Remove default arguments from CFX_FxgeDevice.

Remove unused dithering code.

Review-Url: https://codereview.chromium.org/2010813003

13 files changed, 47 insertions, 180 deletions

diff --git a/core/fpdfapi/fpdf_render/fpdf_render.cpp b/core/fpdfapi/fpdf_render/fpdf_render.cpp
index b69863b5b0..a3dbbdb3f2 100644
--- a/core/fpdfapi/fpdf_render/fpdf_render.cpp
+++ b/core/fpdfapi/fpdf_render/fpdf_render.cpp
@@ -142,7 +142,6 @@ CPDF_RenderStatus::CPDF_RenderStatus()
       m_HalftoneLimit(0),
       m_bPrint(FALSE),
       m_Transparency(0),
-      m_DitherBits(0),
       m_bDropObjects(FALSE),
       m_bStdCS(FALSE),
       m_GroupFamily(0),
@@ -170,7 +169,6 @@ FX_BOOL CPDF_RenderStatus::Initialize(CPDF_RenderContext* pContext,
                                       FX_BOOL bLoadMask) {
   m_pContext = pContext;
   m_pDevice = pDevice;
-  m_DitherBits = pDevice->GetDeviceCaps(FXDC_DITHER_BITS);
   m_bPrint = m_pDevice->GetDeviceClass() != FXDC_DISPLAY;
   if (pDeviceMatrix) {
     m_DeviceMatrix = *pDeviceMatrix;
@@ -320,28 +318,6 @@ FX_BOOL CPDF_RenderStatus::GetObjectClippedRect(const CPDF_PageObject* pObj,
   rect.Intersect(rtClip);
   return rect.IsEmpty();
 }
-void CPDF_RenderStatus::DitherObjectArea(const CPDF_PageObject* pObj,
-                                         const CFX_Matrix* pObj2Device) {
-  CFX_DIBitmap* pBitmap = m_pDevice->GetBitmap();
-  if (!pBitmap) {
-    return;
-  }
-  FX_RECT rect;
-  if (GetObjectClippedRect(pObj, pObj2Device, FALSE, rect)) {
-    return;
-  }
-  if (m_DitherBits == 2) {
-    static FX_ARGB pal[4] = {0, 85, 170, 255};
-    pBitmap->DitherFS(pal, 4, &rect);
-  } else if (m_DitherBits == 3) {
-    static FX_ARGB pal[8] = {0, 36, 73, 109, 146, 182, 219, 255};
-    pBitmap->DitherFS(pal, 8, &rect);
-  } else if (m_DitherBits == 4) {
-    static FX_ARGB pal[16] = {0,   17,  34,  51,  68,  85,  102, 119,
-                              136, 153, 170, 187, 204, 221, 238, 255};
-    pBitmap->DitherFS(pal, 16, &rect);
-  }
-}
 
 void CPDF_RenderStatus::ProcessObjectNoClip(const CPDF_PageObject* pObj,
                                             const CFX_Matrix* pObj2Device) {
@@ -788,7 +764,7 @@ FX_BOOL CPDF_RenderStatus::ProcessTransparency(const CPDF_PageObject* pPageObj,
 
     m_pDevice->GetDIBits(oriDevice.get(), rect.left, rect.top);
   }
-  if (!bitmap_device.Create(width, height, FXDIB_Argb, 0, oriDevice.get()))
+  if (!bitmap_device.Create(width, height, FXDIB_Argb, oriDevice.get()))
     return TRUE;
 
   CFX_DIBitmap* bitmap = bitmap_device.GetBitmap();
@@ -804,7 +780,7 @@ FX_BOOL CPDF_RenderStatus::ProcessTransparency(const CPDF_PageObject* pPageObj,
 
