gecko-dev/gfx/thebes/gfxFT2FontBase.cpp

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/* -*- 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 "gfxFT2FontBase.h"
#include "gfxFT2Utils.h"
#include "harfbuzz/hb.h"
#include "mozilla/Likely.h"
#include "gfxFontConstants.h"
#include "gfxFontUtils.h"
#include <algorithm>
#include <dlfcn.h>
#include FT_TRUETYPE_TAGS_H
#include FT_TRUETYPE_TABLES_H
#include FT_ADVANCES_H
#include FT_MULTIPLE_MASTERS_H
#ifndef FT_FACE_FLAG_COLOR
#define FT_FACE_FLAG_COLOR ( 1L << 14 )
#endif
using namespace mozilla::gfx;
gfxFT2FontBase::gfxFT2FontBase(const RefPtr<UnscaledFontFreeType>& aUnscaledFont,
cairo_scaled_font_t *aScaledFont,
gfxFontEntry *aFontEntry,
const gfxFontStyle *aFontStyle)
: gfxFont(aUnscaledFont, aFontEntry, aFontStyle, kAntialiasDefault, aScaledFont)
, mSpaceGlyph(0)
{
mEmbolden = aFontStyle->NeedsSyntheticBold(aFontEntry);
cairo_scaled_font_reference(mScaledFont);
InitMetrics();
}
gfxFT2FontBase::~gfxFT2FontBase()
{
cairo_scaled_font_destroy(mScaledFont);
}
uint32_t
gfxFT2FontBase::GetGlyph(uint32_t aCharCode)
{
// FcFreeTypeCharIndex needs to lock the FT_Face and can end up searching
// through all the postscript glyph names in the font. Therefore use a
// lightweight cache, which is stored on the cairo_font_face_t.
cairo_font_face_t *face =
cairo_scaled_font_get_font_face(GetCairoScaledFont());
if (cairo_font_face_status(face) != CAIRO_STATUS_SUCCESS)
return 0;
// This cache algorithm and size is based on what is done in
// cairo_scaled_font_text_to_glyphs and pango_fc_font_real_get_glyph. I
// think the concept is that adjacent characters probably come mostly from
// one Unicode block. This assumption is probably not so valid with
// scripts with large character sets as used for East Asian languages.
struct CmapCacheSlot {
uint32_t mCharCode;
uint32_t mGlyphIndex;
};
const uint32_t kNumSlots = 256;
static cairo_user_data_key_t sCmapCacheKey;
CmapCacheSlot *slots = static_cast<CmapCacheSlot*>
(cairo_font_face_get_user_data(face, &sCmapCacheKey));
if (!slots) {
// cairo's caches can keep some cairo_font_faces alive past our last
// destroy, so the destroy function (free) for the cache must be
// callable from cairo without any assumptions about what other
// modules have not been shutdown.
slots = static_cast<CmapCacheSlot*>
(calloc(kNumSlots, sizeof(CmapCacheSlot)));
if (!slots)
return 0;
cairo_status_t status =
cairo_font_face_set_user_data(face, &sCmapCacheKey, slots, free);
if (status != CAIRO_STATUS_SUCCESS) { // OOM
free(slots);
return 0;
}
// Invalidate slot 0 by setting its char code to something that would
// never end up in slot 0. All other slots are already invalid
// because they have mCharCode = 0 and a glyph for char code 0 will
// always be in the slot 0.
slots[0].mCharCode = 1;
}
CmapCacheSlot *slot = &slots[aCharCode % kNumSlots];
if (slot->mCharCode != aCharCode) {
slot->mCharCode = aCharCode;
slot->mGlyphIndex = gfxFT2LockedFace(this).GetGlyph(aCharCode);
}
return slot->mGlyphIndex;
}
void
gfxFT2FontBase::GetGlyphExtents(uint32_t aGlyph, cairo_text_extents_t* aExtents)
{
MOZ_ASSERT(aExtents != nullptr, "aExtents must not be NULL");
cairo_glyph_t glyphs[1];
glyphs[0].index = aGlyph;
glyphs[0].x = 0.0;
glyphs[0].y = 0.0;
// cairo does some caching for us here but perhaps a small gain could be
// made by caching more. It is usually only the advance that is needed,
// so caching only the advance could allow many requests to be cached with
// little memory use. Ideally this cache would be merged with
// gfxGlyphExtents.
