未签名的char*缓冲区到系统::绘图:: bitmap

Question

我正在尝试创建一个工具/资产转换器，该工具/资产转换器使用该字体将字体栅格栅格到XNA游戏的纹理页面 freetype2 引擎。

下面，第一个图像是freetype2的直接输出1 引擎。第二张图像是尝试将其转换为一个后的结果 System::Drawing::Bitmap.

目标http://www.freeimagehosting.net/uploads/fb102ee6da.jpg CurrentResult http://www.freeimagehosting.net/uploads/9EA77FA307.JPG

关于这里发生的事情的任何提示/提示/想法将不胜感激。解释字节布局和像素格式的文章的链接也将很有帮助。

  FT_Bitmap *bitmap = &face->glyph->bitmap;

  int width = (face->bitmap->metrics.width / 64);
  int height = (face->bitmap->metrics.height / 64);

  // must be aligned on a 32 bit boundary or 4 bytes
  int depth = 8;
  int stride = ((width * depth + 31) & ~31) >> 3;
  int bytes = (int)(stride * height);

  // as *.bmp
  array<Byte>^ values = gcnew array<Byte>(bytes);  
  Marshal::Copy((IntPtr)glyph->buffer, values, 0, bytes);

  Bitmap^ systemBitmap = gcnew Bitmap(width, height, PixelFormat::Format24bppRgb);

  // create bitmap data, lock pixels to be written.
  BitmapData^ bitmapData = systemBitmap->LockBits(Rectangle(0, 0, width, height), ImageLockMode::WriteOnly, bitmap->PixelFormat);
  Marshal::Copy(values, 0, bitmapData->Scan0, bytes);
  systemBitmap->UnlockBits(bitmapData);

  systemBitmap->Save("Test.bmp");

更新. 。将PixelforMat更改为 8bppIndexed.

  FT_Bitmap *bitmap = &face->glyph->bitmap; 

  // stride must be aligned on a 32 bit boundary or 4 bytes
  int depth = 8;
  int stride = ((width * depth + 31) & ~31) >> 3;
  int bytes = (int)(stride * height);

  target = gcnew Bitmap(width, height, PixelFormat::Format8bppIndexed);

  // create bitmap data, lock pixels to be written.
  BitmapData^ bitmapData = target->LockBits(Rectangle(0, 0, width, height), ImageLockMode::WriteOnly, target->PixelFormat);  

  array<Byte>^ values = gcnew array<Byte>(bytes);  
  Marshal::Copy((IntPtr)bitmap->buffer, values, 0, bytes);
  Marshal::Copy(values, 0, bitmapData->Scan0, bytes);

  target->UnlockBits(bitmapData);

Answer 1

啊哈。解决了。

FT_Bitmap 是8位图像，所以正确 PixelFormat 曾是 8bppIndexed, ，这导致了此输出。不与32 Byte边界保持一致http://www.freeimagehosting.net/uploads/dd90fa2252.jpg

System::Drawing::Bitmap 需要在32位边界上对齐。

我正在计算大步，但在编写位图时没有填充它。复制 FT_Bitmap 缓冲区到a byte[] 然后写给 MemoryStream, ，添加必要的填充。

  int stride = ((width * pixelDepth + 31) & ~31) >> 3;
  int padding = stride - (((width * pixelDepth) + 7) / 8);

  array<Byte>^ pad = gcnew array<Byte>(padding);
  array<Byte>^ buffer = gcnew array<Byte>(size);  
  Marshal::Copy((IntPtr)source->buffer, buffer, 0, size);

  MemoryStream^ ms = gcnew MemoryStream();

  for (int i = 0; i < height; ++i)
  {
    ms->Write(buffer, i * width, width);
    ms->Write(pad, 0, padding);    
  }

固定了记忆，因此GC会不理会。

  // pin memory and create bitmap
  GCHandle handle = GCHandle::Alloc(ms->ToArray(), GCHandleType::Pinned);
  target = gcnew Bitmap(width, height, stride, PixelFormat::Format8bppIndexed, handle.AddrOfPinnedObject());   
  ms->Close();

因为没有 Format8bppIndexed 灰色图像仍然不正确。

Alt Text http://www.freeimagehosting.net/uploads/8a883b7dce.png

然后将位图调色板更改为灰度256。

  // 256-level greyscale palette
  ColorPalette^ palette = target->Palette;
  for (int i = 0; i < palette->Entries->Length; ++i)
    palette->Entries[i] = Color::FromArgb(i,i,i);

  target->Palette = palette;

Alt Text http://www.freeimagehosting.net/uploads/59A745269E.jpg

---

最终解决方案。

  error = FT_Load_Char(face, ch, FT_LOAD_RENDER);
  if (error)
    throw gcnew InvalidOperationException("Failed to load and render character");

  FT_Bitmap *source = &face->glyph->bitmap; 

  int width = (face->glyph->metrics.width / 64);
  int height = (face->glyph->metrics.height / 64);
  int pixelDepth = 8;   
  int size = width * height;

  // stride must be aligned on a 32 bit boundary or 4 bytes
  // padding is the number of bytes to add to make each row a 32bit aligned row
  int stride = ((width * pixelDepth + 31) & ~31) >> 3;
  int padding = stride - (((width * pixelDepth) + 7) / 8);

  array<Byte>^ pad = gcnew array<Byte>(padding);
  array<Byte>^ buffer = gcnew array<Byte>(size);  
  Marshal::Copy((IntPtr)source->buffer, buffer, 0, size);

  MemoryStream^ ms = gcnew MemoryStream();

  for (int i = 0; i < height; ++i)
  {
    ms->Write(buffer, i * width, width);
    ms->Write(pad, 0, padding);    
  }

  // pin memory and create bitmap
  GCHandle handle = GCHandle::Alloc(ms->ToArray(), GCHandleType::Pinned);
  target = gcnew Bitmap(width, height, stride, PixelFormat::Format8bppIndexed, handle.AddrOfPinnedObject());   
  ms->Close();

  // 256-level greyscale palette
  ColorPalette^ palette = target->Palette;
  for (int i = 0; i < palette->Entries->Length; ++i)
    palette->Entries[i] = Color::FromArgb(i,i,i);

  target->Palette = palette;

  FT_Done_FreeType(library);

Answer 2

您的“深度”值与位图的PixelFormat不符。匹配格式24BPPRGB需要24。位图的PF也需要匹配ft_bitmap的PF和大步，我看不到您照顾好这些。