_.get(); }
// Get the theme provider from the parent widget.
virtual ui::ThemeProvider* GetThemeProvider() const;
// RTL painting --------------------------------------------------------------
// This method determines whether the gfx::Canvas object passed to
// View::Paint() needs to be transformed such that anything drawn on the
// canvas object during View::Paint() is flipped horizontally.
// By default, this function returns false (which is the initial value of
// |flip_canvas_on_paint_for_rtl_ui_|). View subclasses that need to paint on
// a flipped gfx::Canvas when the UI layout is right-to-left need to call
// EnableCanvasFlippingForRTLUI().
bool FlipCanvasOnPaintForRTLUI() const {
return flip_canvas_on_paint_for_rtl_ui_ ? base::i18n::IsRTL() : false;
// Enables or disables flipping of the gfx::Canvas during View::Paint().
// Note that if canvas flipping is enabled, the canvas will be flipped only
// if the UI layout is right-to-left; that is, the canvas will be flipped
// only if base::i18n::IsRTL() returns true.
// Enabling canvas flipping is useful for leaf views that draw a bitmap that
// needs to be flipped horizontally when the UI layout is right-to-left
// (views::Button, for example). This method is helpful for such classes
// because their drawing logic stays the same and they can become agnostic to
// the UI directionality.
void EnableCanvasFlippingForRTLUI(bool enable) {
flip_canvas_on_paint_for_rtl_ui_ = enable;
// Accelerated painting ------------------------------------------------------
// Enable/Disable accelerated compositing.
static void set_use_acceleration_when_possible(bool use);
static bool get_use_acceleration_when_possible();
// Input ---------------------------------------------------------------------
// The points (and mouse locations) in the following functions are in the
// view's coordinates, except for a RootView.
// Returns the deepest visible descendant that contains the specified point.
virtual View* GetEventHandlerForPoint(const gfx::Point& point);
// Return the cursor that should be used for this view or the default cursor.
// The event location is in the receiver's coordinate system. The caller is
// responsible for managing the lifetime of the returned object, though that
// lifetime may vary from platform to platform. On Windows, the cursor is a
// shared resource, but Gtk destroys the returned cursor after setting it.
virtual gfx::NativeCursor GetCursor(const MouseEvent& event);
// Convenience to test whether a point is within this view's bounds
virtual bool HitTest(const gfx::Point& l) const;
// This method is invoked when the user clicks on this view.
// The provided event is in the receiver's coordinate system.
// Return true if you processed the event and want to receive subsequent
// MouseDraggged and MouseReleased events. This also stops the event from
// bubbling. If you return false, the event will bubble through parent
// views.
// If you remove yourself from the tree while processing this, event bubbling
// stops as if you returned true, but you will not receive future events.
// The return value is ignored in this case.
// Default implementation returns true if a ContextMenuController has been
// set, false otherwise. Override as needed.
virtual bool OnMousePressed(const MouseEvent& event);
// This method is invoked when the user clicked on this control.
// and is still moving the mouse with a button pressed.
// The provided event is in the receiver's coordinate system.
// Return true if you processed the event and want to receive
// subsequent MouseDragged and MouseReleased events.
// Default implementation returns true if a ContextMenuController has been
// set, false otherwise. Override as needed.
virtual bool OnMouseDragged(const MouseEvent& event);
// This method is invoked when the user releases the mouse
// button. The event is in the receiver's coordinate system.
// Default implementation notifies the ContextMenuController is appropriate.
// Subclasses that wish to honor the ContextMenuController should invoke
// super.
virtual void OnMouseReleased(const MouseEvent& event);
// This method is invoked when the mouse press/drag was canceled by a
// system/user gesture.
virtual void OnMouseCaptureLost();
// This method is invoked when the mouse is above this control
// The event is in the receiver's coordinate system.
// Default implementation does nothing. Override as needed.
virtual void OnMouseMoved(const MouseEvent& event);
// This method is invoked when the mouse enters this control.
// Default implementation does nothing. Override as needed.
virtual void OnMouseEntered(const MouseEvent& event);
// This method is invoked when the mouse exits this control
// The provided event location is always (0, 0)
// Default implementation does nothing. Override as needed.
virtual void OnMouseExited(const MouseEvent& event);
// This method is invoked for each touch event. Default implementation
// does nothing. Override as needed.
virtual ui::TouchStatus OnTouchEvent(const TouchEvent& event);
// Set the MouseHandler for a drag session.
