1 files changed, 314 insertions, 280 deletions

diff --git a/core/fpdfapi/render/cpdf_rendershading.cpp b/core/fpdfapi/render/cpdf_rendershading.cpp
index 53fb79a66..ce7543b6e 100644
--- a/core/fpdfapi/render/cpdf_rendershading.cpp
+++ b/core/fpdfapi/render/cpdf_rendershading.cpp
@@ -1,4 +1,4 @@
-// Copyright 2019 PDFium Authors. All rights reserved.
+// Copyright 2019 The PDFium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -6,9 +6,10 @@
 
 #include "core/fpdfapi/render/cpdf_rendershading.h"
 
+#include <math.h>
+
 #include <algorithm>
 #include <array>
-#include <cmath>
 #include <memory>
 #include <utility>
 #include <vector>
@@ -25,9 +26,16 @@
 #include "core/fpdfapi/render/cpdf_renderoptions.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span_util.h"
 #include "core/fxge/cfx_defaultrenderdevice.h"
+#include "core/fxge/cfx_fillrenderoptions.h"
+#include "core/fxge/cfx_path.h"
 #include "core/fxge/dib/cfx_dibitmap.h"
-#include "core/fxge/fx_dib.h"
+#include "core/fxge/dib/fx_dib.h"
+#include "third_party/base/check.h"
+#include "third_party/base/check_op.h"
+#include "third_party/base/cxx17_backports.h"
+#include "third_party/base/span.h"
 
 namespace {
 
@@ -57,28 +65,28 @@ std::array<FX_ARGB, kShadingSteps> GetShadingSteps(
     const RetainPtr<CPDF_ColorSpace>& pCS,
     int alpha,
     size_t results_count) {
-  ASSERT(results_count >= CountOutputsFromFunctions(funcs));
-  ASSERT(results_count >= pCS->CountComponents());
+  DCHECK(results_count >= CountOutputsFromFunctions(funcs));
+  DCHECK(results_count >= pCS->CountComponents());
   std::array<FX_ARGB, kShadingSteps> shading_steps;
   std::vector<float> result_array(results_count);
   float diff = t_max - t_min;
   for (int i = 0; i < kShadingSteps; ++i) {
     float input = diff * i / kShadingSteps + t_min;
-    int offset = 0;
+    pdfium::span<float> result_span = pdfium::make_span(result_array);
     for (const auto& func : funcs) {
-      if (func) {
-        int nresults = 0;
-        if (func->Call(&input, 1, &result_array[offset], &nresults))
-          offset += nresults;
-      }
+      if (!func)
+        continue;
+      absl::optional<uint32_t> nresults =
+          func->Call(pdfium::make_span(&input, 1), result_span);
+      if (nresults.has_value())
+        result_span = result_span.subspan(nresults.value());
     }
     float R = 0.0f;
     float G = 0.0f;
     float B = 0.0f;
-    pCS->GetRGB(result_array.data(), &R, &G, &B);
-    shading_steps[i] =
-        FXARGB_TODIB(ArgbEncode(alpha, FXSYS_roundf(R * 255),
-                                FXSYS_roundf(G * 255), FXSYS_roundf(B * 255)));
+    pCS->GetRGB(result_array, &R, &G, &B);
+    shading_steps[i] = ArgbEncode(alpha, FXSYS_roundf(R * 255),
+                                  FXSYS_roundf(G * 255), FXSYS_roundf(B * 255));
   }
   return shading_steps;
 }
@@ -89,26 +97,26 @@ void DrawAxialShading(const RetainPtr<CFX_DIBitmap>& pBitmap,
                       const std::vector<std::unique_ptr<CPDF_Function>>& funcs,
                       const RetainPtr<CPDF_ColorSpace>& pCS,
                       int alpha) {
-  ASSERT(pBitmap->GetFormat() == FXDIB_Argb);
+  DCHECK_EQ(pBitmap->GetFormat(), FXDIB_Format::kArgb);
 
   const uint32_t total_results = GetValidatedOutputsCount(funcs, pCS);
   if (total_results == 0)
     return;
 
-  const CPDF_Array* pCoords = pDict->GetArrayFor("Coords");
+  RetainPtr<const CPDF_Array> pCoords = pDict->GetArrayFor("Coords");
   if (!pCoords)
     return;
 
-  float start_x = pCoords->GetNumberAt(0);
-  float start_y = pCoords->GetNumberAt(1);
-  float end_x = pCoords->GetNumberAt(2);
-  float end_y = pCoords->GetNumberAt(3);
+  float start_x = pCoords->GetFloatAt(0);
+  float start_y = pCoords->GetFloatAt(1);
+  float end_x = pCoords->GetFloatAt(2);
+  float end_y = pCoords->GetFloatAt(3);
   float t_min = 0;
   float t_max = 1.0f;
-  const CPDF_Array* pArray = pDict->GetArrayFor("Domain");
+  RetainPtr<const CPDF_Array> pArray = pDict->GetArrayFor("Domain");
   if (pArray) {
-    t_min = pArray->GetNumberAt(0);
-    t_max = pArray->GetNumberAt(1);
+    t_min = pArray->GetFloatAt(0);
+    t_max = pArray->GetFloatAt(1);
   }
   pArray = pDict->GetArrayFor("Extend");
   const bool bStartExtend = pArray && pArray->GetBooleanAt(0, false);
@@ -123,18 +131,17 @@ void DrawAxialShading(const RetainPtr<CFX_DIBitmap>& pBitmap,
   std::array<FX_ARGB, kShadingSteps> shading_steps =
       GetShadingSteps(t_min, t_max, funcs, pCS, alpha, total_results);
 