cairo_scaled_font_glyph_extents(GetCairoScaledFont(), glyphs, 1, aExtents);
}
// aScale is intended for a 16.16 x/y_scale of an FT_Size_Metrics
static inline FT_Long
ScaleRoundDesignUnits(FT_Short aDesignMetric, FT_Fixed aScale)
{
FT_Long fixed26dot6 = FT_MulFix(aDesignMetric, aScale);
return ROUND_26_6_TO_INT(fixed26dot6);
}
// Snap a line to pixels while keeping the center and size of the line as
// close to the original position as possible.
//
// Pango does similar snapping for underline and strikethrough when fonts are
// hinted, but nsCSSRendering::GetTextDecorationRectInternal always snaps the
// top and size of lines. Optimizing the distance between the line and
// baseline is probably good for the gap between text and underline, but
// optimizing the center of the line is better for positioning strikethough.
static void
SnapLineToPixels(gfxFloat& aOffset, gfxFloat& aSize)
{
gfxFloat snappedSize = std::max(floor(aSize + 0.5), 1.0);
// Correct offset for change in size
gfxFloat offset = aOffset - 0.5 * (aSize - snappedSize);
// Snap offset
aOffset = floor(offset + 0.5);
aSize = snappedSize;
}
/**
* Get extents for a simple character representable by a single glyph.
* The return value is the glyph id of that glyph or zero if no such glyph
* exists. aExtents is only set when this returns a non-zero glyph id.
*/
uint32_t
gfxFT2FontBase::GetCharExtents(char aChar, cairo_text_extents_t* aExtents)
{
FT_UInt gid = GetGlyph(aChar);
if (gid) {
GetGlyphExtents(gid, aExtents);
}
return gid;
}
/**
* Get glyph id and width for a simple character.
* The return value is the glyph id of that glyph or zero if no such glyph
* exists. aWidth is only set when this returns a non-zero glyph id.
* This is just for use during initialization, and doesn't use the width cache.
*/
uint32_t
gfxFT2FontBase::GetCharWidth(char aChar, gfxFloat* aWidth)
{
FT_UInt gid = GetGlyph(aChar);
if (gid) {
int32_t width;
if (!GetFTGlyphAdvance(gid, &width)) {
cairo_text_extents_t extents;
GetGlyphExtents(gid, &extents);
width = NS_lround(0x10000 * extents.x_advance);
}
*aWidth = FLOAT_FROM_16_16(width);
}
return gid;
}
void
gfxFT2FontBase::InitMetrics()
{
mFUnitsConvFactor = 0.0;
if (MOZ_UNLIKELY(GetStyle()->size <= 0.0) ||
MOZ_UNLIKELY(GetStyle()->sizeAdjust == 0.0)) {
memset(&mMetrics, 0, sizeof(mMetrics)); // zero initialize
mSpaceGlyph = GetGlyph(' ');
return;
}
// Explicitly lock the face so we can release it early before calling
// back into Cairo below.
FT_Face face = cairo_ft_scaled_font_lock_face(GetCairoScaledFont());
if (MOZ_UNLIKELY(!face)) {
// No face. This unfortunate situation might happen if the font
// file is (re)moved at the wrong time.