// A drag session is a stream of mouse events starting
// with a MousePressed event, followed by several MouseDragged
// events and finishing with a MouseReleased event.
// This method should be only invoked while processing a
// MouseDragged or MousePressed event.
// All further mouse dragged and mouse up events will be sent
// the MouseHandler, even if it is reparented to another window.
// The MouseHandler is automatically cleared when the control
// comes back from processing the MouseReleased event.
// Note: if the mouse handler is no longer connected to a
// view hierarchy, events won't be sent.
virtual void SetMouseHandler(View* new_mouse_handler);
// Invoked when a key is pressed or released.
// Subclasser should return true if the event has been processed and false
// otherwise. If the event has not been processed, the parent will be given a
// chance.
virtual bool OnKeyPressed(const KeyEvent& event);
virtual bool OnKeyReleased(const KeyEvent& event);
// Invoked when the user uses the mousewheel. Implementors should return true
// if the event has been processed and false otherwise. This message is sent
// if the view is focused. If the event has not been processed, the parent
// will be given a chance.
virtual bool OnMouseWheel(const MouseWheelEvent& event);
// Returns the View's TextInputClient instance or NULL if the View doesn't
// support text input.
virtual TextInputClient* GetTextInputClient();
// Convenience method to retrieve the InputMethod associated with the
// Widget that contains this view. Returns NULL if this view is not part of a
// view hierarchy with a Widget.
virtual InputMethod* GetInputMethod();
// Accelerators --------------------------------------------------------------
// Sets a keyboard accelerator for that view. When the user presses the
// accelerator key combination, the AcceleratorPressed method is invoked.
// Note that you can set multiple accelerators for a view by invoking this
// method several times.
virtual void AddAccelerator(const Accelerator& accelerator);
// Removes the specified accelerator for this view.
virtual void RemoveAccelerator(const Accelerator& accelerator);
// Removes all the keyboard accelerators for this view.
virtual void ResetAccelerators();
// TODO(beng): Move to an AcceleratorTarget override section.
// Called when a keyboard accelerator is pressed.
// Derived classes should implement desired behavior and return true if they
// handled the accelerator.
virtual bool AcceleratorPressed(const Accelerator& accelerator);
// Focus ---------------------------------------------------------------------
// Returns whether this view currently has the focus.
virtual bool HasFocus() const;
// Returns the view that should be selected next when pressing Tab.
View* GetNextFocusableView();
const View* GetNextFocusableView() const;
// Returns the view that should be selected next when pressing Shift-Tab.
View* GetPreviousFocusableView();
// Sets the component that should be selected next when pressing Tab, and
// makes the current view the precedent view of the specified one.
// Note that by default views are linked in the order they have been added to
// their container. Use this method if you want to modify the order.
// IMPORTANT NOTE: loops in the focus hierarchy are not supported.
void SetNextFocusableView(View* view);
// Sets whether this view can accept the focus.
// Note that this is false by default so that a view used as a container does
// not get the focus.
void set_focusable(bool focusable) { focusable_ = focusable; }
// Returns true if the view is focusable (IsFocusable) and visible in the root
// view. See also IsFocusable.
bool IsFocusableInRootView() const;
// Return whether this view is focusable when the user requires full keyboard
// access, even though it may not be normally focusable.
bool IsAccessibilityFocusableInRootView() const;
// Set whether this view can be made focusable if the user requires
// full keyboard access, even though it's not normally focusable.
// Note that this is false by default.
void set_accessibility_focusable(bool accessibility_focusable) {
accessibility_focusable_ = accessibility_focusable;
// Convenience method to retrieve the FocusManager associated with the
// Widget that contains this view. This can return NULL if this view is not
// part of a view hierarchy with a Widget.
virtual FocusManager* GetFocusManager();
virtual const FocusManager* GetFocusManager() const;
// Request the keyboard focus. The receiving view will become the
// focused view.
virtual void RequestFocus();
// Invoked when a view is about to be requested for focus due to the focus
// traversal. Reverse is this request was generated going backward
// (Shift-Tab).
virtual void AboutToRequestFocusFromTabTraversal(bool reverse) { }
// Invoked when a key is pressed before the key event is processed (and
// potentially eaten) by the focus manager for tab traversal, accelerators and
// other focus related actions.
// The default implementation returns false, ensuring that tab traversal and
// accelerators processing is performed.
