start a wrapper for color fonts

src/fonts/SkGScalerContext.cpp

+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkGScalerContext.h"
+#include "SkGlyph.h"
+#include "SkPath.h"
+#include "SkCanvas.h"
+
+class SkGScalerContext : public SkScalerContext {
+public:
+    SkGScalerContext(SkGTypeface*, const SkDescriptor*);
+    virtual ~SkGScalerContext();
+    
+protected:
+    virtual unsigned generateGlyphCount() SK_OVERRIDE;
+    virtual uint16_t generateCharToGlyph(SkUnichar) SK_OVERRIDE;
+    virtual void generateAdvance(SkGlyph*) SK_OVERRIDE;
+    virtual void generateMetrics(SkGlyph*) SK_OVERRIDE;
+    virtual void generateImage(const SkGlyph&) SK_OVERRIDE;
+    virtual void generatePath(const SkGlyph&, SkPath*) SK_OVERRIDE;
+    virtual void generateFontMetrics(SkPaint::FontMetrics* mX,
+                                     SkPaint::FontMetrics* mY) SK_OVERRIDE;
+    
+private:
+    SkGTypeface*     fFace;
+    SkScalerContext* fProxy;
+    SkMatrix         fMatrix;
+};
+
+#define STD_SIZE    1
+
+#include "SkDescriptor.h"
+
+SkGScalerContext::SkGScalerContext(SkGTypeface* face, const SkDescriptor* desc)
+        : SkScalerContext(face, desc)
+        , fFace(face)
+{
+
+    size_t  descSize = SkDescriptor::ComputeOverhead(1) + sizeof(SkScalerContext::Rec);
+    SkAutoDescriptor ad(descSize);
+    SkDescriptor*    newDesc = ad.getDesc();
+
+    newDesc->init();
+    void* entry = newDesc->addEntry(kRec_SkDescriptorTag,
+                                    sizeof(SkScalerContext::Rec), &fRec);
+    {
+        SkScalerContext::Rec* rec = (SkScalerContext::Rec*)entry;
+        rec->fTextSize = STD_SIZE;
+        rec->fPreScaleX = SK_Scalar1;
+        rec->fPreSkewX = 0;
+        rec->fPost2x2[0][0] = rec->fPost2x2[1][1] = SK_Scalar1;
+        rec->fPost2x2[1][0] = rec->fPost2x2[0][1] = 0;
+    }
+    SkASSERT(descSize == newDesc->getLength());
+    newDesc->computeChecksum();
+
+    fProxy = face->proxy()->createScalerContext(newDesc);
+
+    fRec.getSingleMatrix(&fMatrix);
+    fMatrix.preScale(SK_Scalar1 / STD_SIZE, SK_Scalar1 / STD_SIZE);
+}
+
+SkGScalerContext::~SkGScalerContext() {
+    SkDELETE(fProxy);
+}
+
+unsigned SkGScalerContext::generateGlyphCount() {
+    return fProxy->getGlyphCount();
+}
+
+uint16_t SkGScalerContext::generateCharToGlyph(SkUnichar uni) {
+    return fProxy->charToGlyphID(uni);
+}
+
+void SkGScalerContext::generateAdvance(SkGlyph* glyph) {
+    fProxy->getAdvance(glyph);
+    
+    SkVector advance;
+    fMatrix.mapXY(SkFixedToScalar(glyph->fAdvanceX),
+                  SkFixedToScalar(glyph->fAdvanceY), &advance);
+    glyph->fAdvanceX = SkScalarToFixed(advance.fX);
+    glyph->fAdvanceY = SkScalarToFixed(advance.fY);
+}
+
+void SkGScalerContext::generateMetrics(SkGlyph* glyph) {
+    fProxy->getMetrics(glyph);
+
+    SkVector advance;
+    fMatrix.mapXY(SkFixedToScalar(glyph->fAdvanceX),
+                  SkFixedToScalar(glyph->fAdvanceY), &advance);
+    glyph->fAdvanceX = SkScalarToFixed(advance.fX);
+    glyph->fAdvanceY = SkScalarToFixed(advance.fY);
+
+    SkPath path;
+    fProxy->getPath(*glyph, &path);
+    path.transform(fMatrix);
+
+    SkRect storage;
+    const SkPaint& paint = fFace->paint();
+    const SkRect& newBounds = paint.doComputeFastBounds(path.getBounds(),
+                                                        &storage,
+                                                        SkPaint::kFill_Style);
+    SkIRect ibounds;
+    newBounds.roundOut(&ibounds);
+    glyph->fLeft = ibounds.fLeft;
+    glyph->fTop = ibounds.fTop;
+    glyph->fWidth = ibounds.width();
+    glyph->fHeight = ibounds.height();
+    glyph->fMaskFormat = SkMask::kARGB32_Format;
+}
+
+void SkGScalerContext::generateImage(const SkGlyph& glyph) {
+    if (SkMask::kARGB32_Format == glyph.fMaskFormat) {
+        SkPath path;
+        fProxy->getPath(glyph, &path);
+        
+        SkBitmap bm;
+        bm.setConfig(SkBitmap::kARGB_8888_Config, glyph.fWidth, glyph.fHeight,
