Add helpers to work with FXDIB_Format.

Helper functions make getting the bpp and component count more readable.

Change-Id: Ie0f97d52136d11ef5251f6e22748e87aea289ae1
Reviewed-on: https://pdfium-review.googlesource.com/28572
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>

8 files changed, 100 insertions, 92 deletions

diff --git a/core/fxcodec/codec/fx_codec_progress.cpp b/core/fxcodec/codec/fx_codec_progress.cpp
index 7e29524b2f..8807879e6e 100644
--- a/core/fxcodec/codec/fx_codec_progress.cpp
+++ b/core/fxcodec/codec/fx_codec_progress.cpp
@@ -1478,12 +1478,10 @@ void CCodec_ProgressiveDecoder::ReSampleScanline(
   int des_left = m_startX;
   uint8_t* des_scan =
       pDeviceBitmap->GetBuffer() + des_line * pDeviceBitmap->GetPitch();
-  int src_bpp = src_format & 0xff;
-  int des_bpp = pDeviceBitmap->GetBPP();
-  int src_Bpp = src_bpp >> 3;
-  int des_Bpp = des_bpp >> 3;
-  src_scan += src_left * src_Bpp;
-  des_scan += des_left * des_Bpp;
+  int src_bytes_per_pixel = (src_format & 0xff) / 8;
+  int dest_bytes_per_pixel = pDeviceBitmap->GetBPP() / 8;
+  src_scan += src_left * src_bytes_per_pixel;
+  des_scan += des_left * dest_bytes_per_pixel;
   for (int des_col = 0; des_col < m_sizeX; des_col++) {
     PixelWeight* pPixelWeights = m_WeightHorz.GetPixelWeight(des_col);
     switch (m_TransMethod) {
@@ -1523,7 +1521,7 @@ void CCodec_ProgressiveDecoder::ReSampleScanline(
              j++) {
           int pixel_weight =
               pPixelWeights->m_Weights[j - pPixelWeights->m_SrcStart];
-          const uint8_t* src_pixel = src_scan + j * src_Bpp;
+          const uint8_t* src_pixel = src_scan + j * src_bytes_per_pixel;
           des_b += pixel_weight * (*src_pixel++);
           des_g += pixel_weight * (*src_pixel++);
           des_r += pixel_weight * (*src_pixel);
@@ -1537,7 +1535,7 @@ void CCodec_ProgressiveDecoder::ReSampleScanline(
              j++) {
           int pixel_weight =
               pPixelWeights->m_Weights[j - pPixelWeights->m_SrcStart];
-          const uint8_t* src_pixel = src_scan + j * src_Bpp;
+          const uint8_t* src_pixel = src_scan + j * src_bytes_per_pixel;
           uint8_t src_b = 0;
           uint8_t src_g = 0;
           uint8_t src_r = 0;
@@ -1562,7 +1560,7 @@ void CCodec_ProgressiveDecoder::ReSampleScanline(
           des_g += pixel_weight * src_scan[j];
         }
         memset(des_scan, (uint8_t)(des_g >> 16), 3);
-        des_scan += des_Bpp;
+        des_scan += dest_bytes_per_pixel;
       } break;
       case 8: {
         int des_r = 0, des_g = 0, des_b = 0;
@@ -1578,7 +1576,7 @@ void CCodec_ProgressiveDecoder::ReSampleScanline(
         *des_scan++ = (uint8_t)((des_b) >> 16);
         *des_scan++ = (uint8_t)((des_g) >> 16);
         *des_scan++ = (uint8_t)((des_r) >> 16);
-        des_scan += des_Bpp - 3;
+        des_scan += dest_bytes_per_pixel - 3;
       } break;
       case 12: {
         if (m_pBmpContext) {
@@ -1620,7 +1618,7 @@ void CCodec_ProgressiveDecoder::ReSampleScanline(
              j++) {
           int pixel_weight =
               pPixelWeights->m_Weights[j - pPixelWeights->m_SrcStart];
-          const uint8_t* src_pixel = src_scan + j * src_Bpp;
+          const uint8_t* src_pixel = src_scan + j * src_bytes_per_pixel;
           des_b += pixel_weight * (*src_pixel++);
           des_g += pixel_weight * (*src_pixel++);
           des_r += pixel_weight * (*src_pixel);
@@ -1628,7 +1626,7 @@ void CCodec_ProgressiveDecoder::ReSampleScanline(
         *des_scan++ = (uint8_t)((des_b) >> 16);
         *des_scan++ = (uint8_t)((des_g) >> 16);
         *des_scan++ = (uint8_t)((des_r) >> 16);
-        des_scan += des_Bpp - 3;
+        des_scan += dest_bytes_per_pixel - 3;
       } break;
       case 10: {
         uint32_t des_b = 0, des_g = 0, des_r = 0;
@@ -1636,7 +1634,7 @@ void CCodec_ProgressiveDecoder::ReSampleScanline(
              j++) {
           int pixel_weight =
               pPixelWeights->m_Weights[j - pPixelWeights->m_SrcStart];
-          const uint8_t* src_pixel = src_scan + j * src_Bpp;
+          const uint8_t* src_pixel = src_scan + j * src_bytes_per_pixel;
           uint8_t src_b = 0;
           uint8_t src_g = 0;
           uint8_t src_r = 0;
@@ -1650,7 +1648,7 @@ void CCodec_ProgressiveDecoder::ReSampleScanline(
         *des_scan++ = (uint8_t)((des_b) >> 16);
         *des_scan++ = (uint8_t)((des_g) >> 16);
         *des_scan++ = (uint8_t)((des_r) >> 16);
-        des_scan += des_Bpp - 3;
+        des_scan += dest_bytes_per_pixel - 3;
       } break;
       case 11: {
         uint32_t des_alpha = 0, des_r = 0, des_g = 0, des_b = 0;
@@ -1658,7 +1656,7 @@ void CCodec_ProgressiveDecoder::ReSampleScanline(
              j++) {
           int pixel_weight =
               pPixelWeights->m_Weights[j - pPixelWeights->m_SrcStart];
-          const uint8_t* src_pixel = src_scan + j * src_Bpp;
+          const uint8_t* src_pixel = src_scan + j * src_bytes_per_pixel;
           pixel_weight = pixel_weight * src_pixel[3] / 255;
           des_b += pixel_weight * (*src_pixel++);
           des_g += pixel_weight * (*src_pixel++);
diff --git a/core/fxge/dib/cfx_dibitmap.cpp b/core/fxge/dib/cfx_dibitmap.cpp
index ae9bf244f0..9fa9776df0 100644
--- a/core/fxge/dib/cfx_dibitmap.cpp
+++ b/core/fxge/dib/cfx_dibitmap.cpp
@@ -19,7 +19,7 @@
 
