Add a nanobench for drawing glyphs as paths

Bug: skia:
Change-Id: I6e620befd2fe8e84f744e79e9287d9d2d19ffa57
Reviewed-on: https://skia-review.googlesource.com/21389
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>

bench/PathTextBench.cpp

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "Benchmark.h"
+#include "SkCanvas.h"
+#include "SkGlyphCache.h"
+#include "SkPaint.h"
+#include "SkPath.h"
+#include "SkRandom.h"
+
+static constexpr int kScreenWidth = 1500;
+static constexpr int kScreenHeight = 1500;
+
+static constexpr int kNumDraws = 2000;
+
+// I and l are rects on OS X.
+static constexpr char kGlyphs[] =  "ABCDEFGH7JKLMNOPQRSTUVWXYZabcdefghijk1mnopqrstuvwxyz";
+static constexpr int kNumGlyphs = sizeof(kGlyphs) - 1;
+static_assert(52 == kNumGlyphs, "expected 52 glyphs");
+
+/*
+ * This class benchmarks drawing many glyphs at random scales and rotations.
+ */
+class PathTextBench : public Benchmark {
+public:
+    bool isVisual() override { return true; }
+
+private:
+    const char* onGetName() override {
+        return "path_text";
+    }
+    SkIPoint onGetSize() override { return SkIPoint::Make(kScreenWidth, kScreenHeight); }
+
+    void onDelayedSetup() override {
+        SkPaint defaultPaint;
+        SkAutoGlyphCache agc(defaultPaint, nullptr, &SkMatrix::I());
+        SkGlyphCache* cache = agc.getCache();
+        for (int i = 0; i < kNumGlyphs; ++i) {
+            SkGlyphID id = cache->unicharToGlyph(kGlyphs[i]);
+            cache->getScalerContext()->getPath(SkPackedGlyphID(id), &fGlyphs[i]);
+        }
+
+        SkRandom rand;
+        for (int i = 0; i < kNumDraws; ++i) {
+            const SkPath& glyph = fGlyphs[i % kNumGlyphs];
+            const SkRect& bounds = glyph.getBounds();
+            float glyphSize = SkTMax(bounds.width(), bounds.height());
+
+            float t0 = pow(rand.nextF(), 100);
+            float size = (1 - t0) * SkTMin(kScreenWidth, kScreenHeight) / 50 +
+                         t0 * SkTMin(kScreenWidth, kScreenHeight) / 3;
+            float scale = size / glyphSize;
+            float t1 = rand.nextF(), t2 = rand.nextF();
+            fXforms[i].setTranslate((1 - t1) * sqrt(2) * scale/2 * glyphSize +
+                                     t1 * (kScreenWidth - sqrt(2) * scale/2 * glyphSize),
+                                     (1 - t2) * sqrt(2) * scale/2 * glyphSize +
+                                     t2 * (kScreenHeight - sqrt(2) * scale/2 * glyphSize));
+            fXforms[i].preRotate(rand.nextF() * 360);
+            fXforms[i].preTranslate(-scale/2 * bounds.width(), -scale/2 * bounds.height());
+            fXforms[i].preScale(scale, scale);
+            fPaints[i].setAntiAlias(true);
+            fPaints[i].setColor(rand.nextU() | 0x80808080);
+        }
+    }
+
+    void onDraw(int loops, SkCanvas* canvas) override {
+        SkAutoCanvasRestore acr(canvas, true);
+        for (int i = 0; i < kNumDraws; ++i) {
+            const SkPath& glyph = fGlyphs[i % kNumGlyphs];
+            canvas->setMatrix(fXforms[i]);
+            canvas->drawPath(glyph, fPaints[i]);
+        }
+    }
+
+    SkPath fGlyphs[kNumGlyphs];
+    SkPaint fPaints[kNumDraws];
+    SkMatrix fXforms[kNumDraws];
+
+    typedef Benchmark INHERITED;
+};
+
+DEF_BENCH(return new PathTextBench;)

gn/bench.gni

@@ -84,6 +84,7 @@ bench_sources = [
   "$_bench/PatchBench.cpp",
   "$_bench/PathBench.cpp",
   "$_bench/PathIterBench.cpp",
+  "$_bench/PathTextBench.cpp",
   "$_bench/PDFBench.cpp",
   "$_bench/PerlinNoiseBench.cpp",
   "$_bench/PictureNestingBench.cpp",