Give names to the shading types

Currently the shading types are referenced by number. This Cl creates and enum
and updates the code to use the enum names instead of magic numbers.

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1418623011 .

4 files changed, 97 insertions, 40 deletions

diff --git a/core/include/fpdfapi/fpdf_resource.h b/core/include/fpdfapi/fpdf_resource.h
index 9fe6e2b95f..dee15cf941 100644
--- a/core/include/fpdfapi/fpdf_resource.h
+++ b/core/include/fpdfapi/fpdf_resource.h
@@ -679,6 +679,19 @@ class CPDF_TilingPattern : public CPDF_Pattern {
 
   CPDF_Form* m_pForm;
 };
+
+typedef enum {
+  kInvalidShading = 0,
+  kFunctionBasedShading = 1,
+  kAxialShading = 2,
+  kRadialShading = 3,
+  kFreeFormGouraudTriangleMeshShading = 4,
+  kLatticeFormGouraudTriangleMeshShading = 5,
+  kCoonsPatchMeshShading = 6,
+  kTensorProductPatchMeshShading = 7,
+  kMaxShading = 8
+} ShadingType;
+
 class CPDF_ShadingPattern : public CPDF_Pattern {
  public:
   CPDF_ShadingPattern(CPDF_Document* pDoc,
@@ -688,6 +701,13 @@ class CPDF_ShadingPattern : public CPDF_Pattern {
 
   ~CPDF_ShadingPattern() override;
 
+  bool IsMeshShading() const {
+    return m_ShadingType == kFreeFormGouraudTriangleMeshShading ||
+           m_ShadingType == kLatticeFormGouraudTriangleMeshShading ||
+           m_ShadingType == kCoonsPatchMeshShading ||
+           m_ShadingType == kTensorProductPatchMeshShading;
+  }
+
   CPDF_Object* m_pShadingObj;
 
   FX_BOOL m_bShadingObj;
@@ -696,7 +716,7 @@ class CPDF_ShadingPattern : public CPDF_Pattern {
 
   FX_BOOL Reload();
 
-  int m_ShadingType;
+  ShadingType m_ShadingType;
 
   CPDF_ColorSpace* m_pCS;  // Still keep m_pCS as some CPDF_ColorSpace (name
                            // object) are not managed as counted objects. Refer
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
index b12a65a844..3057948959 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
@@ -1092,12 +1092,13 @@ void CPDF_StreamContentParser::Handle_SetColorPS_Stroke() {
   }
   FX_Free(values);
 }
-CFX_FloatRect _GetShadingBBox(CPDF_Stream* pStream,
-                              int type,
-                              const CFX_AffineMatrix* pMatrix,
-                              CPDF_Function** pFuncs,
-                              int nFuncs,
-                              CPDF_ColorSpace* pCS);
+CFX_FloatRect GetShadingBBox(CPDF_Stream* pStream,
+                             ShadingType type,
+                             const CFX_AffineMatrix* pMatrix,
+                             CPDF_Function** pFuncs,
+                             int nFuncs,
+                             CPDF_ColorSpace* pCS);
+
 void CPDF_StreamContentParser::Handle_ShadeFill() {
   if (m_Options.m_bTextOnly) {
     return;
@@ -1127,11 +1128,11 @@ void CPDF_StreamContentParser::Handle_ShadeFill() {
   } else {
     bbox = m_BBox;
   }
-  if (pShading->m_ShadingType >= 4) {
-    bbox.Intersect(_GetShadingBBox(ToStream(pShading->m_pShadingObj),
-                                   pShading->m_ShadingType, &pObj->m_Matrix,
-                                   pShading->m_pFunctions, pShading->m_nFuncs,
-                                   pShading->m_pCS));
+  if (pShading->IsMeshShading()) {
+    bbox.Intersect(GetShadingBBox(ToStream(pShading->m_pShadingObj),
+                                  pShading->m_ShadingType, &pObj->m_Matrix,
+                                  pShading->m_pFunctions, pShading->m_nFuncs,
+                                  pShading->m_pCS));
   }
   pObj->m_Left = bbox.left;
   pObj->m_Right = bbox.right;
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp
index ded6c878ea..b669b3b5d2 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp
@@ -7,6 +7,24 @@
 #include "../../../include/fpdfapi/fpdf_page.h"
 #include "pageint.h"
 
