SkTextBlob shader space workaround.

gm/textblobshader.cpp

+/*
+ * Copyright 2014 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 "SkCanvas.h"
+#include "SkGradientShader.h"
+#include "SkPoint.h"
+#include "SkShader.h"
+#include "SkTextBlob.h"
+#include "SkTDArray.h"
+#include "SkTypeface.h"
+
+// This GM exercises drawTextBlob offset vs. shader space behavior.
+class TextBlobShaderGM : public skiagm::GM {
+public:
+    TextBlobShaderGM(const char* txt) {
+        SkPaint p;
+        size_t txtLen = strlen(txt);
+        fGlyphs.append(p.textToGlyphs(txt, txtLen, NULL));
+        p.textToGlyphs(txt, txtLen, fGlyphs.begin());
+    }
+
+protected:
+
+    virtual void onOnceBeforeDraw() SK_OVERRIDE {
+        SkPaint p;
+        p.setAntiAlias(true);
+        p.setSubpixelText(true);
+        p.setTextSize(30);
+        p.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
+
+        SkTextBlobBuilder builder;
+        int glyphCount = fGlyphs.count();
+        const SkTextBlobBuilder::RunBuffer* run;
+
+        run = &builder.allocRun(p, glyphCount, 10, 10, NULL);
+        memcpy(run->glyphs, fGlyphs.begin(), glyphCount * sizeof(uint16_t));
+
+        run = &builder.allocRunPosH(p, glyphCount,  80, NULL);
+        memcpy(run->glyphs, fGlyphs.begin(), glyphCount * sizeof(uint16_t));
+        for (int i = 0; i < glyphCount; ++i) {
+            run->pos[i] = p.getTextSize() * i * .75f;
+        }
+
+        run = &builder.allocRunPos(p, glyphCount, NULL);
+        memcpy(run->glyphs, fGlyphs.begin(), glyphCount * sizeof(uint16_t));
+        for (int i = 0; i < glyphCount; ++i) {
+            run->pos[i * 2] = p.getTextSize() * i * .75f;
+            run->pos[i * 2 + 1] = 150 + 5 * sinf((float)i * 8 / glyphCount);
+        }
+
+        fBlob.reset(builder.build());
+
+        SkColor  colors[2];
+        colors[0] = SK_ColorRED;
+        colors[1] = SK_ColorGREEN;
+
+        SkScalar pos[SK_ARRAY_COUNT(colors)];
+        for (unsigned i = 0; i < SK_ARRAY_COUNT(pos); ++i) {
+            pos[i] = (float)i / (SK_ARRAY_COUNT(pos) - 1);
+        }
+
+        SkISize sz = this->onISize();
+        fShader.reset(SkGradientShader::CreateRadial(SkPoint::Make(SkIntToScalar(sz.width() / 2),
+                                                                   SkIntToScalar(sz.height() / 2)),
+                                                     sz.width() * .66f, colors, pos,
+                                                     SK_ARRAY_COUNT(colors),
+                                                     SkShader::kRepeat_TileMode));
+    }
+
+    virtual uint32_t onGetFlags() const SK_OVERRIDE {
+        return kSkip565_Flag;
+    }
+
+    virtual SkString onShortName() SK_OVERRIDE {
+        return SkString("textblobshader");
+    }
+
+    virtual SkISize onISize() SK_OVERRIDE {
+        return SkISize::Make(640, 480);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        SkPaint p;
+        p.setStyle(SkPaint::kFill_Style);
+        p.setShader(fShader);
+
+        SkISize sz = this->onISize();
+        static const int kXCount = 4;
+        static const int kYCount = 3;
+        for (int i = 0; i < kXCount; ++i) {
+            for (int j = 0; j < kYCount; ++j) {
+                canvas->drawTextBlob(fBlob,
+                                     SkIntToScalar(i * sz.width() / kXCount),
+                                     SkIntToScalar(j * sz.height() / kYCount),
+                                     p);
+            }
+        }
+    }
+
+private:
+    SkTDArray<uint16_t>            fGlyphs;
+    SkAutoTUnref<const SkTextBlob> fBlob;
+    SkAutoTUnref<SkShader>         fShader;
+
+    typedef skiagm::GM INHERITED;
+};
+
+DEF_GM( return SkNEW_ARGS(TextBlobShaderGM, ("Blobber")); )