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-rw-r--r--gfx/thebes/gfxFT2Utils.cpp378
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diff --git a/gfx/thebes/gfxFT2Utils.cpp b/gfx/thebes/gfxFT2Utils.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 "mozilla/Likely.h"
+#include FT_TRUETYPE_TAGS_H
+#include FT_TRUETYPE_TABLES_H
+#include <algorithm>
+
+#ifdef HAVE_FONTCONFIG_FCFREETYPE_H
+#include <fontconfig/fcfreetype.h>
+#endif
+
+#include "prlink.h"
+
+// 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;
+}
+
+void
+gfxFT2LockedFace::GetMetrics(gfxFont::Metrics* aMetrics,
+ uint32_t* aSpaceGlyph)
+{
+ NS_PRECONDITION(aMetrics != nullptr, "aMetrics must not be NULL");
+ NS_PRECONDITION(aSpaceGlyph != nullptr, "aSpaceGlyph must not be NULL");
+
+ if (MOZ_UNLIKELY(!mFace)) {
+ // No face. This unfortunate situation might happen if the font
+ // file is (re)moved at the wrong time.
+ const gfxFloat emHeight = mGfxFont->GetStyle()->size;
+ aMetrics->emHeight = emHeight;
+ aMetrics->maxAscent = aMetrics->emAscent = 0.8 * emHeight;
+ aMetrics->maxDescent = aMetrics->emDescent = 0.2 * emHeight;
+ aMetrics->maxHeight = emHeight;
+ aMetrics->internalLeading = 0.0;
+ aMetrics->externalLeading = 0.2 * emHeight;
+ const gfxFloat spaceWidth = 0.5 * emHeight;
+ aMetrics->spaceWidth = spaceWidth;
+ aMetrics->maxAdvance = spaceWidth;
+ aMetrics->aveCharWidth = spaceWidth;
+ aMetrics->zeroOrAveCharWidth = spaceWidth;
+ const gfxFloat xHeight = 0.5 * emHeight;
+ aMetrics->xHeight = xHeight;
+ aMetrics->capHeight = aMetrics->maxAscent;
+ const gfxFloat underlineSize = emHeight / 14.0;
+ aMetrics->underlineSize = underlineSize;
+ aMetrics->underlineOffset = -underlineSize;
+ aMetrics->strikeoutOffset = 0.25 * emHeight;
+ aMetrics->strikeoutSize = underlineSize;
+
+ *aSpaceGlyph = 0;
+ return;
+ }
+
+ const FT_Size_Metrics& ftMetrics = mFace->size->metrics;
+
+ 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(mFace)) {
+ // 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.
+ yScale = FLOAT_FROM_26_6(FLOAT_FROM_16_16(ftMetrics.y_scale));
+ emHeight = mFace->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.
+ const TT_Header* head =
+ static_cast<TT_Header*>(FT_Get_Sfnt_Table(mFace, ft_sfnt_head));
+ if (head) {
+ gfxFloat emUnit = head->Units_Per_EM;
+ yScale = emHeight / emUnit;
+ }
+ }
+
+ TT_OS2 *os2 =
+ static_cast<TT_OS2*>(FT_Get_Sfnt_Table(mFace, ft_sfnt_os2));
+
+ aMetrics->maxAscent = FLOAT_FROM_26_6(ftMetrics.ascender);
+ aMetrics->maxDescent = -FLOAT_FROM_26_6(ftMetrics.descender);
+ aMetrics->maxAdvance = FLOAT_FROM_26_6(ftMetrics.max_advance);
+
+ gfxFloat lineHeight;
+ if (os2 && os2->sTypoAscender && yScale > 0.0) {
+ aMetrics->emAscent = os2->sTypoAscender * yScale;
+ aMetrics->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) {
+ aMetrics->maxAscent = NS_round(aMetrics->emAscent);
+ aMetrics->maxDescent = NS_round(aMetrics->emDescent);
+ } else {
+ // maxAscent/maxDescent get used for frame heights, and some fonts
+ // don't have the HHEA table ascent/descent set (bug 279032).
+ // We use NS_round here to parallel the pixel-rounded values that
+ // freetype gives us for ftMetrics.ascender/descender.
