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// Copyright 2013 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.
#include <list>
#include <map>
#include <memory>
#include <set>
#include "base/macros.h"
#include "base/optional.h"
#include "base/strings/string16.h"
#include "third_party/skia/include/core/SkColor.h"
#include "ui/gfx/font_list.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/range/range.h"
#include "ui/gfx/text_constants.h"
#include "ui/views/controls/link_listener.h"
#include "ui/views/style/typography.h"
#include "ui/views/view.h"
namespace views {
class Link;
class StyledLabelListener;
// A class which can apply mixed styles to a block of text. Currently, text is
// always multiline. Trailing whitespace in the styled label text is not
// supported and will be trimmed on StyledLabel construction. Leading
// whitespace is respected, provided not only whitespace fits in the first line.
// In this case, leading whitespace is ignored.
class VIEWS_EXPORT StyledLabel : public View, public LinkListener {
// Internal class name.
static const char kViewClassName[];
// TestApi is used for tests to get internal implementation details.
class VIEWS_EXPORT TestApi {
explicit TestApi(StyledLabel* view);
const std::map<View*, gfx::Range>& link_targets();
StyledLabel* const view_;
// Parameters that define label style for a styled label's text range.
struct VIEWS_EXPORT RangeStyleInfo {
RangeStyleInfo(const RangeStyleInfo& copy);
// Creates a range style info with default values for link.
static RangeStyleInfo CreateForLink();
bool IsLink() const;
// Allows full customization of the font used in the range. Ignores the
// StyledLabel's default text context and |text_style|.
base::Optional<gfx::FontList> custom_font;
// The style::TextStyle for this range.
base::Optional<int> text_style;
// Overrides the text color given by |text_style| for this range. Default is
// SK_ColorTRANSPARENT, indicating not to override.
// DEPRECATED: Use TextStyle.
SkColor override_color = SK_ColorTRANSPARENT;
// Tooltip for the range.
base::string16 tooltip;
// If set, the whole range will be put on a single line.
bool disable_line_wrapping = false;
// A custom view shown instead of the underlying text. Ownership of custom
// views must be passed to StyledLabel via AddCustomView().
View* custom_view = nullptr;
// Note that any trailing whitespace in |text| will be trimmed.
StyledLabel(const base::string16& text, StyledLabelListener* listener);
~StyledLabel() override;
// Sets the text to be displayed, and clears any previous styling.
void SetText(const base::string16& text);
const base::string16& text() const { return text_; }
// Returns the font list that results from the default text context and style
// for ranges. This can be used as the basis for a range |custom_font|.
gfx::FontList GetDefaultFontList() const;
// Marks the given range within |text_| with style defined by |style_info|.
// |range| must be contained in |text_|.
void AddStyleRange(const gfx::Range& range, const RangeStyleInfo& style_info);
// Passes ownership of a custom view for use by RangeStyleInfo structs.
void AddCustomView(std::unique_ptr<View> custom_view);
// Set the context of this text. All ranges have the same context.
// |text_context| must be a value from views::style::TextContext.
void SetTextContext(int text_context);
// Set the default text style.
// |text_style| must be a value from views::style::TextStyle.
void SetDefaultTextStyle(int text_style);
// Get or set the distance in pixels between baselines of multi-line text.
// Default is 0, indicating the distance between lines should be the standard
// one for the label's text, font list, and platform.
void SetLineHeight(int height);
// Sets the color of the background on which the label is drawn. This won't
// be explicitly drawn, but the label will force the text color to be
// readable over it.
void SetDisplayedOnBackgroundColor(SkColor color);
SkColor displayed_on_background_color() const {
return displayed_on_background_color_;
void set_auto_color_readability_enabled(bool auto_color_readability) {
auto_color_readability_enabled_ = auto_color_readability;
// Resizes the label so its width is set to the width of the longest line and
// its height deduced accordingly.
// This is only intended for multi-line labels and is useful when the label's
// text contains several lines separated with \n.
// |max_width| is the maximum width that will be used (longer lines will be
// wrapped). If 0, no maximum width is enforced.
void SizeToFit(int max_width);
// View:
const char* GetClassName() const override;
void GetAccessibleNodeData(ui::AXNodeData* node_data) override;
gfx::Size CalculatePreferredSize() const override;
int GetHeightForWidth(int w) const override;
void Layout() override;
void PreferredSizeChanged() override;
// LinkListener implementation:
void LinkClicked(Link* source, int event_flags) override;
// Sets the horizontal alignment; the argument value is mirrored in RTL UI.
void SetHorizontalAlignment(gfx::HorizontalAlignment alignment);
// Clears all the styles applied to the label.
void ClearStyleRanges();
struct StyleRange {
StyleRange(const gfx::Range& range,
const RangeStyleInfo& style_info)
: range(range),
style_info(style_info) {
~StyleRange() {}
bool operator<(const StyleRange& other) const;
gfx::Range range;
RangeStyleInfo style_info;
typedef std::list<StyleRange> StyleRanges;
// Returns the default line height, based on the default style.
int GetDefaultLineHeight() const;
// Returns the FontList that should be used for |range|.
gfx::FontList GetFontListForRange(
const StyleRanges::const_iterator& range) const;
// Calculates how to layout child views, creates them and sets their size and
// position. |width| is the horizontal space, in pixels, that the view has to
// work with. If |dry_run| is true, the view hierarchy is not touched. Caches
// the results in |calculated_size_|, |width_at_last_layout_|, and
// |width_at_last_size_calculation_|. Returns the needed size.
gfx::Size CalculateAndDoLayout(int width, bool dry_run);
// Adjusts the offsets of the views in a line for alignment and other line
// parameters.
void AdvanceOneLine(int* line_number,
gfx::Point* offset,
int* max_line_height,
int width,
std::vector<View*>* views_in_a_line,
bool new_line = true);
// The text to display.
base::string16 text_;
int text_context_ = style::CONTEXT_LABEL;
int default_text_style_ = style::STYLE_PRIMARY;
// Line height. If zero, style::GetLineHeight() is used.
int specified_line_height_;
// The listener that will be informed of link clicks.
StyledLabelListener* listener_;
// The ranges that should be linkified, sorted by start position.
StyleRanges style_ranges_;
// A mapping from a view to the range it corresponds to in |text_|. Only views
// that correspond to ranges with is_link style set will be added to the map.
std::map<View*, gfx::Range> link_targets_;
// Owns the custom views used to replace ranges of text with icons, etc.
std::set<std::unique_ptr<View>> custom_views_;
// This variable saves the result of the last GetHeightForWidth call in order
// to avoid repeated calculation.
mutable gfx::Size calculated_size_;
mutable int width_at_last_size_calculation_;
int width_at_last_layout_;
// Background color on which the label is drawn, for auto color readability.
SkColor displayed_on_background_color_;
bool displayed_on_background_color_set_;
// Controls whether the text is automatically re-colored to be readable on the
// background.
bool auto_color_readability_enabled_;
// The horizontal alignment. This value is flipped for RTL. The default
// behavior is to align left in LTR UI and right in RTL UI.
gfx::HorizontalAlignment horizontal_alignment_ = gfx::ALIGN_LEFT;
} // namespace views