gecko-dev/gfx/thebes/gfxDWriteShaper.cpp

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "gfxDWriteShaper.h"
#include "gfxWindowsPlatform.h"

#include <dwrite.h>

#include "gfxDWriteTextAnalysis.h"

#include "nsCRT.h"

bool
gfxDWriteShaper::ShapeText(gfxContext      *aContext,
                           const char16_t *aText,
                           uint32_t         aOffset,
                           uint32_t         aLength,
                           int32_t          aScript,
                           gfxShapedText   *aShapedText)
{
    HRESULT hr;
    // TODO: Handle TEXT_DISABLE_OPTIONAL_LIGATURES

    DWRITE_READING_DIRECTION readingDirection = 
        aShapedText->IsRightToLeft()
            ? DWRITE_READING_DIRECTION_RIGHT_TO_LEFT
            : DWRITE_READING_DIRECTION_LEFT_TO_RIGHT;

    gfxDWriteFont *font = static_cast<gfxDWriteFont*>(mFont);

    gfxShapedText::CompressedGlyph g;

    IDWriteTextAnalyzer *analyzer =
        gfxWindowsPlatform::GetPlatform()->GetDWriteAnalyzer();
    if (!analyzer) {
        return false;
    }

    /**
     * There's an internal 16-bit limit on some things inside the analyzer,
     * but we never attempt to shape a word longer than 32K characters
     * in a single call, so we cannot exceed that limit.
     */
    UINT32 length = aLength;
    char16ptr_t text = aText;

    TextAnalysis analysis(text, length, nullptr, readingDirection);
    TextAnalysis::Run *runHead;
    hr = analysis.GenerateResults(analyzer, &runHead);

    if (FAILED(hr)) {
        NS_WARNING("Analyzer failed to generate results.");
        return false;
    }

    int32_t appUnitsPerDevPixel = aShapedText->GetAppUnitsPerDevUnit();

    UINT32 maxGlyphs = 0;
trymoreglyphs:
    if ((UINT32_MAX - 3 * length / 2 + 16) < maxGlyphs) {
        // This isn't going to work, we're going to cross the UINT32 upper
        // limit. Give up.
        NS_WARNING("Shaper needs to generate more than 2^32 glyphs?!");
        return false;
    }
    maxGlyphs += 3 * length / 2 + 16;

    nsAutoTArray<UINT16, 400> clusters;
    nsAutoTArray<UINT16, 400> indices;
    nsAutoTArray<DWRITE_SHAPING_TEXT_PROPERTIES, 400> textProperties;
    nsAutoTArray<DWRITE_SHAPING_GLYPH_PROPERTIES, 400> glyphProperties;
    if (!clusters.SetLength(length) ||
        !indices.SetLength(maxGlyphs) || 
        !textProperties.SetLength(maxGlyphs) ||
        !glyphProperties.SetLength(maxGlyphs)) {
        NS_WARNING("Shaper failed to allocate memory.");
        return false;
    }

    UINT32 actualGlyphs;

    hr = analyzer->GetGlyphs(text, length,
            font->GetFontFace(), FALSE, 
            readingDirection == DWRITE_READING_DIRECTION_RIGHT_TO_LEFT,
            &runHead->mScript, nullptr, nullptr, nullptr, nullptr, 0,
            maxGlyphs, clusters.Elements(), textProperties.Elements(),
            indices.Elements(), glyphProperties.Elements(), &actualGlyphs);

    if (hr == HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER)) {
        // We increase the amount of glyphs and try again.
        goto trymoreglyphs;
    }
    if (FAILED(hr)) {
        NS_WARNING("Analyzer failed to get glyphs.");
        return false;
    }

