new animated sample to show subpixel translate bug with high quality scaling

samplecode/SampleSubpixelTranslate.cpp

Index: samplecode/SampleSubpixelTranslate.cpp
diff --git a/samplecode/SampleSubpixelTranslate.cpp b/samplecode/SampleSubpixelTranslate.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..dd1ba110a6ffe725b16ab09dc5c5226460ae6761
--- /dev/null
+++ b/samplecode/SampleSubpixelTranslate.cpp
@@ -0,0 +1,126 @@
+
+/*
+ * 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 "gm.h"
+#include "SampleCode.h"
+#include "SkBlurMaskFilter.h"
+#include "SkColorPriv.h"
+#include "SkCanvas.h"
+#include "SkImageDecoder.h"
+#include "SkRandom.h"
+#include "SkStream.h"
+
+// Intended to exercise pixel snapping observed with scaled images (and
+// with non-scaled images, but for a different reason):  Bug 1145
+
+class SubpixelTranslateView : public SampleView {
+public:
+    SubpixelTranslateView(const char imageFilename[],
+                          float horizontalVelocity,
+                          float verticalVelocity)
+      : fFilename(imageFilename),
+        fHorizontalVelocity(horizontalVelocity),
+        fVerticalVelocity(verticalVelocity) {
+      SkString path(skiagm::GM::GetResourcePath());
+      path.append("/");
+      path.append(fFilename);
+
+      SkImageDecoder *codec = NULL;
+      SkFILEStream stream(path.c_str());
+      if (stream.isValid()) {
+          codec = SkImageDecoder::Factory(&stream);
+      }
+      if (codec) {
+          stream.rewind();
+          codec->decode(&stream, &fBM, SkBitmap::kARGB_8888_Config,
+                        SkImageDecoder::kDecodePixels_Mode);
+          SkDELETE(codec);
+      } else {
+          fBM.allocN32Pixels(1, 1);
+          *(fBM.getAddr32(0,0)) = 0xFF0000FF; // red == bad
+      }
+      fCurPos = SkPoint::Make(0,0);
+      fSize = 200;
+    }
+
+protected:
+    SkBitmap fBM;
+    SkString fFilename;
+    int fSize;
+    float fHorizontalVelocity, fVerticalVelocity;
+
+    SkPoint fCurPos;
+
+    // overrides from SkEventSink
+    virtual bool onQuery(SkEvent* evt) SK_OVERRIDE {
+        if (SampleCode::TitleQ(*evt)) {
+            SampleCode::TitleR(evt, "SubpixelTranslate");
+            return true;
+        }
+        return this->INHERITED::onQuery(evt);
+    }
+
+    virtual void onDrawContent(SkCanvas* canvas) SK_OVERRIDE {
+
+        static const SkPaint::FilterLevel gLevels[] = {
+            SkPaint::kNone_FilterLevel,
+            SkPaint::kLow_FilterLevel,
+            SkPaint::kMedium_FilterLevel,
+            SkPaint::kHigh_FilterLevel
+        };
+
+        SkPaint paint;
+        paint.setTextSize(48);
+
+        paint.setAntiAlias(true);
+        for (size_t i = 0; i < SK_ARRAY_COUNT(gLevels); ++i) {
+            paint.setFilterLevel(gLevels[i]);
+            SkRect r = SkRect::MakeXYWH( fCurPos.fX + i * (fSize + 10), fCurPos.fY, fSize, fSize );
+            canvas->drawBitmapRect( fBM, r, &paint );
+        }
+
+        canvas->drawText( "AA Scaled", strlen("AA Scaled"), fCurPos.fX + SK_ARRAY_COUNT(gLevels) * (fSize + 10), fCurPos.fY + fSize/2, paint );
+
+        paint.setAntiAlias(false);
+        for (size_t i = 0; i < SK_ARRAY_COUNT(gLevels); ++i) {
+            paint.setFilterLevel(gLevels[i]);
+            SkRect r = SkRect::MakeXYWH( fCurPos.fX + i * (fSize + 10), fCurPos.fY + fSize + 10, fSize, fSize );
+            canvas->drawBitmapRect( fBM, r, &paint );
+        }
+        canvas->drawText( "Scaled", strlen("Scaled"), fCurPos.fX + SK_ARRAY_COUNT(gLevels) * (fSize + 10), fCurPos.fY + fSize + 10 + fSize/2, paint );
+
+        paint.setAntiAlias(true);
+        for (size_t i = 0; i < SK_ARRAY_COUNT(gLevels); ++i) {
+            paint.setFilterLevel(gLevels[i]);
+            canvas->drawBitmap( fBM, fCurPos.fX + i * (fBM.width() + 10), fCurPos.fY + 2*(fSize + 10), &paint );
+        }
+
+        canvas->drawText( "AA No Scale", strlen("AA No Scale"), fCurPos.fX + SK_ARRAY_COUNT(gLevels) * (fBM.width() + 10), fCurPos.fY + 2*(fSize + 10) + fSize/2, paint );
+
+        paint.setAntiAlias(false);
+        for (size_t i = 0; i < SK_ARRAY_COUNT(gLevels); ++i) {
+            paint.setFilterLevel(gLevels[i]);
+            canvas->drawBitmap( fBM, fCurPos.fX + i * (fBM.width() + 10), fCurPos.fY + 2*(fSize + 10) + fBM.height() + 10, &paint );
+        }
+
+        canvas->drawText( "No Scale", strlen("No Scale"), fCurPos.fX + SK_ARRAY_COUNT(gLevels) * (fBM.width() + 10), fCurPos.fY + 2*(fSize + 10) + fBM.height() + 10 + fSize/2, paint );
+
+
+        fCurPos.fX += fHorizontalVelocity;
+        fCurPos.fY += fVerticalVelocity;
+        this->inval(NULL);
+    }
+
+private:
+    typedef SampleView INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static SkView* MyFactory() { return new SubpixelTranslateView("mandrill_256.png", .05, .05); }
+static SkViewRegister reg(MyFactory);