Add GM to exercise high quality anisotropic scaling

High quality anisotropic is an interesting edge case for the gpu backend. For scales that are both minimizing and maximizing Ganesh falls back to MipMaps which can turn out too blurry.

BUG=472864

Review URL: https://codereview.chromium.org/1058133003

2 files changed, 115 insertions, 0 deletions

diff --git a/gm/anisotropic.cpp b/gm/anisotropic.cpp
new file mode 100644
index 0000000000..a004d750e1
--- /dev/null
+++ b/gm/anisotropic.cpp
@@ -0,0 +1,114 @@
+/*
+ * 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"
+
+namespace skiagm {
+
+// This GM exercises HighQuality anisotropic filtering.
+class AnisotropicGM : public GM {
+public:
+    AnisotropicGM() : fFilterQuality(kHigh_SkFilterQuality) {
+        this->setBGColor(0xFFCCCCCC);
+    }
+
+protected:
+
+    SkString onShortName() override { return SkString("anisotropic_hq"); }
+
+    SkISize onISize() override {
+        return SkISize::Make(2*kImageSize + 3*kSpacer,
+                             kNumVertImages*kImageSize + (kNumVertImages+1)*kSpacer);
+    }
+
+    // Create an image consisting of lines radiating from its center
+    void onOnceBeforeDraw() override {
+        static const int kNumLines = 100;
+        static const SkScalar kAngleStep = 360.0f / kNumLines;
+        static const int kInnerOffset = 10;
+
+        fBM.allocN32Pixels(kImageSize, kImageSize, true);
+
+        SkCanvas canvas(fBM);
+
+        canvas.clear(SK_ColorWHITE);
+
+        SkPaint p;
+        p.setAntiAlias(true);
+
+        SkScalar angle = 0.0f, sin, cos;
+
+        canvas.translate(kImageSize/2.0f, kImageSize/2.0f);
+        for (int i = 0; i < kNumLines; ++i, angle += kAngleStep) {
+            sin = SkScalarSinCos(angle, &cos);
+            canvas.drawLine(cos * kInnerOffset, sin * kInnerOffset,
+                            cos * kImageSize/2, sin * kImageSize/2, p);
+        }
+    }
+
+    void draw(SkCanvas* canvas, int x, int y, int xSize, int ySize) {
+        SkRect r = SkRect::MakeXYWH(SkIntToScalar(x), SkIntToScalar(y),
+                                    SkIntToScalar(xSize), SkIntToScalar(ySize));
+        SkPaint p;
+        p.setFilterQuality(fFilterQuality);
+        canvas->drawBitmapRect(fBM, r, &p);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        SkScalar gScales[] = { 0.9f, 0.8f, 0.75f, 0.6f, 0.5f, 0.4f, 0.25f, 0.2f, 0.1f };
+        
+        SkASSERT(kNumVertImages-1 == (int)SK_ARRAY_COUNT(gScales)/2);
+
+        // Minimize vertically
+        for (int i = 0; i < (int)SK_ARRAY_COUNT(gScales); ++i) {
+            int height = SkScalarFloorToInt(fBM.height() * gScales[i]);
+
+            int yOff;
+            if (i <= (int)SK_ARRAY_COUNT(gScales)/2) {
+                yOff = kSpacer + i * (fBM.height() + kSpacer);
+            } else {
+                // Position the more highly squashed images with their less squashed counterparts
+                yOff = (SK_ARRAY_COUNT(gScales) - i) * (fBM.height() + kSpacer) - height;
+            }
+
+            this->draw(canvas, kSpacer, yOff, fBM.width(), height);
+        }
+
+        // Minimize horizontally
+        for (int i = 0; i < (int)SK_ARRAY_COUNT(gScales); ++i) {
+            int width = SkScalarFloorToInt(fBM.width() * gScales[i]);
+
+            int xOff, yOff;
+            if (i <= (int)SK_ARRAY_COUNT(gScales)/2) {
+                xOff = fBM.width() + 2*kSpacer;
+                yOff = kSpacer + i * (fBM.height() + kSpacer);
+            } else {
+                // Position the more highly squashed images with their less squashed counterparts
+                xOff = fBM.width() + 2*kSpacer + fBM.width() - width;
+                yOff = kSpacer + (SK_ARRAY_COUNT(gScales) - i - 1) * (fBM.height() + kSpacer);
+            }
+
+            this->draw(canvas, xOff, yOff, width, fBM.height());
+        }
+    }
+
+private:
+    static const int kImageSize     = 256;
+    static const int kSpacer        = 10;
+    static const int kNumVertImages = 5;
+
+    SkBitmap         fBM;
+    SkFilterQuality  fFilterQuality;
+
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM( return SkNEW(AnisotropicGM); )
+
+}
diff --git a/gyp/gmslides.gypi b/gyp/gmslides.gypi
index d2db10690b..02297c32b3 100644
--- a/gyp/gmslides.gypi
+++ b/gyp/gmslides.gypi
@@ -22,6 +22,7 @@
         '../gm/addarc.cpp',
         '../gm/all_bitmap_configs.cpp',
         '../gm/alphagradients.cpp',
+        '../gm/anisotropic.cpp',
         '../gm/arcofzorro.cpp',
         '../gm/arithmode.cpp',
         '../gm/astcbitmap.cpp',