const gfxFloat emHeight = GetAdjustedSize();
mMetrics.emHeight = emHeight;
mMetrics.maxAscent = mMetrics.emAscent = 0.8 * emHeight;
mMetrics.maxDescent = mMetrics.emDescent = 0.2 * emHeight;
mMetrics.maxHeight = emHeight;
mMetrics.internalLeading = 0.0;
mMetrics.externalLeading = 0.2 * emHeight;
const gfxFloat spaceWidth = 0.5 * emHeight;
mMetrics.spaceWidth = spaceWidth;
mMetrics.maxAdvance = spaceWidth;
mMetrics.aveCharWidth = spaceWidth;
mMetrics.zeroOrAveCharWidth = spaceWidth;
const gfxFloat xHeight = 0.5 * emHeight;
mMetrics.xHeight = xHeight;
mMetrics.capHeight = mMetrics.maxAscent;
const gfxFloat underlineSize = emHeight / 14.0;
mMetrics.underlineSize = underlineSize;
mMetrics.underlineOffset = -underlineSize;
mMetrics.strikeoutOffset = 0.25 * emHeight;
mMetrics.strikeoutSize = underlineSize;
SanitizeMetrics(&mMetrics, false);
return;
}
if (face->face_flags & FT_FACE_FLAG_MULTIPLE_MASTERS) {
// Resolve variations from entry (descriptor) and style (property)
AutoTArray<gfxFontVariation,8> settings;
mFontEntry->GetVariationsForStyle(settings, mStyle);
SetupVarCoords(mFontEntry->GetMMVar(), settings, &mCoords);
if (!mCoords.IsEmpty()) {
#if MOZ_TREE_FREETYPE
FT_Set_Var_Design_Coordinates(face, mCoords.Length(), mCoords.Elements());
#else
typedef FT_Error (*SetCoordsFunc)(FT_Face, FT_UInt, FT_Fixed*);
static SetCoordsFunc setCoords;
static bool firstTime = true;
if (firstTime) {
firstTime = false;
setCoords = (SetCoordsFunc)
dlsym(RTLD_DEFAULT, "FT_Set_Var_Design_Coordinates");
}
if (setCoords) {
(*setCoords)(face, mCoords.Length(), mCoords.Elements());
}
#endif
}
}
const FT_Size_Metrics& ftMetrics = face->size->metrics;
mMetrics.maxAscent = FLOAT_FROM_26_6(ftMetrics.ascender);
mMetrics.maxDescent = -FLOAT_FROM_26_6(ftMetrics.descender);
mMetrics.maxAdvance = FLOAT_FROM_26_6(ftMetrics.max_advance);
gfxFloat lineHeight = FLOAT_FROM_26_6(ftMetrics.height);
gfxFloat emHeight;
// Scale for vertical design metric conversion: pixels per design unit.
// If this remains at 0.0, we can't use metrics from OS/2 etc.
gfxFloat yScale = 0.0;
if (FT_IS_SCALABLE(face)) {
// Prefer FT_Size_Metrics::x_scale to x_ppem as x_ppem does not
// have subpixel accuracy.
//
// FT_Size_Metrics::y_scale is in 16.16 fixed point format. Its
// (fractional) value is a factor that converts vertical metrics from
// design units to units of 1/64 pixels, so that the result may be
// interpreted as pixels in 26.6 fixed point format.
mFUnitsConvFactor = FLOAT_FROM_26_6(FLOAT_FROM_16_16(ftMetrics.x_scale));
yScale = FLOAT_FROM_26_6(FLOAT_FROM_16_16(ftMetrics.y_scale));
emHeight = face->units_per_EM * yScale;
} else { // Not scalable.
emHeight = ftMetrics.y_ppem;
// FT_Face doc says units_per_EM and a bunch of following fields
// are "only relevant to scalable outlines". If it's an sfnt,
// we can get units_per_EM from the 'head' table instead; otherwise,
// we don't have a unitsPerEm value so we can't compute/use yScale or
// mFUnitsConvFactor (x scale).
const TT_Header* head =
static_cast<TT_Header*>(FT_Get_Sfnt_Table(face, ft_sfnt_head));
if (head) {
// Bug 1267909 - Even if the font is not explicitly scalable,
// if the face has color bitmaps, it should be treated as scalable
// and scaled to the desired size. Metrics based on y_ppem need
// to be rescaled for the adjusted size. This makes metrics agree
// with the scales we pass to Cairo for Fontconfig fonts.