+namespace {
+
+const int kSingleCoordinatePair = 1;
+const int kTensorCoordinatePairs = 16;
+const int kCoonsCoordinatePairs = 12;
+
+const int kSingleColorPerPatch = 1;
+const int kQuadColorsPerPatch = 4;
+
+ShadingType ToShadingType(int type) {
+  return (type > static_cast<int>(kInvalidShading) &&
+          type < static_cast<int>(kMaxShading))
+             ? static_cast<ShadingType>(type)
+             : kInvalidShading;
+}
+
+}  // namespace
+
 CPDF_Pattern::CPDF_Pattern(const CFX_AffineMatrix* pParentMatrix)
     : m_pPatternObj(NULL),
       m_PatternType(PATTERN_TILING),
@@ -78,7 +96,7 @@ CPDF_ShadingPattern::CPDF_ShadingPattern(CPDF_Document* pDoc,
   } else {
     m_pShadingObj = pPatternObj;
   }
-  m_ShadingType = 0;
+  m_ShadingType = kInvalidShading;
   m_pCS = NULL;
   m_nFuncs = 0;
   for (int i = 0; i < 4; i++) {
@@ -98,15 +116,16 @@ void CPDF_ShadingPattern::Clear() {
   if (pCS && m_pDocument) {
     m_pDocument->GetPageData()->ReleaseColorSpace(pCS->GetArray());
   }
-  m_ShadingType = 0;
+  m_ShadingType = kInvalidShading;
   m_pCS = NULL;
   m_pCountedCS = NULL;
   m_nFuncs = 0;
 }
+
 FX_BOOL CPDF_ShadingPattern::Load() {
-  if (m_ShadingType != 0) {
+  if (m_ShadingType != kInvalidShading)
     return TRUE;
-  }
+
   CPDF_Dictionary* pShadingDict =
       m_pShadingObj ? m_pShadingObj->GetDict() : NULL;
   if (pShadingDict == NULL) {
@@ -139,10 +158,12 @@ FX_BOOL CPDF_ShadingPattern::Load() {
   if (m_pCS) {
     m_pCountedCS = pDocPageData->FindColorSpacePtr(m_pCS->GetArray());
   }
-  m_ShadingType = pShadingDict->GetInteger(FX_BSTRC("ShadingType"));
+
+  m_ShadingType =
+      ToShadingType(pShadingDict->GetInteger(FX_BSTRC("ShadingType")));
 
   // We expect to have a stream if our shading type is a mesh.
-  if (m_ShadingType >= 4 && !ToStream(m_pShadingObj))
+  if (IsMeshShading() && !ToStream(m_pShadingObj))
     return FALSE;
 
   return TRUE;
@@ -253,12 +274,13 @@ FX_BOOL CPDF_MeshStream::GetVertexRow(CPDF_MeshVertex* vertex,
   }
   return TRUE;
 }
-CFX_FloatRect _GetShadingBBox(CPDF_Stream* pStream,
-                              int type,
-                              const CFX_AffineMatrix* pMatrix,
-                              CPDF_Function** pFuncs,
-                              int nFuncs,
-                              CPDF_ColorSpace* pCS) {
+
+CFX_FloatRect GetShadingBBox(CPDF_Stream* pStream,
+                             ShadingType type,
+                             const CFX_AffineMatrix* pMatrix,
+                             CPDF_Function** pFuncs,
+                             int nFuncs,
+                             CPDF_ColorSpace* pCS) {
   if (!pStream || !pStream->IsStream() || !pFuncs || !pCS)
     return CFX_FloatRect(0, 0, 0, 0);
 
