Add heuristic for improving text rendering in CPDF_CharPosList::Load
This CL uses the following algorithm for improving substitute font spacing (we
are assuming the text layout is horizontal):
* Calculate PDFWidth, the width that the PDF says the glyph should have.
* Calculate FTWidth, the width calculated by freetype for the glyph, using the
substitute font that we'll use to render it. Note that some embedded fonts have
PDFWidth == FTWidth + 1, so we consider that to be matching widths.
* If PDFWidth > FTWidth + 1 , move the x coordinate by the difference / 2 so
that the glyph is rendered in a more centered spot and the text looks better.
* If PDFWidth < FTWidth, transform the glyph horizontally by PDFWidth / FTWidth
so that the glyph gets compressed and does not overlap with surrounding glyphs.
Bug: chromium:431507
Change-Id: Ia378344253fabe44d93af4daab98bb3b7bca22de
Reviewed-on: https://pdfium-review.googlesource.com/6630
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Nicolás Peña <npm@chromium.org>
diff --git a/DEPS b/DEPS
index 7cecfe5..67159e0 100644
--- a/DEPS
+++ b/DEPS
@@ -19,7 +19,7 @@
'jinja2_revision': 'd34383206fa42d52faa10bb9931d6d538f3a57e0',
'jpeg_turbo_revision': '7260e4d8b8e1e40b17f03fafdf1cd83296900f76',
'markupsafe_revision': '8f45f5cfa0009d2a70589bcda0349b8cb2b72783',
- 'pdfium_tests_revision': '5379e0a6580443318c8192cdfc78a76e880ca3f6',
+ 'pdfium_tests_revision': '692df048179862d2e2eae2492e33a4673debe8bc',
'skia_revision': 'bb581ce30f55360fd3a12e7f5aa1fe324b16d085',
'tools_memory_revision': '427f10475e1a8d72424c29d00bf689122b738e5d',
'trace_event_revision': '06294c8a4a6f744ef284cd63cfe54dbf61eea290',
diff --git a/core/fpdfapi/font/cpdf_font.cpp b/core/fpdfapi/font/cpdf_font.cpp
index 1faa4ec..bdd3464 100644
--- a/core/fpdfapi/font/cpdf_font.cpp
+++ b/core/fpdfapi/font/cpdf_font.cpp
@@ -159,6 +159,10 @@
return m_pToUnicodeMap ? m_pToUnicodeMap->ReverseLookup(unicode) : 0;
}
+bool CPDF_Font::HasFontWidths() const {
+ return true;
+}
+
void CPDF_Font::LoadFontDescriptor(CPDF_Dictionary* pFontDesc) {
m_Flags = pFontDesc->GetIntegerFor("Flags", FXFONT_NONSYMBOLIC);
int ItalicAngle = 0;
diff --git a/core/fpdfapi/font/cpdf_font.h b/core/fpdfapi/font/cpdf_font.h
index 1fef77b..f705422 100644
--- a/core/fpdfapi/font/cpdf_font.h
+++ b/core/fpdfapi/font/cpdf_font.h
@@ -61,6 +61,7 @@
virtual int GlyphFromCharCodeExt(uint32_t charcode);
virtual CFX_WideString UnicodeFromCharCode(uint32_t charcode) const;
virtual uint32_t CharCodeFromUnicode(wchar_t Unicode) const;
+ virtual bool HasFontWidths() const;
const CFX_ByteString& GetBaseFont() const { return m_BaseFont; }
CFX_SubstFont* GetSubstFont() const { return m_Font.GetSubstFont(); }
diff --git a/core/fpdfapi/font/cpdf_simplefont.cpp b/core/fpdfapi/font/cpdf_simplefont.cpp
index ebf2cb6..a6c3ba0 100644
--- a/core/fpdfapi/font/cpdf_simplefont.cpp
+++ b/core/fpdfapi/font/cpdf_simplefont.cpp
@@ -212,3 +212,7 @@
return ret;
return m_Encoding.CharCodeFromUnicode(unicode);
}
+
