support gradients and stroke+fill

To draw paths that are stroked and filled with a pair of colors,
reduce the fill by the width of the stroke. This is implemented
with path ops subtracting the resolved stroke shape from the
fill shape. This permits rendering the result without requiring
an offscreen bitmap.

The implementation for stroke+fill requires a new entry into
the graphics engine, so a bit was added to device caps for that.

Extract the gradient information out of the axial gradient
function descriptions, and when possible, use Skia to draw
the linear gradient directly. This requires making the function
descriptions non-opaque, and adding a bit to device caps for
another entry into the graphics engine.

BUG=

Review URL: https://codereview.chromium.org/1828283002

1 files changed, 27 insertions, 4 deletions

diff --git a/core/fxge/ge/fx_ge_device.cpp b/core/fxge/ge/fx_ge_device.cpp
index b8ddfec841..eefac5c033 100644
--- a/core/fxge/ge/fx_ge_device.cpp
+++ b/core/fxge/ge/fx_ge_device.cpp
@@ -109,6 +109,7 @@ void CFX_RenderDevice::UpdateClipBox() {
   m_ClipBox.right = m_Width;
   m_ClipBox.bottom = m_Height;
 }
+
 FX_BOOL CFX_RenderDevice::DrawPath(const CFX_PathData* pPathData,
                                    const CFX_Matrix* pObject2Device,
                                    const CFX_GraphStateData* pGraphState,
@@ -224,6 +225,31 @@ FX_BOOL CFX_RenderDevice::DrawPath(const CFX_PathData* pPathData,
   }
   if ((fill_mode & 3) && fill_alpha && stroke_alpha < 0xff &&
       (fill_mode & FX_FILL_STROKE)) {
+    if (m_RenderCaps & FXRC_FILLSTROKE_PATH) {
+      return m_pDeviceDriver->DrawPath(pPathData, pObject2Device, pGraphState,
+                                       fill_color, stroke_color, fill_mode,
+                                       alpha_flag, pIccTransform, blend_type);
+    }
+    return DrawFillStrokePath(pPathData, pObject2Device, pGraphState,
+                              fill_color, stroke_color, fill_mode, alpha_flag,
+                              pIccTransform, blend_type);
+  }
+  return m_pDeviceDriver->DrawPath(pPathData, pObject2Device, pGraphState,
+                                   fill_color, stroke_color, fill_mode,
+                                   alpha_flag, pIccTransform, blend_type);
+}
+
+// This can be removed once PDFium entirely relies on Skia
+FX_BOOL CFX_RenderDevice::DrawFillStrokePath(
+    const CFX_PathData* pPathData,
+    const CFX_Matrix* pObject2Device,
+    const CFX_GraphStateData* pGraphState,
+    FX_DWORD fill_color,
+    FX_DWORD stroke_color,
+    int fill_mode,
+    int alpha_flag,
+    void* pIccTransform,
+    int blend_type) {
     if (!(m_RenderCaps & FXRC_GET_BITS)) {
       return FALSE;
     }
@@ -272,11 +298,8 @@ FX_BOOL CFX_RenderDevice::DrawPath(const CFX_PathData* pPathData,
                      FXSYS_round(rect.Height() * fScaleY));
     return m_pDeviceDriver->SetDIBits(&bitmap, 0, &src_rect, rect.left,
                                       rect.top, FXDIB_BLEND_NORMAL);
-  }
-  return m_pDeviceDriver->DrawPath(pPathData, pObject2Device, pGraphState,
-                                   fill_color, stroke_color, fill_mode,
-                                   alpha_flag, pIccTransform, blend_type);
 }
+
 FX_BOOL CFX_RenderDevice::SetPixel(int x,
                                    int y,
                                    FX_DWORD color,