Add fallback fonts in pdfium

core/fpdfapi/fpdf_render/fpdf_render_text.cpp

Index: core/fpdfapi/fpdf_render/fpdf_render_text.cpp
diff --git a/core/fpdfapi/fpdf_render/fpdf_render_text.cpp b/core/fpdfapi/fpdf_render/fpdf_render_text.cpp
index 080a7578a77dfa2f7a97a223e7318edfa6e0a23a..b98f2abd756f72f19e03badc7f994daa5ec9edd2 100644
--- a/core/fpdfapi/fpdf_render/fpdf_render_text.cpp
+++ b/core/fpdfapi/fpdf_render/fpdf_render_text.cpp
@@ -371,6 +371,7 @@ class CPDF_RefType3Cache {
   CPDF_Type3Font* const m_pType3Font;
 };
 
+// TODO(npm) Font fallback for type 3 fonts? (Completely separate code!!)

[Lei Zhang, 2016/08/24 04:43:11]

TODO(username): Comment.

[npm, 2016/08/24 14:39:22]

Done.

 FX_BOOL CPDF_RenderStatus::ProcessType3Text(const CPDF_TextObject* textobj,
                                             const CFX_Matrix* pObj2Device) {
   CPDF_Type3Font* pType3Font = textobj->m_TextState.GetFont()->AsType3Font();
@@ -572,6 +573,17 @@ void CPDF_CharPosList::Load(int nChars,
       charpos.m_bFontStyle = true;
     }
     charpos.m_GlyphIndex = pFont->GlyphFromCharCode(CharCode, &bVert);
+    if (charpos.m_GlyphIndex != static_cast<uint32_t>(-1)) {
+      charpos.m_FallbackFontPosition = -1;
+    } else {
+      charpos.m_FallbackFontPosition =
+          pFont->FallbackFontFromCharcode(CharCode, &bVert);
+      if (charpos.m_FallbackFontPosition >= 0) {
+        charpos.m_GlyphIndex = pFont->FallbackGlyphFromCharcode(
+            charpos.m_FallbackFontPosition, CharCode, &bVert);
+      }
+    }
+// TODO(npm) Figure out how this affects m_ExtGID
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
     charpos.m_ExtGID = pFont->GlyphFromCharCodeExt(CharCode);
 #endif
@@ -629,10 +641,30 @@ FX_BOOL CPDF_TextRenderer::DrawTextPath(CFX_RenderDevice* pDevice,
                          : nullptr;
   CPDF_CharPosList CharPosList;
   CharPosList.Load(nChars, pCharCodes, pCharPos, pFont, font_size);
-  return pDevice->DrawTextPathWithFlags(
-      CharPosList.m_nChars, CharPosList.m_pCharPos, &pFont->m_Font, pCache,
-      font_size, pText2User, pUser2Device, pGraphState, fill_argb, stroke_argb,
-      pClippingPath, nFlag);
+  FX_BOOL bDraw = TRUE;

[Lei Zhang, 2016/08/24 04:43:11]

Use bool?

[npm, 2016/08/24 14:39:22]

DrawTextPath returns FX_BOOL

+  int32_t pFontPosition = CharPosList.m_pCharPos[0].m_FallbackFontPosition;

[dsinclair, 2016/08/23 20:58:02]

can m_pCharPos length be 0?

[npm, 2016/08/24 14:39:22]

Done.

+  uint32_t pStartIndex = 0;

[Lei Zhang, 2016/08/24 04:43:11]

Not a pointer, ditto for |pFontPosition| above.

[npm, 2016/08/24 14:39:22]

Done.

+  for (uint32_t i = 0; i < CharPosList.m_nChars; i++) {
+    int32_t pCurFontPosition = CharPosList.m_pCharPos[i].m_FallbackFontPosition;
+    if (pFontPosition != pCurFontPosition) {

[dsinclair, 2016/08/23 20:58:01]

if (pFontPosition == pCurFontPosition)
  continue;

[npm, 2016/08/24 14:39:22]

Done.

+      auto font = pFontPosition == -1

[Lei Zhang, 2016/08/24 04:43:11]

Is |font| a pointer? Use auto*

[npm, 2016/08/24 14:39:22]

Done.