// Subclasses should return true if they want to process the key event and not
// have it processed as an accelerator (if any) or as a tab traversal (if the
// key event is for the TAB key). In that case, OnKeyPressed will
// subsequently be invoked for that event.
virtual bool SkipDefaultKeyEventProcessing(const KeyEvent& event);
// Subclasses that contain traversable children that are not directly
// accessible through the children hierarchy should return the associated
// FocusTraversable for the focus traversal to work properly.
virtual FocusTraversable* GetFocusTraversable();
// Subclasses that can act as a "pane" must implement their own
// FocusTraversable to keep the focus trapped within the pane.
// If this method returns an object, any view that's a direct or
// indirect child of this view will always use this FocusTraversable
// rather than the one from the widget.
virtual FocusTraversable* GetPaneFocusTraversable();
// Tooltips ------------------------------------------------------------------
// Gets the tooltip for this View. If the View does not have a tooltip,
// return false. If the View does have a tooltip, copy the tooltip into
// the supplied string and return true.
// Any time the tooltip text that a View is displaying changes, it must
// invoke TooltipTextChanged.
// |p| provides the coordinates of the mouse (relative to this view).
virtual bool GetTooltipText(const gfx::Point& p, string16* tooltip) const;
// Returns the location (relative to this View) for the text on the tooltip
// to display. If false is returned (the default), the tooltip is placed at
// a default position.
virtual bool GetTooltipTextOrigin(const gfx::Point& p, gfx::Point* loc) const;
// Context menus -------------------------------------------------------------
// Sets the ContextMenuController. Setting this to non-null makes the View
// process mouse events.
ContextMenuController* context_menu_controller() {
return context_menu_controller_;
void set_context_menu_controller(ContextMenuController* menu_controller) {
context_menu_controller_ = menu_controller;
// Provides default implementation for context menu handling. The default
// implementation calls the ShowContextMenu of the current
// ContextMenuController (if it is not NULL). Overridden in subclassed views
// to provide right-click menu display triggerd by the keyboard (i.e. for the
// Chrome toolbar Back and Forward buttons). No source needs to be specified,
// as it is always equal to the current View.
virtual void ShowContextMenu(const gfx::Point& p,
bool is_mouse_gesture);
// Drag and drop -------------------------------------------------------------
DragController* drag_controller() { return drag_controller_; }
void set_drag_controller(DragController* drag_controller) {
drag_controller_ = drag_controller;
// During a drag and drop session when the mouse moves the view under the
// mouse is queried for the drop types it supports by way of the
// GetDropFormats methods. If the view returns true and the drag site can
// provide data in one of the formats, the view is asked if the drop data
// is required before any other drop events are sent. Once the
// data is available the view is asked if it supports the drop (by way of
// the CanDrop method). If a view returns true from CanDrop,
// OnDragEntered is sent to the view when the mouse first enters the view,
// as the mouse moves around within the view OnDragUpdated is invoked.
// If the user releases the mouse over the view and OnDragUpdated returns a
// valid drop, then OnPerformDrop is invoked. If the mouse moves outside the
// view or over another view that wants the drag, OnDragExited is invoked.
// Similar to mouse events, the deepest view under the mouse is first checked
// if it supports the drop (Drop). If the deepest view under
// the mouse does not support the drop, the ancestors are walked until one
// is found that supports the drop.
// Override and return the set of formats that can be dropped on this view.
// |formats| is a bitmask of the formats defined bye OSExchangeData::Format.
// The default implementation returns false, which means the view doesn't
// support dropping.
virtual bool GetDropFormats(
int* formats,
std::set<OSExchangeData::CustomFormat>* custom_formats);
// Override and return true if the data must be available before any drop
// methods should be invoked. The default is false.
virtual bool AreDropTypesRequired();
// A view that supports drag and drop must override this and return true if
// data contains a type that may be dropped on this view.
virtual bool CanDrop(const OSExchangeData& data);
// OnDragEntered is invoked when the mouse enters this view during a drag and
// drop session and CanDrop returns true. This is immediately
// followed by an invocation of OnDragUpdated, and eventually one of
// OnDragExited or OnPerformDrop.
virtual void OnDragEntered(const DropTargetEvent& event);
// Invoked during a drag and drop session while the mouse is over the view.
