src/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/debug/trace_event.h"
   8 #include "cc/debug/rendering_stats_instrumentation.h"
   9 #include "cc/resources/layer_painter.h"
  10 #include "third_party/skia/include/core/SkCanvas.h"
  11 #include "third_party/skia/include/core/SkRect.h"
  12 #include "third_party/skia/include/core/SkScalar.h"
  13 #include "ui/gfx/geometry/rect_conversions.h"
  14 #include "ui/gfx/geometry/rect_f.h"
  15 #include "ui/gfx/skia_util.h"
  16
  17 namespace cc {
  18
  19 ContentLayerUpdater::ContentLayerUpdater(
  20     scoped_ptr<LayerPainter> painter,
  21     RenderingStatsInstrumentation* stats_instrumentation,
  22     int layer_id)
  23     : rendering_stats_instrumentation_(stats_instrumentation),
  24       layer_id_(layer_id),
  25       layer_is_opaque_(false),
  26       layer_fills_bounds_completely_(false),
  27       painter_(painter.Pass()),
  28       background_color_(SK_ColorTRANSPARENT) {
  29 }
  30
  31 ContentLayerUpdater::~ContentLayerUpdater() {}
  32
  33 void ContentLayerUpdater::set_rendering_stats_instrumentation(
  34     RenderingStatsInstrumentation* rsi) {
  35   rendering_stats_instrumentation_ = rsi;
  36 }
  37
  38 void ContentLayerUpdater::PaintContents(SkCanvas* canvas,
  39                                         const gfx::Size& layer_content_size,
  40                                         const gfx::Rect& paint_rect,
  41                                         float contents_width_scale,
  42                                         float contents_height_scale) {
  43   TRACE_EVENT0("cc", "ContentLayerUpdater::PaintContents");
  44   if (!canvas)
  45     return;
  46   canvas->save();
  47   canvas->translate(SkIntToScalar(-paint_rect.x()),
  48                     SkIntToScalar(-paint_rect.y()));
  49
  50   // The |canvas| backing should be sized to hold the |paint_rect|.
  51   DCHECK_EQ(paint_rect.width(), canvas->getBaseLayerSize().width());
  52   DCHECK_EQ(paint_rect.height(), canvas->getBaseLayerSize().height());
  53
  54   const bool is_scaled =
  55       contents_width_scale != 1.f || contents_height_scale != 1.f;
  56
  57   if (is_scaled && (layer_is_opaque_ || layer_fills_bounds_completely_)) {
  58     // Even if completely covered, for rasterizations that touch the edge of the
  59     // layer, we also need to raster the background color underneath the last
  60     // texel (since the paint won't cover it).
  61     //
  62     // The final texel of content may only be partially covered by a
  63     // rasterization; this rect represents the content rect that is fully
  64     // covered by content.
  65     const gfx::Rect layer_content_rect = gfx::Rect(layer_content_size);
  66     gfx::Rect deflated_layer_content_rect = layer_content_rect;
  67     deflated_layer_content_rect.Inset(0, 0, 1, 1);
  68
  69     if (!layer_content_rect.Contains(deflated_layer_content_rect)) {
  70       // Drawing at most 1 x 1 x (canvas width + canvas height) texels is 2-3X
  71       // faster than clearing, so special case this.
  72       DCHECK_LE(paint_rect.right(), layer_content_rect.right());
  73       DCHECK_LE(paint_rect.bottom(), layer_content_rect.bottom());
  74       canvas->save();
  75       canvas->clipRect(gfx::RectToSkRect(layer_content_rect),
  76                        SkRegion::kReplace_Op);
  77       canvas->clipRect(gfx::RectToSkRect(deflated_layer_content_rect),
  78                        SkRegion::kDifference_Op);
  79       canvas->drawColor(background_color_, SkXfermode::kSrc_Mode);
  80       canvas->restore();
  81     }
  82   }
  83
  84   gfx::Rect layer_rect;
  85   if (is_scaled) {
  86     canvas->scale(SkFloatToScalar(contents_width_scale),
  87                   SkFloatToScalar(contents_height_scale));
  88
  89     // NOTE: this may go beyond the bounds of the layer, but that shouldn't
  90     // cause problems (anything beyond the layer is clipped out).
  91     layer_rect = gfx::ScaleToEnclosingRect(
  92         paint_rect, 1.f / contents_width_scale, 1.f / contents_height_scale);
  93   } else {
  94     layer_rect = paint_rect;
  95   }
  96
  97   SkRect layer_sk_rect = SkRect::MakeXYWH(
  98       layer_rect.x(), layer_rect.y(), layer_rect.width(), layer_rect.height());
  99
 100   canvas->clipRect(layer_sk_rect);
 101
 102   // If the layer has opaque contents or will fill the bounds completely there
 103   // is no need to clear the canvas before painting.
 104   if (!layer_is_opaque_ && !layer_fills_bounds_completely_) {
 105     TRACE_EVENT0("cc", "Clear");
 106     canvas->drawColor(SK_ColorTRANSPARENT, SkXfermode::kSrc_Mode);
 107   }
 108
 109   painter_->Paint(canvas, layer_rect);
 110   canvas->restore();
 111
 112   paint_rect_ = paint_rect;
 113 }
 114
 115 void ContentLayerUpdater::SetOpaque(bool opaque) {
 116   layer_is_opaque_ = opaque;
 117 }
 118
 119 void ContentLayerUpdater::SetFillsBoundsCompletely(bool fills_bounds) {
 120   layer_fills_bounds_completely_ = fills_bounds;
 121 }
 122
 123 void ContentLayerUpdater::SetBackgroundColor(SkColor background_color) {
 124   background_color_ = background_color;
 125 }
 126
 127 }  // namespace cc