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/*
* Copyright (C) 2005, 2008, 2010 Apple Inc. All rights reserved.
* Copyright (C) 2006 Alexey Proskuryakov
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "third_party/blink/renderer/platform/fonts/font_metrics.h"
#include "build/build_config.h"
#include "third_party/blink/renderer/platform/fonts/font_platform_data.h"
#include "third_party/blink/renderer/platform/fonts/vdmx_parser.h"
#include "third_party/skia/include/core/SkFont.h"
#include "third_party/skia/include/core/SkFontMetrics.h"
#include "third_party/skia/include/core/SkTypeface.h"
namespace blink {
#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID) || \
BUILDFLAG(IS_FUCHSIA)
// This is the largest VDMX table which we'll try to load and parse.
static const size_t kMaxVDMXTableSize = 1024 * 1024; // 1 MB
#endif
void FontMetrics::AscentDescentWithHacks(
float& ascent,
float& descent,
const FontPlatformData& platform_data,
const SkFont& font,
bool subpixel_ascent_descent,
std::optional<float> ascent_override,
std::optional<float> descent_override) {
SkTypeface* face = font.getTypeface();
DCHECK(face);
SkFontMetrics metrics;
font.getMetrics(&metrics);
if (ascent_override)
metrics.fAscent = -platform_data.size() * ascent_override.value();
if (descent_override)
metrics.fDescent = platform_data.size() * descent_override.value();
int vdmx_ascent = 0, vdmx_descent = 0;
bool is_vdmx_valid = false;
#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID) || \
BUILDFLAG(IS_FUCHSIA)
// Manually digging up VDMX metrics is only applicable when bytecode hinting
// using FreeType. With DirectWrite or CoreText, no bytecode hinting is ever
// done. This code should be pushed into FreeType (hinted font metrics).
static const uint32_t kVdmxTag = SkSetFourByteTag('V', 'D', 'M', 'X');
int pixel_size = platform_data.size() + 0.5;
// TODO(xiaochengh): How do we support ascent/descent override with VDMX?
if (!ascent_override && !descent_override && !font.isForceAutoHinting() &&
(font.getHinting() == SkFontHinting::kFull ||
font.getHinting() == SkFontHinting::kNormal)) {
size_t vdmx_size = face->getTableSize(kVdmxTag);
if (vdmx_size && vdmx_size < kMaxVDMXTableSize) {
uint8_t* vdmx_table = (uint8_t*)WTF::Partitions::FastMalloc(
vdmx_size, WTF_HEAP_PROFILER_TYPE_NAME(FontMetrics));
if (vdmx_table &&
face->getTableData(kVdmxTag, 0, vdmx_size, vdmx_table) == vdmx_size &&
ParseVDMX(&vdmx_ascent, &vdmx_descent, vdmx_table, vdmx_size,
pixel_size))
is_vdmx_valid = true;
WTF::Partitions::FastFree(vdmx_table);
}
}
#endif
// Beware those who step here: This code is designed to match Win32 font
// metrics *exactly* except:
// - the adjustment of ascent/descent on Linux/Android
// - metrics.fAscent and .fDesscent are not rounded to int for tiny fonts
if (is_vdmx_valid) {
ascent = vdmx_ascent;
descent = -vdmx_descent;
} else if (subpixel_ascent_descent &&
(-metrics.fAscent < 3 ||
-metrics.fAscent + metrics.fDescent < 2)) {
// For tiny fonts, the rounding of fAscent and fDescent results in equal
// baseline for different types of text baselines (crbug.com/338908).
// Please see CanvasRenderingContext2D::getFontBaseline for the heuristic.
ascent = -metrics.fAscent;
descent = metrics.fDescent;
} else {
ascent = SkScalarRoundToScalar(-metrics.fAscent);
descent = SkScalarRoundToScalar(metrics.fDescent);
#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID) || \
BUILDFLAG(IS_FUCHSIA)
// When subpixel positioning is enabled, if the descent is rounded down,
// the descent part of the glyph may be truncated when displayed in a
// 'overflow: hidden' container. To avoid that, borrow 1 unit from the
// ascent when possible.
if (descent < metrics.fDescent &&
platform_data.GetFontRenderStyle().use_subpixel_positioning &&
ascent >= 1) {
++descent;
--ascent;
}
#endif
}
#if BUILDFLAG(IS_MAC)
// We are preserving this ascent hack to match Safari's ascent adjustment
// in their SimpleFontDataMac.mm, for details see crbug.com/445830.
// 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.
String family_name = platform_data.FontFamilyName();
if (family_name == font_family_names::kTimes ||
family_name == font_family_names::kHelvetica ||
family_name == font_family_names::kCourier)
ascent += floorf(((ascent + descent) * 0.15f) + 0.5f);
#endif
}
float FontMetrics::FloatAscentInternal(
FontBaseline baseline_type,
ApplyBaselineTable apply_baseline_table) const {
switch (baseline_type) {
case kAlphabeticBaseline:
NOTREACHED();
case kCentralBaseline:
return FloatHeight() / 2;
// The following computations are based on 'dominant-baseline' support in
// the legacy SVG <text>.
case kTextUnderBaseline:
return FloatHeight();
case kIdeographicUnderBaseline:
if (ideographic_baseline_position_.has_value() && apply_baseline_table) {
return float_ascent_ - ideographic_baseline_position_.value();
}
return FloatHeight();
case kXMiddleBaseline:
return float_ascent_ - XHeight() / 2;
case kMathBaseline:
// TODO(layout-dev): Should refer to 'math' in OpenType or 'bsln' value 4
// in TrueType AAT.
return float_ascent_ * 0.5f;
case kHangingBaseline:
if (hanging_baseline_position_.has_value(), apply_baseline_table) {
return float_ascent_ - hanging_baseline_position_.value();
}
return float_ascent_ * 0.2f;
case kTextOverBaseline:
return 0;
}
NOTREACHED();
}
int FontMetrics::IntAscentInternal(
FontBaseline baseline_type,
ApplyBaselineTable apply_baseline_table) const {
switch (baseline_type) {
case kAlphabeticBaseline:
NOTREACHED();
case kCentralBaseline:
return Height() - Height() / 2;
// The following computations are based on 'dominant-baseline' support in
// the legacy SVG <text>.
case kTextUnderBaseline:
return Height();
case kIdeographicUnderBaseline:
if (ideographic_baseline_position_.has_value() && apply_baseline_table) {
return static_cast<int>(
int_ascent_ -
static_cast<int>(lroundf(ideographic_baseline_position_.value())));
}
return Height();
case kXMiddleBaseline:
return int_ascent_ - static_cast<int>(XHeight() / 2);
case kMathBaseline:
if (hanging_baseline_position_.has_value() && apply_baseline_table) {
return int_ascent_ -
static_cast<int>(lroundf(hanging_baseline_position_.value()));
}
return int_ascent_ / 2;
case kHangingBaseline:
// TODO(layout-dev): Should refer to 'hang' in OpenType or 'bsln' value 3
// in TrueType AAT.
return int_ascent_ * 2 / 10;
case kTextOverBaseline:
return 0;
}
NOTREACHED();
}
}
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