// This should return a bitmask of the DragDropTypes::DragOperation supported
// based on the location of the event. Return 0 to indicate the drop should
// not be accepted.
virtual int OnDragUpdated(const DropTargetEvent& event);
// Invoked during a drag and drop session when the mouse exits the views, or
// when the drag session was canceled and the mouse was over the view.
virtual void OnDragExited();
// Invoked during a drag and drop session when OnDragUpdated returns a valid
// operation and the user release the mouse.
virtual int OnPerformDrop(const DropTargetEvent& event);
// Invoked from DoDrag after the drag completes. This implementation does
// nothing, and is intended for subclasses to do cleanup.
virtual void OnDragDone();
// Returns true if the mouse was dragged enough to start a drag operation.
// delta_x and y are the distance the mouse was dragged.
static bool ExceededDragThreshold(int delta_x, int delta_y);
// Accessibility -------------------------------------------------------------
// Modifies |state| to reflect the current accessible state of this view.
virtual void GetAccessibleState(ui::AccessibleViewState* state) { }
// Returns an instance of the native accessibility interface for this view.
virtual gfx::NativeViewAccessible GetNativeViewAccessible();
// Scrolling -----------------------------------------------------------------
// TODO(beng): Figure out if this can live somewhere other than View, i.e.
// closer to ScrollView.
// Scrolls the specified region, in this View's coordinate system, to be
// visible. View's implementation passes the call onto the parent View (after
// adjusting the coordinates). It is up to views that only show a portion of
// the child view, such as Viewport, to override appropriately.
virtual void ScrollRectToVisible(const gfx::Rect& rect);
// The following methods are used by ScrollView to determine the amount
// to scroll relative to the visible bounds of the view. For example, a
// return value of 10 indicates the scrollview should scroll 10 pixels in
// the appropriate direction.
// Each method takes the following parameters:
// is_horizontal: if true, scrolling is along the horizontal axis, otherwise
// the vertical axis.
// is_positive: if true, scrolling is by a positive amount. Along the
// vertical axis scrolling by a positive amount equates to
// scrolling down.
// The return value should always be positive and gives the number of pixels
// to scroll. ScrollView interprets a return value of 0 (or negative)
// to scroll by a default amount.
// See VariableRowHeightScrollHelper and FixedRowHeightScrollHelper for
// implementations of common cases.
virtual int GetPageScrollIncrement(ScrollView* scroll_view,
bool is_horizontal, bool is_positive);
virtual int GetLineScrollIncrement(ScrollView* scroll_view,
bool is_horizontal, bool is_positive);
// Size and disposition ------------------------------------------------------
// Override to be notified when the bounds of the view have changed.
virtual void OnBoundsChanged(const gfx::Rect& previous_bounds);
// Called when the preferred size of a child view changed. This gives the
// parent an opportunity to do a fresh layout if that makes sense.
virtual void ChildPreferredSizeChanged(View* child) {}
// Invalidates the layout and calls ChildPreferredSizeChanged on the parent
// if there is one. Be sure to call View::PreferredSizeChanged when
// overriding such that the layout is properly invalidated.
virtual void PreferredSizeChanged();
// Override returning true when the view needs to be notified when its visible
// bounds relative to the root view may have changed. Only used by
// NativeViewHost.
virtual bool NeedsNotificationWhenVisibleBoundsChange() const;
// Notification that this View's visible bounds relative to the root view may
// have changed. The visible bounds are the region of the View not clipped by
// its ancestors. This is used for clipping NativeViewHost.
virtual void OnVisibleBoundsChanged();
// Override to be notified when the enabled state of this View has
// changed. The default implementation calls SchedulePaint() on this View.
virtual void OnEnabledChanged();
// Tree operations -----------------------------------------------------------
// This method is invoked when the tree changes.
// When a view is removed, it is invoked for all children and grand
// children. For each of these views, a notification is sent to the
// view and all parents.
// When a view is added, a notification is sent to the view, all its
// parents, and all its children (and grand children)
// Default implementation does nothing. Override to perform operations
// required when a view is added or removed from a view hierarchy
// parent is the new or old parent. Child is the view being added or
// removed.
virtual void ViewHierarchyChanged(bool is_add, View* parent, View* child);
// When SetVisible() changes the visibility of a view, this method is
// invoked for that view as well as all the children recursively.
virtual void VisibilityChanged(View* starting_from, bool is_visible);
// Called when the native view hierarchy changed.
// |attached| is true if that view has been attached to a new NativeView
// hierarchy, false if it has been detached.