     pTextMask->Clear(0);
     CFX_FxgeDevice text_device;
-    text_device.Attach(pTextMask.get());
+    text_device.Attach(pTextMask.get(), false, nullptr, false);
     for (uint32_t i = 0; i < pPageObj->m_ClipPath.GetTextCount(); i++) {
       CPDF_TextObject* textobj = pPageObj->m_ClipPath.GetText(i);
       if (!textobj) {
@@ -890,7 +866,7 @@ CFX_DIBitmap* CPDF_RenderStatus::GetBackdrop(const CPDF_PageObject* pObj,
   FinalMatrix.Scale(scaleX, scaleY);
   pBackdrop->Clear(pBackdrop->HasAlpha() ? 0 : 0xffffffff);
   CFX_FxgeDevice device;
-  device.Attach(pBackdrop.get());
+  device.Attach(pBackdrop.get(), false, nullptr, false);
   m_pContext->Render(&device, pObj, &m_Options, &FinalMatrix);
   return pBackdrop.release();
 }
@@ -900,7 +876,7 @@ void CPDF_RenderContext::GetBackground(CFX_DIBitmap* pBuffer,
                                        const CPDF_RenderOptions* pOptions,
                                        CFX_Matrix* pFinalMatrix) {
   CFX_FxgeDevice device;
-  device.Attach(pBuffer);
+  device.Attach(pBuffer, false, nullptr, false);
 
   FX_RECT rect(0, 0, device.GetWidth(), device.GetHeight());
   device.FillRect(&rect, 0xffffffff);
@@ -1282,7 +1258,7 @@ FX_BOOL CPDF_ScaledRenderBuffer::Initialize(CPDF_RenderContext* pContext,
       return FALSE;
 
     if (iPitch * iHeight <= _FPDFAPI_IMAGESIZE_LIMIT_ &&
-        m_pBitmapDevice->Create(iWidth, iHeight, dibFormat)) {
+        m_pBitmapDevice->Create(iWidth, iHeight, dibFormat, nullptr)) {
       break;
     }
     m_Matrix.Scale(0.5f, 0.5f);
diff --git a/core/fpdfapi/fpdf_render/fpdf_render_image.cpp b/core/fpdfapi/fpdf_render/fpdf_render_image.cpp
index f7e57c0fa6..d3fbb7990c 100644
--- a/core/fpdfapi/fpdf_render/fpdf_render_image.cpp
+++ b/core/fpdfapi/fpdf_render/fpdf_render_image.cpp
@@ -523,9 +523,9 @@ FX_BOOL CPDF_ImageRenderer::DrawPatternImage(const CFX_Matrix* pObj2Device) {
   int width = rect.Width();
   int height = rect.Height();
   CFX_FxgeDevice bitmap_device1;
-  if (!bitmap_device1.Create(rect.Width(), rect.Height(), FXDIB_Rgb32)) {
+  if (!bitmap_device1.Create(rect.Width(), rect.Height(), FXDIB_Rgb32, nullptr))
     return TRUE;
-  }
+
   bitmap_device1.GetBitmap()->Clear(0xffffff);
   {
     CPDF_RenderStatus bitmap_render;
@@ -545,7 +545,8 @@ FX_BOOL CPDF_ImageRenderer::DrawPatternImage(const CFX_Matrix* pObj2Device) {
   }
   {
     CFX_FxgeDevice bitmap_device2;
-    if (!bitmap_device2.Create(rect.Width(), rect.Height(), FXDIB_8bppRgb)) {
+    if (!bitmap_device2.Create(rect.Width(), rect.Height(), FXDIB_8bppRgb,
+                               nullptr)) {
       return TRUE;
     }
     bitmap_device2.GetBitmap()->Clear(0);
@@ -621,9 +622,9 @@ FX_BOOL CPDF_ImageRenderer::DrawMaskedImage() {
   int width = rect.Width();
   int height = rect.Height();
   CFX_FxgeDevice bitmap_device1;
-  if (!bitmap_device1.Create(width, height, FXDIB_Rgb32)) {
+  if (!bitmap_device1.Create(width, height, FXDIB_Rgb32, nullptr))
     return TRUE;
-  }
+
   bitmap_device1.GetBitmap()->Clear(0xffffff);
   {
     CPDF_RenderStatus bitmap_render;
@@ -638,9 +639,9 @@ FX_BOOL CPDF_ImageRenderer::DrawMaskedImage() {
   }
   {
     CFX_FxgeDevice bitmap_device2;
-    if (!bitmap_device2.Create(width, height, FXDIB_8bppRgb)) {
+    if (!bitmap_device2.Create(width, height, FXDIB_8bppRgb, nullptr))
       return TRUE;
-    }
+
     bitmap_device2.GetBitmap()->Clear(0);
     CPDF_RenderStatus bitmap_render;
     bitmap_render.Initialize(m_pRenderStatus->m_pContext, &bitmap_device2, NULL,
@@ -900,17 +901,15 @@ CFX_DIBitmap* CPDF_RenderStatus::LoadSMask(CPDF_Dictionary* pSMaskDict,
   FX_BOOL bLuminosity = pSMaskDict->GetStringBy("S") != "Alpha";
   int width = pClipRect->right - pClipRect->left;
   int height = pClipRect->bottom - pClipRect->top;
+  FXDIB_Format format;
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
-  if (!bitmap_device.Create(width, height,
-                            bLuminosity ? FXDIB_Rgb32 : FXDIB_8bppMask)) {
-    return NULL;
-  }
+  format = bLuminosity ? FXDIB_Rgb32 : FXDIB_8bppMask;
 #else
-  if (!bitmap_device.Create(width, height,
-                            bLuminosity ? FXDIB_Rgb : FXDIB_8bppMask)) {
-    return NULL;
-  }
+  format = bLuminosity ? FXDIB_Rgb : FXDIB_8bppMask;
 #endif
+  if (!bitmap_device.Create(width, height, format, nullptr))
+    return nullptr;
+
   CFX_DIBitmap& bitmap = *bitmap_device.GetBitmap();
   CPDF_Object* pCSObj = NULL;
   CPDF_ColorSpace* pCS = NULL;
diff --git a/core/fpdfapi/fpdf_render/fpdf_render_pattern.cpp b/core/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
index 393b993e35..754394da70 100644
--- a/core/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
+++ b/core/fpdfapi/fpdf_render/fpdf_render_pattern.cpp
@@ -752,7 +752,7 @@ void DrawCoonPatchMeshes(
   ASSERT(pBitmap->GetFormat() == FXDIB_Argb);
 