if (face->face_flags & FT_FACE_FLAG_COLOR) {
emHeight = GetAdjustedSize();
gfxFloat adjustScale = emHeight / ftMetrics.y_ppem;
mMetrics.maxAscent *= adjustScale;
mMetrics.maxDescent *= adjustScale;
mMetrics.maxAdvance *= adjustScale;
lineHeight *= adjustScale;
}
gfxFloat emUnit = head->Units_Per_EM;
mFUnitsConvFactor = ftMetrics.x_ppem / emUnit;
yScale = emHeight / emUnit;
}
}
TT_OS2 *os2 =
static_cast<TT_OS2*>(FT_Get_Sfnt_Table(face, ft_sfnt_os2));
if (os2 && os2->sTypoAscender && yScale > 0.0) {
mMetrics.emAscent = os2->sTypoAscender * yScale;
mMetrics.emDescent = -os2->sTypoDescender * yScale;
FT_Short typoHeight =
os2->sTypoAscender - os2->sTypoDescender + os2->sTypoLineGap;
lineHeight = typoHeight * yScale;
// If the OS/2 fsSelection USE_TYPO_METRICS bit is set,
// set maxAscent/Descent from the sTypo* fields instead of hhea.
const uint16_t kUseTypoMetricsMask = 1 << 7;
if ((os2->fsSelection & kUseTypoMetricsMask) ||
// maxAscent/maxDescent get used for frame heights, and some fonts
// don't have the HHEA table ascent/descent set (bug 279032).
(mMetrics.maxAscent == 0.0 && mMetrics.maxDescent == 0.0)) {
// We use NS_round here to parallel the pixel-rounded values that
// freetype gives us for ftMetrics.ascender/descender.
mMetrics.maxAscent = NS_round(mMetrics.emAscent);
mMetrics.maxDescent = NS_round(mMetrics.emDescent);
}
} else {
mMetrics.emAscent = mMetrics.maxAscent;
mMetrics.emDescent = mMetrics.maxDescent;
}
// gfxFont::Metrics::underlineOffset is the position of the top of the
// underline.
//
// FT_FaceRec documentation describes underline_position as "the
// center of the underlining stem". This was the original definition
// of the PostScript metric, but in the PostScript table of OpenType
// fonts the metric is "the top of the underline"
// (http://www.microsoft.com/typography/otspec/post.htm), and FreeType
// (up to version 2.3.7) doesn't make any adjustment.
//
// Therefore get the underline position directly from the table
// ourselves when this table exists. Use FreeType's metrics for
// other (including older PostScript) fonts.
if (face->underline_position && face->underline_thickness && yScale > 0.0) {
mMetrics.underlineSize = face->underline_thickness * yScale;
TT_Postscript *post = static_cast<TT_Postscript*>
(FT_Get_Sfnt_Table(face, ft_sfnt_post));
if (post && post->underlinePosition) {
mMetrics.underlineOffset = post->underlinePosition * yScale;
} else {
mMetrics.underlineOffset = face->underline_position * yScale
+ 0.5 * mMetrics.underlineSize;
}
} else { // No underline info.
// Imitate Pango.
mMetrics.underlineSize = emHeight / 14.0;
mMetrics.underlineOffset = -mMetrics.underlineSize;
}
if (os2 && os2->yStrikeoutSize && os2->yStrikeoutPosition && yScale > 0.0) {
mMetrics.strikeoutSize = os2->yStrikeoutSize * yScale;
mMetrics.strikeoutOffset = os2->yStrikeoutPosition * yScale;
} else { // No strikeout info.
mMetrics.strikeoutSize = mMetrics.underlineSize;
// Use OpenType spec's suggested position for Roman font.