-  int pitch = pBitmap->GetPitch();
   CFX_Matrix matrix = mtObject2Bitmap.GetInverse();
   for (int row = 0; row < height; row++) {
     uint32_t* dib_buf =
-        reinterpret_cast<uint32_t*>(pBitmap->GetBuffer() + row * pitch);
+        reinterpret_cast<uint32_t*>(pBitmap->GetWritableScanline(row).data());
     for (int column = 0; column < width; column++) {
       CFX_PointF pos = matrix.Transform(
           CFX_PointF(static_cast<float>(column), static_cast<float>(row)));
       float scale =
           (((pos.x - start_x) * x_span) + ((pos.y - start_y) * y_span)) /
           axis_len_square;
-      int index = (int32_t)(scale * (kShadingSteps - 1));
+      int index = static_cast<int32_t>(scale * (kShadingSteps - 1));
       if (index < 0) {
         if (!bStartExtend)
           continue;
@@ -157,28 +164,28 @@ void DrawRadialShading(const RetainPtr<CFX_DIBitmap>& pBitmap,
                        const std::vector<std::unique_ptr<CPDF_Function>>& funcs,
                        const RetainPtr<CPDF_ColorSpace>& pCS,
                        int alpha) {
-  ASSERT(pBitmap->GetFormat() == FXDIB_Argb);
+  DCHECK_EQ(pBitmap->GetFormat(), FXDIB_Format::kArgb);
 
   const uint32_t total_results = GetValidatedOutputsCount(funcs, pCS);
   if (total_results == 0)
     return;
 
-  const CPDF_Array* pCoords = pDict->GetArrayFor("Coords");
+  RetainPtr<const CPDF_Array> pCoords = pDict->GetArrayFor("Coords");
   if (!pCoords)
     return;
 
-  float start_x = pCoords->GetNumberAt(0);
-  float start_y = pCoords->GetNumberAt(1);
-  float start_r = pCoords->GetNumberAt(2);
-  float end_x = pCoords->GetNumberAt(3);
-  float end_y = pCoords->GetNumberAt(4);
-  float end_r = pCoords->GetNumberAt(5);
+  float start_x = pCoords->GetFloatAt(0);
+  float start_y = pCoords->GetFloatAt(1);
+  float start_r = pCoords->GetFloatAt(2);
+  float end_x = pCoords->GetFloatAt(3);
+  float end_y = pCoords->GetFloatAt(4);
+  float end_r = pCoords->GetFloatAt(5);
   float t_min = 0;
   float t_max = 1.0f;
-  const CPDF_Array* pArray = pDict->GetArrayFor("Domain");
+  RetainPtr<const CPDF_Array> pArray = pDict->GetArrayFor("Domain");
   if (pArray) {
-    t_min = pArray->GetNumberAt(0);
-    t_max = pArray->GetNumberAt(1);
+    t_min = pArray->GetFloatAt(0);
+    t_max = pArray->GetFloatAt(1);
   }
   pArray = pDict->GetArrayFor("Extend");
   const bool bStartExtend = pArray && pArray->GetBooleanAt(0, false);
@@ -191,19 +198,16 @@ void DrawRadialShading(const RetainPtr<CFX_DIBitmap>& pBitmap,
   const float dy = end_y - start_y;
   const float dr = end_r - start_r;
   const float a = dx * dx + dy * dy - dr * dr;
-  const bool a_is_float_zero = IsFloatZero(a);
+  const bool a_is_float_zero = FXSYS_IsFloatZero(a);
 
   int width = pBitmap->GetWidth();
   int height = pBitmap->GetHeight();
-  int pitch = pBitmap->GetPitch();
-
-  bool bDecreasing =
-      (dr < 0 && static_cast<int>(sqrt(dx * dx + dy * dy)) < -dr);
+  bool bDecreasing = dr < 0 && static_cast<int>(FXSYS_sqrt2(dx, dy)) < -dr;
 
   CFX_Matrix matrix = mtObject2Bitmap.GetInverse();
   for (int row = 0; row < height; row++) {
     uint32_t* dib_buf =
-        reinterpret_cast<uint32_t*>(pBitmap->GetBuffer() + row * pitch);
+        reinterpret_cast<uint32_t*>(pBitmap->GetWritableScanline(row).data());
     for (int column = 0; column < width; column++) {
       CFX_PointF pos = matrix.Transform(
           CFX_PointF(static_cast<float>(column), static_cast<float>(row)));
@@ -212,7 +216,7 @@ void DrawRadialShading(const RetainPtr<CFX_DIBitmap>& pBitmap,
       float b = -2 * (pos_dx * dx + pos_dy * dy + start_r * dr);
       float c = pos_dx * pos_dx + pos_dy * pos_dy - start_r * start_r;
       float s;
-      if (IsFloatZero(b)) {
+      if (FXSYS_IsFloatZero(b)) {
         s = sqrt(-c / a);
       } else if (a_is_float_zero) {
         s = -c / b;
@@ -256,57 +260,57 @@ void DrawFuncShading(const RetainPtr<CFX_DIBitmap>& pBitmap,
                      const std::vector<std::unique_ptr<CPDF_Function>>& funcs,
                      const RetainPtr<CPDF_ColorSpace>& pCS,
                      int alpha) {
-  ASSERT(pBitmap->GetFormat() == FXDIB_Argb);
+  DCHECK_EQ(pBitmap->GetFormat(), FXDIB_Format::kArgb);
 
   const uint32_t total_results = GetValidatedOutputsCount(funcs, pCS);
   if (total_results == 0)
     return;
 
-  const CPDF_Array* pDomain = pDict->GetArrayFor("Domain");
+  RetainPtr<const CPDF_Array> pDomain = pDict->GetArrayFor("Domain");
   float xmin = 0.0f;
   float ymin = 0.0f;
   float xmax = 1.0f;
   float ymax = 1.0f;
   if (pDomain) {
-    xmin = pDomain->GetNumberAt(0);
-    xmax = pDomain->GetNumberAt(1);
-    ymin = pDomain->GetNumberAt(2);
-    ymax = pDomain->GetNumberAt(3);
+    xmin = pDomain->GetFloatAt(0);
+    xmax = pDomain->GetFloatAt(1);
+    ymin = pDomain->GetFloatAt(2);
+    ymax = pDomain->GetFloatAt(3);
   }
   CFX_Matrix mtDomain2Target = pDict->GetMatrixFor("Matrix");
   CFX_Matrix matrix =
       mtObject2Bitmap.GetInverse() * mtDomain2Target.GetInverse();
   int width = pBitmap->GetWidth();
   int height = pBitmap->GetHeight();
-  int pitch = pBitmap->GetPitch();
 
