From 4db9046e56c884a350fa2c5087f8d5b8110463c4 Mon Sep 17 00:00:00 2001 From: Nicolas Pena Date: Mon, 19 Jun 2017 17:07:40 -0400 Subject: Add heuristic for improving text rendering in CPDF_CharPosList::Load MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Commit-Queue: Nicolás Peña --- core/fpdfapi/render/cpdf_charposlist.cpp | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) (limited to 'core/fpdfapi/render') diff --git a/core/fpdfapi/render/cpdf_charposlist.cpp b/core/fpdfapi/render/cpdf_charposlist.cpp index d4c6b3b5f9..68df46bdad 100644 --- a/core/fpdfapi/render/cpdf_charposlist.cpp +++ b/core/fpdfapi/render/cpdf_charposlist.cpp @@ -44,13 +44,16 @@ void CPDF_CharPosList::Load(const std::vector& charCodes, charpos.m_ExtGID = pFont->GlyphFromCharCodeExt(CharCode); GlyphID = charpos.m_ExtGID; #endif + CFX_Font* pCurrentFont; if (GlyphID != static_cast(-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 @@ void CPDF_CharPosList::Load(const std::vector& charCodes, 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(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 @@ void CPDF_CharPosList::Load(const std::vector& charCodes, 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; -- cgit v1.2.3