   CFX_FxgeDevice device;
-  device.Attach(pBitmap);
+  device.Attach(pBitmap, false, nullptr, false);
   CPDF_MeshStream stream(funcs, pCS);
   if (!stream.Load(pShadingStream))
     return;
@@ -830,7 +830,7 @@ std::unique_ptr<CFX_DIBitmap> DrawPatternBitmap(
     return std::unique_ptr<CFX_DIBitmap>();
   }
   CFX_FxgeDevice bitmap_device;
-  bitmap_device.Attach(pBitmap.get());
+  bitmap_device.Attach(pBitmap.get(), false, nullptr, false);
   pBitmap->Clear(0);
   CFX_FloatRect cell_bbox = pPattern->bbox();
   pPattern->pattern_to_form()->TransformRect(cell_bbox);
diff --git a/core/fpdfapi/fpdf_render/fpdf_render_text.cpp b/core/fpdfapi/fpdf_render/fpdf_render_text.cpp
index e4ee49afc9..a3df1c2214 100644
--- a/core/fpdfapi/fpdf_render/fpdf_render_text.cpp
+++ b/core/fpdfapi/fpdf_render/fpdf_render_text.cpp
@@ -437,7 +437,8 @@ FX_BOOL CPDF_RenderStatus::ProcessType3Text(const CPDF_TextObject* textobj,
         FX_RECT rect = rect_f.GetOutterRect();
         CFX_FxgeDevice bitmap_device;
         if (!bitmap_device.Create((int)(rect.Width() * sa),
-                                  (int)(rect.Height() * sd), FXDIB_Argb)) {
+                                  (int)(rect.Height() * sd), FXDIB_Argb,
+                                  nullptr)) {
           return TRUE;
         }
         bitmap_device.GetBitmap()->Clear(0);
diff --git a/core/fpdfapi/fpdf_render/render_int.h b/core/fpdfapi/fpdf_render/render_int.h
index 46689d3b68..98822797b0 100644
--- a/core/fpdfapi/fpdf_render/render_int.h
+++ b/core/fpdfapi/fpdf_render/render_int.h
@@ -123,6 +123,7 @@ class CPDF_RenderStatus {
  public:
   CPDF_RenderStatus();
   ~CPDF_RenderStatus();
+
   FX_BOOL Initialize(class CPDF_RenderContext* pContext,
                      CFX_RenderDevice* pDevice,
                      const CFX_Matrix* pDeviceMatrix,
@@ -155,6 +156,7 @@ class CPDF_RenderStatus {
  protected:
   friend class CPDF_ImageRenderer;
   friend class CPDF_RenderContext;
+
   void ProcessClipPath(CPDF_ClipPath ClipPath, const CFX_Matrix* pObj2Device);
   void DrawClipPath(CPDF_ClipPath ClipPath, const CFX_Matrix* pObj2Device);
   FX_BOOL ProcessTransparency(const CPDF_PageObject* PageObj,
@@ -242,20 +244,17 @@ class CPDF_RenderStatus {
   FX_ARGB GetFillArgb(const CPDF_PageObject* pObj,
                       FX_BOOL bType3 = FALSE) const;
   FX_ARGB GetStrokeArgb(const CPDF_PageObject* pObj) const;
-  CPDF_RenderContext* m_pContext;
-  FX_BOOL m_bStopped;
-  void DitherObjectArea(const CPDF_PageObject* pObj,
-                        const CFX_Matrix* pObj2Device);
   FX_BOOL GetObjectClippedRect(const CPDF_PageObject* pObj,
                                const CFX_Matrix* pObj2Device,
                                FX_BOOL bLogical,
                                FX_RECT& rect) const;
   void GetScaledMatrix(CFX_Matrix& matrix) const;
 
