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      1 /*
      2  * Copyright 2011 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 "SkColorPriv.h"
     11 #include "SkShader.h"
     12 
     13 #include "SkArithmeticMode.h"
     14 #include "SkGradientShader.h"
     15 #define WW  100
     16 #define HH  32
     17 
     18 static SkBitmap make_bm() {
     19     SkBitmap bm;
     20     bm.setConfig(SkBitmap::kARGB_8888_Config, WW, HH);
     21     bm.allocPixels();
     22     bm.eraseColor(SK_ColorTRANSPARENT);
     23     return bm;
     24 }
     25 
     26 static SkBitmap make_src() {
     27     SkBitmap bm = make_bm();
     28     SkCanvas canvas(bm);
     29     SkPaint paint;
     30     SkPoint pts[] = { {0, 0}, {SkIntToScalar(WW), SkIntToScalar(HH)} };
     31     SkColor colors[] = {
     32         SK_ColorTRANSPARENT, SK_ColorGREEN, SK_ColorCYAN,
     33         SK_ColorRED, SK_ColorMAGENTA, SK_ColorWHITE,
     34     };
     35     SkShader* s = SkGradientShader::CreateLinear(pts, colors, NULL, SK_ARRAY_COUNT(colors),
     36                                                  SkShader::kClamp_TileMode);
     37     paint.setShader(s)->unref();
     38     canvas.drawPaint(paint);
     39     return bm;
     40 }
     41 
     42 static SkBitmap make_dst() {
     43     SkBitmap bm = make_bm();
     44     SkCanvas canvas(bm);
     45     SkPaint paint;
     46     SkPoint pts[] = { {0, SkIntToScalar(HH)}, {SkIntToScalar(WW), 0} };
     47     SkColor colors[] = {
     48         SK_ColorBLUE, SK_ColorYELLOW, SK_ColorBLACK, SK_ColorGREEN, SK_ColorGRAY
     49     };
     50     SkShader* s = SkGradientShader::CreateLinear(pts, colors, NULL, SK_ARRAY_COUNT(colors),
     51                                                  SkShader::kClamp_TileMode);
     52     paint.setShader(s)->unref();
     53     canvas.drawPaint(paint);
     54     return bm;
     55 }
     56 
     57 static void show_k_text(SkCanvas* canvas, SkScalar x, SkScalar y, const SkScalar k[]) {
     58     SkPaint paint;
     59     paint.setTextSize(SkIntToScalar(24));
     60     paint.setAntiAlias(true);
     61     for (int i = 0; i < 4; ++i) {
     62         SkString str;
     63         str.appendScalar(k[i]);
     64         SkScalar width = paint.measureText(str.c_str(), str.size());
     65         canvas->drawText(str.c_str(), str.size(), x, y + paint.getTextSize(), paint);
     66         x += width + SkIntToScalar(10);
     67     }
     68 }
     69 
     70 class ArithmodeGM : public skiagm::GM {
     71 public:
     72     ArithmodeGM () {}
     73 
     74 protected:
     75 
     76     virtual SkString onShortName() {
     77         return SkString("arithmode");
     78     }
     79 
     80     virtual SkISize onISize() { return SkISize::Make(640, 480); }
     81 
     82     virtual void onDraw(SkCanvas* canvas) {
     83         SkBitmap src = make_src();
     84         SkBitmap dst = make_dst();
     85 
     86         const SkScalar one = SK_Scalar1;
     87         static const SkScalar K[] = {
     88             0, 0, 0, 0,
     89             0, 0, 0, one,
     90             0, one, 0, 0,
     91             0, 0, one, 0,
     92             0, one, one, 0,
     93             0, one, -one, 0,
     94             0, one/2, one/2, 0,
     95             0, one/2, one/2, one/4,
     96             0, one/2, one/2, -one/4,
     97             one/4, one/2, one/2, 0,
     98             -one/4, one/2, one/2, 0,
     99         };
    100 
    101         const SkScalar* k = K;
    102         const SkScalar* stop = k + SK_ARRAY_COUNT(K);
    103         SkScalar y = 0;
    104         SkScalar gap = SkIntToScalar(src.width() + 20);
    105         while (k < stop) {
    106             SkScalar x = 0;
    107             canvas->drawBitmap(src, x, y, NULL);
    108             x += gap;
    109             canvas->drawBitmap(dst, x, y, NULL);
    110             x += gap;
    111             SkRect rect = SkRect::MakeXYWH(x, y, SkIntToScalar(WW), SkIntToScalar(HH));
    112             canvas->saveLayer(&rect, NULL);
    113             canvas->drawBitmap(dst, x, y, NULL);
    114             SkXfermode* xfer = SkArithmeticMode::Create(k[0], k[1], k[2], k[3]);
    115             SkPaint paint;
    116             paint.setXfermode(xfer)->unref();
    117             canvas->drawBitmap(src, x, y, &paint);
    118             canvas->restore();
    119             x += gap;
    120             show_k_text(canvas, x, y, k);
    121             k += 4;
    122             y += SkIntToScalar(src.height() + 12);
    123         }
    124     }
    125 
    126 private:
    127     typedef GM INHERITED;
    128 };
    129 
    130 ///////////////////////////////////////////////////////////////////////////////
    131 
    132 static skiagm::GM* MyFactory(void*) { return new ArithmodeGM; }
    133 static skiagm::GMRegistry reg(MyFactory);
    134