+bool CPDF_SimpleFont::HasFontWidths() const {
+ return !m_bUseFontWidth;
+}
diff --git a/core/fpdfapi/font/cpdf_simplefont.h b/core/fpdfapi/font/cpdf_simplefont.h
index 3e414fa..6a22f46 100644
--- a/core/fpdfapi/font/cpdf_simplefont.h
+++ b/core/fpdfapi/font/cpdf_simplefont.h
@@ -29,6 +29,8 @@
CPDF_FontEncoding* GetEncoding() { return &m_Encoding; }
+ bool HasFontWidths() const override;
+
protected:
virtual void LoadGlyphMap() = 0;
diff --git a/core/fpdfapi/render/cpdf_charposlist.cpp b/core/fpdfapi/render/cpdf_charposlist.cpp
index d4c6b3b..68df46b 100644
--- a/core/fpdfapi/render/cpdf_charposlist.cpp
+++ b/core/fpdfapi/render/cpdf_charposlist.cpp
@@ -44,13 +44,16 @@
charpos.m_ExtGID = pFont->GlyphFromCharCodeExt(CharCode);
GlyphID = charpos.m_ExtGID;
#endif
+ CFX_Font* pCurrentFont;
if (GlyphID != static_cast<uint32_t>(-1)) {
charpos.m_FallbackFontPosition = -1;
+ pCurrentFont = pFont->GetFont();
} else {
charpos.m_FallbackFontPosition =
pFont->FallbackFontFromCharcode(CharCode);
charpos.m_GlyphIndex = pFont->FallbackGlyphFromCharcode(
charpos.m_FallbackFontPosition, CharCode);
+ pCurrentFont = pFont->GetFontFallback(charpos.m_FallbackFontPosition);
#if _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
charpos.m_ExtGID = charpos.m_GlyphIndex;
#endif
@@ -63,6 +66,29 @@
charpos.m_Origin = CFX_PointF(iChar ? charPos[iChar - 1] : 0, 0);
charpos.m_bGlyphAdjust = false;
+
+ float scalingFactor = 1.0f;
+ if (!pFont->IsEmbedded() && pFont->HasFontWidths() && !bVertWriting &&
+ !(pCurrentFont->GetSubstFont()->m_SubstFlags & FXFONT_SUBST_MM)) {
+ int pdfGlyphWidth = pFont->GetCharWidthF(CharCode);
+ int ftGlyphWidth =
+ pCurrentFont ? pCurrentFont->GetGlyphWidth(charpos.m_GlyphIndex) : 0;
+ if (ftGlyphWidth && pdfGlyphWidth > ftGlyphWidth + 1) {
+ // Move the initial x position by half of the excess (transformed to
+ // text space coordinates).
+ charpos.m_Origin.x +=
+ (pdfGlyphWidth - ftGlyphWidth) * FontSize / 2000.0f;
+ } else if (pdfGlyphWidth && ftGlyphWidth &&
+ pdfGlyphWidth < ftGlyphWidth) {
+ scalingFactor = static_cast<float>(pdfGlyphWidth) / ftGlyphWidth;
+ ASSERT(scalingFactor >= 0.0f);
+ charpos.m_AdjustMatrix[0] = scalingFactor;
+ charpos.m_AdjustMatrix[1] = 0.0f;
+ charpos.m_AdjustMatrix[2] = 0.0f;
+ charpos.m_AdjustMatrix[3] = 1.0f;
+ charpos.m_bGlyphAdjust = true;
+ }
+ }
if (!pCIDFont)
continue;
@@ -79,9 +105,11 @@
const uint8_t* pTransform = pCIDFont->GetCIDTransform(CID);
if (pTransform && !bVert) {
- charpos.m_AdjustMatrix[0] = pCIDFont->CIDTransformToFloat(pTransform[0]);
+ charpos.m_AdjustMatrix[0] =
+ pCIDFont->CIDTransformToFloat(pTransform[0]) * scalingFactor;
+ charpos.m_AdjustMatrix[1] =
+ pCIDFont->CIDTransformToFloat(pTransform[1]) * scalingFactor;
charpos.m_AdjustMatrix[2] = pCIDFont->CIDTransformToFloat(pTransform[2]);
- charpos.m_AdjustMatrix[1] = pCIDFont->CIDTransformToFloat(pTransform[1]);
charpos.m_AdjustMatrix[3] = pCIDFont->CIDTransformToFloat(pTransform[3]);
charpos.m_Origin.x +=
pCIDFont->CIDTransformToFloat(pTransform[4]) * FontSize;