mMetrics.strikeoutOffset = emHeight * 409.0 / 2048.0
+ 0.5 * mMetrics.strikeoutSize;
}
SnapLineToPixels(mMetrics.strikeoutOffset, mMetrics.strikeoutSize);
if (os2 && os2->sxHeight && yScale > 0.0) {
mMetrics.xHeight = os2->sxHeight * yScale;
} else {
// CSS 2.1, section 4.3.2 Lengths: "In the cases where it is
// impossible or impractical to determine the x-height, a value of
// 0.5em should be used."
mMetrics.xHeight = 0.5 * emHeight;
}
// aveCharWidth is used for the width of text input elements so be
// liberal rather than conservative in the estimate.
if (os2 && os2->xAvgCharWidth) {
// Round to pixels as this is compared with maxAdvance to guess
// whether this is a fixed width font.
mMetrics.aveCharWidth =
ScaleRoundDesignUnits(os2->xAvgCharWidth, ftMetrics.x_scale);
} else {
mMetrics.aveCharWidth = 0.0; // updated below
}
if (os2 && os2->sCapHeight && yScale > 0.0) {
mMetrics.capHeight = os2->sCapHeight * yScale;
} else {
mMetrics.capHeight = mMetrics.maxAscent;
}
// Release the face lock to safely load glyphs with GetCharExtents if
// necessary without recursively locking.
cairo_ft_scaled_font_unlock_face(GetCairoScaledFont());
gfxFloat width;
mSpaceGlyph = GetCharWidth(' ', &width);
if (mSpaceGlyph) {
mMetrics.spaceWidth = width;
} else {
mMetrics.spaceWidth = mMetrics.maxAdvance; // guess
}
if (GetCharWidth('0', &width)) {
mMetrics.zeroOrAveCharWidth = width;
} else {
mMetrics.zeroOrAveCharWidth = 0.0;
}
// Prefering a measured x over sxHeight because sxHeight doesn't consider
// hinting, but maybe the x extents are not quite right in some fancy
// script fonts. CSS 2.1 suggests possibly using the height of an "o",
// which would have a more consistent glyph across fonts.
cairo_text_extents_t extents;
if (GetCharExtents('x', &extents) && extents.y_bearing < 0.0) {
mMetrics.xHeight = -extents.y_bearing;
mMetrics.aveCharWidth =
std::max(mMetrics.aveCharWidth, extents.x_advance);
}
if (GetCharExtents('H', &extents) && extents.y_bearing < 0.0) {
mMetrics.capHeight = -extents.y_bearing;
}
mMetrics.aveCharWidth =
std::max(mMetrics.aveCharWidth, mMetrics.zeroOrAveCharWidth);
if (mMetrics.aveCharWidth == 0.0) {
mMetrics.aveCharWidth = mMetrics.spaceWidth;
}
if (mMetrics.zeroOrAveCharWidth == 0.0) {
mMetrics.zeroOrAveCharWidth = mMetrics.aveCharWidth;
}
// Apparently hinting can mean that max_advance is not always accurate.
mMetrics.maxAdvance =
std::max(mMetrics.maxAdvance, mMetrics.aveCharWidth);
mMetrics.maxHeight = mMetrics.maxAscent + mMetrics.maxDescent;
// Make the line height an integer number of pixels so that lines will be
// equally spaced (rather than just being snapped to pixels, some up and
// some down). Layout calculates line height from the emHeight +
// internalLeading + externalLeading, but first each of these is rounded
// to layout units. To ensure that the result is an integer number of
// pixels, round each of the components to pixels.
mMetrics.emHeight = floor(emHeight + 0.5);
// maxHeight will normally be an integer, but round anyway in case
// FreeType is configured differently.
mMetrics.internalLeading =
floor(mMetrics.maxHeight - mMetrics.emHeight + 0.5);
// Text input boxes currently don't work well with lineHeight
// significantly less than maxHeight (with Verdana, for example).
