Add support for blending of LCD for all blend modes.

gm/lcdblendmodes.cpp

Index: gm/lcdblendmodes.cpp
diff --git a/gm/lcdblendmodes.cpp b/gm/lcdblendmodes.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..a2494cc343fb14e6d7cd9881c84cbec574554c76
--- /dev/null
+++ b/gm/lcdblendmodes.cpp
@@ -0,0 +1,133 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+/* 
+ * Tests text rendering with LCD and the various blend modes.
+ */
+
+#include "gm.h"
+#include "SkCanvas.h"
+#include "SkGradientShader.h"
+
+namespace skiagm {
+
+static const int kColWidth = 180;
+static const int kNumCols = 4;
+static const int kWidth = kColWidth * kNumCols;
+static const int kHeight = 750;
+
+static SkShader* make_shader(const SkRect& bounds) {
+    const SkPoint pts[] = {
+        { bounds.left(), bounds.top() },
+        { bounds.right(), bounds.bottom() },
+    };
+    const SkColor colors[] = {
+        SK_ColorRED, SK_ColorGREEN,
+    };
+    return SkGradientShader::CreateLinear(pts,
+                                          colors, nullptr, SK_ARRAY_COUNT(colors),
+                                          SkShader::kRepeat_TileMode);
+}
+
+class LcdBlendGM : public skiagm::GM {
+public:
+    LcdBlendGM() {
+        const int kPointSize = 25;
+        fTextHeight = SkIntToScalar(kPointSize);
+    }
+    
+protected:
+    SkString onShortName() override {
+        SkString name("lcdblendmodes");
+        name.append(sk_tool_utils::major_platform_os_name());
+        return name;
+    }
+    
+    SkISize onISize() override { return SkISize::Make(kWidth, kHeight); }
+    
+    void onDraw(SkCanvas* canvas) override {
+        this->drawColumn(canvas, SK_ColorBLACK, SK_ColorWHITE, false);
+        canvas->translate(SkIntToScalar(kColWidth), 0);
+        this->drawColumn(canvas, SK_ColorWHITE, SK_ColorBLACK, false);
+        canvas->translate(SkIntToScalar(kColWidth), 0);
+        this->drawColumn(canvas, SK_ColorGREEN, SK_ColorMAGENTA, false);
+        canvas->translate(SkIntToScalar(kColWidth), 0);
+        this->drawColumn(canvas, SK_ColorCYAN, SK_ColorMAGENTA, true);
+    }
+
+    void drawColumn(SkCanvas* canvas, SkColor backgroundColor, SkColor textColor, bool useGrad) {
+        const struct {
+            SkXfermode::Mode  fMode;
+            const char*       fLabel;
+        } gModes[] = {
+            { SkXfermode::kClear_Mode,        "Clear"       },
+            { SkXfermode::kSrc_Mode,          "Src"         },
+            { SkXfermode::kDst_Mode,          "Dst"         },
+            { SkXfermode::kSrcOver_Mode,      "SrcOver"     },
+            { SkXfermode::kDstOver_Mode,      "DstOver"     },
+            { SkXfermode::kSrcIn_Mode,        "SrcIn"       },
+            { SkXfermode::kDstIn_Mode,        "DstIn"       },
+            { SkXfermode::kSrcOut_Mode,       "SrcOut"      },
+            { SkXfermode::kDstOut_Mode,       "DstOut"      },
+            { SkXfermode::kSrcATop_Mode,      "SrcATop"     },
+            { SkXfermode::kDstATop_Mode,      "DstATop"     },
+            { SkXfermode::kXor_Mode,          "Xor"         },
+            { SkXfermode::kPlus_Mode,         "Plus"        },
+            { SkXfermode::kModulate_Mode,     "Modulate"    },
+            { SkXfermode::kScreen_Mode,       "Screen"      },
+            { SkXfermode::kOverlay_Mode,      "Overlay"     },
+            { SkXfermode::kDarken_Mode,       "Darken"      },
+            { SkXfermode::kLighten_Mode,      "Lighten"     },
+            { SkXfermode::kColorDodge_Mode,   "ColorDodge"  },
+            { SkXfermode::kColorBurn_Mode,    "ColorBurn"   },
+            { SkXfermode::kHardLight_Mode,    "HardLight"   },
+            { SkXfermode::kSoftLight_Mode,    "SoftLight"   },
+            { SkXfermode::kDifference_Mode,   "Difference"  },
+            { SkXfermode::kExclusion_Mode,    "Exclusion"   },
+            { SkXfermode::kMultiply_Mode,     "Multiply"    },
+            { SkXfermode::kHue_Mode,          "Hue"         },
+            { SkXfermode::kSaturation_Mode,   "Saturation"  },
+            { SkXfermode::kColor_Mode,        "Color"       },
+            { SkXfermode::kLuminosity_Mode,   "Luminosity"  },
+        };
+        // Draw background rect
+        SkPaint backgroundPaint;
+        backgroundPaint.setColor(backgroundColor);
+        canvas->drawRectCoords(0, 0, SkIntToScalar(kColWidth), SkIntToScalar(kHeight),
+                               backgroundPaint);
+        SkScalar y = fTextHeight;
+        for (size_t m = 0; m < SK_ARRAY_COUNT(gModes); m++) {
+            SkAutoTUnref<SkXfermode> xfermode(SkXfermode::Create(gModes[m].fMode));
+            SkPaint paint;
+            paint.setColor(textColor);
+            paint.setAntiAlias(true);
+            paint.setSubpixelText(true);
+            paint.setLCDRenderText(true);
+            paint.setTextSize(fTextHeight);
+            paint.setXfermode(xfermode);
+            sk_tool_utils::set_portable_typeface(&paint);
+            if (useGrad) {
+                SkRect r;
+                r.setXYWH(0, y - fTextHeight, SkIntToScalar(kColWidth), fTextHeight);
+                paint.setShader(make_shader(r))->unref();
+            }
+            SkString string(gModes[m].fLabel);
+            canvas->drawText(gModes[m].fLabel, string.size(), 0, y, paint);
+            y+=fTextHeight;
+        }
+    }
+    
+private:
+    SkScalar fTextHeight;
+    typedef skiagm::GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM( return new LcdBlendGM; )
+}