Delphi Data Compression Processing (2)
Buffer: pchar;
Count: integer;
Begin
File: // Read the size of the original image from the compressed image stream
CompressedStream.Readbuffer (Count, Sizeof (count);
File: / / According to the size of the image size, allocate memory blocks to be read.
GetMem (buffer, count);
Deststream: = TMEMORYSTREAM.CREATE;
SourceStream: = TDecompressionStream.create (CompressedStream);
Try
File: // Reconnect the compressed image, and then store into the buffer memory block
SourceStream.Readbuffer (buffer ^, count);
File: // Save the original image stream to the DestStream stream
Deststream.writebuffer (buffer ^, count);
DestStream.position: = 0; // Reset stream pointer
// Load the original image stream from the DestStream stream
Bmp.LoadFromstream (Deststream);
Finally
FreeMem (buffer);
Deststream.free;
END;
END;
4. Compressed button onclick event
Procedure TFORM1.BUTTON1CLICK (Sender: TOBJECT);
VAR
BMP: TBITMAP;
CompressedStream: TMemoryStream;
Begin
BMP: = Tbitmap.create;
CompressedStream: = TMEMORYSTREAM.CREATE
Try
File: // Capture the current screen, save the image to GetScreen (BMP) in the BMP object;
File: // Save the image in the BMP object to the memory stream
Bmp.savetostream (CompressedStream);
File: // Compress the original image stream according to the default compression ratio
CompressBitmap (CompressedStream, CLDEFAULT);
File: // Save the image stream after the compression as a file in custom format
CompressedStream.savetofile ('c: /cj.dat');
Finally
Bmp.free;
CompressedStream.Free;
END;
END;
5. Unzip button onclick event
Procedure TFORM1.BUTTON2CLICK (Sender: TOBJECT);
VAR
CompressedStream: TfileStream;
BMP: TBITMAP;
Begin
BMP: = Tbitmap.create;
File: // Open a custom compressed format file with a read-only mode of the file stream
CompressedStream: = TFileStream.create ('c: /cj.dat', fmopenread);
Try
File: // Decompress the compressed image stream
UncompressBitmap (CompressedStream, BMP);
File: / / Restore the original image stream into the specified BMP file
Bmp.savetofile ('c: /cj.bmp');
Finally
Bmp.free;
CompressedStream.Free;
END;
END;
In addition, the TcompressionStream object also provides the CompressionRate property, which is used to describe the compression ratio after compression of the original data, and the onprogress event is triggered during the compression and decompression process, and the developer can write the progress in the event. Code.