-  ASSERT(total_results >= CountOutputsFromFunctions(funcs));
-  ASSERT(total_results >= pCS->CountComponents());
+  DCHECK(total_results >= CountOutputsFromFunctions(funcs));
+  DCHECK(total_results >= pCS->CountComponents());
   std::vector<float> result_array(total_results);
   for (int row = 0; row < height; ++row) {
-    uint32_t* dib_buf = (uint32_t*)(pBitmap->GetBuffer() + row * pitch);
+    uint32_t* dib_buf =
+        reinterpret_cast<uint32_t*>(pBitmap->GetWritableScanline(row).data());
     for (int column = 0; column < width; column++) {
       CFX_PointF pos = matrix.Transform(
           CFX_PointF(static_cast<float>(column), static_cast<float>(row)));
       if (pos.x < xmin || pos.x > xmax || pos.y < ymin || pos.y > ymax)
         continue;
 
-      float input[] = {pos.x, pos.y};
-      int offset = 0;
+      float input[2] = {pos.x, pos.y};
+      pdfium::span<float> result_span = pdfium::make_span(result_array);
       for (const auto& func : funcs) {
-        if (func) {
-          int nresults;
-          if (func->Call(input, 2, &result_array[offset], &nresults))
-            offset += nresults;
-        }
+        if (!func)
+          continue;
+        absl::optional<uint32_t> nresults = func->Call(input, result_span);
+        if (nresults.has_value())
+          result_span = result_span.subspan(nresults.value());
       }
-
       float R = 0.0f;
       float G = 0.0f;
       float B = 0.0f;
-      pCS->GetRGB(result_array.data(), &R, &G, &B);
-      dib_buf[column] = FXARGB_TODIB(ArgbEncode(
-          alpha, (int32_t)(R * 255), (int32_t)(G * 255), (int32_t)(B * 255)));
+      pCS->GetRGB(result_array, &R, &G, &B);
+      dib_buf[column] = ArgbEncode(alpha, static_cast<int32_t>(R * 255),
+                                   static_cast<int32_t>(G * 255),
+                                   static_cast<int32_t>(B * 255));
     }
   }
 }
@@ -340,9 +344,8 @@ void DrawGouraud(const RetainPtr<CFX_DIBitmap>& pBitmap,
   if (min_y == max_y)
     return;
 
-  int min_yi = std::max(static_cast<int>(floor(min_y)), 0);
-  int max_yi = static_cast<int>(ceil(max_y));
-
+  int min_yi = std::max(static_cast<int>(floorf(min_y)), 0);
+  int max_yi = static_cast<int>(ceilf(max_y));
   if (max_yi >= pBitmap->GetHeight())
     max_yi = pBitmap->GetHeight() - 1;
 
@@ -371,40 +374,42 @@ void DrawGouraud(const RetainPtr<CFX_DIBitmap>& pBitmap,
     if (nIntersects != 2)
       continue;
 
-    int min_x, max_x, start_index, end_index;
+    int min_x;
+    int max_x;
+    int start_index;
+    int end_index;
     if (inter_x[0] < inter_x[1]) {
-      min_x = (int)floor(inter_x[0]);
-      max_x = (int)ceil(inter_x[1]);
+      min_x = static_cast<int>(floorf(inter_x[0]));
+      max_x = static_cast<int>(ceilf(inter_x[1]));
       start_index = 0;
       end_index = 1;
     } else {
-      min_x = (int)floor(inter_x[1]);
-      max_x = (int)ceil(inter_x[0]);
+      min_x = static_cast<int>(floorf(inter_x[1]));
+      max_x = static_cast<int>(ceilf(inter_x[0]));
       start_index = 1;
       end_index = 0;
     }
 
-    int start_x = std::max(min_x, 0);
-    int end_x = max_x;
-    if (end_x > pBitmap->GetWidth())
-      end_x = pBitmap->GetWidth();
-
-    uint8_t* dib_buf =
-        pBitmap->GetBuffer() + y * pBitmap->GetPitch() + start_x * 4;
+    int start_x = pdfium::clamp(min_x, 0, pBitmap->GetWidth());
+    int end_x = pdfium::clamp(max_x, 0, pBitmap->GetWidth());
     float r_unit = (r[end_index] - r[start_index]) / (max_x - min_x);
     float g_unit = (g[end_index] - g[start_index]) / (max_x - min_x);
     float b_unit = (b[end_index] - b[start_index]) / (max_x - min_x);
-    float R = r[start_index] + (start_x - min_x) * r_unit;
-    float G = g[start_index] + (start_x - min_x) * g_unit;
-    float B = b[start_index] + (start_x - min_x) * b_unit;
+    float r_result = r[start_index] + (start_x - min_x) * r_unit;
+    float g_result = g[start_index] + (start_x - min_x) * g_unit;
+    float b_result = b[start_index] + (start_x - min_x) * b_unit;
+    pdfium::span<uint8_t> dib_span =
+        pBitmap->GetWritableScanline(y).subspan(start_x * 4);
+
     for (int x = start_x; x < end_x; x++) {
-      R += r_unit;
-      G += g_unit;
-      B += b_unit;
-      FXARGB_SETDIB(dib_buf,
-                    ArgbEncode(alpha, (int32_t)(R * 255), (int32_t)(G * 255),
-                               (int32_t)(B * 255)));
-      dib_buf += 4;
+      uint8_t* dib_buf = dib_span.data();
+      r_result += r_unit;
+      g_result += g_unit;
+      b_result += b_unit;
+      FXARGB_SETDIB(dib_buf, ArgbEncode(alpha, static_cast<int>(r_result * 255),
+                                        static_cast<int>(g_result * 255),
+                                        static_cast<int>(b_result * 255)));
+      dib_span = dib_span.subspan(4);
     }
   }
 }
@@ -412,21 +417,19 @@ void DrawGouraud(const RetainPtr<CFX_DIBitmap>& pBitmap,
 void DrawFreeGouraudShading(
     const RetainPtr<CFX_DIBitmap>& pBitmap,
     const CFX_Matrix& mtObject2Bitmap,
-    const CPDF_Stream* pShadingStream,
+    RetainPtr<const CPDF_Stream> pShadingStream,
     const std::vector<std::unique_ptr<CPDF_Function>>& funcs,
-    const RetainPtr<CPDF_ColorSpace>& pCS,
+    RetainPtr<CPDF_ColorSpace> pCS,
     int alpha) {
-  ASSERT(pBitmap->GetFormat() == FXDIB_Argb);
+  DCHECK_EQ(pBitmap->GetFormat(), FXDIB_Format::kArgb);
 
