SimpleFontDataWin.cpp   [plain text]

/*
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission. 
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#include "config.h"
#include "Font.h"

#include "FontCache.h"
#include "FloatRect.h"
#include "FontDescription.h"
#include "HWndDC.h"
#include <mlang.h>
#include <wtf/MathExtras.h>
#include <wtf/win/GDIObject.h>

namespace WebCore {

const float cSmallCapsFontSizeMultiplier = 0.7f;

static bool g_shouldApplyMacAscentHack;

void Font::setShouldApplyMacAscentHack(bool b)
{
    g_shouldApplyMacAscentHack = b;
}

bool Font::shouldApplyMacAscentHack()
{
    return g_shouldApplyMacAscentHack;
}

float Font::ascentConsideringMacAscentHack(const WCHAR* faceName, float ascent, float descent)
{
    if (!shouldApplyMacAscentHack())
        return ascent;

    // This code comes from FontDataMac.mm. We only ever do this when running regression tests so that our metrics will match Mac.

    // We need to adjust Times, Helvetica, and Courier to closely match the
    // vertical metrics of their Microsoft counterparts that are the de facto
    // web standard. The AppKit adjustment of 20% is too big and is
    // incorrectly added to line spacing, so we use a 15% adjustment instead
    // and add it to the ascent.
    if (!wcscmp(faceName, L"Times") || !wcscmp(faceName, L"Helvetica") || !wcscmp(faceName, L"Courier"))
        ascent += floorf(((ascent + descent) * 0.15f) + 0.5f);

    return ascent;
}

void Font::initGDIFont()
{
    if (!m_platformData.size()) {
        m_fontMetrics.reset();
        m_avgCharWidth = 0;
        m_maxCharWidth = 0;
        return;
    }

    HWndDC hdc(0);
    HGDIOBJ oldFont = SelectObject(hdc, m_platformData.hfont());
    OUTLINETEXTMETRIC metrics;
    GetOutlineTextMetrics(hdc, sizeof(metrics), &metrics);
    TEXTMETRIC& textMetrics = metrics.otmTextMetrics;
    float ascent, descent, lineGap;
    // The Open Font Format describes the OS/2 USE_TYPO_METRICS flag as follows:
    // "If set, it is strongly recommended to use OS/2.sTypoAscender - OS/2.sTypoDescender+ OS/2.sTypoLineGap as a value for default line spacing for this font."
    const UINT useTypoMetricsMask = 1 << 7;
    if (metrics.otmfsSelection & useTypoMetricsMask) {
        ascent = metrics.otmAscent;
        descent = metrics.otmDescent;
        lineGap = metrics.otmLineGap;
    } else {
        ascent = textMetrics.tmAscent;
        descent = textMetrics.tmDescent;
        lineGap = textMetrics.tmExternalLeading;
    }
    m_fontMetrics.setAscent(ascent);
    m_fontMetrics.setDescent(descent);
    m_fontMetrics.setLineGap(lineGap);
    m_fontMetrics.setLineSpacing(lroundf(ascent) + lroundf(descent) + lroundf(lineGap));
    m_avgCharWidth = textMetrics.tmAveCharWidth;
    m_maxCharWidth = textMetrics.tmMaxCharWidth;
    float xHeight = ascent * 0.56f; // Best guess for xHeight if no x glyph is present.
    GLYPHMETRICS gm;
    static const MAT2 identity = { 0, 1,  0, 0,  0, 0,  0, 1 };
    DWORD len = GetGlyphOutline(hdc, 'x', GGO_METRICS, &gm, 0, 0, &identity);
    if (len != GDI_ERROR && gm.gmptGlyphOrigin.y > 0)
        xHeight = gm.gmptGlyphOrigin.y;
    m_fontMetrics.setXHeight(xHeight);
    m_fontMetrics.setUnitsPerEm(metrics.otmEMSquare);

    SelectObject(hdc, oldFont);
}

void Font::platformCharWidthInit()
{
    // GDI Fonts init charwidths in initGDIFont.
    if (!m_platformData.useGDI()) {
        m_avgCharWidth = 0.f;
        m_maxCharWidth = 0.f;
        initCharWidths();
    }
}

void Font::platformDestroy()
{
    ScriptFreeCache(&m_scriptCache);
    delete m_scriptFontProperties;
}

