Saving Images

Images can be saved to the files on disk, to the streams or to a memory referenced by a pointer. The following table lists functions which can be used for saving images. These are low level functions operating on TImageData structure.

Function nameUsage
SaveImageToFile Save single image to file
SaveImageToStream Save single image to stream (TStream descendants, Object Pascal only)
SaveImageToMemory Save single image to memory
SaveMultiImageToFile Save multiple images to file
SaveMultiImageToStream Save multiple images to stream (TStream descendants, Object Pascal only)
SaveMultiImageToMemory Save multiple images to memory

You can learn how to use these functions from the following code fragments.

This example creates empty image and draws diagonal line from left-top to right-bottom corner. Finally, image is saved to the file.

  SysUtils, Classes, ImagingTypes, Imaging;
  Img: TImageData;
  I: LongInt;
  // call this before using any TImageData record
  // create 8 bit grayscale image
  NewImage(1024, 1024, ifGray8, Img);
  // draw diagonal line by direct writing to image's memory
  for I := 0 to Img.Width - 1 do
    PByteArray(@PByteArray(Img.Bits)[I * Img.Width])[I] := 128;
  // save image to file
  SaveImageToFile('/home/galfar/images/line.tga', Img);
  // memory occupied by image is freed

In this example DDS image is loaded from stream. All contained subimages are then compressed to DXT5 format and written to output stream.

procedure LoadAndSaveSomethingInDXT5(InStream, OutStream: TStream);
  Images: TDynImageDataArray;
  I: LongInt;
  // load DDS multiimage from stream to Images array
  LoadMultiImageFromStream(InStream, Images);
  // convert all loaded images to DXT5 format
  for I := 0 to Length(Images) - 1 do
    ConvertImage(Images[I], ifDXT5);
  // save converted images to output stream in DDS format
  SaveMultiImageToStream('dds', OutStream, Images);
  // all images are freed