+                     glyph.rowBytes());
+        bm.setPixels(glyph.fImage);
+        bm.eraseColor(0);
+        
+        SkCanvas canvas(bm);
+        canvas.translate(-glyph.fLeft, -glyph.fTop);
+        canvas.concat(fMatrix);
+        canvas.drawPath(path, fFace->paint());
+    } else {
+        fProxy->getImage(glyph);
+    }
+}
+
+void SkGScalerContext::generatePath(const SkGlyph& glyph, SkPath* path) {
+    fProxy->getPath(glyph, path);
+    path->transform(fMatrix);
+}
+
+void SkGScalerContext::generateFontMetrics(SkPaint::FontMetrics*,
+                                           SkPaint::FontMetrics* metrics) {
+    fProxy->getFontMetrics(metrics);
+    if (metrics) {
+        SkScalar scale = fMatrix.getScaleY();
+        metrics->fTop = SkScalarMul(metrics->fTop, scale);
+        metrics->fAscent = SkScalarMul(metrics->fAscent, scale);
+        metrics->fDescent = SkScalarMul(metrics->fDescent, scale);
+        metrics->fBottom = SkScalarMul(metrics->fBottom, scale);
+        metrics->fLeading = SkScalarMul(metrics->fLeading, scale);
+        metrics->fAvgCharWidth = SkScalarMul(metrics->fAvgCharWidth, scale);
+        metrics->fXMin = SkScalarMul(metrics->fXMin, scale);
+        metrics->fXMax = SkScalarMul(metrics->fXMax, scale);
+        metrics->fXHeight = SkScalarMul(metrics->fXHeight, scale);
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+#include "SkTypefaceCache.h"
+
+SkGTypeface::SkGTypeface(SkTypeface* proxy, const SkPaint& paint)
+    : SkTypeface(proxy->style(), SkTypefaceCache::NewFontID(), false)
+    , fProxy(SkRef(proxy))
+    , fPaint(paint) {}
+
+SkGTypeface::~SkGTypeface() {
+    fProxy->unref();
+}
+
+SkScalerContext* SkGTypeface::onCreateScalerContext(
+                                            const SkDescriptor* desc) const {
+    return SkNEW_ARGS(SkGScalerContext, (const_cast<SkGTypeface*>(this), desc));
+}
+
+void SkGTypeface::onFilterRec(SkScalerContextRec* rec) const {
+    fProxy->filterRec(rec);
+}
+
+SkAdvancedTypefaceMetrics* SkGTypeface::onGetAdvancedTypefaceMetrics(
+                                SkAdvancedTypefaceMetrics::PerGlyphInfo info,
+                                const uint32_t* glyphIDs,
+                                uint32_t glyphIDsCount) const {
+    return fProxy->getAdvancedTypefaceMetrics(info, glyphIDs, glyphIDsCount);
+}
+
+SkStream* SkGTypeface::onOpenStream(int* ttcIndex) const {
+    return fProxy->openStream(ttcIndex);
+}
+
+void SkGTypeface::onGetFontDescriptor(SkFontDescriptor* desc,
+                                      bool* isLocal) const {
+    fProxy->getFontDescriptor(desc, isLocal);
+}
+
+int SkGTypeface::onGetUPEM() const {
+    return fProxy->getUnitsPerEm();
+}
+
+int SkGTypeface::onGetTableTags(SkFontTableTag tags[]) const {
+    return fProxy->getTableTags(tags);
+}
+
+size_t SkGTypeface::onGetTableData(SkFontTableTag tag, size_t offset,
+                                    size_t length, void* data) const {
+    return fProxy->getTableData(tag, offset, length, data);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+#if 0
+// under construction -- defining a font purely in terms of skia primitives
+// ala an SVG-font.
+class SkGFont : public SkRefCnt {
+public:
+    virtual ~SkGFont();
+    
+    int unicharToGlyph(SkUnichar) const;
+    
+    int countGlyphs() const { return fCount; }
+    
+    float getAdvance(int index) const {
+        SkASSERT((unsigned)index < (unsigned)fCount);
+        return fGlyphs[index].fAdvance;
+    }
+    
+    const SkPath& getPath(int index) const {
+        SkASSERT((unsigned)index < (unsigned)fCount);
+        return fGlyphs[index].fPath;
+    }
+    
+private:
+    struct Glyph {
+        SkUnichar   fUni;
+        float       fAdvance;
+        SkPath      fPath;
+    };
+    int fCount;
+    Glyph* fGlyphs;
+    
+    friend class SkGFontBuilder;
+    SkGFont(int count, Glyph* array);
+};
+
+class SkGFontBuilder {
+public:
+    
+};
+#endif