lineHeight = floor(std::max(lineHeight, mMetrics.maxHeight) + 0.5);
mMetrics.externalLeading =
lineHeight - mMetrics.internalLeading - mMetrics.emHeight;
// Ensure emAscent + emDescent == emHeight
gfxFloat sum = mMetrics.emAscent + mMetrics.emDescent;
mMetrics.emAscent = sum > 0.0 ?
mMetrics.emAscent * mMetrics.emHeight / sum : 0.0;
mMetrics.emDescent = mMetrics.emHeight - mMetrics.emAscent;
SanitizeMetrics(&mMetrics, false);
#if 0
// printf("font name: %s %f\n", NS_ConvertUTF16toUTF8(GetName()).get(), GetStyle()->size);
// printf ("pango font %s\n", pango_font_description_to_string (pango_font_describe (font)));
fprintf (stderr, "Font: %s\n", NS_ConvertUTF16toUTF8(GetName()).get());
fprintf (stderr, " emHeight: %f emAscent: %f emDescent: %f\n", mMetrics.emHeight, mMetrics.emAscent, mMetrics.emDescent);
fprintf (stderr, " maxAscent: %f maxDescent: %f\n", mMetrics.maxAscent, mMetrics.maxDescent);
fprintf (stderr, " internalLeading: %f externalLeading: %f\n", mMetrics.externalLeading, mMetrics.internalLeading);
fprintf (stderr, " spaceWidth: %f aveCharWidth: %f xHeight: %f\n", mMetrics.spaceWidth, mMetrics.aveCharWidth, mMetrics.xHeight);
fprintf (stderr, " uOff: %f uSize: %f stOff: %f stSize: %f\n", mMetrics.underlineOffset, mMetrics.underlineSize, mMetrics.strikeoutOffset, mMetrics.strikeoutSize);
#endif
}
const gfxFont::Metrics&
gfxFT2FontBase::GetHorizontalMetrics()
{
return mMetrics;
}
// Get the glyphID of a space
uint32_t
gfxFT2FontBase::GetSpaceGlyph()
{
return mSpaceGlyph;
}
uint32_t
gfxFT2FontBase::GetGlyph(uint32_t unicode, uint32_t variation_selector)
{
if (variation_selector) {
uint32_t id =
gfxFT2LockedFace(this).GetUVSGlyph(unicode, variation_selector);
if (id) {
return id;
}
unicode = gfxFontUtils::GetUVSFallback(unicode, variation_selector);
if (unicode) {
return GetGlyph(unicode);
}
return 0;
}
return GetGlyph(unicode);
}
bool
gfxFT2FontBase::GetFTGlyphAdvance(uint16_t aGID, int32_t* aAdvance)
{
gfxFT2LockedFace face(this);
MOZ_ASSERT(face.get());
if (!face.get()) {
// Failed to get the FT_Face? Give up already.
NS_WARNING("failed to get FT_Face!");
return false;
}
// Due to bugs like 1435234 and 1440938, we currently prefer to fall back
// to reading the advance from cairo extents, unless we're dealing with
// a variation font (for which cairo metrics may be wrong, due to FreeType
// bug 52683).
if (!(face.get()->face_flags & FT_FACE_FLAG_SCALABLE) ||
!(face.get()->face_flags & FT_FACE_FLAG_MULTIPLE_MASTERS)) {
return false;
}
bool hinting = gfxPlatform::GetPlatform()->FontHintingEnabled();
int32_t flags =
hinting ? FT_LOAD_ADVANCE_ONLY
: FT_LOAD_ADVANCE_ONLY | FT_LOAD_NO_AUTOHINT | FT_LOAD_NO_HINTING;
FT_Error ftError = Factory::LoadFTGlyph(face.get(), aGID, flags);
if (ftError != FT_Err_Ok) {
// FT_Face was somehow broken/invalid? Don't try to access glyph slot.
// This probably shouldn't happen, but does: see bug 1440938.
NS_WARNING("failed to load glyph!");
return false;
}
// Due to freetype bug 52683 we MUST use the linearHoriAdvance field when
// dealing with a variation font. (And other fonts would have returned
// earlier, so only variation fonts currently reach here.)
