cc/resources/content_layer_updater.cc

   1 // Copyright 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/resources/content_layer_updater.h"
   6
   7 #include "base/trace_event/trace_event.h"
   8 #include "cc/resources/layer_painter.h"
   9 #include "third_party/skia/include/core/SkCanvas.h"
  10 #include "third_party/skia/include/core/SkRect.h"
  11 #include "third_party/skia/include/core/SkScalar.h"
  12 #include "ui/gfx/geometry/rect_conversions.h"
  13 #include "ui/gfx/geometry/rect_f.h"
  14 #include "ui/gfx/skia_util.h"
  15
  16 namespace cc {
  17
  18 ContentLayerUpdater::ContentLayerUpdater(scoped_ptr<LayerPainter> painter,
  19                                          int layer_id)
  20     : layer_id_(layer_id),
  21       layer_is_opaque_(false),
  22       layer_fills_bounds_completely_(false),
  23       painter_(painter.Pass()),
  24       background_color_(SK_ColorTRANSPARENT) {
  25 }
  26
  27 ContentLayerUpdater::~ContentLayerUpdater() {}
  28
  29 void ContentLayerUpdater::PaintContents(SkCanvas* canvas,
  30                                         const gfx::Size& layer_content_size,
  31                                         const gfx::Rect& paint_rect,
  32                                         float contents_width_scale,
  33                                         float contents_height_scale) {
  34   TRACE_EVENT0("cc", "ContentLayerUpdater::PaintContents");
  35   if (!canvas)
  36     return;
  37   canvas->save();
  38   canvas->translate(SkIntToScalar(-paint_rect.x()),
  39                     SkIntToScalar(-paint_rect.y()));
  40
  41   // The |canvas| backing should be sized to hold the |paint_rect|.
  42   DCHECK_EQ(paint_rect.width(), canvas->getBaseLayerSize().width());
  43   DCHECK_EQ(paint_rect.height(), canvas->getBaseLayerSize().height());
  44
  45   const bool is_scaled =
  46       contents_width_scale != 1.f || contents_height_scale != 1.f;
  47
  48   if (is_scaled && (layer_is_opaque_ || layer_fills_bounds_completely_)) {
  49     // Even if completely covered, for rasterizations that touch the edge of the
  50     // layer, we also need to raster the background color underneath the last
  51     // texel (since the paint won't cover it).
  52     //
  53     // The final texel of content may only be partially covered by a
  54     // rasterization; this rect represents the content rect that is fully
  55     // covered by content.
  56     const gfx::Rect layer_content_rect = gfx::Rect(layer_content_size);
  57     gfx::Rect deflated_layer_content_rect = layer_content_rect;
  58     deflated_layer_content_rect.Inset(0, 0, 1, 1);
  59
  60     if (!layer_content_rect.Contains(deflated_layer_content_rect)) {
  61       // Drawing at most 1 x 1 x (canvas width + canvas height) texels is 2-3X
  62       // faster than clearing, so special case this.
  63       DCHECK_LE(paint_rect.right(), layer_content_rect.right());
  64       DCHECK_LE(paint_rect.bottom(), layer_content_rect.bottom());
  65       canvas->save();
  66       canvas->clipRect(gfx::RectToSkRect(layer_content_rect),
  67                        SkRegion::kReplace_Op);
  68       canvas->clipRect(gfx::RectToSkRect(deflated_layer_content_rect),
  69                        SkRegion::kDifference_Op);
  70       canvas->drawColor(background_color_, SkXfermode::kSrc_Mode);
  71       canvas->restore();
  72     }
  73   }
  74
  75   gfx::Rect layer_rect;
  76   if (is_scaled) {
  77     canvas->scale(SkFloatToScalar(contents_width_scale),
  78                   SkFloatToScalar(contents_height_scale));
  79
  80     // NOTE: this may go beyond the bounds of the layer, but that shouldn't
  81     // cause problems (anything beyond the layer is clipped out).
  82     layer_rect = gfx::ScaleToEnclosingRect(
  83         paint_rect, 1.f / contents_width_scale, 1.f / contents_height_scale);
  84   } else {
  85     layer_rect = paint_rect;
  86   }
  87
  88   SkRect layer_sk_rect = SkRect::MakeXYWH(
  89       layer_rect.x(), layer_rect.y(), layer_rect.width(), layer_rect.height());
  90
  91   canvas->clipRect(layer_sk_rect);
  92
  93   // If the layer has opaque contents or will fill the bounds completely there
  94   // is no need to clear the canvas before painting.
  95   if (!layer_is_opaque_ && !layer_fills_bounds_completely_) {
  96     TRACE_EVENT0("cc", "Clear");
  97     canvas->drawColor(SK_ColorTRANSPARENT, SkXfermode::kSrc_Mode);
  98   }
  99
 100   painter_->Paint(canvas, layer_rect);
 101   canvas->restore();
 102
 103   paint_rect_ = paint_rect;
 104 }
 105
 106 void ContentLayerUpdater::SetOpaque(bool opaque) {
 107   layer_is_opaque_ = opaque;
 108 }
 109
 110 void ContentLayerUpdater::SetFillsBoundsCompletely(bool fills_bounds) {
 111   layer_fills_bounds_completely_ = fills_bounds;
 112 }
 113
 114 void ContentLayerUpdater::SetBackgroundColor(SkColor background_color) {
 115   background_color_ = background_color;
 116 }
 117
 118 }  // namespace cc