[PDF] Add a ToUnicode mapping for fonts.
This makes text in PDFs searchable and copy&paste-able.
Code from arthurhsu@chromium.org. Original review: http://codereview.appspot.com/4428082/
Review URL: http://codereview.appspot.com/4525042
git-svn-id: http://skia.googlecode.com/svn/trunk@1280 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/ports/SkFontHost_FreeType.cpp b/src/ports/SkFontHost_FreeType.cpp
index 5ed66c8..b3cc783 100644
--- a/src/ports/SkFontHost_FreeType.cpp
+++ b/src/ports/SkFontHost_FreeType.cpp
@@ -339,6 +339,56 @@
return true;
}
+static void populate_glyph_to_unicode(FT_Face& face,
+ SkTDArray<SkUnichar>* glyphToUnicode) {
+ // Check and see if we have Unicode cmaps.
+ for (int i = 0; i < face->num_charmaps; ++i) {
+ // CMaps known to support Unicode:
+ // Platform ID Encoding ID Name
+ // ----------- ----------- -----------------------------------
+ // 0 0,1 Apple Unicode
+ // 0 3 Apple Unicode 2.0 (preferred)
+ // 3 1 Microsoft Unicode UCS-2
+ // 3 10 Microsoft Unicode UCS-4 (preferred)
+ //
+ // See Apple TrueType Reference Manual
+ // http://developer.apple.com/fonts/TTRefMan/RM06/Chap6cmap.html
+ // http://developer.apple.com/fonts/TTRefMan/RM06/Chap6name.html#ID
+ // Microsoft OpenType Specification
+ // http://www.microsoft.com/typography/otspec/cmap.htm
+
+ FT_UShort platformId = face->charmaps[i]->platform_id;
+ FT_UShort encodingId = face->charmaps[i]->encoding_id;
+
+ if (platformId != 0 && platformId != 3) {
+ continue;
+ }
+ if (platformId == 3 && encodingId != 1 && encodingId != 10) {
+ continue;
+ }
+ bool preferredMap = ((platformId == 3 && encodingId == 10) ||
+ (platformId == 0 && encodingId == 3));
+
+ FT_Set_Charmap(face, face->charmaps[i]);
+ if (glyphToUnicode->isEmpty()) {
+ glyphToUnicode->setCount(face->num_glyphs);
+ memset(glyphToUnicode->begin(), 0,
+ sizeof(SkUnichar) * face->num_glyphs);
+ }
+
+ // Iterate through each cmap entry.
+ FT_UInt glyphIndex;
+ for (SkUnichar charCode = FT_Get_First_Char(face, &glyphIndex);
+ glyphIndex != 0;
+ charCode = FT_Get_Next_Char(face, charCode, &glyphIndex)) {
+ if (charCode &&
+ ((*glyphToUnicode)[glyphIndex] == 0 || preferredMap)) {
+ (*glyphToUnicode)[glyphIndex] = charCode;
+ }
+ }
+ }
+}
+
// static
SkAdvancedTypefaceMetrics* SkFontHost::GetAdvancedTypefaceMetrics(
uint32_t fontID,
@@ -509,6 +559,12 @@
}
}
+ if (perGlyphInfo & SkAdvancedTypefaceMetrics::kToUnicode_PerGlyphInfo &&
+ info->fType != SkAdvancedTypefaceMetrics::kType1_Font &&
+ face->num_charmaps) {
+ populate_glyph_to_unicode(face, &(info->fGlyphToUnicode));
+ }
+
if (!canEmbed(face))
info->fType = SkAdvancedTypefaceMetrics::kNotEmbeddable_Font;