- protected:
   static const int kRenderMaxRecursionDepth = 64;
   static int s_CurrentRecursionDepth;
 
+  CPDF_RenderContext* m_pContext;
+  FX_BOOL m_bStopped;
   CFX_RenderDevice* m_pDevice;
   CFX_Matrix m_DeviceMatrix;
   CPDF_ClipPath m_LastClipPath;
@@ -266,7 +265,6 @@ class CPDF_RenderStatus {
   std::unique_ptr<CPDF_ImageRenderer> m_pImageRenderer;
   FX_BOOL m_bPrint;
   int m_Transparency;
-  int m_DitherBits;
   FX_BOOL m_bDropObjects;
   FX_BOOL m_bStdCS;
   uint32_t m_GroupFamily;
@@ -275,6 +273,7 @@ class CPDF_RenderStatus {
   FX_ARGB m_T3FillColor;
   int m_curBlend;
 };
+
 class CPDF_ImageLoader {
  public:
   CPDF_ImageLoader()
diff --git a/core/fxge/agg/fx_agg_driver.cpp b/core/fxge/agg/fx_agg_driver.cpp
index 86326f6caf..d7a9ddb530 100644
--- a/core/fxge/agg/fx_agg_driver.cpp
+++ b/core/fxge/agg/fx_agg_driver.cpp
@@ -189,17 +189,15 @@ IFX_RenderDeviceDriver* IFX_RenderDeviceDriver::CreateFxgeDriver(
     FX_BOOL bRgbByteOrder,
     CFX_DIBitmap* pOriDevice,
     FX_BOOL bGroupKnockout) {
-  return new CFX_AggDeviceDriver(pBitmap, 0, bRgbByteOrder, pOriDevice,
+  return new CFX_AggDeviceDriver(pBitmap, bRgbByteOrder, pOriDevice,
                                  bGroupKnockout);
 }
 