 namespace {
 
-const int8_t g_ChannelOffset[] = {0, 2, 1, 0, 0, 1, 2, 3, 3};
+const int8_t kChannelOffset[] = {0, 2, 1, 0, 0, 1, 2, 3, 3};
 
 }  // namespace
 
@@ -274,7 +274,7 @@ bool CFX_DIBitmap::LoadChannel(FXDIB_Channel destChannel,
       if (!pSrcClone)
         return false;
     }
-    srcOffset = g_ChannelOffset[srcChannel];
+    srcOffset = kChannelOffset[srcChannel];
   }
   int destOffset = 0;
   if (destChannel == FXDIB_Alpha) {
@@ -304,7 +304,7 @@ bool CFX_DIBitmap::LoadChannel(FXDIB_Channel destChannel,
         return false;
       }
     }
-    destOffset = g_ChannelOffset[destChannel];
+    destOffset = kChannelOffset[destChannel];
   }
   if (srcChannel == FXDIB_Alpha && pSrcClone->m_pAlphaMask) {
     RetainPtr<CFX_DIBSource> pAlphaMask = pSrcClone->m_pAlphaMask;
@@ -383,7 +383,7 @@ bool CFX_DIBitmap::LoadChannel(FXDIB_Channel destChannel, int value) {
         return false;
       }
     }
-    destOffset = g_ChannelOffset[destChannel];
+    destOffset = kChannelOffset[destChannel];
   }
   int Bpp = GetBPP() / 8;
   if (Bpp == 1) {
@@ -819,14 +819,15 @@ bool CFX_DIBitmap::CalculatePitchAndSize(int height,
   if (width <= 0 || height <= 0)
     return false;
 
