Revert of remove unused SkAvoidXfermode (patchset #2 id:20001 of https://codereview.chromium.org/860583002/)

Reason for revert:
Breaking Android framework build, which still uses AvoidXfermode. (failure shown here: https://android-build.storage.googleapis.com/builds/git_master-skia-linux-razor-userdebug/1689202/565b76b4bd8cc2ffd5aeb37e524f6a35e9b8791995d6e8c719a3a6d83aece936/logs/build_error.log?Signature=lHYyiconR%2BoTzY9ILAKlaUm6nFnpJQPTI4XUei1ZccBRyz6PxspCNvYCDO5za92yZSoy9refHT7uh2Hxlxew1ZBePxKCp2nnwJB7a%2B403kiHMHHawjecsbPnTE9QNNO8XMoqAjujcAplorhwsIBZYOCxb%2Bo5010BCfzTd%2F8GFa8%3D&Expires=1421764644&GoogleAccessId=701025073339-mqn0q2nvir9iurm6q5d00tdv7blbgvjr%40developer.gserviceaccount.com)

Here is the Java class that uses it: https://cs.corp.google.com/#android/frameworks/base/graphics/java/android/graphics/AvoidXfermode.java&sq=package:android

It has been deprecated. The glue code (which actually references the Skia file) is here: https://cs.corp.google.com/#android/frameworks/base/core/jni/android/graphics/Xfermode.cpp&q=Xfermode.cpp&sq=package:android

Mike suggested we move the implementation into Android, which is fine with me.

Original issue's description:
> remove unused SkAvoidXfermode
>
> BUG=skia:
> TBR=
> NOTRY=True
>
> Committed: https://skia.googlesource.com/skia/+/2d02df7a9a50217dac8c1d11681832a927ed79ce

TBR=bsalomon@google.com,reed@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/822953003

3 files changed, 119 insertions, 0 deletions

diff --git a/samplecode/ClockFaceView.cpp b/samplecode/ClockFaceView.cpp
index 2db9753077..1e21bad753 100644
--- a/samplecode/ClockFaceView.cpp
+++ b/samplecode/ClockFaceView.cpp
@@ -18,6 +18,7 @@
 #include "SkColorPriv.h"
 #include "SkColorFilter.h"
 #include "SkTypeface.h"
+#include "SkAvoidXfermode.h"
 
 static inline SkPMColor rgb2gray(SkPMColor c) {
     unsigned r = SkGetPackedR32(c);
diff --git a/samplecode/SampleAll.cpp b/samplecode/SampleAll.cpp
index 16c79c9dbf..537659e0e6 100644
--- a/samplecode/SampleAll.cpp
+++ b/samplecode/SampleAll.cpp
@@ -11,6 +11,7 @@
 #include "SkView.h"
 #include "Sk1DPathEffect.h"
 #include "Sk2DPathEffect.h"
+#include "SkAvoidXfermode.h"
 #include "SkBlurMaskFilter.h"
 #include "SkColorFilter.h"
 #include "SkColorPriv.h"
@@ -572,6 +573,18 @@ protected:
         }
 
         canvas->restore();
+
+        if (1) {
+            SkAutoTUnref<SkAvoidXfermode> mode(SkAvoidXfermode::Create(SK_ColorWHITE, 0xFF,
+                                   SkAvoidXfermode::kTargetColor_Mode));
+            SkPaint paint;
+            x += SkIntToScalar(20);
+            SkRect  r = { x, 0, x + SkIntToScalar(360), SkIntToScalar(700) };
+            paint.setXfermode(mode);
+            paint.setColor(SK_ColorGREEN);
+            paint.setAntiAlias(true);
+            canvas->drawOval(r, paint);
+        }
     }
 