   CPDF_MeshStream stream(kFreeFormGouraudTriangleMeshShading, funcs,
-                         pShadingStream, pCS);
+                         std::move(pShadingStream), std::move(pCS));
   if (!stream.Load())
     return;
 
   CPDF_MeshVertex triangle[3];
-  memset(triangle, 0, sizeof(triangle));
-
-  while (!stream.BitStream()->IsEOF()) {
+  while (!stream.IsEOF()) {
     CPDF_MeshVertex vertex;
     uint32_t flag;
     if (!stream.ReadVertex(mtObject2Bitmap, &vertex, &flag))
@@ -434,9 +437,9 @@ void DrawFreeGouraudShading(
 
     if (flag == 0) {
       triangle[0] = vertex;
-      for (int j = 1; j < 3; j++) {
-        uint32_t tflag;
-        if (!stream.ReadVertex(mtObject2Bitmap, &triangle[j], &tflag))
+      for (int i = 1; i < 3; ++i) {
+        uint32_t dummy_flag;
+        if (!stream.ReadVertex(mtObject2Bitmap, &triangle[i], &dummy_flag))
           return;
       }
     } else {
@@ -453,18 +456,18 @@ void DrawFreeGouraudShading(
 void DrawLatticeGouraudShading(
     const RetainPtr<CFX_DIBitmap>& pBitmap,
     const CFX_Matrix& mtObject2Bitmap,
-    const CPDF_Stream* pShadingStream,
+    RetainPtr<const CPDF_Stream> pShadingStream,
     const std::vector<std::unique_ptr<CPDF_Function>>& funcs,
-    const RetainPtr<CPDF_ColorSpace>& pCS,
+    RetainPtr<CPDF_ColorSpace> pCS,
     int alpha) {
-  ASSERT(pBitmap->GetFormat() == FXDIB_Argb);
+  DCHECK_EQ(pBitmap->GetFormat(), FXDIB_Format::kArgb);
 
   int row_verts = pShadingStream->GetDict()->GetIntegerFor("VerticesPerRow");
   if (row_verts < 2)
     return;
 
   CPDF_MeshStream stream(kLatticeFormGouraudTriangleMeshShading, funcs,
-                         pShadingStream, pCS);
+                         std::move(pShadingStream), std::move(pCS));
   if (!stream.Load())
     return;
 
@@ -474,7 +477,7 @@ void DrawLatticeGouraudShading(
     return;
 
   int last_index = 0;
-  while (1) {
+  while (true) {
     vertices[1 - last_index] = stream.ReadVertexRow(mtObject2Bitmap, row_verts);
     if (vertices[1 - last_index].empty())
       return;
@@ -492,123 +495,127 @@ void DrawLatticeGouraudShading(
   }
 }
 
-struct Coon_BezierCoeff {
-  float a, b, c, d;
-  void FromPoints(float p0, float p1, float p2, float p3) {
+struct CoonBezierCoeff {
+  void InitFromPoints(float p0, float p1, float p2, float p3) {
     a = -p0 + 3 * p1 - 3 * p2 + p3;
     b = 3 * p0 - 6 * p1 + 3 * p2;
     c = -3 * p0 + 3 * p1;
     d = p0;
   }
-  Coon_BezierCoeff first_half() {
-    Coon_BezierCoeff result;
+
+  void InitFromBezierInterpolation(const CoonBezierCoeff& C1,
+                                   const CoonBezierCoeff& C2,
+                                   const CoonBezierCoeff& D1,
+                                   const CoonBezierCoeff& D2) {
+    a = (D1.a + D2.a) / 2;
+    b = (D1.b + D2.b) / 2;
+    c = (D1.c + D2.c) / 2 - (C1.a / 8 + C1.b / 4 + C1.c / 2) +
+        (C2.a / 8 + C2.b / 4) + (-C1.d + D2.d) / 2 - (C2.a + C2.b) / 2;
+    d = C1.a / 8 + C1.b / 4 + C1.c / 2 + C1.d;
+  }
+
+  CoonBezierCoeff first_half() const {
+    CoonBezierCoeff result;
     result.a = a / 8;
     result.b = b / 4;
     result.c = c / 2;
     result.d = d;
     return result;
   }
-  Coon_BezierCoeff second_half() {
-    Coon_BezierCoeff result;
+
+  CoonBezierCoeff second_half() const {
+    CoonBezierCoeff result;
     result.a = a / 8;
     result.b = 3 * a / 8 + b / 4;
     result.c = 3 * a / 8 + b / 2 + c / 2;
     result.d = a / 8 + b / 4 + c / 2 + d;
     return result;
   }
-  void GetPoints(float p[4]) {
+
+  void GetPoints(float p[4]) const {
     p[0] = d;
     p[1] = c / 3 + p[0];
     p[2] = b / 3 - p[0] + 2 * p[1];
     p[3] = a + p[0] - 3 * p[1] + 3 * p[2];
   }
-  void GetPointsReverse(float p[4]) {
-    p[3] = d;
-    p[2] = c / 3 + p[3];
-    p[1] = b / 3 - p[3] + 2 * p[2];
-    p[0] = a + p[3] - 3 * p[2] + 3 * p[1];
-  }
-  void BezierInterpol(Coon_BezierCoeff& C1,
-                      Coon_BezierCoeff& C2,
-                      Coon_BezierCoeff& D1,
-                      Coon_BezierCoeff& D2) {
-    a = (D1.a + D2.a) / 2;
-    b = (D1.b + D2.b) / 2;
-    c = (D1.c + D2.c) / 2 - (C1.a / 8 + C1.b / 4 + C1.c / 2) +
-        (C2.a / 8 + C2.b / 4) + (-C1.d + D2.d) / 2 - (C2.a + C2.b) / 2;
-    d = C1.a / 8 + C1.b / 4 + C1.c / 2 + C1.d;
-  }
-  float Distance() {
+
+  float Distance() const {
     float dis = a + b + c;
     return dis < 0 ? -dis : dis;
   }
+
+  float a;
+  float b;
+  float c;
+  float d;
 };
 