// |native_view| is the NativeView this view was attached/detached from, and
// |root_view| is the root view associated with the NativeView.
// Views created without a native view parent don't have a focus manager.
// When this function is called they could do the processing that requires
// it - like registering accelerators, for example.
virtual void NativeViewHierarchyChanged(bool attached,
gfx::NativeView native_view,
internal::RootView* root_view);
// Painting ------------------------------------------------------------------
// Responsible for calling Paint() on child Views. Override to control the
// order child Views are painted.
virtual void PaintChildren(gfx::Canvas* canvas);
// Override to provide rendering in any part of the View's bounds. Typically
// this is the "contents" of the view. If you override this method you will
// have to call the subsequent OnPaint*() methods manually.
virtual void OnPaint(gfx::Canvas* canvas);
// Override to paint a background before any content is drawn. Typically this
// is done if you are satisfied with a default OnPaint handler but wish to
// supply a different background.
virtual void OnPaintBackground(gfx::Canvas* canvas);
// Override to paint a border not specified by SetBorder().
virtual void OnPaintBorder(gfx::Canvas* canvas);
// Override to paint a focus border (usually a dotted rectangle) around
// relevant contents.
virtual void OnPaintFocusBorder(gfx::Canvas* canvas);
// Accelerated painting ------------------------------------------------------
// This creates a layer for the view, if one does not exist. It then
// passes the texture to a layer associated with the view. While an external
// texture is set, the view will not update the layer contents.
// |texture| cannot be NULL.
// Returns false if it cannot create a layer to which to assign the texture.
bool SetExternalTexture(ui::Texture* texture);
// Returns the offset from this view to the nearest ancestor with a layer.
// If |ancestor| is non-NULL it is set to the nearest ancestor with a layer.
virtual void CalculateOffsetToAncestorWithLayer(
gfx::Point* offset,
ui::Layer** layer_parent);
// If this view has a layer, the layer is reparented to |parent_layer| and its
// bounds is set based on |point|. If this view does not have a layer, then
// recurses through all children. This is used when adding a layer to an
// existing view to make sure all descendants that have layers are parented to
// the right layer.
virtual void MoveLayerToParent(ui::Layer* parent_layer,
const gfx::Point& point);
// Called to update the bounds of any child layers within this View's
// hierarchy when something happens to the hierarchy.
virtual void UpdateChildLayerBounds(const gfx::Point& offset);
// Overridden from ui::LayerDelegate:
virtual void OnPaintLayer(gfx::Canvas* canvas) OVERRIDE;
virtual void OnLayerAnimationEnded(const ui::Animation* animation) OVERRIDE;
// Finds the layer that this view paints to (it may belong to an ancestor
// view), then reorders the immediate children of that layer to match the
// order of the view tree.
virtual void ReorderLayers();
// This reorders the immediate children of |*parent_layer| to match the
// order of the view tree.
virtual void ReorderChildLayers(ui::Layer* parent_layer);
// Input ---------------------------------------------------------------------
// Called by HitTest to see if this View has a custom hit test mask. If the
// return value is true, GetHitTestMask will be called to obtain the mask.
// Default value is false, in which case the View will hit-test against its
// bounds.
virtual bool HasHitTestMask() const;
// Called by HitTest to retrieve a mask for hit-testing against. Subclasses
// override to provide custom shaped hit test regions.
virtual void GetHitTestMask(gfx::Path* mask) const;
// Focus ---------------------------------------------------------------------
// Returns whether this view can accept focus.
// A view can accept focus if it's enabled, focusable and visible.
// This method is intended for views to use when calculating preferred size.
// The FocusManager and other places use IsFocusableInRootView.
virtual bool IsFocusable() const;
// Override to be notified when focus has changed either to or from this View.
virtual void OnFocus();
virtual void OnBlur();
// Handle view focus/blur events for this view.
void Focus();
void Blur();
// System events -------------------------------------------------------------
// Called when the UI theme has changed, overriding allows individual Views to
// do special cleanup and processing (such as dropping resource caches).
// To dispatch a theme changed notification, call Widget::ThemeChanged().
virtual void OnThemeChanged() {}
// Called when the locale has changed, overriding allows individual Views to
// update locale-dependent strings.