 CFX_AggDeviceDriver::CFX_AggDeviceDriver(CFX_DIBitmap* pBitmap,
-                                         int dither_bits,
                                          FX_BOOL bRgbByteOrder,
                                          CFX_DIBitmap* pOriDevice,
                                          FX_BOOL bGroupKnockout) {
   m_pBitmap = pBitmap;
-  m_DitherBits = dither_bits;
   m_pClipRgn = nullptr;
   m_pPlatformBitmap = nullptr;
   m_pPlatformGraphics = nullptr;
@@ -270,8 +268,6 @@ int CFX_AggDeviceDriver::GetDeviceCaps(int caps_id) {
       }
       return flags;
     }
-    case FXDC_DITHER_BITS:
-      return m_DitherBits;
   }
   return 0;
 }
@@ -1784,16 +1780,15 @@ CFX_FxgeDevice::CFX_FxgeDevice() {
 }
 
 bool CFX_FxgeDevice::Attach(CFX_DIBitmap* pBitmap,
-                            int dither_bits,
                             bool bRgbByteOrder,
                             CFX_DIBitmap* pOriDevice,
                             bool bGroupKnockout) {
-  if (!pBitmap) {
+  if (!pBitmap)
     return false;
-  }
+
   SetBitmap(pBitmap);
   IFX_RenderDeviceDriver* pDriver = new CFX_AggDeviceDriver(
-      pBitmap, dither_bits, bRgbByteOrder, pOriDevice, bGroupKnockout);
+      pBitmap, bRgbByteOrder, pOriDevice, bGroupKnockout);
   SetDeviceDriver(pDriver);
   return true;
 }
@@ -1801,7 +1796,6 @@ bool CFX_FxgeDevice::Attach(CFX_DIBitmap* pBitmap,
 bool CFX_FxgeDevice::Create(int width,
                             int height,
                             FXDIB_Format format,
-                            int dither_bits,
                             CFX_DIBitmap* pOriDevice) {
   m_bOwnedBitmap = true;
   CFX_DIBitmap* pBitmap = new CFX_DIBitmap;
@@ -1811,7 +1805,7 @@ bool CFX_FxgeDevice::Create(int width,
   }
   SetBitmap(pBitmap);
   IFX_RenderDeviceDriver* pDriver =
-      new CFX_AggDeviceDriver(pBitmap, dither_bits, FALSE, pOriDevice, FALSE);
+      new CFX_AggDeviceDriver(pBitmap, FALSE, pOriDevice, FALSE);
   SetDeviceDriver(pDriver);
   return true;
 }
diff --git a/core/fxge/agg/fx_agg_driver.h b/core/fxge/agg/fx_agg_driver.h
index a33bc09937..3462b61bb2 100644
--- a/core/fxge/agg/fx_agg_driver.h
+++ b/core/fxge/agg/fx_agg_driver.h
@@ -28,7 +28,6 @@ class CAgg_PathData {
 class CFX_AggDeviceDriver : public IFX_RenderDeviceDriver {
  public:
   CFX_AggDeviceDriver(CFX_DIBitmap* pBitmap,
-                      int dither_bits,
                       FX_BOOL bRgbByteOrder,
                       CFX_DIBitmap* pOriDevice,
                       FX_BOOL bGroupKnockout);
@@ -144,7 +143,6 @@ class CFX_AggDeviceDriver : public IFX_RenderDeviceDriver {
   void* m_pPlatformBitmap;
   void* m_pDwRenderTartget;
   int m_FillFlags;
-  int m_DitherBits;
   FX_BOOL m_bRgbByteOrder;
   CFX_DIBitmap* m_pOriDevice;
   FX_BOOL m_bGroupKnockout;
diff --git a/core/fxge/dib/fx_dib_main.cpp b/core/fxge/dib/fx_dib_main.cpp
index ad6ee0c4e7..85df71e11d 100644
--- a/core/fxge/dib/fx_dib_main.cpp
+++ b/core/fxge/dib/fx_dib_main.cpp
@@ -1371,90 +1371,7 @@ FX_BOOL CFX_DIBitmap::ConvertColorScale(uint32_t forecolor,
   }
   return TRUE;
 }
-FX_BOOL CFX_DIBitmap::DitherFS(const uint32_t* pPalette,
-                               int pal_size,
-                               const FX_RECT* pRect) {
-  if (!m_pBuffer) {
-    return FALSE;
-  }
-  if (m_bpp != 8 && m_pPalette && m_AlphaFlag != 0) {
