1 files changed, 39 insertions, 5 deletions

diff --git a/gm/xfermodes.cpp b/gm/xfermodes.cpp
index 8fbbdbec6a..68d267bd22 100644
--- a/gm/xfermodes.cpp
+++ b/gm/xfermodes.cpp
@@ -11,6 +11,31 @@
 #include "SkXfermode.h"
 #include "SkPM4f.h"
 
+#include "SkArithmeticMode.h"
+
+#define kCustomShift    16
+#define kCustomMask     (~0xFFFF)
+
+enum CustomModes {
+    kArithmetic_CustomMode  = 1 << kCustomShift,
+};
+
+static sk_sp<SkXfermode> make_custom(int customMode) {
+    switch (customMode) {
+        case kArithmetic_CustomMode: {
+            const SkScalar k1 = 0.25;
+            const SkScalar k2 = 0.75;
+            const SkScalar k3 = 0.75;
+            const SkScalar k4 = -0.25;
+            return SkArithmeticMode::Make(k1, k2, k3, k4);
+        }
+        default:
+            break;
+    }
+    SkASSERT(false);
+    return nullptr;
+}
+
 enum SrcType {
     //! A WxH image with a rectangle in the lower right.
     kRectangleImage_SrcType               = 0x01,
@@ -73,6 +98,8 @@ const struct {
     { SkXfermode::kSaturation_Mode,   "Saturation",   kBasic_SrcType },
     { SkXfermode::kColor_Mode,        "Color",        kBasic_SrcType },
     { SkXfermode::kLuminosity_Mode,   "Luminosity",   kBasic_SrcType },
+
+    { SkXfermode::Mode(0xFFFF),       "Arithmetic",   kBasic_SrcType + kArithmetic_CustomMode   },
 };
 
 static void make_bitmaps(int w, int h, SkBitmap* src, SkBitmap* dst,
@@ -118,7 +145,7 @@ class XfermodesGM : public skiagm::GM {
      * uses the implied shape of the drawing command and these modes
      * demonstrate that.
      */
-    void draw_mode(SkCanvas* canvas, SkXfermode::Mode mode, SrcType srcType,
+    void draw_mode(SkCanvas* canvas, sk_sp<SkXfermode> mode, SrcType srcType,
                    SkScalar x, SkScalar y) {
         SkPaint p;
         SkMatrix m;
@@ -126,7 +153,7 @@ class XfermodesGM : public skiagm::GM {
         m.setTranslate(x, y);
 
         canvas->drawBitmap(fSrcB, x, y, &p);
-        p.setXfermodeMode(mode);
+        p.setXfermode(std::move(mode));
         switch (srcType) {
             case kSmallTransparentImage_SrcType: {
                 m.postScale(SK_ScalarHalf, SK_ScalarHalf, x, y);
@@ -214,7 +241,7 @@ protected:
     }
 
     SkISize onISize() override {
-        return SkISize::Make(1990, 570);
+        return SkISize::Make(1990, 660);
     }
 
     void onDraw(SkCanvas* canvas) override {
@@ -242,7 +269,14 @@ protected:
                 if ((gModes[i].fSourceTypeMask & sourceType) == 0) {
                     continue;
                 }
-                SkRect r{ x, y, x+w, y+h };
+                sk_sp<SkXfermode> mode;
+                if (gModes[i].fSourceTypeMask & kCustomMask) {
+                    mode = make_custom(gModes[i].fSourceTypeMask & kCustomMask);
+                } else {
+                    mode = SkXfermode::Make(gModes[i].fMode);
+                }
+                SkRect r;
+                r.set(x, y, x+w, y+h);
 
                 SkPaint p;
                 p.setStyle(SkPaint::kFill_Style);
@@ -250,7 +284,7 @@ protected:
                 canvas->drawRect(r, p);
 
                 canvas->saveLayer(&r, nullptr);
-                draw_mode(canvas, gModes[i].fMode, static_cast<SrcType>(sourceType),
+                draw_mode(canvas, std::move(mode), static_cast<SrcType>(sourceType),
                           r.fLeft, r.fTop);
                 canvas->restore();