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While developing my XNA game I came to another horrible XNA limitation: Texture2D-s (at least on my PC) can't have dimensions higher than 2048*2048. No problem, I quickly wrote my custom texture class, which uses a [System.Drawing.] Bitmap by default and splits the texture into smaller Texture2D-s eventually and displays them as appropriate.
When I made this change I also had to update the method loading the textures. When loading the Texture2D-s in the old version I used Texture2D.FromStream() which worked pretty good but XNA can't even seem to store/load textures higher than the limit so if I tried to load/store a say 4092*2048 png file I ended up having a 2048*2048 Texture2D in my app. Therefore I switched to load the images using [System.Drawing.] Image.FromFile, then cast it to a Bitmap as it doesn't seem to have any limitation. (Later converting this Bitmap to a Texture2D list.)
The problem is that loading the textures this way is noticeably slower because now even those images that are under the 2048*2048 limit will be loaded as a Bitmap then converted to a Texture2D. So I am actually looking for a way to analyze an image file and check its dimensions (width;height) before even loading it into my application. Because if it is under the texture limit I can load it straight into a Texture2D without the need of loading it into a Bitmap then converting it into a single element Texture2D list.
Is there any (clean and possibly very quick) way to get the dimensions of an image file without loading the whole file into the application? And if it is, is it even worth using? As I guess that the slowest instruction is the file opening/seeking here (probably hardware-based, when it comes to hdd-s) and not streaming the contents into the application.