-    return FALSE;
-  }
-  if (m_Width < 4 && m_Height < 4) {
-    return FALSE;
-  }
-  FX_RECT rect(0, 0, m_Width, m_Height);
-  if (pRect) {
-    rect.Intersect(*pRect);
-  }
-  uint8_t translate[256];
-  for (int i = 0; i < 256; i++) {
-    int err2 = 65536;
-    for (int j = 0; j < pal_size; j++) {
-      uint8_t entry = (uint8_t)pPalette[j];
-      int err = (int)entry - i;
-      if (err * err < err2) {
-        err2 = err * err;
-        translate[i] = entry;
-      }
-    }
-  }
-  for (int row = rect.top; row < rect.bottom; row++) {
-    uint8_t* scan = m_pBuffer + row * m_Pitch;
-    uint8_t* next_scan = m_pBuffer + (row + 1) * m_Pitch;
-    for (int col = rect.left; col < rect.right; col++) {
-      int src_pixel = scan[col];
-      int dest_pixel = translate[src_pixel];
-      scan[col] = (uint8_t)dest_pixel;
-      int error = -dest_pixel + src_pixel;
-      if (col < rect.right - 1) {
-        int src = scan[col + 1];
-        src += error * 7 / 16;
-        if (src > 255) {
-          scan[col + 1] = 255;
-        } else if (src < 0) {
-          scan[col + 1] = 0;
-        } else {
-          scan[col + 1] = src;
-        }
-      }
-      if (col < rect.right - 1 && row < rect.bottom - 1) {
-        int src = next_scan[col + 1];
-        src += error * 1 / 16;
-        if (src > 255) {
-          next_scan[col + 1] = 255;
-        } else if (src < 0) {
-          next_scan[col + 1] = 0;
-        } else {
-          next_scan[col + 1] = src;
-        }
-      }
-      if (row < rect.bottom - 1) {
-        int src = next_scan[col];
-        src += error * 5 / 16;
-        if (src > 255) {
-          next_scan[col] = 255;
-        } else if (src < 0) {
-          next_scan[col] = 0;
-        } else {
-          next_scan[col] = src;
-        }
-      }
-      if (col > rect.left && row < rect.bottom - 1) {
-        int src = next_scan[col - 1];
-        src += error * 3 / 16;
-        if (src > 255) {
-          next_scan[col - 1] = 255;
-        } else if (src < 0) {
-          next_scan[col - 1] = 0;
-        } else {
-          next_scan[col - 1] = src;
-        }
-      }
-    }
-  }
-  return TRUE;
-}
+
 CFX_DIBitmap* CFX_DIBSource::FlipImage(FX_BOOL bXFlip, FX_BOOL bYFlip) const {
   CFX_DIBitmap* pFlipped = new CFX_DIBitmap;
   if (!pFlipped->Create(m_Width, m_Height, GetFormat())) {
diff --git a/core/fxge/ge/fx_ge_device.cpp b/core/fxge/ge/fx_ge_device.cpp
index d6c7b18b47..b9bd133e57 100644
--- a/core/fxge/ge/fx_ge_device.cpp
+++ b/core/fxge/ge/fx_ge_device.cpp
@@ -261,7 +261,7 @@ FX_BOOL CFX_RenderDevice::DrawFillStrokePath(
       Backdrop.Copy(&bitmap);
     }
     CFX_FxgeDevice bitmap_device;
-    bitmap_device.Attach(&bitmap, 0, FALSE, &Backdrop, TRUE);
+    bitmap_device.Attach(&bitmap, false, &Backdrop, true);
     CFX_Matrix matrix;
     if (pObject2Device) {
       matrix = *pObject2Device;
diff --git a/core/fxge/include/fx_dib.h b/core/fxge/include/fx_dib.h
index 6504e5fd8f..12ed03c1d3 100644
--- a/core/fxge/include/fx_dib.h
+++ b/core/fxge/include/fx_dib.h
@@ -256,6 +256,7 @@ class CFX_DIBSource {
   int FindPalette(uint32_t color) const;
   void GetPalette(uint32_t* pal, int alpha) const;
 };
+
 class CFX_DIBitmap : public CFX_DIBSource {
  public:
   CFX_DIBitmap();
@@ -357,17 +358,13 @@ class CFX_DIBitmap : public CFX_DIBSource {
 
