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      1 /*
      2  * Copyright 2016 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 "Resources.h"
     10 
     11 #include "SkImageDecoder.h"
     12 #include "SkPixelXorXfermode.h"
     13 #include "SkStream.h"
     14 
     15 class PixelXorXfermodeGM : public skiagm::GM {
     16 public:
     17     PixelXorXfermodeGM() { }
     18 
     19 protected:
     20     SkString onShortName() override {
     21         return SkString("pixelxorxfermode");
     22     }
     23 
     24     SkISize onISize() override { return SkISize::Make(512, 512); }
     25 
     26     void onOnceBeforeDraw() override {
     27         SkImageDecoder* codec = nullptr;
     28         SkString resourcePath = GetResourcePath("mandrill_512.png");
     29         SkFILEStream stream(resourcePath.c_str());
     30         if (stream.isValid()) {
     31             codec = SkImageDecoder::Factory(&stream);
     32         }
     33         if (codec) {
     34             stream.rewind();
     35             codec->decode(&stream, &fBM, kN32_SkColorType, SkImageDecoder::kDecodePixels_Mode);
     36             delete codec;
     37         } else {
     38             fBM.allocN32Pixels(1, 1);
     39             fBM.eraseARGB(255, 255, 0 , 0); // red == bad
     40         }
     41     }
     42 
     43     void onDraw(SkCanvas* canvas) override {
     44         canvas->drawBitmap(fBM, 0, 0);
     45 
     46         SkRect r = SkRect::MakeIWH(256, 256);
     47 
     48         // Negate the red channel of the dst (via the ancillary color) but leave
     49         // the green & blue channels alone
     50         SkPaint p1;
     51         p1.setColor(SK_ColorBLACK); // noop
     52         p1.setXfermode(SkPixelXorXfermode::Create(0x7FFF0000))->unref();
     53 
     54         canvas->drawRect(r, p1);
     55 
     56         r.offsetTo(256.0f, 0.0f);
     57 
     58         // Negate the dst color via the src color
     59         SkPaint p2;
     60         p2.setColor(SK_ColorWHITE);
     61         p2.setXfermode(SkPixelXorXfermode::Create(SK_ColorBLACK))->unref(); // noop
     62 
     63         canvas->drawRect(r, p2);
     64 
     65         r.offsetTo(0.0f, 256.0f);
     66 
     67         // Just return the original color
     68         SkPaint p3;
     69         p3.setColor(SK_ColorBLACK); // noop
     70         p3.setXfermode(SkPixelXorXfermode::Create(SK_ColorBLACK))->unref(); // noop
     71 
     72         canvas->drawRect(r, p3);
     73 
     74         r.offsetTo(256.0f, 256.0f);
     75 
     76         // Negate the red & green channels (via the ancillary color) but leave
     77         // the blue channel alone
     78         SkPaint p4;
     79         p4.setColor(SK_ColorBLACK); // noop
     80         p4.setXfermode(SkPixelXorXfermode::Create(SK_ColorYELLOW))->unref();
     81 
     82         canvas->drawRect(r, p4);
     83     }
     84 
     85 private:
     86     SkBitmap fBM;
     87 
     88     typedef GM INHERITED;
     89 };
     90 
     91 //////////////////////////////////////////////////////////////////////////////
     92 
     93 DEF_GM(return new PixelXorXfermodeGM;)
     94