Don't clobber initial transform with SetMatrix.

tests/RecordDrawTest.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "Test.h"
+#include "RecordTestUtils.h"
 
 #include "SkDebugCanvas.h"
 #include "SkRecord.h"
 #include "SkRecordOpts.h"
 #include "SkRecordDraw.h"
 #include "SkRecorder.h"
 #include "SkRecords.h"
 
 static const int W = 1920, H = 1080;
 
@@ skipping 47 matching lines @@
     SkRecordAnnotateCullingPairs(&record);
 
     // This clip intersects the outer cull, but allows us to quick reject the inner one.
     SkRecord clipped;
     record_clipped(record, SkRect::MakeLTRB(20, 20, 200, 200), &clipped);
 
     // We'll keep the clipRect call from above, and the outer two drawRects, and the push/pop pair.
     // If culling weren't working, we'd see 8 commands recorded here.
     REPORTER_ASSERT(r, 5 == clipped.count());
 }
+
+DEF_TEST(RecordDraw_SetMatrixClobber, r) {
+    // Set up an SkRecord that just scales by 2x,3x.
+    SkRecord scaleRecord;
+    SkRecorder scaleCanvas(SkRecorder::kReadWrite_Mode, &scaleRecord, W, H);
+    SkMatrix scale;
+    scale.setScale(2, 3);
+    scaleCanvas.setMatrix(scale);
+
+    // Set up an SkRecord with an initial +20, +20 translate.
+    SkRecord translateRecord;
+    SkRecorder translateCanvas(SkRecorder::kReadWrite_Mode, &translateRecord, W, H);
+    SkMatrix translate;
+    translate.setTranslate(20, 20);
+    translateCanvas.setMatrix(translate);
+
+    SkRecordDraw(scaleRecord, &translateCanvas);
+
+    // When we look at translateRecord now, it should have its first +20,+20 translate,
+    // then a 2x,3x scale that's been concatted with that +20,+20 translate.
+    const SkRecords::SetMatrix* setMatrix;
+    setMatrix = assert_type<SkRecords::SetMatrix>(r, translateRecord, 0);
+    REPORTER_ASSERT(r, setMatrix->matrix == translate);
+
+    setMatrix = assert_type<SkRecords::SetMatrix>(r, translateRecord, 1);
+    SkMatrix expected = scale;
+    expected.postConcat(translate);
+    REPORTER_ASSERT(r, setMatrix->matrix == expected);
+}