   FX_BOOL ConvertColorScale(uint32_t forecolor, uint32_t backcolor);
 
-  FX_BOOL DitherFS(const uint32_t* pPalette,
-                   int pal_size,
-                   const FX_RECT* pRect = NULL);
-
  protected:
-  uint8_t* m_pBuffer;
+  FX_BOOL GetGrayData(void* pIccTransform = NULL);
 
+  uint8_t* m_pBuffer;
   FX_BOOL m_bExtBuf;
-
-  FX_BOOL GetGrayData(void* pIccTransform = NULL);
 };
+
 class CFX_DIBExtractor {
  public:
   CFX_DIBExtractor(const CFX_DIBSource* pSrc);
diff --git a/core/fxge/include/fx_ge.h b/core/fxge/include/fx_ge.h
index c025c1251e..6a3113d070 100644
--- a/core/fxge/include/fx_ge.h
+++ b/core/fxge/include/fx_ge.h
@@ -161,7 +161,6 @@ class CFX_GraphStateData {
 #define FXDC_HORZ_SIZE 5
 #define FXDC_VERT_SIZE 6
 #define FXDC_RENDER_CAPS 7
-#define FXDC_DITHER_BITS 8
 #define FXDC_DISPLAY 1
 #define FXDC_PRINTER 2
 #define FXRC_GET_BITS 0x01
@@ -402,16 +401,13 @@ class CFX_FxgeDevice : public CFX_RenderDevice {
   ~CFX_FxgeDevice() override;
 
   bool Attach(CFX_DIBitmap* pBitmap,
-              int dither_bits = 0,
-              bool bRgbByteOrder = false,
-              CFX_DIBitmap* pOriDevice = NULL,
-              bool bGroupKnockout = false);
-
+              bool bRgbByteOrder,
+              CFX_DIBitmap* pOriDevice,
+              bool bGroupKnockout);
   bool Create(int width,
               int height,
               FXDIB_Format format,
-              int dither_bits = 0,
-              CFX_DIBitmap* pOriDevice = NULL);
+              CFX_DIBitmap* pOriDevice);
 
 #ifdef _SKIA_SUPPORT_
   bool AttachRecorder(SkPictureRecorder* recorder);
diff --git a/core/fxge/skia/fx_skia_device.cpp b/core/fxge/skia/fx_skia_device.cpp
index e64dfd0a73..452472e40c 100644
--- a/core/fxge/skia/fx_skia_device.cpp
+++ b/core/fxge/skia/fx_skia_device.cpp
@@ -500,14 +500,12 @@ void CFX_SkiaDeviceDriver::PaintStroke(SkPaint* spaint,
 }
 
 CFX_SkiaDeviceDriver::CFX_SkiaDeviceDriver(CFX_DIBitmap* pBitmap,
-                                           int dither_bits,
                                            FX_BOOL bRgbByteOrder,
                                            CFX_DIBitmap* pOriDevice,
                                            FX_BOOL bGroupKnockout)
     : m_pBitmap(pBitmap),
       m_pOriDevice(pOriDevice),
       m_pRecorder(nullptr),
-      m_ditherBits(dither_bits),
       m_bRgbByteOrder(bRgbByteOrder),
       m_bGroupKnockout(bGroupKnockout) {
   SkBitmap skBitmap;
@@ -526,7 +524,6 @@ CFX_SkiaDeviceDriver::CFX_SkiaDeviceDriver(int size_x, int size_y)
     : m_pBitmap(nullptr),
       m_pOriDevice(nullptr),
       m_pRecorder(new SkPictureRecorder),
-      m_ditherBits(0),
       m_bRgbByteOrder(FALSE),
       m_bGroupKnockout(FALSE) {
   m_pRecorder->beginRecording(SkIntToScalar(size_x), SkIntToScalar(size_y));
@@ -537,7 +534,6 @@ CFX_SkiaDeviceDriver::CFX_SkiaDeviceDriver(SkPictureRecorder* recorder)
     : m_pBitmap(nullptr),
       m_pOriDevice(nullptr),
       m_pRecorder(recorder),
-      m_ditherBits(0),
       m_bRgbByteOrder(FALSE),
       m_bGroupKnockout(FALSE) {
   m_pCanvas = m_pRecorder->getRecordingCanvas();
@@ -594,8 +590,6 @@ int CFX_SkiaDeviceDriver::GetDeviceCaps(int caps_id) {
       return FXRC_GET_BITS | FXRC_ALPHA_PATH | FXRC_ALPHA_IMAGE |
              FXRC_BLEND_MODE | FXRC_SOFT_CLIP | FXRC_ALPHA_OUTPUT |
              FXRC_FILLSTROKE_PATH | FXRC_SHADING;
-    case FXDC_DITHER_BITS:
-      return m_ditherBits;
   }
   return 0;
 }
@@ -1095,15 +1089,14 @@ SkPictureRecorder* CFX_FxgeDevice::CreateRecorder(int size_x, int size_y) {
 }
 