-struct Coon_Bezier {
-  Coon_BezierCoeff x, y;
-  void FromPoints(float x0,
-                  float y0,
-                  float x1,
-                  float y1,
-                  float x2,
-                  float y2,
-                  float x3,
-                  float y3) {
-    x.FromPoints(x0, x1, x2, x3);
-    y.FromPoints(y0, y1, y2, y3);
-  }
-
-  Coon_Bezier first_half() {
-    Coon_Bezier result;
+struct CoonBezier {
+  void InitFromPoints(float x0,
+                      float y0,
+                      float x1,
+                      float y1,
+                      float x2,
+                      float y2,
+                      float x3,
+                      float y3) {
+    x.InitFromPoints(x0, x1, x2, x3);
+    y.InitFromPoints(y0, y1, y2, y3);
+  }
+
+  void InitFromBezierInterpolation(const CoonBezier& C1,
+                                   const CoonBezier& C2,
+                                   const CoonBezier& D1,
+                                   const CoonBezier& D2) {
+    x.InitFromBezierInterpolation(C1.x, C2.x, D1.x, D2.x);
+    y.InitFromBezierInterpolation(C1.y, C2.y, D1.y, D2.y);
+  }
+
+  CoonBezier first_half() const {
+    CoonBezier result;
     result.x = x.first_half();
     result.y = y.first_half();
     return result;
   }
 
-  Coon_Bezier second_half() {
-    Coon_Bezier result;
+  CoonBezier second_half() const {
+    CoonBezier result;
     result.x = x.second_half();
     result.y = y.second_half();
     return result;
   }
 
-  void BezierInterpol(Coon_Bezier& C1,
-                      Coon_Bezier& C2,
-                      Coon_Bezier& D1,
-                      Coon_Bezier& D2) {
-    x.BezierInterpol(C1.x, C2.x, D1.x, D2.x);
-    y.BezierInterpol(C1.y, C2.y, D1.y, D2.y);
-  }
-
-  void GetPoints(std::vector<FX_PATHPOINT>& pPoints, size_t start_idx) {
-    float p[4];
-    int i;
-    x.GetPoints(p);
-    for (i = 0; i < 4; i++)
-      pPoints[start_idx + i].m_Point.x = p[i];
-
-    y.GetPoints(p);
-    for (i = 0; i < 4; i++)
-      pPoints[start_idx + i].m_Point.y = p[i];
+  void GetPoints(pdfium::span<CFX_Path::Point> path_points) const {
+    constexpr size_t kPointsCount = 4;
+    float points_x[kPointsCount];
+    float points_y[kPointsCount];
+    x.GetPoints(points_x);
+    y.GetPoints(points_y);
+    for (size_t i = 0; i < kPointsCount; ++i)
+      path_points[i].m_Point = {points_x[i], points_y[i]};
+  }
+
+  void GetPointsReverse(pdfium::span<CFX_Path::Point> path_points) const {
+    constexpr size_t kPointsCount = 4;
+    float points_x[kPointsCount];
+    float points_y[kPointsCount];
+    x.GetPoints(points_x);
+    y.GetPoints(points_y);
+    for (size_t i = 0; i < kPointsCount; ++i) {
+      size_t reverse_index = kPointsCount - i - 1;
+      path_points[i].m_Point = {points_x[reverse_index],
+                                points_y[reverse_index]};
+    }
   }
 
-  void GetPointsReverse(std::vector<FX_PATHPOINT>& pPoints, size_t start_idx) {
-    float p[4];
-    int i;
-    x.GetPointsReverse(p);
-    for (i = 0; i < 4; i++)
-      pPoints[i + start_idx].m_Point.x = p[i];
+  float Distance() const { return x.Distance() + y.Distance(); }
 
-    y.GetPointsReverse(p);
-    for (i = 0; i < 4; i++)
-      pPoints[i + start_idx].m_Point.y = p[i];
-  }
-
-  float Distance() { return x.Distance() + y.Distance(); }
+  CoonBezierCoeff x;
+  CoonBezierCoeff y;
 };
 
 int Interpolate(int p1, int p2, int delta1, int delta2, bool* overflow) {
-  pdfium::base::CheckedNumeric<int> p = p2;
+  FX_SAFE_INT32 p = p2;
   p -= p1;
   p *= delta1;
   p /= delta2;
@@ -632,15 +639,11 @@ int BiInterpolImpl(int c0,
   return Interpolate(x1, x2, y, y_scale, overflow);
 }
 
-struct Coon_Color {
-  Coon_Color() { memset(comp, 0, sizeof(int) * 3); }
+struct CoonColor {
+  CoonColor() = default;
 
   // Returns true if successful, false if overflow detected.
-  bool BiInterpol(Coon_Color colors[4],
-                  int x,
-                  int y,
-                  int x_scale,
-                  int y_scale) {
+  bool BiInterpol(CoonColor colors[4], int x, int y, int x_scale, int y_scale) {
     bool overflow = false;
     for (int i = 0; i < 3; i++) {
       comp[i] = BiInterpolImpl(colors[0].comp[i], colors[1].comp[i],
@@ -650,27 +653,28 @@ struct Coon_Color {
     return !overflow;
   }
 
-  int Distance(Coon_Color& o) {
+  int Distance(const CoonColor& o) const {
     return std::max({abs(comp[0] - o.comp[0]), abs(comp[1] - o.comp[1]),
                      abs(comp[2] - o.comp[2])});
   }
 
-  int comp[3];
+  int comp[3] = {};
 };
 
