Use CompositeMask instead of TransferBitmap when drawing type 3 text

core/fpdfapi/render/fpdf_render_text.cpp

Index: core/fpdfapi/render/fpdf_render_text.cpp
diff --git a/core/fpdfapi/render/fpdf_render_text.cpp b/core/fpdfapi/render/fpdf_render_text.cpp
index b8f44f8bd91294b3163d3a153a3de6bd51c9e330..d4ee392dfeb4f0f7042936824a49df10782b08b4 100644
--- a/core/fpdfapi/render/fpdf_render_text.cpp
+++ b/core/fpdfapi/render/fpdf_render_text.cpp
@@ -275,7 +275,6 @@ FX_BOOL CPDF_RenderStatus::ProcessType3Text(CPDF_TextObject* textobj,
         CFX_GlyphBitmap* pBitmap = pCache->LoadGlyph(charcode, &matrix, sa, sd);
         if (!pBitmap)
           continue;
-
         int origin_x = FXSYS_round(matrix.e);
         int origin_y = FXSYS_round(matrix.f);
         if (glyphs.empty()) {
@@ -302,7 +301,6 @@ FX_BOOL CPDF_RenderStatus::ProcessType3Text(CPDF_TextObject* textobj,
 
   if (glyphs.empty())
     return TRUE;
-
   FX_RECT rect = FXGE_GetGlyphsBBox(glyphs, 0, sa, sd);
   CFX_DIBitmap bitmap;
   if (!bitmap.Create(static_cast<int>(rect.Width() * sa),
@@ -314,13 +312,25 @@ FX_BOOL CPDF_RenderStatus::ProcessType3Text(CPDF_TextObject* textobj,
     if (!glyph.m_pGlyph)
       continue;
 
-    bitmap.TransferBitmap(
-        static_cast<int>(
-            (glyph.m_OriginX + glyph.m_pGlyph->m_Left - rect.left) * sa),
-        static_cast<int>((glyph.m_OriginY - glyph.m_pGlyph->m_Top - rect.top) *
-                         sd),
-        glyph.m_pGlyph->m_Bitmap.GetWidth(),
-        glyph.m_pGlyph->m_Bitmap.GetHeight(), &glyph.m_pGlyph->m_Bitmap, 0, 0);
+    pdfium::base::CheckedNumeric<int> left = glyph.m_OriginX;

[Lei Zhang, 2016/10/28 18:58:20]

nit: include the header for CheckedNumeric.

[npm, 2016/10/28 19:26:25]

Done.

+    left += glyph.m_pGlyph->m_Left;
+    left -= rect.left;
+    left *= sa;
+    if (!left.IsValid())
+      continue;
+
+    pdfium::base::CheckedNumeric<int> top = glyph.m_OriginY;
+    top -= glyph.m_pGlyph->m_Top;
+    top -= rect.top;
+    top *= sd;
+    if (!top.IsValid())
+      continue;
+
+    bitmap.CompositeMask(left.ValueOrDie(), top.ValueOrDie(),
+                         glyph.m_pGlyph->m_Bitmap.GetWidth(),
+                         glyph.m_pGlyph->m_Bitmap.GetHeight(),
+                         &glyph.m_pGlyph->m_Bitmap, fill_argb, 0, 0,
+                         FXDIB_BLEND_NORMAL, nullptr, FALSE, 0, nullptr);
   }
   m_pDevice->SetBitMask(&bitmap, rect.left, rect.top, fill_argb);
   return TRUE;