+ aMetrics->maxAscent =
+ std::max(aMetrics->maxAscent, NS_round(aMetrics->emAscent));
+ aMetrics->maxDescent =
+ std::max(aMetrics->maxDescent, NS_round(aMetrics->emDescent));
+ }
+ } else {
+ aMetrics->emAscent = aMetrics->maxAscent;
+ aMetrics->emDescent = aMetrics->maxDescent;
+ lineHeight = FLOAT_FROM_26_6(ftMetrics.height);
+ }
+
+ cairo_text_extents_t extents;
+ *aSpaceGlyph = GetCharExtents(' ', &extents);
+ if (*aSpaceGlyph) {
+ aMetrics->spaceWidth = extents.x_advance;
+ } else {
+ aMetrics->spaceWidth = aMetrics->maxAdvance; // guess
+ }
+
+ aMetrics->zeroOrAveCharWidth = 0.0;
+ if (GetCharExtents('0', &extents)) {
+ aMetrics->zeroOrAveCharWidth = extents.x_advance;
+ }
+
+ // 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.
+ if (GetCharExtents('x', &extents) && extents.y_bearing < 0.0) {
+ aMetrics->xHeight = -extents.y_bearing;
+ aMetrics->aveCharWidth = extents.x_advance;
+ } else {
+ if (os2 && os2->sxHeight && yScale > 0.0) {
+ aMetrics->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."
+ aMetrics->xHeight = 0.5 * emHeight;
+ }
+ aMetrics->aveCharWidth = 0.0; // updated below
+ }
+
+ if (GetCharExtents('H', &extents) && extents.y_bearing < 0.0) {
+ aMetrics->capHeight = -extents.y_bearing;
+ } else {
+ if (os2 && os2->sCapHeight && yScale > 0.0) {
+ aMetrics->capHeight = os2->sCapHeight * yScale;
+ } else {
+ aMetrics->capHeight = aMetrics->maxAscent;
+ }
+ }
+
+ // 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.
+ gfxFloat avgCharWidth =
+ ScaleRoundDesignUnits(os2->xAvgCharWidth, ftMetrics.x_scale);
+ aMetrics->aveCharWidth =
+ std::max(aMetrics->aveCharWidth, avgCharWidth);
+ }
+ aMetrics->aveCharWidth =
+ std::max(aMetrics->aveCharWidth, aMetrics->zeroOrAveCharWidth);
+ if (aMetrics->aveCharWidth == 0.0) {
+ aMetrics->aveCharWidth = aMetrics->spaceWidth;
+ }
+ if (aMetrics->zeroOrAveCharWidth == 0.0) {
+ aMetrics->zeroOrAveCharWidth = aMetrics->aveCharWidth;
+ }
+ // Apparently hinting can mean that max_advance is not always accurate.
+ aMetrics->maxAdvance =
+ std::max(aMetrics->maxAdvance, aMetrics->aveCharWidth);
+
+ // 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 (mFace->underline_position && mFace->underline_thickness && yScale > 0.0) {
+ aMetrics->underlineSize = mFace->underline_thickness * yScale;
+ TT_Postscript *post = static_cast<TT_Postscript*>
+ (FT_Get_Sfnt_Table(mFace, ft_sfnt_post));
+ if (post && post->underlinePosition) {
+ aMetrics->underlineOffset = post->underlinePosition * yScale;
+ } else {
+ aMetrics->underlineOffset = mFace->underline_position * yScale
+ + 0.5 * aMetrics->underlineSize;
+ }
+ } else { // No underline info.
+ // Imitate Pango.
+ aMetrics->underlineSize = emHeight / 14.0;
+ aMetrics->underlineOffset = -aMetrics->underlineSize;
+ }
+
+ if (os2 && os2->yStrikeoutSize && os2->yStrikeoutPosition && yScale > 0.0) {
+ aMetrics->strikeoutSize = os2->yStrikeoutSize * yScale;
+ aMetrics->strikeoutOffset = os2->yStrikeoutPosition * yScale;
+ } else { // No strikeout info.
+ aMetrics->strikeoutSize = aMetrics->underlineSize;
+ // Use OpenType spec's suggested position for Roman font.
+ aMetrics->strikeoutOffset = emHeight * 409.0 / 2048.0
+ + 0.5 * aMetrics->strikeoutSize;
+ }
+ SnapLineToPixels(aMetrics->strikeoutOffset, aMetrics->strikeoutSize);
+
+ aMetrics->maxHeight = aMetrics->maxAscent + aMetrics->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.
+ aMetrics->emHeight = floor(emHeight + 0.5);
+
+ // maxHeight will normally be an integer, but round anyway in case
+ // FreeType is configured differently.
+ aMetrics->internalLeading =
+ floor(aMetrics->maxHeight - aMetrics->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, aMetrics->maxHeight) + 0.5);
+ aMetrics->externalLeading =
+ lineHeight - aMetrics->internalLeading - aMetrics->emHeight;
+
+ // Ensure emAscent + emDescent == emHeight
+ gfxFloat sum = aMetrics->emAscent + aMetrics->emDescent;
+ aMetrics->emAscent = sum > 0.0 ?