 private:
diff --git a/samplecode/SampleAvoid.cpp b/samplecode/SampleAvoid.cpp
new file mode 100644
index 0000000000..aa7ca0e8ef
--- /dev/null
+++ b/samplecode/SampleAvoid.cpp
@@ -0,0 +1,105 @@
+
+/*
+ * Copyright 2011 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "SampleCode.h"
+#include "SkView.h"
+#include "SkCanvas.h"
+#include "SkGradientShader.h"
+#include "SkAvoidXfermode.h"
+
+///////////////////////////////////////////////////////////////////////////////
+
+class AvoidView : public SampleView {
+    SkShader* fShader;
+
+    enum {
+        W = 480,
+        H = 320
+    };
+public:
+    AvoidView() {
+        SkColor colors[] = { SK_ColorRED, SK_ColorYELLOW, SK_ColorGREEN, SK_ColorCYAN, SK_ColorBLUE };
+
+#if 0
+        SkPoint pts[] = { 0, 0, SkIntToScalar(100), SkIntToScalar(100) };
+        fShader = SkGradientShader::CreateLinear(pts, colors, NULL,
+                                                 SK_ARRAY_COUNT(colors),
+                                                 SkShader::kMirror_TileMode);
+#else
+        SkPoint pts[] = { { SkIntToScalar(W)/2, SkIntToScalar(H)/2 } };
+        fShader = SkGradientShader::CreateRadial(pts[0], SkIntToScalar(H)/5,
+                                                 colors, NULL,
+                                                 SK_ARRAY_COUNT(colors),
+                                                 SkShader::kMirror_TileMode);
+#endif
+    }
+
+    virtual ~AvoidView() {
+        fShader->unref();
+    }
+
+protected:
+    virtual bool onQuery(SkEvent* evt) {
+        if (SampleCode::TitleQ(*evt)) {
+            SampleCode::TitleR(evt, "AvoidXfermode");
+            return true;
+        }
+        return this->INHERITED::onQuery(evt);
+    }
+
+    virtual void onDrawContent(SkCanvas* canvas) {
+        SkPaint paint;
+        SkRect r = { 0, 0, SkIntToScalar(W), SkIntToScalar(H) };
+
+        canvas->translate(r.width() / 6, r.height() / 6);
+
+        paint.setShader(fShader);
+        canvas->drawRect(r, paint);
+
+        static const struct {
+            int                     fTolerance;
+            SkAvoidXfermode::Mode   fMode;
+            float                   fDX, fDY;
+        } gData[] = {
+            { 16,       SkAvoidXfermode::kAvoidColor_Mode, 0, 0 },
+            { 255-16,   SkAvoidXfermode::kAvoidColor_Mode, 1, 0 },
+            { 16,       SkAvoidXfermode::kTargetColor_Mode, 0, 1 },
+            { 255-16,   SkAvoidXfermode::kTargetColor_Mode, 1, 1 },
+        };
+
+        paint.setShader(NULL);
+        paint.setColor(SK_ColorMAGENTA);
+
+        SkPaint frameP;
+        frameP.setStyle(SkPaint::kStroke_Style);
+
+        for (size_t i = 0; i < SK_ARRAY_COUNT(gData); i++) {
+            SkAutoTUnref<SkAvoidXfermode> mode(SkAvoidXfermode::Create(
+                SK_ColorGREEN, gData[i].fTolerance, gData[i].fMode));
+            paint.setXfermode(mode);
+            int div = 3;
+            SkRect rr = { 0, 0, r.width()/div, r.height()/div };
+            rr.offset(r.width()/4 - rr.width()/2, r.height()/4 - rr.height()/2);
+            rr.offset(r.width() * gData[i].fDX/2, r.height() * gData[i].fDY/2);
+            canvas->drawRect(rr, paint);
+            paint.setXfermode(NULL);
+
+            canvas->drawRect(rr, frameP);
+        }
+    }
+
+private:
+    typedef SampleView INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static SkView* MyFactory() {
+    return new AvoidView;
+}
+
+static SkViewRegister reg(MyFactory);