-#define COONCOLOR_THRESHOLD 4
-struct CPDF_PatchDrawer {
+struct PatchDrawer {
+  static constexpr int kCoonColorThreshold = 4;
+
   void Draw(int x_scale,
             int y_scale,
             int left,
             int bottom,
-            Coon_Bezier C1,
-            Coon_Bezier C2,
-            Coon_Bezier D1,
-            Coon_Bezier D2) {
+            CoonBezier C1,
+            CoonBezier C2,
+            CoonBezier D1,
+            CoonBezier D2) {
     bool bSmall = C1.Distance() < 2 && C2.Distance() < 2 && D1.Distance() < 2 &&
                   D2.Distance() < 2;
-    Coon_Color div_colors[4];
+    CoonColor div_colors[4];
     int d_bottom = 0;
     int d_left = 0;
     int d_top = 0;
@@ -699,35 +703,37 @@ struct CPDF_PatchDrawer {
     }
 
     if (bSmall ||
-        (d_bottom < COONCOLOR_THRESHOLD && d_left < COONCOLOR_THRESHOLD &&
-         d_top < COONCOLOR_THRESHOLD && d_right < COONCOLOR_THRESHOLD)) {
-      std::vector<FX_PATHPOINT>& pPoints = path.GetPoints();
-      C1.GetPoints(pPoints, 0);
-      D2.GetPoints(pPoints, 3);
-      C2.GetPointsReverse(pPoints, 6);
-      D1.GetPointsReverse(pPoints, 9);
-      int fillFlags = FXFILL_WINDING | FXFILL_FULLCOVER;
+        (d_bottom < kCoonColorThreshold && d_left < kCoonColorThreshold &&
+         d_top < kCoonColorThreshold && d_right < kCoonColorThreshold)) {
+      pdfium::span<CFX_Path::Point> points = path.GetPoints();
+      C1.GetPoints(points.subspan(0, 4));
+      D2.GetPoints(points.subspan(3, 4));
+      C2.GetPointsReverse(points.subspan(6, 4));
+      D1.GetPointsReverse(points.subspan(9, 4));
+      CFX_FillRenderOptions fill_options(
+          CFX_FillRenderOptions::WindingOptions());
+      fill_options.full_cover = true;
       if (bNoPathSmooth)
-        fillFlags |= FXFILL_NOPATHSMOOTH;
+        fill_options.aliased_path = true;
       pDevice->DrawPath(
-          &path, nullptr, nullptr,
+          path, nullptr, nullptr,
           ArgbEncode(alpha, div_colors[0].comp[0], div_colors[0].comp[1],
                      div_colors[0].comp[2]),
-          0, fillFlags);
+          0, fill_options);
     } else {
-      if (d_bottom < COONCOLOR_THRESHOLD && d_top < COONCOLOR_THRESHOLD) {
-        Coon_Bezier m1;
-        m1.BezierInterpol(D1, D2, C1, C2);
+      if (d_bottom < kCoonColorThreshold && d_top < kCoonColorThreshold) {
+        CoonBezier m1;
+        m1.InitFromBezierInterpolation(D1, D2, C1, C2);
         y_scale *= 2;
         bottom *= 2;
         Draw(x_scale, y_scale, left, bottom, C1, m1, D1.first_half(),
              D2.first_half());
         Draw(x_scale, y_scale, left, bottom + 1, m1, C2, D1.second_half(),
              D2.second_half());
-      } else if (d_left < COONCOLOR_THRESHOLD &&
-                 d_right < COONCOLOR_THRESHOLD) {
-        Coon_Bezier m2;
-        m2.BezierInterpol(C1, C2, D1, D2);
+      } else if (d_left < kCoonColorThreshold &&
+                 d_right < kCoonColorThreshold) {
+        CoonBezier m2;
+        m2.InitFromBezierInterpolation(C1, C2, D1, D2);
         x_scale *= 2;
         left *= 2;
         Draw(x_scale, y_scale, left, bottom, C1.first_half(), C2.first_half(),
@@ -735,13 +741,14 @@ struct CPDF_PatchDrawer {
         Draw(x_scale, y_scale, left + 1, bottom, C1.second_half(),
              C2.second_half(), m2, D2);
       } else {
-        Coon_Bezier m1, m2;
-        m1.BezierInterpol(D1, D2, C1, C2);
-        m2.BezierInterpol(C1, C2, D1, D2);
-        Coon_Bezier m1f = m1.first_half();
-        Coon_Bezier m1s = m1.second_half();
-        Coon_Bezier m2f = m2.first_half();
-        Coon_Bezier m2s = m2.second_half();
+        CoonBezier m1;
+        CoonBezier m2;
+        m1.InitFromBezierInterpolation(D1, D2, C1, C2);
+        m2.InitFromBezierInterpolation(C1, C2, D1, D2);
+        CoonBezier m1f = m1.first_half();
+        CoonBezier m1s = m1.second_half();
+        CoonBezier m2f = m2.first_half();
+        CoonBezier m2s = m2.second_half();
         x_scale *= 2;
         y_scale *= 2;
         left *= 2;
@@ -759,49 +766,54 @@ struct CPDF_PatchDrawer {
   }
 
   int max_delta;
-  CFX_PathData path;
+  CFX_Path path;
   CFX_RenderDevice* pDevice;
   int bNoPathSmooth;
   int alpha;
-  Coon_Color patch_colors[4];
+  CoonColor patch_colors[4];
 };
 
 void DrawCoonPatchMeshes(
     ShadingType type,
     const RetainPtr<CFX_DIBitmap>& pBitmap,
     const CFX_Matrix& mtObject2Bitmap,
-    const CPDF_Stream* pShadingStream,
+    RetainPtr<const CPDF_Stream> pShadingStream,
     const std::vector<std::unique_ptr<CPDF_Function>>& funcs,
-    const RetainPtr<CPDF_ColorSpace>& pCS,
+    RetainPtr<CPDF_ColorSpace> pCS,
     bool bNoPathSmooth,
     int alpha) {
-  ASSERT(pBitmap->GetFormat() == FXDIB_Argb);
-  ASSERT(type == kCoonsPatchMeshShading ||
+  DCHECK_EQ(pBitmap->GetFormat(), FXDIB_Format::kArgb);
+  DCHECK(type == kCoonsPatchMeshShading ||
          type == kTensorProductPatchMeshShading);
 
