CODEWITHSUNDEEP
cgif
maximus
maximus

Reputation: 4302

What is wrong in this code: giflib library usage

I have read the giflib usage explanation and wrote the following code:

GifFileType *gifFile = DGifOpenFileName("D:\\my.gif00.gif");
DGifSlurp(gifFile);
int h = gifFile->SHeight;
int w = gifFile->SWidth;
int count = gifFile->ImageCount;
GifPixelType *myPixels = new GifPixelType[w]; 

int errcode = DGifGetLine(gifFile, myPixels, 1);
if (errcode == GIF_OK) {
} else {
    PrintGifError();
}

As you see there, any file I set into the DGifOpenFileName function as argument results in an error, the PrintGifError() prints out the following message:

GIF-LIB error: #Pixels bigger than Width * Height.

I can't understand what is wrong in my code. what I want is to read the gif file's pixels, Edit them then set back to the gif file. Could you help with this issue?

Upvotes: 0

Views: 1470

Answers (1)

This isn't my real name
This isn't my real name

Reputation: 5039

As far as I can tell, this seems to indicate that you gif file is corrupt.

The problem is that you shouldn't be using DGifGetLine(). The function DGifSlurp() reads the entire GIF file into the gifFile structure. Internally, it calls DGifGetLine() (and a fair few other things), and by the time it returns, the entire file has been processed. Trying to call DGifGetLine() after that doesn't make sense.

This is what dgif_lib.c says about DGifSlurp():

/******************************************************************************
 This routine reads an entire GIF into core, hanging all its state info off
 the GifFileType pointer.  Call DGifOpenFileName() or DGifOpenFileHandle()
 first to initialize I/O.  Its inverse is EGifSpew().
*******************************************************************************/

Upvotes: 5

Related Questions