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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.allocN32Pixels(WW, HH);
     21     bm.eraseColor(SK_ColorTRANSPARENT);
     22     return bm;
     23 }
     24 
     25 static SkBitmap make_src() {
     26     SkBitmap bm = make_bm();
     27     SkCanvas canvas(bm);
     28     SkPaint paint;
     29     SkPoint pts[] = { {0, 0}, {SkIntToScalar(WW), SkIntToScalar(HH)} };
     30     SkColor colors[] = {
     31         SK_ColorTRANSPARENT, SK_ColorGREEN, SK_ColorCYAN,
     32         SK_ColorRED, SK_ColorMAGENTA, SK_ColorWHITE,
     33     };
     34     SkShader* s = SkGradientShader::CreateLinear(pts, colors, NULL, SK_ARRAY_COUNT(colors),
     35                                                  SkShader::kClamp_TileMode);
     36     paint.setShader(s)->unref();
     37     canvas.drawPaint(paint);
     38     return bm;
     39 }
     40 
     41 static SkBitmap make_dst() {
     42     SkBitmap bm = make_bm();
     43     SkCanvas canvas(bm);
     44     SkPaint paint;
     45     SkPoint pts[] = { {0, SkIntToScalar(HH)}, {SkIntToScalar(WW), 0} };
     46     SkColor colors[] = {
     47         SK_ColorBLUE, SK_ColorYELLOW, SK_ColorBLACK, SK_ColorGREEN, SK_ColorGRAY
     48     };
     49     SkShader* s = SkGradientShader::CreateLinear(pts, colors, NULL, SK_ARRAY_COUNT(colors),
     50                                                  SkShader::kClamp_TileMode);
     51     paint.setShader(s)->unref();
     52     canvas.drawPaint(paint);
     53     return bm;
     54 }
     55 
     56 static void show_k_text(SkCanvas* canvas, SkScalar x, SkScalar y, const SkScalar k[]) {
     57     SkPaint paint;
     58     paint.setTextSize(SkIntToScalar(24));
     59     paint.setAntiAlias(true);
     60     for (int i = 0; i < 4; ++i) {
     61         SkString str;
     62         str.appendScalar(k[i]);
     63         SkScalar width = paint.measureText(str.c_str(), str.size());
     64         canvas->drawText(str.c_str(), str.size(), x, y + paint.getTextSize(), paint);
     65         x += width + SkIntToScalar(10);
     66     }
     67 }
     68 
     69 class ArithmodeGM : public skiagm::GM {
     70 public:
     71     ArithmodeGM () {}
     72 
     73 protected:
     74 
     75     virtual SkString onShortName() {
     76         return SkString("arithmode");
     77     }
     78 
     79     virtual SkISize onISize() { return SkISize::Make(640, 480); }
     80 
     81     virtual void onDraw(SkCanvas* canvas) {
     82         SkBitmap src = make_src();
     83         SkBitmap dst = make_dst();
     84 
     85         const SkScalar one = SK_Scalar1;
     86         static const SkScalar K[] = {
     87             0, 0, 0, 0,
     88             0, 0, 0, one,
     89             0, one, 0, 0,
     90             0, 0, one, 0,
     91             0, one, one, 0,
     92             0, one, -one, 0,
     93             0, one/2, one/2, 0,
     94             0, one/2, one/2, one/4,
     95             0, one/2, one/2, -one/4,
     96             one/4, one/2, one/2, 0,
     97             -one/4, one/2, one/2, 0,
     98         };
     99 
    100         const SkScalar* k = K;
    101         const SkScalar* stop = k + SK_ARRAY_COUNT(K);
    102         SkScalar y = 0;
    103         SkScalar gap = SkIntToScalar(src.width() + 20);
    104         while (k < stop) {
    105             SkScalar x = 0;
    106             canvas->drawBitmap(src, x, y, NULL);
    107             x += gap;
    108             canvas->drawBitmap(dst, x, y, NULL);
    109             x += gap;
    110             SkRect rect = SkRect::MakeXYWH(x, y, SkIntToScalar(WW), SkIntToScalar(HH));
    111             canvas->saveLayer(&rect, NULL);
    112             canvas->drawBitmap(dst, x, y, NULL);
    113             SkXfermode* xfer = SkArithmeticMode::Create(k[0], k[1], k[2], k[3]);
    114             SkPaint paint;
    115             paint.setXfermode(xfer)->unref();
    116             canvas->drawBitmap(src, x, y, &paint);
    117             canvas->restore();
    118             x += gap;
    119             show_k_text(canvas, x, y, k);
    120             k += 4;
    121             y += SkIntToScalar(src.height() + 12);
    122         }
    123     }
    124 
    125 private:
    126     typedef GM INHERITED;
    127 };
    128 
    129 ///////////////////////////////////////////////////////////////////////////////
    130 
    131 static skiagm::GM* MyFactory(void*) { return new ArithmodeGM; }
    132 static skiagm::GMRegistry reg(MyFactory);
    133