    WORD gID = indices[0];
    nsAutoTArray<FLOAT, 400> advances;
    nsAutoTArray<DWRITE_GLYPH_OFFSET, 400> glyphOffsets;
    if (!advances.SetLength(actualGlyphs) || 
        !glyphOffsets.SetLength(actualGlyphs)) {
        NS_WARNING("Shaper failed to allocate memory.");
        return false;
    }

    if (!static_cast<gfxDWriteFont*>(mFont)->mUseSubpixelPositions) {
        hr = analyzer->GetGdiCompatibleGlyphPlacements(
                                          text,
                                          clusters.Elements(),
                                          textProperties.Elements(),
                                          length,
                                          indices.Elements(),
                                          glyphProperties.Elements(),
                                          actualGlyphs,
                                          font->GetFontFace(),
                                          font->GetAdjustedSize(),
                                          1.0,
                                          nullptr,
                                          FALSE,
                                          FALSE,
                                          FALSE,
                                          &runHead->mScript,
                                          nullptr,
                                          nullptr,
                                          nullptr,
                                          0,
                                          advances.Elements(),
                                          glyphOffsets.Elements());
    } else {
        hr = analyzer->GetGlyphPlacements(text,
                                          clusters.Elements(),
                                          textProperties.Elements(),
                                          length,
                                          indices.Elements(),
                                          glyphProperties.Elements(),
                                          actualGlyphs,
                                          font->GetFontFace(),
                                          font->GetAdjustedSize(),
                                          FALSE,
                                          FALSE,
                                          &runHead->mScript,
                                          nullptr,
                                          nullptr,
                                          nullptr,
                                          0,
                                          advances.Elements(),
                                          glyphOffsets.Elements());
    }
    if (FAILED(hr)) {
        NS_WARNING("Analyzer failed to get glyph placements.");
        return false;
    }

    nsAutoTArray<gfxShapedText::DetailedGlyph,1> detailedGlyphs;
    gfxShapedText::CompressedGlyph *charGlyphs =
        aShapedText->GetCharacterGlyphs();

    for (unsigned int c = 0; c < length; c++) {
        uint32_t k = clusters[c];
        uint32_t absC = aOffset + c;

        if (c > 0 && k == clusters[c - 1]) {
            // This is a cluster continuation. No glyph here.
            gfxShapedText::CompressedGlyph &g = charGlyphs[absC];
            NS_ASSERTION(!g.IsSimpleGlyph(), "overwriting a simple glyph");
            g.SetComplex(g.IsClusterStart(), false, 0);
            continue;
        }

        // Count glyphs for this character
        uint32_t glyphCount = actualGlyphs - k;
        uint32_t nextClusterOffset;
        for (nextClusterOffset = c + 1; 
            nextClusterOffset < length; ++nextClusterOffset) {
            if (clusters[nextClusterOffset] > k) {
                glyphCount = clusters[nextClusterOffset] - k;
                break;
            }
        }
        int32_t advance = (int32_t)(advances[k] * appUnitsPerDevPixel);
        if (glyphCount == 1 && advance >= 0 &&
            glyphOffsets[k].advanceOffset == 0 &&
            glyphOffsets[k].ascenderOffset == 0 &&
            charGlyphs[absC].IsClusterStart() &&
            gfxShapedText::CompressedGlyph::IsSimpleAdvance(advance) &&
            gfxShapedText::CompressedGlyph::IsSimpleGlyphID(indices[k])) {
              charGlyphs[absC].SetSimpleGlyph(advance, indices[k]);
        } else {
            if (detailedGlyphs.Length() < glyphCount) {
                if (!detailedGlyphs.AppendElements(
                    glyphCount - detailedGlyphs.Length())) {
                    continue;
                }
            }
            float totalAdvance = 0;
            for (unsigned int z = 0; z < glyphCount; z++) {
                detailedGlyphs[z].mGlyphID = indices[k + z];
                detailedGlyphs[z].mAdvance = 
                    (int32_t)(advances[k + z]
                       * appUnitsPerDevPixel);
                if (readingDirection == 
                    DWRITE_READING_DIRECTION_RIGHT_TO_LEFT) {
                    detailedGlyphs[z].mXOffset = 
                        (totalAdvance + 
                          glyphOffsets[k + z].advanceOffset)
                        * appUnitsPerDevPixel;
                } else {
                    detailedGlyphs[z].mXOffset = 
                        glyphOffsets[k + z].advanceOffset *
                        appUnitsPerDevPixel;
                }
                detailedGlyphs[z].mYOffset = 
                    -glyphOffsets[k + z].ascenderOffset *
                    appUnitsPerDevPixel;
                totalAdvance += advances[k + z];
            }
            aShapedText->SetGlyphs(
                absC,
                g.SetComplex(charGlyphs[absC].IsClusterStart(),
                             true,
                             glyphCount),
                detailedGlyphs.Elements());
        }
    }

    return true;
}