M20 Ash: Animate window header transition from active to inactive

ash/wm/frame_painter.cc

Index: ash/wm/frame_painter.cc
diff --git a/ash/wm/frame_painter.cc b/ash/wm/frame_painter.cc
index d9e72ab6dc1e66c8be539a528d124a3e03589131..29e942be826c287590e0571c5acc0d7bec040dbf 100644
--- a/ash/wm/frame_painter.cc
+++ b/ash/wm/frame_painter.cc
@@ -12,6 +12,7 @@
 #include "third_party/skia/include/core/SkPath.h"
 #include "third_party/skia/include/core/SkShader.h"
 #include "ui/aura/window.h"
+#include "ui/base/animation/slide_animation.h"
 #include "ui/base/hit_test.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/base/theme_provider.h"
@@ -59,10 +60,13 @@ const SkColor kHeaderContentSeparatorColor = SkColorSetRGB(128, 128, 128);
 const int kCloseButtonOffsetX = 0;
 // Space between close button and top edge of window.
 const int kCloseButtonOffsetY = 0;
+// Duration of crossfade animation for activating and deactivating frame.
+const int kActivationCrossfadeDurationMs = 200;
 
 // Tiles an image into an area, rounding the top corners.
 void TileRoundRect(gfx::Canvas* canvas,
                    int x, int y, int w, int h,
+                   SkPaint* paint,
                    const SkBitmap& bitmap,
                    int corner_radius) {
   SkRect rect;
@@ -76,12 +80,10 @@ void TileRoundRect(gfx::Canvas* canvas,
   SkPath path;
   path.addRoundRect(rect, radii, SkPath::kCW_Direction);
 
-  SkPaint paint;
   SkShader* shader = SkShader::CreateBitmapShader(bitmap,
                                                   SkShader::kRepeat_TileMode,
                                                   SkShader::kRepeat_TileMode);
   paint.setShader(shader);

[James Cook, 2012/03/20 03:37:03]

paint-> ?

-  paint.setXfermodeMode(SkXfermode::kSrcOver_Mode);
   // CreateBitmapShader returns a Shader with a reference count of one, we
   // need to unref after paint takes ownership of the shader.
   shader->unref();
@@ -104,7 +106,10 @@ FramePainter::FramePainter()
       top_edge_(NULL),
       top_right_corner_(NULL),
       header_left_edge_(NULL),
-      header_right_edge_(NULL) {
+      header_right_edge_(NULL),
+      previous_theme_frame_(NULL),
+      crossfade_theme_frame_(NULL),
+      crossfade_animation_(NULL) {
 }
 
 FramePainter::~FramePainter() {
@@ -225,13 +230,40 @@ void FramePainter::PaintHeader(views::NonClientFrameView* view,
                                const SkBitmap* theme_frame,
                                const SkBitmap* theme_frame_overlay) {
 
-  // Draw the header background, clipping the corners to be rounded.
+  if (previous_theme_frame_ && previous_theme_frame_ != theme_frame) {
+    crossfade_animation_.reset(new ui::SlideAnimation(this));
+    crossfade_theme_frame_ = previous_theme_frame_;
+    crossfade_animation_->SetSlideDuration(kActivationCrossfadeDurationMs);
+    crossfade_animation_->Show();
+  }
+
+  header_frame_bounds_ = gfx::Rect(0, 0, view->width(), theme_frame->height());
   const int kCornerRadius = 2;
+
+  SkPaint paint;
+  if (crossfade_animation_.get() && crossfade_animation_->is_animating()) {
+    uint8 theme_alpha = crossfade_animation_->GetCurrentValue() * 255;
+
+    // Draw the old header background, clipping the corners to be rounded.
+    paint.setAlpha(255 - theme_alpha);
+    paint.setXfermodeMode(SkXfermode::kPlus_Mode);
+    TileRoundRect(canvas,
+                  0, 0, view->width(), theme_frame->height(),
+                  &paint,
+                  *crossfade_theme_frame_,
+                  kCornerRadius);
+
+    paint.setAlpha(theme_alpha);
+  }
+
+  // Draw the header background, clipping the corners to be rounded.
   TileRoundRect(canvas,
-                0, 0, view->width(), theme_frame->height(),
+                0, 0, view->width(), theme_frame->height(), &paint,
                 *theme_frame,
                 kCornerRadius);
 
+  previous_theme_frame_ = theme_frame;
+
   // Draw the theme frame overlay, if available.
   if (theme_frame_overlay)
     canvas->DrawBitmapInt(*theme_frame_overlay, 0, 0);
@@ -358,6 +390,13 @@ void FramePainter::LayoutHeader(views::NonClientFrameView* view,
 }
 
 ///////////////////////////////////////////////////////////////////////////////
+// ui::AnimationDelegate overrides:
+
+void FramePainter::AnimationProgressed(const ui::Animation* animation) {
+  frame_->SchedulePaintInRect(gfx::Rect(header_frame_bounds_));
+}
+
+///////////////////////////////////////////////////////////////////////////////
 // FramePainter, private:
 
 void FramePainter::SetButtonImages(views::ImageButton* button,