+                      ? &pFont->m_Font
+                      : pFont->m_FontFallbacks[pFontPosition].get();
+      bDraw &= pDevice->DrawTextPathWithFlags(
+          i - pStartIndex, CharPosList.m_pCharPos + pStartIndex, font, pCache,
+          font_size, pText2User, pUser2Device, pGraphState, fill_argb,
+          stroke_argb, pClippingPath, nFlag);
+      pFontPosition = pCurFontPosition;
+      pStartIndex = i;
+    }
+  }
+  auto font = pFontPosition == -1 ? &pFont->m_Font
+                                  : pFont->m_FontFallbacks[pFontPosition].get();
+  bDraw &= pDevice->DrawTextPathWithFlags(
+      CharPosList.m_nChars - pStartIndex, CharPosList.m_pCharPos + pStartIndex,
+      font, pCache, font_size, pText2User, pUser2Device, pGraphState, fill_argb,
+      stroke_argb, pClippingPath, nFlag);
+  return bDraw;
 }
 
 // static
@@ -735,9 +767,28 @@ FX_BOOL CPDF_TextRenderer::DrawNormalText(CFX_RenderDevice* pDevice,
   if (pFont->IsCIDFont()) {
     FXGE_flags |= FXFONT_CIDFONT;
   }
-  return pDevice->DrawNormalText(CharPosList.m_nChars, CharPosList.m_pCharPos,
-                                 &pFont->m_Font, pCache, font_size,
-                                 pText2Device, fill_argb, FXGE_flags);
+  FX_BOOL bDraw = TRUE;
+  int32_t pFontPosition = CharPosList.m_pCharPos[0].m_FallbackFontPosition;

[dsinclair, 2016/08/23 20:58:01]

Same comments as above.

[npm, 2016/08/24 14:39:22]

Done.

+  uint32_t pStartIndex = 0;
+  for (uint32_t i = 0; i < CharPosList.m_nChars; i++) {
+    int32_t pCurFontPosition = CharPosList.m_pCharPos[i].m_FallbackFontPosition;
+    if (pFontPosition != pCurFontPosition) {
+      auto font = pFontPosition == -1
+                      ? &pFont->m_Font
+                      : pFont->m_FontFallbacks[pFontPosition].get();
+      bDraw &= pDevice->DrawNormalText(
+          i - pStartIndex, CharPosList.m_pCharPos + pStartIndex, font, pCache,
+          font_size, pText2Device, fill_argb, FXGE_flags);
+      pFontPosition = pCurFontPosition;
+      pStartIndex = i;
+    }
+  }
+  auto font = pFontPosition == -1 ? &pFont->m_Font
+                                  : pFont->m_FontFallbacks[pFontPosition].get();
+  bDraw &= pDevice->DrawNormalText(
+      CharPosList.m_nChars - pStartIndex, CharPosList.m_pCharPos + pStartIndex,
+      font, pCache, font_size, pText2Device, fill_argb, FXGE_flags);
+  return bDraw;
 }
 
 void CPDF_RenderStatus::DrawTextPathWithPattern(const CPDF_TextObject* textobj,
@@ -770,15 +821,26 @@ void CPDF_RenderStatus::DrawTextPathWithPattern(const CPDF_TextObject* textobj,
   } else {
     pCache = CFX_GEModule::Get()->GetFontCache();
   }
-  CFX_FaceCache* pFaceCache = pCache->GetCachedFace(&pFont->m_Font);
-  CFX_AutoFontCache autoFontCache(pCache, &pFont->m_Font);
   CPDF_CharPosList CharPosList;
   CharPosList.Load(textobj->m_nChars, textobj->m_pCharCodes,
                    textobj->m_pCharPos, pFont, font_size);
+  std::vector<CFX_FaceCache*> pFaceCaches;

[Lei Zhang, 2016/08/24 04:43:11]

Also not a pointer, thus the p-prefix is slightly misleading.

[npm, 2016/08/24 14:39:22]

Done.

+  std::vector<CFX_AutoFontCache> autoFontCaches;
+  pFaceCaches.push_back(pCache->GetCachedFace(&pFont->m_Font));
+  autoFontCaches.push_back(CFX_AutoFontCache(pCache, &pFont->m_Font));
+  for (auto& font : pFont->m_FontFallbacks) {
+    pFaceCaches.push_back(pCache->GetCachedFace(font.get()));
+    autoFontCaches.push_back(CFX_AutoFontCache(pCache, font.get()));
+  }
   for (uint32_t i = 0; i < CharPosList.m_nChars; i++) {
     FXTEXT_CHARPOS& charpos = CharPosList.m_pCharPos[i];
-    const CFX_PathData* pPath = pFaceCache->LoadGlyphPath(
-        &pFont->m_Font, charpos.m_GlyphIndex, charpos.m_FontCharWidth);
+    auto font =
+        charpos.m_FallbackFontPosition == -1
+            ? &pFont->m_Font
+            : pFont->m_FontFallbacks[charpos.m_FallbackFontPosition].get();
+    const CFX_PathData* pPath =
+        pFaceCaches[charpos.m_FallbackFontPosition + 1]->LoadGlyphPath(
+            font, charpos.m_GlyphIndex, charpos.m_FontCharWidth);
     if (!pPath) {
       continue;
     }