third_party/WebKit/Source/platform/fonts/win/FontPlatformDataWin.cpp

/*
 * Copyright (C) 2006, 2007 Apple Computer, Inc.
 * Copyright (c) 2006, 2007, 2008, 2009, 2012 Google Inc. All rights reserved.
 *
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 * modification, are permitted provided that the following conditions are
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 * notice, this list of conditions and the following disclaimer.
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 * in the documentation and/or other materials provided with the
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#include "platform/fonts/FontPlatformData.h"

#include "SkTypeface.h"
#include "platform/LayoutTestSupport.h"
#include "platform/fonts/FontCache.h"
#include "platform/graphics/GraphicsContext.h"
#include <windows.h>

namespace blink {

// Maximum font size, in pixels, at which embedded bitmaps will be used
// if available.
const float kMaxSizeForEmbeddedBitmap = 24.0f;

void FontPlatformData::setupPaint(SkPaint* paint, float, const Font*) const
{
    const float ts = m_textSize >= 0 ? m_textSize : 12;
    paint->setTextSize(SkFloatToScalar(m_textSize));
    paint->setTypeface(typeface());
    paint->setFakeBoldText(m_syntheticBold);
    paint->setTextSkewX(m_syntheticItalic ? -SK_Scalar1 / 4 : 0);

    uint32_t textFlags = paintTextFlags();
    uint32_t flags = paint->getFlags();
    static const uint32_t textFlagsMask = SkPaint::kAntiAlias_Flag |
        SkPaint::kLCDRenderText_Flag;
    flags &= ~textFlagsMask;

    if (ts <= kMaxSizeForEmbeddedBitmap)
        flags |= SkPaint::kEmbeddedBitmapText_Flag;

    if (ts >= m_minSizeForAntiAlias) {

        // Disable subpixel text for certain older fonts at smaller sizes as
        // they tend to get quite blurry at non-integer sizes and positions.
        // For high-DPI this workaround isn't required.
        if ((ts >= m_minSizeForSubpixel
                || FontCache::fontCache()->deviceScaleFactor() >= 1.5)

            // Subpixel text positioning looks pretty bad without font
            // smoothing. Disable it unless some type of font smoothing is used.
            // As most tests run without font smoothing we enable it for tests
            // to ensure we get good test coverage matching the more common
            // smoothing enabled behavior.
            && ((textFlags & SkPaint::kAntiAlias_Flag)
                || LayoutTestSupport::isRunningLayoutTest()))
            flags |= SkPaint::kSubpixelText_Flag;

        SkASSERT(!(textFlags & ~textFlagsMask));
        flags |= textFlags;
    }

    paint->setFlags(flags);
}

static bool isWebFont(const String& familyName)
{
    // Web-fonts have artifical names constructed to always be:
    // 1. 24 characters, followed by a '\0'
    // 2. the last two characters are '=='
    return familyName.length() == 24
        && '=' == familyName[22] && '=' == familyName[23];
}

static int computePaintTextFlags(String fontFamilyName)
{
    if (LayoutTestSupport::isRunningLayoutTest())
        return LayoutTestSupport::isFontAntialiasingEnabledForTest() ? SkPaint::kAntiAlias_Flag : 0;

    int textFlags = 0;
    if (FontCache::fontCache()->antialiasedTextEnabled()) {
        int lcdFlag = FontCache::fontCache()->lcdTextEnabled()
            ? SkPaint::kLCDRenderText_Flag
            : 0;
        textFlags = SkPaint::kAntiAlias_Flag | lcdFlag;
    }

    // Many web-fonts are so poorly hinted that they are terrible to read when drawn in BW.
    // In these cases, we have decided to FORCE these fonts to be drawn with at least grayscale AA,
    // even when the System (getSystemTextFlags) tells us to draw only in BW.
    if (isWebFont(fontFamilyName))
        textFlags |= SkPaint::kAntiAlias_Flag;

    return textFlags;
}


void FontPlatformData::querySystemForRenderStyle()
{
    m_paintTextFlags = computePaintTextFlags(fontFamilyName());
}

} // namespace blink