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/*
* Copyright 2009 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkHarfBuzzFont.h"
#include "SkFontHost.h"
#include "SkPaint.h"
#include "SkPath.h"
// HB_Fixed is a 26.6 fixed point format.
static inline HB_Fixed SkScalarToHarfbuzzFixed(SkScalar value) {
#ifdef SK_SCALAR_IS_FLOAT
return static_cast<HB_Fixed>(value * 64);
#else
// convert .16 to .6
return value >> (16 - 6);
#endif
}
static HB_Bool stringToGlyphs(HB_Font hbFont, const HB_UChar16* characters,
hb_uint32 length, HB_Glyph* glyphs,
hb_uint32* glyphsSize, HB_Bool isRTL) {
SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
SkPaint paint;
paint.setTypeface(font->getTypeface());
paint.setTextEncoding(SkPaint::kUTF16_TextEncoding);
int numGlyphs = paint.textToGlyphs(characters, length * sizeof(uint16_t),
reinterpret_cast<uint16_t*>(glyphs));
// HB_Glyph is 32-bit, but Skia outputs only 16-bit numbers. So our
// |glyphs| array needs to be converted.
for (int i = numGlyphs - 1; i >= 0; --i) {
uint16_t value;
// We use a memcpy to avoid breaking strict aliasing rules.
memcpy(&value, reinterpret_cast<char*>(glyphs) + sizeof(uint16_t) * i, sizeof(uint16_t));
glyphs[i] = value;
}
*glyphsSize = numGlyphs;
return 1;
}
static void glyphsToAdvances(HB_Font hbFont, const HB_Glyph* glyphs,
hb_uint32 numGlyphs, HB_Fixed* advances, int flags) {
SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
SkPaint paint;
font->setupPaint(&paint);
paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
SkAutoMalloc storage(numGlyphs * (sizeof(SkScalar) + sizeof(uint16_t)));
SkScalar* scalarWidths = reinterpret_cast<SkScalar*>(storage.get());
uint16_t* glyphs16 = reinterpret_cast<uint16_t*>(scalarWidths + numGlyphs);
// convert HB 32bit glyphs to skia's 16bit
for (hb_uint32 i = 0; i < numGlyphs; ++i) {
glyphs16[i] = SkToU16(glyphs[i]);
}
paint.getTextWidths(glyphs16, numGlyphs * sizeof(uint16_t), scalarWidths);
for (hb_uint32 i = 0; i < numGlyphs; ++i) {
advances[i] = SkScalarToHarfbuzzFixed(scalarWidths[i]);
}
}
static HB_Bool canRender(HB_Font hbFont, const HB_UChar16* characters,
hb_uint32 length) {
SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
SkPaint paint;
paint.setTypeface(font->getTypeface());
paint.setTextEncoding(SkPaint::kUTF16_TextEncoding);
return paint.containsText(characters, length * sizeof(uint16_t));
}
static HB_Error getOutlinePoint(HB_Font hbFont, HB_Glyph glyph, int flags,
hb_uint32 index, HB_Fixed* xPos, HB_Fixed* yPos,
hb_uint32* resultingNumPoints) {
SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
SkPaint paint;
font->setupPaint(&paint);
paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
if (flags & HB_ShaperFlag_UseDesignMetrics) {
paint.setHinting(SkPaint::kNo_Hinting);
}
SkPath path;
uint16_t glyph16 = SkToU16(glyph);
paint.getTextPath(&glyph16, sizeof(glyph16), 0, 0, &path);
int numPoints = path.countPoints();
if (index >= numPoints) {
return HB_Err_Invalid_SubTable;
}
SkPoint pt = path.getPoint(index);
*xPos = SkScalarToHarfbuzzFixed(pt.fX);
*yPos = SkScalarToHarfbuzzFixed(pt.fY);
*resultingNumPoints = numPoints;
return HB_Err_Ok;
}
static void getGlyphMetrics(HB_Font hbFont, HB_Glyph glyph,
HB_GlyphMetrics* metrics) {
SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
SkPaint paint;
font->setupPaint(&paint);
paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
SkScalar width;
SkRect bounds;
uint16_t glyph16 = SkToU16(glyph);
paint.getTextWidths(&glyph16, sizeof(glyph16), &width, &bounds);
metrics->x = SkScalarToHarfbuzzFixed(bounds.fLeft);
metrics->y = SkScalarToHarfbuzzFixed(bounds.fTop);
metrics->width = SkScalarToHarfbuzzFixed(bounds.width());
metrics->height = SkScalarToHarfbuzzFixed(bounds.height());
metrics->xOffset = SkScalarToHarfbuzzFixed(width);
// We can't actually get the |y| correct because Skia doesn't export
// the vertical advance. However, nor we do ever render vertical text at
// the moment so it's unimportant.
metrics->yOffset = 0;
}
static HB_Fixed getFontMetric(HB_Font hbFont, HB_FontMetric metric)
{
SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
SkPaint paint;
SkPaint::FontMetrics skiaMetrics;
font->setupPaint(&paint);
paint.getFontMetrics(&skiaMetrics);
switch (metric) {
case HB_FontAscent:
return SkScalarToHarfbuzzFixed(-skiaMetrics.fAscent);
default:
SkDebugf("--- unknown harfbuzz metric enum %d\n", metric);
return 0;
}
}
static HB_FontClass gSkHarfBuzzFontClass = {
stringToGlyphs,
glyphsToAdvances,
canRender,
getOutlinePoint,
getGlyphMetrics,
getFontMetric,
};
const HB_FontClass& SkHarfBuzzFont::GetFontClass() {
return gSkHarfBuzzFontClass;
}
HB_Error SkHarfBuzzFont::GetFontTableFunc(void* voidface, const HB_Tag tag,
HB_Byte* buffer, HB_UInt* len) {
SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(voidface);
uint32_t uniqueID = SkTypeface::UniqueID(font->getTypeface());
const size_t tableSize = SkFontHost::GetTableSize(uniqueID, tag);
if (!tableSize) {
return HB_Err_Invalid_Argument;
}
// If Harfbuzz specified a NULL buffer then it's asking for the size.
if (!buffer) {
*len = tableSize;
return HB_Err_Ok;
}
if (*len < tableSize) {
// is this right, or should we just copy less than the full table?
return HB_Err_Invalid_Argument;
}
SkFontHost::GetTableData(uniqueID, tag, 0, tableSize, buffer);
return HB_Err_Ok;
}
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