-  if (!(format & 0xff))
+  int bpp = GetBppFromFormat(format);
+  if (!bpp)
     return false;
 
-  if ((INT_MAX - 31) / width < (format & 0xff))
+  if ((INT_MAX - 31) / width < bpp)
     return false;
 
   if (!*pitch)
-    *pitch = static_cast<uint32_t>((width * (format & 0xff) + 31) / 32 * 4);
+    *pitch = static_cast<uint32_t>((width * bpp + 31) / 32 * 4);
 
   if ((1 << 30) / *pitch < static_cast<uint32_t>(height))
     return false;
@@ -1190,7 +1191,7 @@ bool CFX_DIBitmap::ConvertFormat(FXDIB_Format dest_format) {
     }
     return true;
   }
-  int dest_bpp = dest_format & 0xff;
+  int dest_bpp = GetBppFromFormat(dest_format);
   int dest_pitch = (dest_bpp * m_Width + 31) / 32 * 4;
   std::unique_ptr<uint8_t, FxFreeDeleter> dest_buf(
       FX_TryAlloc(uint8_t, dest_pitch * m_Height + 4));
diff --git a/core/fxge/dib/cfx_dibsource.cpp b/core/fxge/dib/cfx_dibsource.cpp
index 86bec23c67..f140a5e838 100644
--- a/core/fxge/dib/cfx_dibsource.cpp
+++ b/core/fxge/dib/cfx_dibsource.cpp
@@ -22,23 +22,6 @@
 
 namespace {
 
-class CFX_Palette {
- public:
-  explicit CFX_Palette(const RetainPtr<CFX_DIBSource>& pBitmap);
-  ~CFX_Palette();
-
-  const uint32_t* GetPalette() { return m_Palette.data(); }
-  const std::pair<uint32_t, uint32_t>* GetLuts() const { return m_Luts.data(); }
-  int32_t GetLutCount() const { return m_lut; }
-  void SetAmountLut(int row, uint32_t value) { m_Luts[row].first = value; }
-
- private:
-  std::vector<uint32_t> m_Palette;
-  // (Amount, Color) pairs
-  std::vector<std::pair<uint32_t, uint32_t>> m_Luts;
-  int m_lut;
-};
-
 void ColorDecode(uint32_t pal_v, uint8_t* r, uint8_t* g, uint8_t* b) {
   *r = static_cast<uint8_t>((pal_v & 0xf00) >> 4);
   *g = static_cast<uint8_t>(pal_v & 0x0f0);
@@ -64,6 +47,23 @@ void Obtain_Pal(std::pair<uint32_t, uint32_t>* luts,
   }
 }
 
+class CFX_Palette {
+ public:
+  explicit CFX_Palette(const RetainPtr<CFX_DIBSource>& pBitmap);
+  ~CFX_Palette();
+
+  const uint32_t* GetPalette() { return m_Palette.data(); }
+  const std::pair<uint32_t, uint32_t>* GetLuts() const { return m_Luts.data(); }
+  int32_t GetLutCount() const { return m_lut; }
+  void SetAmountLut(int row, uint32_t value) { m_Luts[row].first = value; }
+
+ private:
+  std::vector<uint32_t> m_Palette;
+  // (Amount, Color) pairs
+  std::vector<std::pair<uint32_t, uint32_t>> m_Luts;
+  int m_lut;
+};
+
 CFX_Palette::CFX_Palette(const RetainPtr<CFX_DIBSource>& pBitmap)
     : m_Palette(256), m_Luts(4096), m_lut(0) {
   int bpp = pBitmap->GetBPP() / 8;
@@ -368,7 +368,7 @@ void ConvertBuffer_Rgb2PltRgb8(uint8_t* dest_buf,
   memcpy(dst_plt, pal, sizeof(uint32_t) * 256);
 }
 