// To dispatch a locale changed notification, call Widget::LocaleChanged().
virtual void OnLocaleChanged() {}
// Tooltips ------------------------------------------------------------------
// Views must invoke this when the tooltip text they are to display changes.
void TooltipTextChanged();
// Context menus -------------------------------------------------------------
// Returns the location, in screen coordinates, to show the context menu at
// when the context menu is shown from the keyboard. This implementation
// returns the middle of the visible region of this view.
// This method is invoked when the context menu is shown by way of the
// keyboard.
virtual gfx::Point GetKeyboardContextMenuLocation();
// Drag and drop -------------------------------------------------------------
// These are cover methods that invoke the method of the same name on
// the DragController. Subclasses may wish to override rather than install
// a DragController.
// See DragController for a description of these methods.
virtual int GetDragOperations(const gfx::Point& press_pt);
virtual void WriteDragData(const gfx::Point& press_pt, OSExchangeData* data);
// Returns whether we're in the middle of a drag session that was initiated
// by us.
bool InDrag();
// Returns how much the mouse needs to move in one direction to start a
// drag. These methods cache in a platform-appropriate way. These values are
// used by the public static method ExceededDragThreshold().
static int GetHorizontalDragThreshold();
static int GetVerticalDragThreshold();
// Debugging -----------------------------------------------------------------
#if !defined(NDEBUG)
// Returns string containing a graph of the views hierarchy in graphViz DOT
// language ( Can be called within debugger and save
// to a file to compile/view.
// Note: Assumes initial call made with first = true.
virtual std::string PrintViewGraph(bool first);
// Some classes may own an object which contains the children to displayed in
// the views hierarchy. The above function gives the class the flexibility to
// decide which object should be used to obtain the children, but this
// function makes the decision explicit.
std::string DoPrintViewGraph(bool first, View* view_with_children);
friend class internal::NativeWidgetView;
friend class internal::RootView;
friend class FocusManager;
friend class ViewStorage;
friend class Widget;
friend class PaintLock;
// Used to track a drag. RootView passes this into
// ProcessMousePressed/Dragged.
struct DragInfo {
// Sets possible_drag to false and start_x/y to 0. This is invoked by
// RootView prior to invoke ProcessMousePressed.
void Reset();
// Sets possible_drag to true and start_pt to the specified point.
// This is invoked by the target view if it detects the press may generate
// a drag.
void PossibleDrag(const gfx::Point& p);
// Whether the press may generate a drag.
bool possible_drag;
// Coordinates of the mouse press.
gfx::Point start_pt;
// Painting -----------------------------------------------------------------
enum SchedulePaintType {
// Indicates the size is the same (only the origin changed).
// Indicates the size changed (and possibly the origin).
// Invoked before and after the bounds change to schedule painting the old and
// new bounds.
void SchedulePaintBoundsChanged(SchedulePaintType type);
// Common Paint() code shared by accelerated and non-accelerated code paths to
// invoke OnPaint() on the View.
void PaintCommon(gfx::Canvas* canvas);
// Tree operations -----------------------------------------------------------
// Removes |view| from the hierarchy tree. If |update_focus_cycle| is true,
// the next and previous focusable views of views pointing to this view are
// updated. If |update_tool_tip| is true, the tooltip is updated. If
// |delete_removed_view| is true, the view is also deleted (if it is parent
// owned).
void DoRemoveChildView(View* view,
bool update_focus_cycle,
bool update_tool_tip,
bool delete_removed_view);
// Call ViewHierarchyChanged for all child views on all parents
void PropagateRemoveNotifications(View* parent);
// Call ViewHierarchyChanged for all children
void PropagateAddNotifications(View* parent, View* child);
// Propagates NativeViewHierarchyChanged() notification through all the
// children.
void PropagateNativeViewHierarchyChanged(bool attached,
gfx::NativeView native_view,
internal::RootView* root_view);
// Takes care of registering/unregistering accelerators if
// |register_accelerators| true and calls ViewHierarchyChanged().
void ViewHierarchyChangedImpl(bool register_accelerators,
bool is_add,
View* parent,
View* child);
// Size and disposition ------------------------------------------------------
// Call VisibilityChanged() recursively for all children.
void PropagateVisibilityNotifications(View* from, bool is_visible);
// Registers/unregisters accelerators as necessary and calls
// VisibilityChanged().
void VisibilityChangedImpl(View* starting_from, bool is_visible);
// Responsible for propagating bounds change notifications to relevant
// views.
void BoundsChanged(const gfx::Rect& previous_bounds);
// Visible bounds notification registration.
