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      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 "base/time/time.h"
      9 #include "cc/debug/rendering_stats_instrumentation.h"
     10 #include "cc/resources/layer_painter.h"
     11 #include "third_party/skia/include/core/SkCanvas.h"
     12 #include "third_party/skia/include/core/SkPaint.h"
     13 #include "third_party/skia/include/core/SkRect.h"
     14 #include "third_party/skia/include/core/SkScalar.h"
     15 #include "ui/gfx/rect_conversions.h"
     16 #include "ui/gfx/rect_f.h"
     17 #include "ui/gfx/skia_util.h"
     18 
     19 namespace cc {
     20 
     21 ContentLayerUpdater::ContentLayerUpdater(
     22     scoped_ptr<LayerPainter> painter,
     23     RenderingStatsInstrumentation* stats_instrumentation,
     24     int layer_id)
     25     : rendering_stats_instrumentation_(stats_instrumentation),
     26       layer_id_(layer_id),
     27       layer_is_opaque_(false),
     28       layer_fills_bounds_completely_(false),
     29       painter_(painter.Pass()),
     30       background_color_(SK_ColorTRANSPARENT) {
     31 }
     32 
     33 ContentLayerUpdater::~ContentLayerUpdater() {}
     34 
     35 void ContentLayerUpdater::set_rendering_stats_instrumentation(
     36     RenderingStatsInstrumentation* rsi) {
     37   rendering_stats_instrumentation_ = rsi;
     38 }
     39 
     40 void ContentLayerUpdater::PaintContents(SkCanvas* canvas,
     41                                         const gfx::Size& layer_content_size,
     42                                         const gfx::Rect& paint_rect,
     43                                         float contents_width_scale,
     44                                         float contents_height_scale) {
     45   TRACE_EVENT0("cc", "ContentLayerUpdater::PaintContents");
     46   if (!canvas)
     47     return;
     48   canvas->save();
     49   canvas->translate(SkIntToScalar(-paint_rect.x()),
     50                     SkIntToScalar(-paint_rect.y()));
     51 
     52   // The |canvas| backing should be sized to hold the |paint_rect|.
     53   DCHECK_EQ(paint_rect.width(), canvas->getBaseLayerSize().width());
     54   DCHECK_EQ(paint_rect.height(), canvas->getBaseLayerSize().height());
     55 
     56   const bool is_scaled =
     57       contents_width_scale != 1.f || contents_height_scale != 1.f;
     58 
     59   if (is_scaled && (layer_is_opaque_ || layer_fills_bounds_completely_)) {
     60     // Even if completely covered, for rasterizations that touch the edge of the
     61     // layer, we also need to raster the background color underneath the last
     62     // texel (since the paint won't cover it).
     63     //
     64     // The final texel of content may only be partially covered by a
     65     // rasterization; this rect represents the content rect that is fully
     66     // covered by content.
     67     const gfx::Rect layer_content_rect = gfx::Rect(layer_content_size);
     68     gfx::Rect deflated_layer_content_rect = layer_content_rect;
     69     deflated_layer_content_rect.Inset(0, 0, 1, 1);
     70 
     71     if (!layer_content_rect.Contains(deflated_layer_content_rect)) {
     72       // Drawing at most 1 x 1 x (canvas width + canvas height) texels is 2-3X
     73       // faster than clearing, so special case this.
     74       DCHECK_LE(paint_rect.right(), layer_content_rect.right());
     75       DCHECK_LE(paint_rect.bottom(), layer_content_rect.bottom());
     76       canvas->save();
     77       canvas->clipRect(gfx::RectToSkRect(layer_content_rect),
     78                        SkRegion::kReplace_Op);
     79       canvas->clipRect(gfx::RectToSkRect(deflated_layer_content_rect),
     80                        SkRegion::kDifference_Op);
     81       canvas->drawColor(background_color_, SkXfermode::kSrc_Mode);
     82       canvas->restore();
     83     }
     84   }
     85 
     86   gfx::Rect layer_rect;
     87   if (is_scaled) {
     88     canvas->scale(SkFloatToScalar(contents_width_scale),
     89                   SkFloatToScalar(contents_height_scale));
     90 
     91     // NOTE: this may go beyond the bounds of the layer, but that shouldn't
     92     // cause problems (anything beyond the layer is clipped out).
     93     layer_rect = gfx::ScaleToEnclosingRect(
     94         paint_rect, 1.f / contents_width_scale, 1.f / contents_height_scale);
     95   } else {
     96     layer_rect = paint_rect;
     97   }
     98 
     99   SkRect layer_sk_rect = SkRect::MakeXYWH(
    100       layer_rect.x(), layer_rect.y(), layer_rect.width(), layer_rect.height());
    101 
    102   canvas->clipRect(layer_sk_rect);
    103 
    104   // If the layer has opaque contents or will fill the bounds completely there
    105   // is no need to clear the canvas before painting.
    106   if (!layer_is_opaque_ && !layer_fills_bounds_completely_) {
    107     TRACE_EVENT0("cc", "Clear");
    108     canvas->drawColor(SK_ColorTRANSPARENT, SkXfermode::kSrc_Mode);
    109   }
    110 
    111   painter_->Paint(canvas, layer_rect);
    112   canvas->restore();
    113 
    114   paint_rect_ = paint_rect;
    115 }
    116 
    117 void ContentLayerUpdater::SetOpaque(bool opaque) {
    118   layer_is_opaque_ = opaque;
    119 }
    120 
    121 void ContentLayerUpdater::SetFillsBoundsCompletely(bool fills_bounds) {
    122   layer_fills_bounds_completely_ = fills_bounds;
    123 }
    124 
    125 void ContentLayerUpdater::SetBackgroundColor(SkColor background_color) {
    126   background_color_ = background_color;
    127 }
    128 
    129 }  // namespace cc
    130