@@ -268,19 +290,29 @@ CFX_FloatRect _GetShadingBBox(CPDF_Stream* pStream,
 
   CFX_FloatRect rect;
   FX_BOOL bStarted = FALSE;
-  FX_BOOL bGouraud = type == 4 || type == 5;
-  int full_point_count = type == 7 ? 16 : (type == 6 ? 12 : 1);
-  int full_color_count = (type == 6 || type == 7) ? 4 : 1;
+  FX_BOOL bGouraud = type == kFreeFormGouraudTriangleMeshShading ||
+                     type == kLatticeFormGouraudTriangleMeshShading;
+
+  int point_count = kSingleCoordinatePair;
+  if (type == kTensorProductPatchMeshShading)
+    point_count = kTensorCoordinatePairs;
+  else if (type == kCoonsPatchMeshShading)
+    point_count = kCoonsCoordinatePairs;
+
+  int color_count = kSingleColorPerPatch;
+  if (type == kCoonsPatchMeshShading || type == kTensorProductPatchMeshShading)
+    color_count = kQuadColorsPerPatch;
+
   while (!stream.m_BitStream.IsEOF()) {
     FX_DWORD flag = 0;
-    if (type != 5) {
+    if (type != kLatticeFormGouraudTriangleMeshShading)
       flag = stream.GetFlag();
-    }
-    int point_count = full_point_count, color_count = full_color_count;
+
     if (!bGouraud && flag) {
       point_count -= 4;
       color_count -= 2;
     }
+
     for (int i = 0; i < point_count; i++) {
       FX_FLOAT x, y;
       stream.GetCoords(x, y);
diff --git a/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp b/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
index 4ed6c07675..467ffc900c 100644
--- a/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
+++ b/core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
@@ -868,33 +868,37 @@ void CPDF_RenderStatus::DrawShading(CPDF_ShadingPattern* pPattern,
   pBitmap->Clear(background);
   int fill_mode = m_Options.m_Flags;
   switch (pPattern->m_ShadingType) {
-    case 1:
+    case kInvalidShading:
+    case kMaxShading:
+      return;
+    case kFunctionBasedShading:
       DrawFuncShading(pBitmap, &FinalMatrix, pDict, pFuncs, nFuncs, pColorSpace,
                       alpha);
       break;
-    case 2:
+    case kAxialShading:
       DrawAxialShading(pBitmap, &FinalMatrix, pDict, pFuncs, nFuncs,
                        pColorSpace, alpha);
       break;
-    case 3:
+    case kRadialShading:
       DrawRadialShading(pBitmap, &FinalMatrix, pDict, pFuncs, nFuncs,
                         pColorSpace, alpha);
       break;
-    case 4: {
+    case kFreeFormGouraudTriangleMeshShading: {
       DrawFreeGouraudShading(pBitmap, &FinalMatrix,
                              ToStream(pPattern->m_pShadingObj), pFuncs, nFuncs,
                              pColorSpace, alpha);
     } break;
-    case 5: {
+    case kLatticeFormGouraudTriangleMeshShading: {
       DrawLatticeGouraudShading(pBitmap, &FinalMatrix,
                                 ToStream(pPattern->m_pShadingObj), pFuncs,
                                 nFuncs, pColorSpace, alpha);
     } break;
-    case 6:
-    case 7: {
-      DrawCoonPatchMeshes(pPattern->m_ShadingType - 6, pBitmap, &FinalMatrix,
-                          ToStream(pPattern->m_pShadingObj), pFuncs, nFuncs,
-                          pColorSpace, fill_mode, alpha);
+    case kCoonsPatchMeshShading:
+    case kTensorProductPatchMeshShading: {
+      DrawCoonPatchMeshes(
+          pPattern->m_ShadingType == kTensorProductPatchMeshShading, pBitmap,
+          &FinalMatrix, ToStream(pPattern->m_pShadingObj), pFuncs, nFuncs,
+          pColorSpace, fill_mode, alpha);
     } break;
   }
   if (bAlphaMode) {