From 16b3f69d1c3260b8bdeb8c5058eaf4b6f4f2060a Mon Sep 17 00:00:00 2001
From: Adrian Johnson <ajohnson@redneon.com>
Date: Tue, 7 Feb 2012 16:03:45 +1030
Subject: [PATCH] cairo: adjust subtitute font width using first character in
 each string

instead of the letter 'm'. Bug 36536 has a PDF where the non embedded
font has bad widths for unused characters included the letter 'm'.
---
 poppler/CairoFontEngine.cc |   19 ++++++++-----------
 poppler/CairoFontEngine.h  |    2 +-
 poppler/CairoOutputDev.cc  |   35 ++++++++++++++++++++++++++++-------
 3 files changed, 37 insertions(+), 19 deletions(-)

diff --git a/poppler/CairoFontEngine.cc b/poppler/CairoFontEngine.cc
index c9d2d0c..7e8ba91 100644
--- a/poppler/CairoFontEngine.cc
+++ b/poppler/CairoFontEngine.cc
@@ -104,21 +104,13 @@ CairoFont::getGlyph(CharCode code,
 }
 
 double
-CairoFont::getSubstitutionCorrection(GfxFont *gfxFont)
+CairoFont::getSubstitutionCorrection(GfxFont *gfxFont, CharCode code)
 {
   double w1, w2;
-  CharCode code;
-  char *name;
 
   // for substituted fonts: adjust the font matrix -- compare the
-  // width of 'm' in the original font and the substituted font
+  // width of the character in the original font and the substituted font
   if (isSubstitute() && !gfxFont->isCIDFont()) {
-    for (code = 0; code < 256; ++code) {
-      if ((name = ((Gfx8BitFont *)gfxFont)->getCharName(code)) &&
-	  name[0] == 'm' && name[1] == '\0') {
-	break;
-      }
-    }
     if (code < 256) {
       w1 = ((Gfx8BitFont *)gfxFont)->getWidth(code);
       {
@@ -129,8 +121,13 @@ CairoFont::getSubstitutionCorrection(GfxFont *gfxFont)
 	cairo_font_options_set_hint_metrics(options, CAIRO_HINT_METRICS_OFF);
 	cairo_scaled_font_t *scaled_font = cairo_scaled_font_create(cairo_font_face, &m, &m, options);
 
+        cairo_glyph_t glyph;
+        glyph.index = getGlyph(code, NULL, 0);
+        glyph.x = 0;
+        glyph.y = 0;
+
 	cairo_text_extents_t extents;
-	cairo_scaled_font_text_extents(scaled_font, "m", &extents);
+	cairo_scaled_font_glyph_extents(scaled_font, &glyph, 1, &extents);
 
 	cairo_scaled_font_destroy(scaled_font);
 	cairo_font_options_destroy(options);
diff --git a/poppler/CairoFontEngine.h b/poppler/CairoFontEngine.h
index 6335348..5a1a5ca 100644
--- a/poppler/CairoFontEngine.h
+++ b/poppler/CairoFontEngine.h
@@ -53,7 +53,7 @@ public:
   virtual GBool matches(Ref &other, GBool printing);
   cairo_font_face_t *getFontFace(void);
   unsigned long getGlyph(CharCode code, Unicode *u, int uLen);
-  double getSubstitutionCorrection(GfxFont *gfxFont);
+  double getSubstitutionCorrection(GfxFont *gfxFont, CharCode code);
 
   GBool isSubstitute() { return substitute; }
 protected:
diff --git a/poppler/CairoOutputDev.cc b/poppler/CairoOutputDev.cc
index dab1e47..8ae448a 100644
--- a/poppler/CairoOutputDev.cc
+++ b/poppler/CairoOutputDev.cc
@@ -607,15 +607,11 @@ void CairoOutputDev::updateFont(GfxState *state) {
 
   use_show_text_glyphs = state->getFont()->hasToUnicodeCMap() &&
     cairo_surface_has_show_text_glyphs (cairo_get_target (cairo));
- 
+
   double fontSize = state->getFontSize();
   double *m = state->getTextMat();
-  /* NOTE: adjusting by a constant is hack. The correct solution
-   * is probably to use user-fonts and compute the scale on a per
-   * glyph basis instead of for the entire font */
-  double w = currentFont->getSubstitutionCorrection(state->getFont());
-  matrix.xx = m[0] * fontSize * state->getHorizScaling() * w;
-  matrix.yx = m[1] * fontSize * state->getHorizScaling() * w;
+  matrix.xx = m[0] * fontSize * state->getHorizScaling();
+  matrix.yx = m[1] * fontSize * state->getHorizScaling();
   matrix.xy = -m[2] * fontSize;
   matrix.yy = -m[3] * fontSize;
   matrix.x0 = 0;
@@ -1123,6 +1119,31 @@ void CairoOutputDev::drawChar(GfxState *state, double x, double y,
 			      CharCode code, int nBytes, Unicode *u, int uLen)
 {
   if (currentFont) {
+
+    /* Adjust width of substitute fonts to match the width of the
+     * first character in the string. (Bug 36536) */
+    if (glyphCount == 0 && currentFont->isSubstitute()) {
+      double w = currentFont->getSubstitutionCorrection(state->getFont(), code);
+      if (w != 1.0) {
+        /* NOTE: adjusting by a constant is hack. The correct solution
+         * is probably to use user-fonts and compute the scale on a per
+         * glyph basis instead of for the entire font */
+        double fontSize = state->getFontSize();
+        double *m = state->getTextMat();
+        cairo_matrix_t matrix;
+        matrix.xx = m[0] * fontSize * state->getHorizScaling() * w;
+        matrix.yx = m[1] * fontSize * state->getHorizScaling() * w;
+        matrix.xy = -m[2] * fontSize;
+        matrix.yy = -m[3] * fontSize;
+        matrix.x0 = 0;
+        matrix.y0 = 0;
+
+        LOG(printf ("substitute font matrix: %f %f %f %f\n", matrix.xx, matrix.yx, matrix.xy, matrix.yy));
+
+        cairo_set_font_matrix (cairo, &matrix);
+      }
+    }
+
     glyphs[glyphCount].index = currentFont->getGlyph (code, u, uLen);
     glyphs[glyphCount].x = x - originX;
     glyphs[glyphCount].y = y - originY;
-- 
1.7.5.4