unsigned char * buffer到System :: Drawing :: Bitmap [英] unsigned char* buffer to System::Drawing::Bitmap

问题描述

我正在尝试创建一个工具/资源转换器，使用 FreeType2 引擎。

I'm trying to create a tool/asset converter that rasterises a font to a texture page for an XNA game using the FreeType2 engine.

下面，第一个图片是FreeType2的直接输出] 1 引擎。第二个图像是尝试将其转换为 System :: Drawing :: Bitmap 后的结果。

Below, the first image is the direct output from the FreeType2]1 engine. The second image is the result after attempting to convert it to a System::Drawing::Bitmap.

img src =http://www.freeimagehosting.net/uploads/fb102ee6da.jpgalt =target>

这里的任何提示/提示/想法将非常感谢。链接到解释字节布局和像素格式的文章也很有帮助。

Any hints/tips/ideas on what is going on here would be greatly appreciated. Links to articles explaining byte layout and pixel formats would also be helpful.

  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 。

Update. Changed PixelFormat to 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);

推荐答案

啊哈。工作了。

FT_Bitmap 是一个8位图片，因此正确的 PixelFormat 8bppIndexed ，这导致了此输出。

FT_Bitmap is an 8bit image, so the correct PixelFormat was 8bppIndexed, which resulted this output.

System :: Drawing :: Bitmap 需要在32位边界上对齐。

System::Drawing::Bitmap needs to be aligned on a 32 bit boundary.

但是没有填充它，当写位图。将 FT_Bitmap 缓冲区复制到 byte [] ，然后将其写入 MemoryStream ，添加必要的填充。

I was calculating the stride but was not padding it when writing the bitmap. Copied the FT_Bitmap buffer to a byte[] and then wrote that to a MemoryStream, adding the necessary padding.

  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);    
  }

固定内存，让GC独自留下。

Pinned the memory so the GC would leave it alone.

  // 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();

由于没有 Format8bppIndexed 仍然不正确。

As there is no Format8bppIndexed Grey the image was still not correct.

然后将位图调色板更改为灰度256。

Then changed the bitmap palette to grey scale 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;

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);

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