Unwritable Image

[newmikeman]

I must have got something wrong but I can't see it.

I use the following bit of code to find out how big the JPEG will be when I'm about to write an image to a memory block. The hRGB points to an RGB image that has just been read elsewhere in the program.

hDest = _IS40_OpenNullDest(0);
ui = _IS40_WriteJPG (hDest, hRGB, iwid, ihgt, 24, iwid*3, 80, NULL, 1<<5);
dw = _IS40_GetLastError ();
ui=_IS40_CloseDest(hDest);

When the image dimensions are similar to thumbnail size, like 160x120 it's fine. When I do two 640x480 images, the first one returns a reasonable size, but all subsequent images return 0, with a last error of 4.

Thanks for any hints please.

[Admin]

i can't reproduce the problem. here's the code i'm using:

 for (int i=0;i < 10;i++)
 {
     UINT32 w = 640, h=480;
     BYTE * buf = new BYTE [640 * 480 * 3];
     HISDEST hDest = IS40_OpenNullDest(0);
     UINT32 sz = IS40_WriteJPG(hDest, buf, w, h, 24, w * 3, 90, NULL, 0);         
     TRACE("%d\n", sz);
     IS40_CloseDest(hDest);
     delete [] buf;
 }

[newmikeman]

Sorry, it looks like the pointer to the RGB got invalidated somewhere. My fault.