Preserve GrContext's matrix when calling SkShader::asNewEffect.

src/gpu/SkGr.cpp

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGr.h"
 #include "SkColorFilter.h"
 #include "SkConfig8888.h"
@@ skipping 360 matching lines @@
             grPaint->setColor(SkColor2GrColor(filtered));
         } else {
             SkAutoTUnref<GrEffectRef> effect(colorFilter->asNewEffect(context));
             if (NULL != effect.get()) {
                 grPaint->addColorEffect(effect);
             }
         }
     }
 }
 
+/**
+ * Unlike GrContext::AutoMatrix, this doesn't require setting a new matrix. GrContext::AutoMatrix
+ * likes to set the new matrix in its constructor because it is usually necessary to simulataneously
+ * update a GrPaint. This AutoMatrix is used while initially setting up GrPaint, however.
+ */
+class AutoMatrix {
+public:
+    AutoMatrix(GrContext* context) {
+        fMatrix = context->getMatrix();
+        fContext = context;
+    }
+    ~AutoMatrix() {
+        SkASSERT(NULL != fContext);
+        fContext->setMatrix(fMatrix);
+    }
+private:
+    GrContext* fContext;
+    SkMatrix fMatrix;
+};
+
 void SkPaint2GrPaintShader(GrContext* context, const SkPaint& skPaint,
                            bool constantColor, GrPaint* grPaint) {
     SkShader* shader = skPaint.getShader();
     if (NULL == shader) {
         SkPaint2GrPaintNoShader(context, skPaint, false, constantColor, grPaint);
         return;
     }
 
-    // SkShader::asNewEffect() may do offscreen rendering. Setup default drawing state and require
-    // the shader to set a render target.
-    GrContext::AutoWideOpenIdentityDraw awo(context, NULL);
+    // SkShader::asNewEffect() may do offscreen rendering. Save off the current RT, clip, and
+    // matrix. We don't reset the matrix on the context because SkShader::asNewEffect may use
+    // GrContext::getMatrix() to know the transformation from local coords to device space.
+    GrContext::AutoRenderTarget art(context, NULL);
+    GrContext::AutoClip ac(context, GrContext::AutoClip::kWideOpen_InitialClip);
+    AutoMatrix am(context);
 
     // setup the shader as the first color effect on the paint
     SkAutoTUnref<GrEffectRef> effect(shader->asNewEffect(context, skPaint, NULL));
     if (NULL != effect.get()) {
         grPaint->addColorEffect(effect);
         // Now setup the rest of the paint.
         SkPaint2GrPaintNoShader(context, skPaint, true, false, grPaint);
     } else {
         // We still don't have SkColorShader::asNewEffect() implemented.
         SkShader::GradientInfo info;
         SkColor                color;
 
         info.fColors = &color;
         info.fColorOffsets = NULL;
         info.fColorCount = 1;
         if (SkShader::kColor_GradientType == shader->asAGradient(&info)) {
             SkPaint copy(skPaint);
             copy.setShader(NULL);
             // modulate the paint alpha by the shader's solid color alpha
             U8CPU newA = SkMulDiv255Round(SkColorGetA(color), copy.getAlpha());
             copy.setColor(SkColorSetA(color, newA));
             SkPaint2GrPaintNoShader(context, copy, false, constantColor, grPaint);
         } else {
             SkPaint2GrPaintNoShader(context, skPaint, false, constantColor, grPaint);
         }
     }
 }