Cximage memory conversion Image

Recently, it is required to convert BMP to JPEG format. Previously, we used the GDI + method. This method has a major defect in that it cannot implement cross-platform processing. If you have less time to talk about it, go to the topic.

Cximage cximagebmp (prgbbuffer, dwrgbsize, cximage_format_bmp );

Cximagebmp. Save ("D: \ ttt.jpg", cximage_format_jpg );

This method is normal. The 24-bit BMP image in RGB format is successfully converted to a local JPG file and saved.

 

However, the following memory conversion method fails.

Byte * pjpgdatatemp = new byte [1024*1024];

Int ljpgsize = 0;

Bool B = cximagebmp. encode (pjpgdatatemp, ljpgsize, cximage_format_jpg );

On the one hand, the return value of the function is false; on the other hand, the Data Length, ljpgsize is 0.

 

Later, the modification was successful.

Byte * pjpgdatatemp = NULL;

Int ljpgsize = 0;

Bool B = cximagebmp. encode (pjpgdatatemp, ljpgsize, cximage_format_jpg );

 

Why? We can view the following information from the cximage: encode () Definition:

Bool cximage: encode (byte * & buffer, long & size, DWORD imagetype)
{
If (buffer! = NULL)

{
Strcpy (info. szlasterror, "the buffer must be empty ");
Return false;
}

Cxmemfile file;
File. open ();
If (encode (& file, imagetype ))

{
Buffer = file. getbuffer ();
Size = file. Size ();
Return true;
}

Return false;
}

The truth is clear!