RefPtr<Font> Font::platformCreateScaledFont(const FontDescription& fontDescription, float scaleFactor) const
{
    float scaledSize = scaleFactor * m_platformData.size();
    if (isCustomFont())
        return Font::create(FontPlatformData::cloneWithSize(m_platformData, scaledSize), true, false);

    LOGFONT winfont;
    GetObject(m_platformData.hfont(), sizeof(LOGFONT), &winfont);
    winfont.lfHeight = -lroundf(scaledSize * (m_platformData.useGDI() ? 1 : 32));
    auto hfont = adoptGDIObject(::CreateFontIndirect(&winfont));
    return Font::create(FontPlatformData(WTFMove(hfont), scaledSize, m_platformData.syntheticBold(), m_platformData.syntheticOblique(), m_platformData.useGDI()), isCustomFont(), false);
}

void Font::determinePitch()
{
    if (isCustomFont()) {
        m_treatAsFixedPitch = false;
        return;
    }

    // TEXTMETRICS have this.  Set m_treatAsFixedPitch based off that.
    HWndDC dc(0);
    SaveDC(dc);
    SelectObject(dc, m_platformData.hfont());

    // Yes, this looks backwards, but the fixed pitch bit is actually set if the font
    // is *not* fixed pitch.  Unbelievable but true.
    TEXTMETRIC tm;
    GetTextMetrics(dc, &tm);
    m_treatAsFixedPitch = ((tm.tmPitchAndFamily & TMPF_FIXED_PITCH) == 0);

    RestoreDC(dc, -1);
}

FloatRect Font::boundsForGDIGlyph(Glyph glyph) const
{
    HWndDC hdc(0);
    SetGraphicsMode(hdc, GM_ADVANCED);
    HGDIOBJ oldFont = SelectObject(hdc, m_platformData.hfont());

    GLYPHMETRICS gdiMetrics;
    static const MAT2 identity = { 0, 1,  0, 0,  0, 0,  0, 1 };
    GetGlyphOutline(hdc, glyph, GGO_METRICS | GGO_GLYPH_INDEX, &gdiMetrics, 0, 0, &identity);

    SelectObject(hdc, oldFont);

    return FloatRect(gdiMetrics.gmptGlyphOrigin.x, -gdiMetrics.gmptGlyphOrigin.y,
        gdiMetrics.gmBlackBoxX + m_syntheticBoldOffset, gdiMetrics.gmBlackBoxY); 
}

float Font::widthForGDIGlyph(Glyph glyph) const
{
    HWndDC hdc(0);
    SetGraphicsMode(hdc, GM_ADVANCED);
    HGDIOBJ oldFont = SelectObject(hdc, m_platformData.hfont());

    GLYPHMETRICS gdiMetrics;
    static const MAT2 identity = { 0, 1,  0, 0,  0, 0,  0, 1 };
    GetGlyphOutline(hdc, glyph, GGO_METRICS | GGO_GLYPH_INDEX, &gdiMetrics, 0, 0, &identity);
    float result = gdiMetrics.gmCellIncX + m_syntheticBoldOffset;

    SelectObject(hdc, oldFont);

    return result;
}

SCRIPT_FONTPROPERTIES* Font::scriptFontProperties() const
{
    if (!m_scriptFontProperties) {
        m_scriptFontProperties = new SCRIPT_FONTPROPERTIES;
        memset(m_scriptFontProperties, 0, sizeof(SCRIPT_FONTPROPERTIES));
        m_scriptFontProperties->cBytes = sizeof(SCRIPT_FONTPROPERTIES);
        HRESULT result = ScriptGetFontProperties(0, scriptCache(), m_scriptFontProperties);
        if (result == E_PENDING) {
            HWndDC dc(0);
            SaveDC(dc);
            SelectObject(dc, m_platformData.hfont());
            ScriptGetFontProperties(dc, scriptCache(), m_scriptFontProperties);
            RestoreDC(dc, -1);
        }
    }
    return m_scriptFontProperties;
}

} // namespace WebCore