how to get the picture's resolution, file's size quickly without open the file?
i now use
QPixmap xxx(filePath);
int w = xxx.width();
int h = xxx.height();
...........
.........
as for file size, i use
QImage xxx(filePath);
int size = xxx.byteCount();
..........
..........
you could write a method that opens the file a reads only these information instead of loading all data.
But in this case you have to handle manually the binary data of the different image formats.