-void ConvertBuffer_1bppMask2Rgb(FXDIB_Format dst_format,
+void ConvertBuffer_1bppMask2Rgb(FXDIB_Format dest_format,
                                 uint8_t* dest_buf,
                                 int dest_pitch,
                                 int width,
@@ -376,29 +376,28 @@ void ConvertBuffer_1bppMask2Rgb(FXDIB_Format dst_format,
                                 const RetainPtr<CFX_DIBSource>& pSrcBitmap,
                                 int src_left,
                                 int src_top) {
-  int comps = (dst_format & 0xff) / 8;
-  uint8_t set_gray, reset_gray;
-  set_gray = 0xff;
-  reset_gray = 0x00;
+  int comps = GetCompsFromFormat(dest_format);
+  static constexpr uint8_t kSetGray = 0xff;
+  static constexpr uint8_t kResetGray = 0x00;
   for (int row = 0; row < height; ++row) {
     uint8_t* dest_scan = dest_buf + row * dest_pitch;
     const uint8_t* src_scan = pSrcBitmap->GetScanline(src_top + row);
     for (int col = src_left; col < src_left + width; ++col) {
       if (src_scan[col / 8] & (1 << (7 - col % 8))) {
-        dest_scan[0] = set_gray;
-        dest_scan[1] = set_gray;
-        dest_scan[2] = set_gray;
+        dest_scan[0] = kSetGray;
+        dest_scan[1] = kSetGray;
+        dest_scan[2] = kSetGray;
       } else {
-        dest_scan[0] = reset_gray;
-        dest_scan[1] = reset_gray;
-        dest_scan[2] = reset_gray;
+        dest_scan[0] = kResetGray;
+        dest_scan[1] = kResetGray;
+        dest_scan[2] = kResetGray;
       }
       dest_scan += comps;
     }
   }
 }
 
-void ConvertBuffer_8bppMask2Rgb(FXDIB_Format dst_format,
+void ConvertBuffer_8bppMask2Rgb(FXDIB_Format dest_format,
                                 uint8_t* dest_buf,
                                 int dest_pitch,
                                 int width,
@@ -406,7 +405,7 @@ void ConvertBuffer_8bppMask2Rgb(FXDIB_Format dst_format,
                                 const RetainPtr<CFX_DIBSource>& pSrcBitmap,
                                 int src_left,
                                 int src_top) {
-  int comps = (dst_format & 0xff) / 8;
+  int comps = GetCompsFromFormat(dest_format);
   for (int row = 0; row < height; ++row) {
     uint8_t* dest_scan = dest_buf + row * dest_pitch;
     const uint8_t* src_scan = pSrcBitmap->GetScanline(src_top + row) + src_left;
@@ -421,7 +420,7 @@ void ConvertBuffer_8bppMask2Rgb(FXDIB_Format dst_format,
   }
 }
 
-void ConvertBuffer_1bppPlt2Rgb(FXDIB_Format dst_format,
+void ConvertBuffer_1bppPlt2Rgb(FXDIB_Format dest_format,
                                uint8_t* dest_buf,
                                int dest_pitch,
                                int width,
@@ -429,7 +428,7 @@ void ConvertBuffer_1bppPlt2Rgb(FXDIB_Format dst_format,
                                const RetainPtr<CFX_DIBSource>& pSrcBitmap,
                                int src_left,
                                int src_top) {
-  int comps = (dst_format & 0xff) / 8;
+  int comps = GetCompsFromFormat(dest_format);
   uint32_t* src_plt = pSrcBitmap->GetPalette();
   uint32_t plt[2];
   uint8_t* bgr_ptr = reinterpret_cast<uint8_t*>(plt);
@@ -472,7 +471,7 @@ void ConvertBuffer_1bppPlt2Rgb(FXDIB_Format dst_format,
   }
 }
 