+ aMetrics->emAscent * aMetrics->emHeight / sum : 0.0;
+ aMetrics->emDescent = aMetrics->emHeight - aMetrics->emAscent;
+}
+
+uint32_t
+gfxFT2LockedFace::GetGlyph(uint32_t aCharCode)
+{
+ if (MOZ_UNLIKELY(!mFace))
+ return 0;
+
+#ifdef HAVE_FONTCONFIG_FCFREETYPE_H
+ // FcFreeTypeCharIndex will search starting from the most recently
+ // selected charmap. This can cause non-determistic behavior when more
+ // than one charmap supports a character but with different glyphs, as
+ // with older versions of MS Gothic, for example. Always prefer a Unicode
+ // charmap, if there is one. (FcFreeTypeCharIndex usually does the
+ // appropriate Unicode conversion, but some fonts have non-Roman glyphs
+ // for FT_ENCODING_APPLE_ROMAN characters.)
+ if (!mFace->charmap || mFace->charmap->encoding != FT_ENCODING_UNICODE) {
+ FT_Select_Charmap(mFace, FT_ENCODING_UNICODE);
+ }
+
+ return FcFreeTypeCharIndex(mFace, aCharCode);
+#else
+ return FT_Get_Char_Index(mFace, aCharCode);
+#endif
+}
+
+typedef FT_UInt (*GetCharVariantFunction)(FT_Face face,
+ FT_ULong charcode,
+ FT_ULong variantSelector);
+
+uint32_t
+gfxFT2LockedFace::GetUVSGlyph(uint32_t aCharCode, uint32_t aVariantSelector)
+{
+ NS_PRECONDITION(aVariantSelector, "aVariantSelector should not be NULL");
+
+ if (MOZ_UNLIKELY(!mFace))
+ return 0;
+
+ // This function is available from FreeType 2.3.6 (June 2008).
+ static CharVariantFunction sGetCharVariantPtr = FindCharVariantFunction();
+ if (!sGetCharVariantPtr)
+ return 0;
+
+#ifdef HAVE_FONTCONFIG_FCFREETYPE_H
+ // FcFreeTypeCharIndex may have changed the selected charmap.
+ // FT_Face_GetCharVariantIndex needs a unicode charmap.
+ if (!mFace->charmap || mFace->charmap->encoding != FT_ENCODING_UNICODE) {
+ FT_Select_Charmap(mFace, FT_ENCODING_UNICODE);
+ }
+#endif
+
+ return (*sGetCharVariantPtr)(mFace, aCharCode, aVariantSelector);
+}
+
+uint32_t
+gfxFT2LockedFace::GetCharExtents(char aChar, cairo_text_extents_t* aExtents)
+{
+ NS_PRECONDITION(aExtents != nullptr, "aExtents must not be NULL");
+
+ if (!mFace)
+ return 0;
+
+ FT_UInt gid = mGfxFont->GetGlyph(aChar);
+ if (gid) {
+ mGfxFont->GetGlyphExtents(gid, aExtents);
+ }
+
+ return gid;
+}
+
+gfxFT2LockedFace::CharVariantFunction
+gfxFT2LockedFace::FindCharVariantFunction()
+{
+ // This function is available from FreeType 2.3.6 (June 2008).
+ PRLibrary *lib = nullptr;
+ CharVariantFunction function =
+ reinterpret_cast<CharVariantFunction>
+ (PR_FindFunctionSymbolAndLibrary("FT_Face_GetCharVariantIndex", &lib));
+ if (!lib) {
+ return nullptr;
+ }
+
+ FT_Int major;
+ FT_Int minor;
+ FT_Int patch;
+ FT_Library_Version(mFace->glyph->library, &major, &minor, &patch);
+
+ // Versions 2.4.0 to 2.4.3 crash if configured with
+ // FT_CONFIG_OPTION_OLD_INTERNALS. Presence of the symbol FT_Alloc
+ // indicates FT_CONFIG_OPTION_OLD_INTERNALS.
+ if (major == 2 && minor == 4 && patch < 4 &&
+ PR_FindFunctionSymbol(lib, "FT_Alloc")) {
+ function = nullptr;
+ }
+
+ // Decrement the reference count incremented in
+ // PR_FindFunctionSymbolAndLibrary.
+ PR_UnloadLibrary(lib);
+
+ return function;
+}
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