 bool CFX_FxgeDevice::Attach(CFX_DIBitmap* pBitmap,
-                            int dither_bits,
                             bool bRgbByteOrder,
                             CFX_DIBitmap* pOriDevice,
                             bool bGroupKnockout) {
   if (!pBitmap)
     return false;
   SetBitmap(pBitmap);
-  SetDeviceDriver(new CFX_SkiaDeviceDriver(pBitmap, dither_bits, bRgbByteOrder,
-                                           pOriDevice, bGroupKnockout));
+  SetDeviceDriver(new CFX_SkiaDeviceDriver(pBitmap, bRgbByteOrder, pOriDevice,
+                                           bGroupKnockout));
   return true;
 }
 
@@ -1117,7 +1110,6 @@ bool CFX_FxgeDevice::AttachRecorder(SkPictureRecorder* recorder) {
 bool CFX_FxgeDevice::Create(int width,
                             int height,
                             FXDIB_Format format,
-                            int dither_bits,
                             CFX_DIBitmap* pOriDevice) {
   m_bOwnedBitmap = TRUE;
   CFX_DIBitmap* pBitmap = new CFX_DIBitmap;
@@ -1127,7 +1119,7 @@ bool CFX_FxgeDevice::Create(int width,
   }
   SetBitmap(pBitmap);
   CFX_SkiaDeviceDriver* pDriver =
-      new CFX_SkiaDeviceDriver(pBitmap, dither_bits, FALSE, pOriDevice, FALSE);
+      new CFX_SkiaDeviceDriver(pBitmap, FALSE, pOriDevice, FALSE);
   SetDeviceDriver(pDriver);
   return true;
 }
diff --git a/core/fxge/skia/fx_skia_device.h b/core/fxge/skia/fx_skia_device.h
index 79097ade18..dd3ba420e8 100644
--- a/core/fxge/skia/fx_skia_device.h
+++ b/core/fxge/skia/fx_skia_device.h
@@ -17,11 +17,10 @@ struct SkIRect;
 class CFX_SkiaDeviceDriver : public IFX_RenderDeviceDriver {
  public:
   CFX_SkiaDeviceDriver(CFX_DIBitmap* pBitmap,
-                       int dither_bits,
                        FX_BOOL bRgbByteOrder,
                        CFX_DIBitmap* pOriDevice,
                        FX_BOOL bGroupKnockout);
-  CFX_SkiaDeviceDriver(SkPictureRecorder* recorder);
+  explicit CFX_SkiaDeviceDriver(SkPictureRecorder* recorder);
   CFX_SkiaDeviceDriver(int size_x, int size_y);
   ~CFX_SkiaDeviceDriver() override;
 
@@ -145,7 +144,6 @@ class CFX_SkiaDeviceDriver : public IFX_RenderDeviceDriver {
   CFX_DIBitmap* m_pOriDevice;
   SkCanvas* m_pCanvas;
   SkPictureRecorder* const m_pRecorder;
-  int m_ditherBits;
   FX_BOOL m_bRgbByteOrder;
   FX_BOOL m_bGroupKnockout;
 };