-void ConvertBuffer_8bppPlt2Rgb(FXDIB_Format dst_format,
+void ConvertBuffer_8bppPlt2Rgb(FXDIB_Format dest_format,
                                uint8_t* dest_buf,
                                int dest_pitch,
                                int width,
@@ -480,7 +479,7 @@ void ConvertBuffer_8bppPlt2Rgb(FXDIB_Format dst_format,
                                const RetainPtr<CFX_DIBSource>& pSrcBitmap,
                                int src_left,
                                int src_top) {
-  int comps = (dst_format & 0xff) / 8;
+  int comps = GetCompsFromFormat(dest_format);
   uint32_t* src_plt = pSrcBitmap->GetPalette();
   uint32_t plt[256];
   uint8_t* bgr_ptr = reinterpret_cast<uint8_t*>(plt);
@@ -1218,7 +1217,7 @@ bool CFX_DIBSource::ConvertBuffer(
     int src_top,
     std::unique_ptr<uint32_t, FxFreeDeleter>* p_pal) {
   FXDIB_Format src_format = pSrcBitmap->GetFormat();
-  const int bpp = src_format & 0xff;
+  const int bpp = GetBppFromFormat(src_format);
   switch (dest_format) {
     case FXDIB_8bppMask: {
       return ConvertBuffer_8bppMask(bpp, dest_buf, dest_pitch, width, height,
diff --git a/core/fxge/dib/cfx_filtereddib.cpp b/core/fxge/dib/cfx_filtereddib.cpp
index 96fc8062a0..1d5ed6200c 100644
--- a/core/fxge/dib/cfx_filtereddib.cpp
+++ b/core/fxge/dib/cfx_filtereddib.cpp
@@ -17,9 +17,9 @@ void CFX_FilteredDIB::LoadSrc(const RetainPtr<CFX_DIBSource>& pSrc) {
   m_Width = pSrc->GetWidth();
   m_Height = pSrc->GetHeight();
   FXDIB_Format format = GetDestFormat();
-  m_bpp = static_cast<uint8_t>(format);
+  m_bpp = GetBppFromFormat(format);
   m_AlphaFlag = static_cast<uint8_t>(format >> 8);
-  m_Pitch = (m_Width * (format & 0xff) + 31) / 32 * 4;
+  m_Pitch = (m_Width * m_bpp + 31) / 32 * 4;
   m_pPalette.reset(GetDestPalette());
   m_Scanline.resize(m_Pitch);
 }
diff --git a/core/fxge/dib/cfx_scanlinecompositor.cpp b/core/fxge/dib/cfx_scanlinecompositor.cpp
index a1254e2116..ae27ee0246 100644
--- a/core/fxge/dib/cfx_scanlinecompositor.cpp
+++ b/core/fxge/dib/cfx_scanlinecompositor.cpp
@@ -2833,7 +2833,7 @@ bool CFX_ScanlineCompositor::Init(FXDIB_Format dest_format,
   m_DestFormat = dest_format;
   m_BlendType = blend_type;
   m_bRgbByteOrder = bRgbByteOrder;
-  if ((dest_format & 0xff) == 1)
+  if (GetBppFromFormat(dest_format) == 1)
     return false;
   if (m_SrcFormat == FXDIB_1bppMask || m_SrcFormat == FXDIB_8bppMask) {
     InitSourceMask(alpha_flag, mask_color);
@@ -2846,9 +2846,10 @@ bool CFX_ScanlineCompositor::Init(FXDIB_Format dest_format,
       return true;
 