FT_Fixed advance = face.get()->glyph->linearHoriAdvance;
// If freetype emboldening is being used, and it's not a zero-width glyph,
// adjust the advance to account for the increased width.
if (mEmbolden && advance > 0) {
// This is the embolden "strength" used by FT_GlyphSlot_Embolden,
// converted from 26.6 to 16.16
FT_Fixed strength = 1024 *
FT_MulFix(face.get()->units_per_EM,
face.get()->size->metrics.y_scale) / 24;
advance += strength;
}
// Round the 16.16 fixed-point value to whole pixels for better consistency
// with how cairo renders the glyphs.
*aAdvance = (advance + 0x8000) & 0xffff0000u;
return true;
}
int32_t
gfxFT2FontBase::GetGlyphWidth(DrawTarget& aDrawTarget, uint16_t aGID)
{
if (!mGlyphWidths) {
mGlyphWidths =
mozilla::MakeUnique<nsDataHashtable<nsUint32HashKey,int32_t>>(128);
}
int32_t width;
if (mGlyphWidths->Get(aGID, &width)) {
return width;
}
if (!GetFTGlyphAdvance(aGID, &width)) {
cairo_text_extents_t extents;
GetGlyphExtents(aGID, &extents);
width = NS_lround(0x10000 * extents.x_advance);
}
mGlyphWidths->Put(aGID, width);
return width;
}
bool
gfxFT2FontBase::SetupCairoFont(DrawTarget* aDrawTarget)
{
// The scaled font ctm is not relevant right here because
// cairo_set_scaled_font does not record the scaled font itself, but
// merely the font_face, font_matrix, font_options. The scaled_font used
// for the target can be different from the scaled_font passed to
// cairo_set_scaled_font. (Unfortunately we have measured only for an
// identity ctm.)
cairo_scaled_font_t *cairoFont = GetCairoScaledFont();
if (cairo_scaled_font_status(cairoFont) != CAIRO_STATUS_SUCCESS) {
// Don't cairo_set_scaled_font as that would propagate the error to
// the cairo_t, precluding any further drawing.
return false;
}
// Thoughts on which font_options to set on the context:
//
// cairoFont has been created for screen rendering.
//
// When the context is being used for screen rendering, we should set
// font_options such that the same scaled_font gets used (when the ctm is
// the same). The use of explicit font_options recorded in
// CreateScaledFont ensures that this will happen.
//
// XXXkt: For pdf and ps surfaces, I don't know whether it's better to
// remove surface-specific options, or try to draw with the same
// scaled_font that was used to measure. As the same font_face is being
// used, its font_options will often override some values anyway (unless
// perhaps we remove those from the FcPattern at face creation).
//
// I can't see any significant difference in printing, irrespective of
// what is set here. It's too late to change things here as measuring has
// already taken place. We should really be measuring with a different
// font for pdf and ps surfaces (bug 403513).
cairo_set_scaled_font(gfxFont::RefCairo(aDrawTarget), cairoFont);
return true;
}
// For variation fonts, figure out the variation coordinates to be applied
// for each axis, in freetype's order (which may not match the order of
// axes in mStyle.variationSettings, so we need to search by axis tag).
/*static*/
void
gfxFT2FontBase::SetupVarCoords(FT_MM_Var* aMMVar,
const nsTArray<gfxFontVariation>& aVariations,
nsTArray<FT_Fixed>* aCoords)
{
aCoords->TruncateLength(0);
if (!aMMVar) {
return;
}
for (unsigned i = 0; i < aMMVar->num_axis; ++i) {
aCoords->AppendElement(aMMVar->axis[i].def);
for (const auto& v : aVariations) {
if (aMMVar->axis[i].tag == v.mTag) {
FT_Fixed val = v.mValue * 0x10000;
val = std::min(val, aMMVar->axis[i].maximum);
val = std::max(val, aMMVar->axis[i].minimum);
(*aCoords)[i] = val;
break;
}
}
}
}