   CFX_DefaultRenderDevice device;
-  device.Attach(pBitmap, false, nullptr, false);
-  CPDF_MeshStream stream(type, funcs, pShadingStream, pCS);
+  device.Attach(pBitmap);
+
+  CPDF_MeshStream stream(type, funcs, std::move(pShadingStream),
+                         std::move(pCS));
   if (!stream.Load())
     return;
 
-  CPDF_PatchDrawer patch;
+  PatchDrawer patch;
   patch.alpha = alpha;
   patch.pDevice = &device;
   patch.bNoPathSmooth = bNoPathSmooth;
 
   for (int i = 0; i < 13; i++) {
-    patch.path.AppendPoint(
-        CFX_PointF(), i == 0 ? FXPT_TYPE::MoveTo : FXPT_TYPE::BezierTo, false);
+    patch.path.AppendPoint(CFX_PointF(), i == 0
+                                             ? CFX_Path::Point::Type::kMove
+                                             : CFX_Path::Point::Type::kBezier);
   }
 
   CFX_PointF coords[16];
   int point_count = type == kTensorProductPatchMeshShading ? 16 : 12;
-  while (!stream.BitStream()->IsEOF()) {
+  while (!stream.IsEOF()) {
     if (!stream.CanReadFlag())
       break;
     uint32_t flag = stream.ReadFlag();
-    int iStartPoint = 0, iStartColor = 0, i = 0;
+    int iStartPoint = 0;
+    int iStartColor = 0;
+    int i = 0;
     if (flag) {
       iStartPoint = 4;
       iStartColor = 2;
@@ -809,11 +821,12 @@ void DrawCoonPatchMeshes(
       for (i = 0; i < 4; i++) {
         tempCoords[i] = coords[(flag * 3 + i) % 12];
       }
-      memcpy(coords, tempCoords, sizeof(tempCoords));
-      Coon_Color tempColors[2];
-      tempColors[0] = patch.patch_colors[flag];
-      tempColors[1] = patch.patch_colors[(flag + 1) % 4];
-      memcpy(patch.patch_colors, tempColors, sizeof(Coon_Color) * 2);
+      fxcrt::spancpy(pdfium::make_span(coords), pdfium::make_span(tempCoords));
+      CoonColor tempColors[2] = {
+          tempColors[0] = patch.patch_colors[flag],
+          tempColors[1] = patch.patch_colors[(flag + 1) % 4]};
+      fxcrt::spancpy(pdfium::make_span(patch.patch_colors),
+                     pdfium::make_span(tempColors));
     }
     for (i = iStartPoint; i < point_count; i++) {
       if (!stream.CanReadCoords())
@@ -830,24 +843,28 @@ void DrawCoonPatchMeshes(
       float b;
       std::tie(r, g, b) = stream.ReadColor();
 
-      patch.patch_colors[i].comp[0] = (int32_t)(r * 255);
-      patch.patch_colors[i].comp[1] = (int32_t)(g * 255);
-      patch.patch_colors[i].comp[2] = (int32_t)(b * 255);
+      patch.patch_colors[i].comp[0] = static_cast<int32_t>(r * 255);
+      patch.patch_colors[i].comp[1] = static_cast<int32_t>(g * 255);
+      patch.patch_colors[i].comp[2] = static_cast<int32_t>(b * 255);
     }
-    CFX_FloatRect bbox = CFX_FloatRect::GetBBox(coords, point_count);
+    CFX_FloatRect bbox =
+        CFX_FloatRect::GetBBox(pdfium::make_span(coords).first(point_count));
     if (bbox.right <= 0 || bbox.left >= (float)pBitmap->GetWidth() ||
         bbox.top <= 0 || bbox.bottom >= (float)pBitmap->GetHeight()) {
       continue;
     }
-    Coon_Bezier C1, C2, D1, D2;
-    C1.FromPoints(coords[0].x, coords[0].y, coords[11].x, coords[11].y,
-                  coords[10].x, coords[10].y, coords[9].x, coords[9].y);
-    C2.FromPoints(coords[3].x, coords[3].y, coords[4].x, coords[4].y,
-                  coords[5].x, coords[5].y, coords[6].x, coords[6].y);
-    D1.FromPoints(coords[0].x, coords[0].y, coords[1].x, coords[1].y,
-                  coords[2].x, coords[2].y, coords[3].x, coords[3].y);
-    D2.FromPoints(coords[9].x, coords[9].y, coords[8].x, coords[8].y,
-                  coords[7].x, coords[7].y, coords[6].x, coords[6].y);
+    CoonBezier C1;
+    CoonBezier C2;
+    CoonBezier D1;
+    CoonBezier D2;
+    C1.InitFromPoints(coords[0].x, coords[0].y, coords[11].x, coords[11].y,
+                      coords[10].x, coords[10].y, coords[9].x, coords[9].y);
+    C2.InitFromPoints(coords[3].x, coords[3].y, coords[4].x, coords[4].y,
+                      coords[5].x, coords[5].y, coords[6].x, coords[6].y);
+    D1.InitFromPoints(coords[0].x, coords[0].y, coords[1].x, coords[1].y,
+                      coords[2].x, coords[2].y, coords[3].x, coords[3].y);
+    D2.InitFromPoints(coords[9].x, coords[9].y, coords[8].x, coords[8].y,
+                      coords[7].x, coords[7].y, coords[6].x, coords[6].y);
     patch.Draw(1, 1, 0, 0, C1, C2, D1, D2);
   }
 }
@@ -863,25 +880,26 @@ void CPDF_RenderShading::Draw(CFX_RenderDevice* pDevice,
                               const FX_RECT& clip_rect,
                               int alpha,
                               const CPDF_RenderOptions& options) {
-  const auto& funcs = pPattern->GetFuncs();
-  const CPDF_Dictionary* pDict = pPattern->GetShadingObject()->GetDict();
   RetainPtr<CPDF_ColorSpace> pColorSpace = pPattern->GetCS();
   if (!pColorSpace)
     return;
 
