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      1 #include "SampleCode.h"
      2 #include "SkColorPriv.h"
      3 #include "SkGradientShader.h"
      4 #include "SkView.h"
      5 #include "SkCanvas.h"
      6 #include "SkUtils.h"
      7 
      8 static SkBitmap make_bitmap() {
      9     SkBitmap bm;
     10     SkColorTable* ctable = new SkColorTable(256);
     11 
     12     SkPMColor* c = ctable->lockColors();
     13     for (int i = 0; i < 256; i++) {
     14         c[i] = SkPackARGB32(255 - i, 0, 0, 0);
     15     }
     16     ctable->unlockColors(true);
     17     bm.setConfig(SkBitmap::kIndex8_Config, 256, 256);
     18     bm.allocPixels(ctable);
     19     ctable->unref();
     20 
     21     bm.lockPixels();
     22     const float cx = bm.width() * 0.5f;
     23     const float cy = bm.height() * 0.5f;
     24     for (int y = 0; y < bm.height(); y++) {
     25         float dy = y - cy;
     26         dy *= dy;
     27         uint8_t* p = bm.getAddr8(0, y);
     28         for (int x = 0; x < 256; x++) {
     29             float dx = x - cx;
     30             dx *= dx;
     31             float d = (dx + dy) / (cx/2);
     32             int id = (int)d;
     33             if (id > 255) {
     34                 id = 255;
     35             }
     36             p[x] = id;
     37         }
     38     }
     39     bm.unlockPixels();
     40     return bm;
     41 }
     42 
     43 class ExtractAlphaView : public SampleView {
     44     SkBitmap    fBM8;
     45     SkBitmap    fBM32;
     46     SkBitmap    fBM4;
     47 public:
     48 	ExtractAlphaView() {
     49         fBM8 = make_bitmap();
     50         fBM8.copyTo(&fBM32, SkBitmap::kARGB_8888_Config);
     51         fBM8.copyTo(&fBM4, SkBitmap::kARGB_4444_Config);
     52 
     53         this->setBGColor(0xFFDDDDDD);
     54     }
     55 
     56 protected:
     57     // overrides from SkEventSink
     58     virtual bool onQuery(SkEvent* evt) {
     59         if (SampleCode::TitleQ(*evt)) {
     60             SampleCode::TitleR(evt, "DitherBitmap");
     61             return true;
     62         }
     63         return this->INHERITED::onQuery(evt);
     64     }
     65 
     66     virtual void onDrawContent(SkCanvas* canvas) {
     67         SkPaint paint;
     68         paint.setAntiAlias(true);
     69         paint.setStyle(SkPaint::kStroke_Style);
     70 
     71         SkMatrix matrix;
     72         matrix.setScale(3.55f, 80.f);
     73         canvas->setMatrix(matrix);
     74 
     75         paint.setStrokeWidth(0.0588f);
     76         canvas->drawLine(10, 5, 30, 4.8f, paint);
     77 
     78         paint.setStrokeWidth(0.06f);
     79         canvas->drawLine(20, 5, 40, 4.8f, paint);
     80     }
     81 
     82 private:
     83     typedef SampleView INHERITED;
     84 };
     85 
     86 //////////////////////////////////////////////////////////////////////////////
     87 
     88 static SkView* MyFactory() { return new ExtractAlphaView; }
     89 static SkViewRegister reg(MyFactory);
     90 
     91