// When a view is added to a hierarchy, it and all its children are asked if
// they need to be registered for "visible bounds within root" notifications
// (see comment on OnVisibleBoundsChanged()). If they do, they are registered
// with every ancestor between them and the root of the hierarchy.
static void RegisterChildrenForVisibleBoundsNotification(View* view);
static void UnregisterChildrenForVisibleBoundsNotification(View* view);
void RegisterForVisibleBoundsNotification();
void UnregisterForVisibleBoundsNotification();
// Adds/removes view to the list of descendants that are notified any time
// this views location and possibly size are changed.
void AddDescendantToNotify(View* view);
void RemoveDescendantToNotify(View* view);
// Transformations -----------------------------------------------------------
// Returns in |transform| the transform to get from coordinates of |ancestor|
// to this. Returns true if |ancestor| is found. If |ancestor| is not found,
// or NULL, |transform| is set to convert from root view coordinates to this.
bool GetTransformRelativeTo(const View* ancestor,
ui::Transform* transform) const;
// Coordinate conversion -----------------------------------------------------
// This is the actual implementation for ConvertPointToView()
// Attempts a parent -> child conversion and then a
// child -> parent conversion if try_other_direction is true
// Applies necessary transformations during the conversion.
static void ConvertPointToView(const View* src,
const View* dst,
gfx::Point* point,
bool try_other_direction);
// Convert a point in the view's coordinate to an ancestor view's coordinate
// system using necessary transformations. Returns whether the point was
// successfully converted to the ancestor's coordinate system.
bool ConvertPointForAncestor(const View* ancestor, gfx::Point* point) const;
// Convert a point in the ancestor's coordinate system to the view's
// coordinate system using necessary transformations. Returns whether the
// point was successfully from the ancestor's coordinate system to the view's
// coordinate system.
bool ConvertPointFromAncestor(const View* ancestor, gfx::Point* point) const;
// Accelerated painting ------------------------------------------------------
// Disables painting during time critical operations. Used by PaintLock.
// TODO(vollick) Ideally, the widget would not dispatch paints into the
// hierarchy during time critical operations and this would not be needed.
void set_painting_enabled(bool enabled) { painting_enabled_ = enabled; }
// Creates the layer and related fields for this view.
void CreateLayer();
// Parents all un-parented layers within this view's hierarchy to this view's
// layer.
void UpdateParentLayers();
// Updates the view's layer's parent. Called when a view is added to a view
// hierarchy, responsible for parenting the view's layer to the enclosing
// layer in the hierarchy.
void UpdateParentLayer();
// Parents this view's layer to |parent_layer|, and sets its bounds and other
// properties in accordance to |offset|, the view's offset from the
// |parent_layer|.
void ReparentLayer(const gfx::Point& offset, ui::Layer* parent_layer);
// Called to update the layer visibility. The layer will be visible if the
// View itself, and all its parent Views are visible. This also updates
// visibility of the child layers.
void UpdateLayerVisibility();
void UpdateChildLayerVisibility(bool visible);
// Orphans the layers in this subtree that are parented to layers outside of
// this subtree.
void OrphanLayers();
// Destroys the layer associated with this view, and reparents any descendants
// to the destroyed layer's parent.
void DestroyLayer();
// Input ---------------------------------------------------------------------
// RootView invokes these. These in turn invoke the appropriate OnMouseXXX
// method. If a drag is detected, DoDrag is invoked.
bool ProcessMousePressed(const MouseEvent& event, DragInfo* drop_info);
bool ProcessMouseDragged(const MouseEvent& event, DragInfo* drop_info);
void ProcessMouseReleased(const MouseEvent& event);
// RootView will invoke this with incoming TouchEvents. Returns the
// the result of OnTouchEvent.
ui::TouchStatus ProcessTouchEvent(const TouchEvent& event);
// Accelerators --------------------------------------------------------------
// Registers this view's keyboard accelerators that are not registered to
// FocusManager yet, if possible.
void RegisterPendingAccelerators();
// Unregisters all the keyboard accelerators associated with this view.
