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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) {

     return static_cast<HB_Fixed>(value * 64);

 }

 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);

     SkTypeface* typeface = font->getTypeface();

     const size_t tableSize = typeface->getTableSize(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;

     }

     typeface->getTableData(tag, 0, tableSize, buffer);

     return HB_Err_Ok;

 }