src/third_party/skia/gm/discard.cpp

   1 /*
   2  * Copyright 2014 Google Inc.
   3  *
   4  * Use of this source code is governed by a BSD-style license that can be
   5  * found in the LICENSE file.
   6  */
   7
   8 #include "gm.h"
   9 #include "SkCanvas.h"
  10 #include "SkColorShader.h"
  11 #include "SkPaint.h"
  12 #include "SkSurface.h"
  13
  14 #if SK_SUPPORT_GPU
  15
  16 namespace skiagm {
  17
  18 /*
  19  * This GM exercises SkCanvas::discard() by creating an offscreen SkSurface and repeatedly
  20  * discarding it, drawing to it, and then drawing it to the main canvas.
  21  */
  22 class DiscardGM : public GM {
  23
  24 public:
  25     DiscardGM() {
  26     }
  27
  28     virtual uint32_t onGetFlags() const SK_OVERRIDE { return kGPUOnly_Flag; }
  29
  30 protected:
  31     virtual SkString onShortName() SK_OVERRIDE {
  32         return SkString("discard");
  33     }
  34
  35     virtual SkISize onISize() SK_OVERRIDE {
  36         return SkISize::Make(100, 100);
  37     }
  38
  39     virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
  40         GrContext* context = canvas->getGrContext();
  41         if (NULL == context) {
  42             return;
  43         }
  44
  45         SkISize size = this->getISize();
  46         size.fWidth /= 10;
  47         size.fHeight /= 10;
  48         SkImageInfo info = SkImageInfo::MakeN32Premul(size);
  49         SkSurface* surface = SkSurface::NewRenderTarget(context, info);
  50
  51         if (NULL == surface) {
  52             return;
  53         }
  54
  55         canvas->clear(SK_ColorBLACK);
  56
  57         SkRandom rand;
  58         for (int x = 0; x < 10; ++x) {
  59             for (int y = 0; y < 10; ++y) {
  60               surface->getCanvas()->discard();
  61               // Make something that isn't too close to the background color, black.
  62               SkColor color = rand.nextU() | 0xFF404040;
  63               switch (rand.nextULessThan(3)) {
  64                   case 0:
  65                       surface->getCanvas()->drawColor(color);
  66                       break;
  67                   case 1:
  68                       surface->getCanvas()->clear(color);
  69                       break;
  70                   case 2:
  71                       SkColorShader shader(color);
  72                       SkPaint paint;
  73                       paint.setShader(&shader);
  74                       surface->getCanvas()->drawPaint(paint);
  75                       break;
  76               }
  77               surface->draw(canvas, 10.f*x, 10.f*y, NULL);
  78             }
  79         }
  80
  81         surface->getCanvas()->discard();
  82         surface->unref();
  83     }
  84
  85 private:
  86     typedef GM INHERITED;
  87 };
  88
  89 //////////////////////////////////////////////////////////////////////////////
  90
  91 DEF_GM( return SkNEW(DiscardGM); )
  92
  93 } // end namespace
  94
  95 #endif