     InitSourcePalette(src_format, dest_format, pSrcPalette);
-    m_iTransparency =
-        (dest_format == FXDIB_Argb ? 1 : 0) + (dest_format & 0x0200 ? 2 : 0) +
-        (dest_format & 0x0400 ? 4 : 0) + ((src_format & 0xff) == 1 ? 8 : 0);
+    m_iTransparency = (dest_format == FXDIB_Argb ? 1 : 0) +
+                      (dest_format & 0x0200 ? 2 : 0) +
+                      (dest_format & 0x0400 ? 4 : 0) +
+                      (GetBppFromFormat(src_format) == 1 ? 8 : 0);
     return true;
   }
   m_iTransparency =
@@ -2907,15 +2908,16 @@ void CFX_ScanlineCompositor::InitSourceMask(int alpha_flag,
 void CFX_ScanlineCompositor::InitSourcePalette(FXDIB_Format src_format,
                                                FXDIB_Format dest_format,
                                                const uint32_t* pSrcPalette) {
-  bool isSrcCmyk = !!(src_format & 0x0400);
-  bool isDstCmyk = !!(dest_format & 0x0400);
+  bool bIsSrcCmyk = !!(src_format & 0x0400);
+  bool bIsDstCmyk = !!(dest_format & 0x0400);
+  bool bIsDestBpp8 = GetBppFromFormat(dest_format) == 8;
+  int pal_count = 1 << GetBppFromFormat(src_format);
   m_pSrcPalette = nullptr;
   if (pSrcPalette) {
-    if ((dest_format & 0xff) == 8) {
-      int pal_count = 1 << (src_format & 0xff);
+    if (bIsDestBpp8) {
       uint8_t* gray_pal = FX_Alloc(uint8_t, pal_count);
       m_pSrcPalette.reset(reinterpret_cast<uint32_t*>(gray_pal));
-      if (isSrcCmyk) {
+      if (bIsSrcCmyk) {
         for (int i = 0; i < pal_count; ++i) {
           FX_CMYK cmyk = pSrcPalette[i];
           uint8_t r;
@@ -2935,13 +2937,12 @@ void CFX_ScanlineCompositor::InitSourcePalette(FXDIB_Format src_format,
       }
       return;
     }
-    int palsize = 1 << (src_format & 0xff);
-    m_pSrcPalette.reset(FX_Alloc(uint32_t, palsize));
+    m_pSrcPalette.reset(FX_Alloc(uint32_t, pal_count));
     uint32_t* pPalette = m_pSrcPalette.get();
-    if (isDstCmyk == isSrcCmyk) {
-      memcpy(pPalette, pSrcPalette, palsize * sizeof(uint32_t));
+    if (bIsDstCmyk == bIsSrcCmyk) {
+      memcpy(pPalette, pSrcPalette, pal_count * sizeof(uint32_t));
     } else {
-      for (int i = 0; i < palsize; ++i) {
+      for (int i = 0; i < pal_count; ++i) {
         FX_CMYK cmyk = pSrcPalette[i];
         uint8_t r;
         uint8_t g;
@@ -2954,8 +2955,7 @@ void CFX_ScanlineCompositor::InitSourcePalette(FXDIB_Format src_format,
     }
     return;
   }
-  if ((dest_format & 0xff) == 8) {
-    int pal_count = 1 << (src_format & 0xff);
+  if (bIsDestBpp8) {
     uint8_t* gray_pal = FX_Alloc(uint8_t, pal_count);
     if (pal_count == 2) {
       gray_pal[0] = 0;
@@ -2967,18 +2967,17 @@ void CFX_ScanlineCompositor::InitSourcePalette(FXDIB_Format src_format,
     m_pSrcPalette.reset(reinterpret_cast<uint32_t*>(gray_pal));
     return;
   }
-  int palsize = 1 << (src_format & 0xff);
-  m_pSrcPalette.reset(FX_Alloc(uint32_t, palsize));
+  m_pSrcPalette.reset(FX_Alloc(uint32_t, pal_count));
   uint32_t* pPalette = m_pSrcPalette.get();
-  if (palsize == 2) {
-    pPalette[0] = isSrcCmyk ? 255 : 0xff000000;
-    pPalette[1] = isSrcCmyk ? 0 : 0xffffffff;
+  if (pal_count == 2) {
+    pPalette[0] = bIsSrcCmyk ? 255 : 0xff000000;
+    pPalette[1] = bIsSrcCmyk ? 0 : 0xffffffff;
   } else {
-    for (int i = 0; i < palsize; ++i)
-      pPalette[i] = isSrcCmyk ? FX_CCOLOR(i) : (i * 0x10101);
+    for (int i = 0; i < pal_count; ++i)
+      pPalette[i] = bIsSrcCmyk ? FX_CCOLOR(i) : (i * 0x10101);
   }
-  if (isSrcCmyk != isDstCmyk) {
-    for (int i = 0; i < palsize; ++i) {
+  if (bIsSrcCmyk != bIsDstCmyk) {
+    for (int i = 0; i < pal_count; ++i) {
       FX_CMYK cmyk = pPalette[i];
       uint8_t r;
       uint8_t g;
diff --git a/core/fxge/dib/cstretchengine.cpp b/core/fxge/dib/cstretchengine.cpp
index b7aa672a46..9d3923adab 100644
--- a/core/fxge/dib/cstretchengine.cpp
+++ b/core/fxge/dib/cstretchengine.cpp
@@ -229,8 +229,8 @@ CStretchEngine::CStretchEngine(ScanlineComposerIface* pDestBitmap,
                                const RetainPtr<CFX_DIBSource>& pSrcBitmap,
                                int flags)
     : m_DestFormat(dest_format),
-      m_DestBpp(dest_format & 0xff),
-      m_SrcBpp(pSrcBitmap->GetFormat() & 0xff),
+      m_DestBpp(GetBppFromFormat(dest_format)),
+      m_SrcBpp(GetBppFromFormat(pSrcBitmap->GetFormat())),
       m_bHasAlpha(pSrcBitmap->GetFormat() & 0x200),
       m_pSource(pSrcBitmap),
       m_pSrcPalette(pSrcBitmap->GetPalette()),
diff --git a/core/fxge/dib/fx_dib_main.cpp b/core/fxge/dib/fx_dib_main.cpp
index 002fc2e394..546198b7a9 100644
--- a/core/fxge/dib/fx_dib_main.cpp
+++ b/core/fxge/dib/fx_dib_main.cpp
@@ -50,7 +50,7 @@ const int16_t SDP_Table[513] = {
     0,   0,   0,
 };
 
