Support tiling bitmaps outside clip bounds in SkPDFImageShader

gm/clippedbitmapshaders.cpp

Index: gm/clippedbitmapshaders.cpp
diff --git a/gm/clippedbitmapshaders.cpp b/gm/clippedbitmapshaders.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..02d07bf01e5068f926cf9ae1b423c87d76196874
--- /dev/null
+++ b/gm/clippedbitmapshaders.cpp
@@ -0,0 +1,118 @@
+/*
+ * Copyright 2013 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 "SkBitmap.h"
+#include "SkCanvas.h"
+#include "SkColor.h"
+#include "SkShader.h"
+
+namespace skiagm {
+
+// This GM draws a 3x3 grid (with the center element excluded) of rectangles
+// filled with a bitmap shader. The bitmap shader is transformed so that the
+// pattern cell is at the center (excluded) region.
+//
+// In Repeat and Mirror mode, this tests that the bitmap shader still draws
+// even though the pattern cell is outside the clip.
+//
+// In Clamp mode, this tests that the clamp is handled properly. For PDF,
+// (and possibly other exported formats) this also "tests" that the image itself
+// is not stored (well, you'll need to open it up with an external tool to
+// verify that).
+
+static SkBitmap create_bitmap() {
+    SkBitmap bmp;
+    bmp.setConfig(SkBitmap::kARGB_8888_Config, 2, 2);
+    bmp.allocPixels();
+    bmp.lockPixels();
+    uint32_t* pixels = reinterpret_cast<uint32_t*>(bmp.getPixels());
+    pixels[0] = SkPreMultiplyColor(SK_ColorRED);
+    pixels[1] = SkPreMultiplyColor(SK_ColorGREEN);
+    pixels[2] = SkPreMultiplyColor(SK_ColorBLACK);
+    pixels[3] = SkPreMultiplyColor(SK_ColorBLUE);
+    bmp.unlockPixels();
+
+    return bmp;
+}
+
+static const SkScalar RECT_SIZE = 64;
+static const SkScalar SLIDE_SIZE = 300;
+
+class ClippedBitmapShadersGM : public GM {
+public:
+    ClippedBitmapShadersGM(SkShader::TileMode mode)
+    : fMode(mode) {
+    }
+
+protected:
+    SkShader::TileMode fMode;
+
+    virtual SkString onShortName() {
+        SkString descriptor;
+        switch (fMode) {
+            case SkShader::kRepeat_TileMode:
+                descriptor = "tile";
+            break;
+            case SkShader::kMirror_TileMode:
+                descriptor = "mirror";
+            break;
+            case SkShader::kClamp_TileMode:
+                descriptor = "clamp";
+            break;
+            default:
+                SkASSERT(false);
+        }
+        descriptor.prepend("clipped-bitmap-shaders-");
+        return descriptor;
+    }
+
+    virtual SkISize onISize() {
+        return SkISize::Make(300, 300);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) {
+        SkBitmap bmp = create_bitmap();
+        SkShader* shader = SkShader::CreateBitmapShader(
+                bmp, fMode, fMode);
+
+        SkPaint paint;
+        SkMatrix s;
+        s.reset();
+        s.setScale(8, 8);
+        s.postTranslate(SLIDE_SIZE / 2, SLIDE_SIZE / 2);
+        shader->setLocalMatrix(s);
+        paint.setShader(shader)->unref();
+
+        SkScalar margin = (SLIDE_SIZE / 3 - RECT_SIZE) / 2;
+        for (int i = 0; i < 3; i++) {
+            SkScalar yOrigin = SLIDE_SIZE / 3 * i + margin;
+            for (int j = 0; j < 3; j++) {
+                SkScalar xOrigin = SLIDE_SIZE / 3 * j + margin;
+                if (i == 1 && j == 1) {
+                    continue;   // skip center element
+                }
+                SkRect rect = SkRect::MakeXYWH(xOrigin, yOrigin,
+                                               RECT_SIZE, RECT_SIZE);
+                canvas->save();
+                canvas->clipRect(rect);
+                canvas->drawRect(rect, paint);
+                canvas->restore();
+            }
+        }
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM( return new ClippedBitmapShadersGM(SkShader::kRepeat_TileMode); )
+DEF_GM( return new ClippedBitmapShadersGM(SkShader::kMirror_TileMode); )
+DEF_GM( return new ClippedBitmapShadersGM(SkShader::kClamp_TileMode); )
+}