fix for cached textblobs look garbled

gm/textblobgeometrychange.cpp

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+
+#include "SkCanvas.h"
+#include "SkSurface.h"
+#include "SkTextBlob.h"
+
+// This tests that we don't try to reuse textblobs from the GPU textblob cache across pixel geometry
+// changes when we have LCD.  crbug/486744
+namespace skiagm {
+class TextBlobGeometryChange : public GM {
+public:
+    TextBlobGeometryChange() { }
+
+protected:
+    SkString onShortName() override {
+        return SkString("textblobgeometrychange");
+    }
+
+    SkISize onISize() override {
+        return SkISize::Make(kWidth, kHeight);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        const char text[] = "Hamburgefons";
+
+        SkPaint paint;
+        sk_tool_utils::set_portable_typeface(&paint);
+        paint.setTextSize(20);
+        paint.setAntiAlias(true);
+        paint.setLCDRenderText(true);
+
+        SkTextBlobBuilder builder;
+
+        sk_tool_utils::add_to_text_blob(&builder, text, paint, 10, 10);
+
+        SkAutoTUnref<const SkTextBlob> blob(builder.build());
+
+        SkImageInfo info = SkImageInfo::MakeN32Premul(200, 200);
+        SkSurfaceProps props(0, kUnknown_SkPixelGeometry);
+        SkAutoTUnref<SkSurface> surface(canvas->newSurface(info, &props));
+        if (surface) {
+            SkCanvas* c = surface->getCanvas();
+
+            // LCD text on white background
+            SkRect rect = SkRect::MakeLTRB(0.f, 0.f, SkIntToScalar(kWidth), kHeight / 2.f);
+            SkPaint rectPaint;
+            rectPaint.setColor(0xffffffff);
+            canvas->drawRect(rect, rectPaint);
+            canvas->drawTextBlob(blob.get(), 10, 50, paint);
+
+            // This should not look garbled since we should disable LCD text in this case
+            // (i.e., unknown pixel geometry)
+            c->clear(0x00ffffff);
+            c->drawTextBlob(blob.get(), 10, 150, paint);
+            surface->draw(canvas, 0, 0, nullptr);
+        } else {
+            const char* text = "This test requires a surface";
+            size_t len = strlen(text);
+            SkPaint paint;
+            canvas->drawText(text, len, 10, 100, paint);
+        }
+    }
+
+private:
+    static const int kWidth = 200;
+    static const int kHeight = 200;
+
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM( return SkNEW(TextBlobGeometryChange); )
+}