-FX_RECT FXDIB_SwapClipBox(FX_RECT& clip,
+FX_RECT FXDIB_SwapClipBox(const FX_RECT& clip,
                           int width,
                           int height,
                           bool bFlipX,
@@ -93,9 +93,9 @@ FX_ARGB AlphaAndColorRefToArgb(int a, FX_COLORREF colorref) {
 }
 
 FX_ARGB StringToFXARGB(const WideStringView& wsValue) {
-  uint8_t r = 0, g = 0, b = 0;
+  static constexpr FX_ARGB kDefaultValue = 0xff000000;
   if (wsValue.GetLength() == 0)
-    return 0xff000000;
+    return kDefaultValue;
 
   int cc = 0;
   const wchar_t* str = wsValue.unterminated_c_str();
@@ -104,8 +104,11 @@ FX_ARGB StringToFXARGB(const WideStringView& wsValue) {
     cc++;
 
   if (cc >= len)
-    return 0xff000000;
+    return kDefaultValue;
 
+  uint8_t r = 0;
+  uint8_t g = 0;
+  uint8_t b = 0;
   while (cc < len) {
     if (str[cc] == ',' || !FXSYS_isDecimalDigit(str[cc]))
       break;
diff --git a/core/fxge/fx_dib.h b/core/fxge/fx_dib.h
index 9acfa51bbe..57e844b946 100644
--- a/core/fxge/fx_dib.h
+++ b/core/fxge/fx_dib.h
@@ -95,6 +95,14 @@ constexpr uint8_t FXSYS_GetBValue(uint32_t bgr) {
 #define FXSYS_GetYValue(cmyk) ((uint8_t)((cmyk) >> 8) & 0xff)
 #define FXSYS_GetKValue(cmyk) ((uint8_t)(cmyk)&0xff)
 
+inline int GetBppFromFormat(FXDIB_Format format) {
+  return format & 0xff;
+}
+
+inline int GetCompsFromFormat(FXDIB_Format format) {
+  return (format & 0xff) / 8;
+}
+
 inline FX_CMYK CmykEncode(int c, int m, int y, int k) {
   return (c << 24) | (m << 16) | (y << 8) | k;
 }
@@ -149,7 +157,7 @@ FX_ARGB StringToFXARGB(const WideStringView& view);
   ((uint8_t)(argb >> 16) | ((uint8_t)(argb >> 8)) << 8 | \
    ((uint8_t)(argb)) << 16 | ((uint8_t)(argb >> 24) << 24))
 
-FX_RECT FXDIB_SwapClipBox(FX_RECT& clip,
+FX_RECT FXDIB_SwapClipBox(const FX_RECT& clip,
                           int width,
                           int height,
                           bool bFlipX,