Add GM to test drawing atlas case

gm/drawminibitmaprect.cpp

Index: gm/drawminibitmaprect.cpp
diff --git a/gm/drawminibitmaprect.cpp b/gm/drawminibitmaprect.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..56f99082f41a859a4f67ba9f5f5ee74dba034bdf
--- /dev/null
+++ b/gm/drawminibitmaprect.cpp
@@ -0,0 +1,143 @@
+/*
+ * Copyright 2015 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 "SkColorPriv.h"
+#include "SkGradientShader.h"
+#include "SkImage.h"
+#include "SkRandom.h"
+#include "SkShader.h"
+#include "SkSurface.h"
+
+static SkImage* makebm(SkCanvas* caller, int w, int h) {
+    SkImageInfo info = SkImageInfo::MakeN32Premul(w, h);
+    SkAutoTUnref<SkSurface> surface(caller->newSurface(info));
+    if (NULL == surface) {
+        surface.reset(SkSurface::NewRaster(info));
+    }
+    SkCanvas* canvas = surface->getCanvas();
+
+    const SkScalar wScalar = SkIntToScalar(w);
+    const SkScalar hScalar = SkIntToScalar(h);
+
+    const SkPoint     pt = { wScalar / 2, hScalar / 2 };
+
+    const SkScalar    radius = 4 * SkMaxScalar(wScalar, hScalar);
+
+    static const SkColor     colors[] = { SK_ColorRED, SK_ColorYELLOW,
+                                          SK_ColorGREEN, SK_ColorMAGENTA,
+                                          SK_ColorBLUE, SK_ColorCYAN,
+                                          SK_ColorRED};
+
+    static const SkScalar    pos[] = {0,
+                                      SK_Scalar1 / 6,
+                                      2 * SK_Scalar1 / 6,
+                                      3 * SK_Scalar1 / 6,
+                                      4 * SK_Scalar1 / 6,
+                                      5 * SK_Scalar1 / 6,
+                                      SK_Scalar1};
+
+    SkASSERT(SK_ARRAY_COUNT(colors) == SK_ARRAY_COUNT(pos));
+    SkPaint     paint;
+    SkRect rect = SkRect::MakeWH(wScalar, hScalar);
+    SkMatrix mat = SkMatrix::I();
+    for (int i = 0; i < 4; ++i) {
+        paint.setShader(SkGradientShader::CreateRadial(
+                        pt, radius,
+                        colors, pos,
+                        SK_ARRAY_COUNT(colors),
+                        SkShader::kRepeat_TileMode,
+                        0, &mat))->unref();
+        canvas->drawRect(rect, paint);
+        rect.inset(wScalar / 8, hScalar / 8);
+        mat.postScale(SK_Scalar1 / 4, SK_Scalar1 / 4);
+    }
+    return surface->newImageSnapshot();
+}
+
+static const int gSize = 1024;
+static const int gSurfaceSize = 2048;
+
+// This GM calls drawImageRect several times using the same texture. This is
+// intended to exercise batching of these calls.
+class DrawMiniBitmapRectGM : public skiagm::GM {
+public:
+    DrawMiniBitmapRectGM(bool antiAlias) : fAA(antiAlias) {
+        fName.set("drawminibitmaprect");
+        if (fAA) {
+            fName.appendf("_aa");
+        }
+    }
+
+protected:
+    SkString onShortName() override { return fName; }
+
+    SkISize onISize() override { return SkISize::Make(gSize, gSize); }
+
+    void onDraw(SkCanvas* canvas) override {
+        if (NULL == fImage) {
+            fImage.reset(makebm(canvas, gSurfaceSize, gSurfaceSize));
+        }
+
+        const SkRect dstRect = { 0, 0, SkIntToScalar(64), SkIntToScalar(64)};
+        static const int kMaxSrcRectSize = 1 << (SkNextLog2(gSurfaceSize) + 2);
+
+        static const int kPadX = 30;
+        static const int kPadY = 40;
+
+        int rowCount = 0;
+        canvas->translate(SkIntToScalar(kPadX), SkIntToScalar(kPadY));
+        canvas->save();
+        SkRandom random;
+
+        SkPaint paint;
+        paint.setAntiAlias(fAA);
+        for (int w = 1; w <= kMaxSrcRectSize; w *= 3) {
+            for (int h = 1; h <= kMaxSrcRectSize; h *= 3) {
+
+                const SkIRect srcRect =
+                        SkIRect::MakeXYWH((gSurfaceSize - w) / 2, (gSurfaceSize - h) / 2, w, h);
+                canvas->save();
+                switch (random.nextU() % 3) {
+                    case 0:
+                        canvas->rotate(random.nextF() * 10.f);
+                        break;
+                    case 1:
+                        canvas->rotate(-random.nextF() * 10.f);
+                        break;
+                    case 2:
+                        // rect stays rect
+                        break;
+                }
+                canvas->drawImageRect(fImage, srcRect, dstRect, &paint,
+                                      SkCanvas::kFast_SrcRectConstraint);
+                canvas->restore();
+
+                canvas->translate(dstRect.width() + SK_Scalar1 * kPadX, 0);
+                ++rowCount;
+                if ((dstRect.width() + 2 * kPadX) * rowCount > gSize) {
+                    canvas->restore();
+                    canvas->translate(0, dstRect.height() + SK_Scalar1 * kPadY);
+                    canvas->save();
+                    rowCount = 0;
+                }
+            }
+        }
+        canvas->restore();
+    }
+
+private:
+    bool                  fAA;
+    SkAutoTUnref<SkImage> fImage;
+    SkString              fName;
+
+    typedef skiagm::GM INHERITED;
+};
+
+DEF_GM( return new DrawMiniBitmapRectGM(true); )
+DEF_GM( return new DrawMiniBitmapRectGM(false); )
+