   FX_ARGB background = 0;
+  RetainPtr<const CPDF_Dictionary> pDict =
+      pPattern->GetShadingObject()->GetDict();
   if (!pPattern->IsShadingObject() && pDict->KeyExist("Background")) {
-    const CPDF_Array* pBackColor = pDict->GetArrayFor("Background");
+    RetainPtr<const CPDF_Array> pBackColor = pDict->GetArrayFor("Background");
     if (pBackColor && pBackColor->size() >= pColorSpace->CountComponents()) {
-      std::vector<float> comps =
-          ReadArrayElementsToVector(pBackColor, pColorSpace->CountComponents());
+      std::vector<float> comps = ReadArrayElementsToVector(
+          pBackColor.Get(), pColorSpace->CountComponents());
 
       float R = 0.0f;
       float G = 0.0f;
       float B = 0.0f;
-      pColorSpace->GetRGB(comps.data(), &R, &G, &B);
-      background = ArgbEncode(255, (int32_t)(R * 255), (int32_t)(G * 255),
-                              (int32_t)(B * 255));
+      pColorSpace->GetRGB(comps, &R, &G, &B);
+      background = ArgbEncode(255, static_cast<int32_t>(R * 255),
+                              static_cast<int32_t>(G * 255),
+                              static_cast<int32_t>(B * 255));
     }
   }
   FX_RECT clip_rect_bbox = clip_rect;
@@ -891,64 +909,80 @@ void CPDF_RenderShading::Draw(CFX_RenderDevice* pDevice,
   }
   bool bAlphaMode = options.ColorModeIs(CPDF_RenderOptions::kAlpha);
   if (pDevice->GetDeviceCaps(FXDC_RENDER_CAPS) & FXRC_SHADING &&
-      pDevice->GetDeviceDriver()->DrawShading(
-          pPattern, &mtMatrix, clip_rect_bbox, alpha, bAlphaMode)) {
+      pDevice->DrawShading(pPattern, &mtMatrix, clip_rect_bbox, alpha,
+                           bAlphaMode)) {
     return;
   }
   CPDF_DeviceBuffer buffer(pContext, pDevice, clip_rect_bbox, pCurObj, 150);
   if (!buffer.Initialize())
     return;
 
-  CFX_Matrix FinalMatrix = mtMatrix * buffer.GetMatrix();
   RetainPtr<CFX_DIBitmap> pBitmap = buffer.GetBitmap();
-  if (!pBitmap->GetBuffer())
+  if (pBitmap->GetBuffer().empty())
     return;
 
-  pBitmap->Clear(background);
+  if (background != 0) {
+    pBitmap->Clear(background);
+  }
+  const CFX_Matrix final_matrix = mtMatrix * buffer.GetMatrix();
+  const auto& funcs = pPattern->GetFuncs();
   switch (pPattern->GetShadingType()) {
     case kInvalidShading:
     case kMaxShading:
       return;
     case kFunctionBasedShading:
-      DrawFuncShading(pBitmap, FinalMatrix, pDict, funcs, pColorSpace, alpha);
+      DrawFuncShading(pBitmap, final_matrix, pDict.Get(), funcs, pColorSpace,
+                      alpha);
       break;
     case kAxialShading:
-      DrawAxialShading(pBitmap, FinalMatrix, pDict, funcs, pColorSpace, alpha);
+      DrawAxialShading(pBitmap, final_matrix, pDict.Get(), funcs, pColorSpace,
+                       alpha);
       break;
     case kRadialShading:
-      DrawRadialShading(pBitmap, FinalMatrix, pDict, funcs, pColorSpace, alpha);
+      DrawRadialShading(pBitmap, final_matrix, pDict.Get(), funcs, pColorSpace,
+                        alpha);
       break;
     case kFreeFormGouraudTriangleMeshShading: {
       // The shading object can be a stream or a dictionary. We do not handle
       // the case of dictionary at the moment.
-      if (const CPDF_Stream* pStream = ToStream(pPattern->GetShadingObject())) {
-        DrawFreeGouraudShading(pBitmap, FinalMatrix, pStream, funcs,
+      RetainPtr<const CPDF_Stream> pStream =
+          ToStream(pPattern->GetShadingObject());
+      if (pStream) {
+        DrawFreeGouraudShading(pBitmap, final_matrix, std::move(pStream), funcs,
                                pColorSpace, alpha);
       }
-    } break;
+      break;
+    }
     case kLatticeFormGouraudTriangleMeshShading: {
       // The shading object can be a stream or a dictionary. We do not handle
       // the case of dictionary at the moment.
-      if (const CPDF_Stream* pStream = ToStream(pPattern->GetShadingObject())) {
-        DrawLatticeGouraudShading(pBitmap, FinalMatrix, pStream, funcs,
-                                  pColorSpace, alpha);
+      RetainPtr<const CPDF_Stream> pStream =
+          ToStream(pPattern->GetShadingObject());
+      if (pStream) {
+        DrawLatticeGouraudShading(pBitmap, final_matrix, std::move(pStream),
+                                  funcs, pColorSpace, alpha);
       }
-    } break;
+      break;
+    }
     case kCoonsPatchMeshShading:
     case kTensorProductPatchMeshShading: {
       // The shading object can be a stream or a dictionary. We do not handle
       // the case of dictionary at the moment.
-      if (const CPDF_Stream* pStream = ToStream(pPattern->GetShadingObject())) {
-        DrawCoonPatchMeshes(pPattern->GetShadingType(), pBitmap, FinalMatrix,
-                            pStream, funcs, pColorSpace,
+      RetainPtr<const CPDF_Stream> pStream =
+          ToStream(pPattern->GetShadingObject());
+      if (pStream) {
+        DrawCoonPatchMeshes(pPattern->GetShadingType(), pBitmap, final_matrix,
+                            std::move(pStream), funcs, pColorSpace,
                             options.GetOptions().bNoPathSmooth, alpha);
       }
-    } break;
+      break;
+    }
   }
   if (bAlphaMode)
-    pBitmap->LoadChannelFromAlpha(FXDIB_Red, pBitmap);
+    pBitmap->SetRedFromBitmap(pBitmap);
 
   if (options.ColorModeIs(CPDF_RenderOptions::kGray))
     pBitmap->ConvertColorScale(0, 0xffffff);
+
   buffer.OutputToDevice();
 }