// |leave_data_intact| if true does not remove data from accelerators_ array,
// so it could be re-registered with other focus manager
void UnregisterAccelerators(bool leave_data_intact);
// Focus ---------------------------------------------------------------------
// Initialize the previous/next focusable views of the specified view relative
// to the view at the specified index.
void InitFocusSiblings(View* view, int index);
// System events -------------------------------------------------------------
// Used to propagate theme changed notifications from the root view to all
// views in the hierarchy.
virtual void PropagateThemeChanged();
// Used to propagate locale changed notifications from the root view to all
// views in the hierarchy.
virtual void PropagateLocaleChanged();
// Tooltips ------------------------------------------------------------------
// Propagates UpdateTooltip() to the TooltipManager for the Widget.
// This must be invoked any time the View hierarchy changes in such a way
// the view under the mouse differs. For example, if the bounds of a View is
// changed, this is invoked. Similarly, as Views are added/removed, this
// is invoked.
void UpdateTooltip();
// Drag and drop -------------------------------------------------------------
// Starts a drag and drop operation originating from this view. This invokes
// WriteDragData to write the data and GetDragOperations to determine the
// supported drag operations. When done, OnDragDone is invoked.
void DoDrag(const MouseEvent& event, const gfx::Point& press_pt);
// Creation and lifetime -----------------------------------------------------
// True if the hierarchy (i.e. the parent View) is responsible for deleting
// this View. Default is true.
bool parent_owned_;
// Attributes ----------------------------------------------------------------
// The id of this View. Used to find this View.
int id_;
// The group of this view. Some view subclasses use this id to find other
// views of the same group. For example radio button uses this information
// to find other radio buttons.
int group_;
// Tree operations -----------------------------------------------------------
// This view's parent.
View* parent_;
// This view's children.
Views children_;
// Size and disposition ------------------------------------------------------
// This View's bounds in the parent coordinate system.
gfx::Rect bounds_;
// Whether this view is visible.
bool visible_;
// Whether this view is enabled.
bool enabled_;
// Whether this view is painting.
bool painting_enabled_;
// Whether or not RegisterViewForVisibleBoundsNotification on the RootView
// has been invoked.
bool registered_for_visible_bounds_notification_;
// List of descendants wanting notification when their visible bounds change.
scoped_ptr<Views> descendants_to_notify_;
// Transformations -----------------------------------------------------------
// Clipping parameters. skia transformation matrix does not give us clipping.
// So we do it ourselves.
float clip_x_;
float clip_y_;
// Layout --------------------------------------------------------------------
// Whether the view needs to be laid out.
bool needs_layout_;
// The View's LayoutManager defines the sizing heuristics applied to child
// Views. The default is absolute positioning according to bounds_.
scoped_ptr<LayoutManager> layout_manager_;
// Painting ------------------------------------------------------------------
// Background
scoped_ptr<Background> background_;
// Border.
scoped_ptr<Border> border_;
// RTL painting --------------------------------------------------------------
// Indicates whether or not the gfx::Canvas object passed to View::Paint()
// is going to be flipped horizontally (using the appropriate transform) on
// right-to-left locales for this View.
bool flip_canvas_on_paint_for_rtl_ui_;
// Accelerated painting ------------------------------------------------------
bool paint_to_layer_;
scoped_ptr<ui::Layer> layer_;
scoped_ptr<LayerPropertySetter> layer_property_setter_;
// Accelerators --------------------------------------------------------------
// true if when we were added to hierarchy we were without focus manager
// attempt addition when ancestor chain changed.
bool accelerator_registration_delayed_;
// Focus manager accelerators registered on.
FocusManager* accelerator_focus_manager_;
// The list of accelerators. List elements in the range
// [0, registered_accelerator_count_) are already registered to FocusManager,
// and the rest are not yet.
scoped_ptr<std::vector<Accelerator> > accelerators_;
size_t registered_accelerator_count_;
// Focus ---------------------------------------------------------------------
// Next view to be focused when the Tab key is pressed.
View* next_focusable_view_;
// Next view to be focused when the Shift-Tab key combination is pressed.
View* previous_focusable_view_;
// Whether this view can be focused.
bool focusable_;
// Whether this view is focusable if the user requires full keyboard access,
// even though it may not be normally focusable.
bool accessibility_focusable_;
// Context menus -------------------------------------------------------------
// The menu controller.
ContextMenuController* context_menu_controller_;
// Drag and drop -------------------------------------------------------------
DragController* drag_controller_;
// Accessibility -------------------------------------------------------------
// The Windows-specific accessibility implementation for this view.
#if defined(OS_WIN)
scoped_refptr<NativeViewAccessibilityWin> native_view_accessibility_win_;
} // namespace views
#endif // VIEWS_VIEW_H_