Move SkAvoidXfermode over from Android

gm/avoidxfermode.cpp

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+#include "Resources.h"
+
+#include "SkImageDecoder.h"
+#include "SkAvoidXfermode.h"
+#include "SkStream.h"
+
+class AvoidXfermodeGM : public skiagm::GM {
+public:
+    AvoidXfermodeGM() { }
+
+protected:
+    SkString onShortName() override {
+        return SkString("avoidxfermode");
+    }
+
+    SkISize onISize() override { return SkISize::Make(128, 128); }
+
+    void onOnceBeforeDraw() override {
+        SkImageDecoder* codec = nullptr;
+        SkString resourcePath = GetResourcePath("color_wheel.png");
+        SkFILEStream stream(resourcePath.c_str());
+        if (stream.isValid()) {
+            codec = SkImageDecoder::Factory(&stream);
+        }
+        if (codec) {
+            stream.rewind();
+            codec->decode(&stream, &fBM, kN32_SkColorType, SkImageDecoder::kDecodePixels_Mode);
+            delete codec;
+        } else {
+            fBM.allocN32Pixels(1, 1);
+            fBM.eraseARGB(255, 255, 0 , 0); // red == bad
+        }
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        canvas->drawBitmap(fBM, 0, 0);
+
+        SkRect r = SkRect::MakeIWH(64, 64);
+
+        // UL corner: replace white with black with a tight tolerance
+        SkPaint p1;
+        p1.setColor(SK_ColorBLACK);
+        p1.setXfermode(SkAvoidXfermode::Create(SK_ColorWHITE,
+                                               5,
+                                               SkAvoidXfermode::kTargetColor_Mode))->unref();
+
+        canvas->drawRect(r, p1);
+
+        r.offsetTo(64, 0.0f);
+
+        // UR corner: draw black everywhere except white with a tight tolerance
+        SkPaint p2;
+        p2.setColor(SK_ColorBLACK);
+        p2.setXfermode(SkAvoidXfermode::Create(SK_ColorWHITE,
+                                               250,
+                                               SkAvoidXfermode::kAvoidColor_Mode))->unref();
+
+        canvas->drawRect(r, p2);
+
+        r.offsetTo(0.0f, 64);
+
+        // LL corner: replace red with blue with a loose tolerance
+        SkPaint p3;
+        p3.setColor(SK_ColorBLUE);
+        p3.setXfermode(SkAvoidXfermode::Create(SK_ColorRED,
+                                               250,
+                                               SkAvoidXfermode::kTargetColor_Mode))->unref();
+
+        canvas->drawRect(r, p3);
+
+        r.offsetTo(64, 64);
+
+        // LR corner: draw black everywhere except red with a loose tolerance
+        SkPaint p4;
+        p4.setColor(SK_ColorBLACK);
+        p4.setXfermode(SkAvoidXfermode::Create(SK_ColorRED,
+                                               5,
+                                               SkAvoidXfermode::kAvoidColor_Mode))->unref();
+
+        canvas->drawRect(r, p4);
+    }
+
+private:
+    SkBitmap fBM;
+
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM(return new AvoidXfermodeGM;)