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// Copyright (c) 2012 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 <memory>
#include "base/macros.h"
#include "ui/compositor/layer.h"
#include "ui/compositor/layer_delegate.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/image/image_skia.h"
#include "ui/wm/wm_export.h"
namespace gfx {
class Image;
} // namespace gfx
namespace wm {
// An ImageGrid is a 3x3 array of ui::Layers, each containing an image.
// As the grid is resized, its images fill the requested space:
// - corner images are not scaled
// - top and bottom images are scaled horizontally
// - left and right images are scaled vertically
// - the center image is scaled in both directions
// If one of the non-center images is smaller than the largest images in its
// row or column, it will be aligned with the outside of the grid. For
// example, given 4x4 top-left and top-right images and a 1x2 top images:
// +--------+---------------------+--------+
// | | top | |
// | top- +---------------------+ top- +
// | left | | right |
// +----+---+ +---+----+
// | | | |
// ...
// This may seem odd at first, but it lets ImageGrid be used to draw shadows
// with curved corners that extend inwards beyond a window's borders. In the
// below example, the top-left corner image is overlaid on top of the window's
// top-left corner:
// +---------+-----------------------
// | .xXX | ^ window's top edge
// | .xXX |
// +---------+
// | xXX|
// | xXX|< window's left edge
// | xXX|
// ...
class WM_EXPORT ImageGrid {
// Helper class for use by tests.
class WM_EXPORT TestAPI {
explicit TestAPI(ImageGrid* grid) : grid_(grid) {}
gfx::Rect top_left_clip_rect() const {
return grid_->top_left_painter_->clip_rect_;
gfx::Rect top_right_clip_rect() const {
return grid_->top_right_painter_->clip_rect_;
gfx::Rect bottom_left_clip_rect() const {
return grid_->bottom_left_painter_->clip_rect_;
gfx::Rect bottom_right_clip_rect() const {
return grid_->bottom_right_painter_->clip_rect_;
// Returns |layer|'s bounds after applying the layer's current transform.
gfx::RectF GetTransformedLayerBounds(const ui::Layer& layer);
ImageGrid* grid_; // not owned
ui::Layer* layer() { return layer_.get(); }
int top_image_height() const { return top_image_height_; }
int bottom_image_height() const { return bottom_image_height_; }
int left_image_width() const { return left_image_width_; }
int right_image_width() const { return right_image_width_; }
// Visible to allow independent layer animations and for testing.
ui::Layer* top_left_layer() const { return top_left_layer_.get(); }
ui::Layer* top_layer() const { return top_layer_.get(); }
ui::Layer* top_right_layer() const { return top_right_layer_.get(); }
ui::Layer* left_layer() const { return left_layer_.get(); }
ui::Layer* center_layer() const { return center_layer_.get(); }
ui::Layer* right_layer() const { return right_layer_.get(); }
ui::Layer* bottom_left_layer() const { return bottom_left_layer_.get(); }
ui::Layer* bottom_layer() const { return bottom_layer_.get(); }
ui::Layer* bottom_right_layer() const { return bottom_right_layer_.get(); }
// Sets the grid to display the passed-in images (any of which can be NULL).
// Ownership of the images remains with the caller. May be called more than
// once to switch images.
void SetImages(const gfx::Image* top_left_image,
const gfx::Image* top_image,
const gfx::Image* top_right_image,
const gfx::Image* left_image,
const gfx::Image* center_image,
const gfx::Image* right_image,
const gfx::Image* bottom_left_image,
const gfx::Image* bottom_image,
const gfx::Image* bottom_right_image);
void SetSize(const gfx::Size& size);
// Sets the grid to a position and size such that the inner edges of the top,
// bottom, left and right images will be flush with |content_bounds_in_dip|.
void SetContentBounds(const gfx::Rect& content_bounds_in_dip);
// Delegate responsible for painting a specific image on a layer.
class ImagePainter : public ui::LayerDelegate {
explicit ImagePainter(const gfx::ImageSkia& image) : image_(image) {}
~ImagePainter() override {}
// Clips |layer| to |clip_rect|. Triggers a repaint if the clipping
// rectangle has changed. An empty rectangle disables clipping.
void SetClipRect(const gfx::Rect& clip_rect, ui::Layer* layer);
// ui::LayerDelegate implementation:
void OnPaintLayer(const ui::PaintContext& context) override;
void OnDelegatedFrameDamage(const gfx::Rect& damage_rect_in_dip) override;
void OnDeviceScaleFactorChanged(float device_scale_factor) override;
base::Closure PrepareForLayerBoundsChange() override;
friend class TestAPI;
const gfx::ImageSkia image_;
gfx::Rect clip_rect_;
enum ImageType {
// Sets |layer_ptr| and |painter_ptr| to display |image| and adds the
// passed-in layer to |layer_|. If image is NULL resets |layer_ptr| and
// |painter_ptr| and removes any existing layer from |layer_|.
// If |type| is either HORIZONTAL or VERTICAL, it may resize the image to
// guarantee that it has minimum size in order for scaling work properly
// with fractional device scale factors.
void SetImage(const gfx::Image* image,
std::unique_ptr<ui::Layer>* layer_ptr,
std::unique_ptr<ImagePainter>* painter_ptr,
ImageType type);
// Layer that contains all of the image layers.
std::unique_ptr<ui::Layer> layer_;
// The grid's dimensions.
gfx::Size size_;
// Heights and widths of the images displayed by |top_layer_|,
// |bottom_layer_|, |left_layer_|, and |right_layer_|.
int top_image_height_;
int bottom_image_height_;
int left_image_width_;
int right_image_width_;
// Heights of the tallest images in the top and bottom rows and the widest
// images in the left and right columns. Note that we may have less actual
// space than this available if the images are large and |size_| is small.
int base_top_row_height_;
int base_bottom_row_height_;
int base_left_column_width_;
int base_right_column_width_;
// Layers used to display the various images. Children of |layer_|.
// Positions for which no images were supplied are NULL.
std::unique_ptr<ui::Layer> top_left_layer_;
std::unique_ptr<ui::Layer> top_layer_;
std::unique_ptr<ui::Layer> top_right_layer_;
std::unique_ptr<ui::Layer> left_layer_;
std::unique_ptr<ui::Layer> center_layer_;
std::unique_ptr<ui::Layer> right_layer_;
std::unique_ptr<ui::Layer> bottom_left_layer_;
std::unique_ptr<ui::Layer> bottom_layer_;
std::unique_ptr<ui::Layer> bottom_right_layer_;
// Delegates responsible for painting the above layers.
// Positions for which no images were supplied are NULL.
std::unique_ptr<ImagePainter> top_left_painter_;
std::unique_ptr<ImagePainter> top_painter_;
std::unique_ptr<ImagePainter> top_right_painter_;
std::unique_ptr<ImagePainter> left_painter_;
std::unique_ptr<ImagePainter> center_painter_;
std::unique_ptr<ImagePainter> right_painter_;
std::unique_ptr<ImagePainter> bottom_left_painter_;
std::unique_ptr<ImagePainter> bottom_painter_;
std::unique_ptr<ImagePainter> bottom_right_painter_;
} // namespace wm