.net Drawing.Graphics.FromImage() returns blank black image
- by joox
I'm trying to rescale uploaded jpeg in asp.net
So I go:
Image original = Image.FromStream(myPostedFile.InputStream);
int w=original.Width, h=original.Height;
using(Graphics g = Graphics.FromImage(original))
{
g.ScaleTransform(0.5f, 0.5f); ... // e.g.
using (Bitmap done = new Bitmap(w, h, g))
{
done.Save( Server.MapPath(saveas), ImageFormat.Jpeg );
//saves blank black, though with correct width and height
}
}
this saves a virgin black jpeg whatever file i give it.
Though if i take input image stream immediately into done bitmap, it does recompress and save it fine, like:
Image original = Image.FromStream(myPostedFile.InputStream);
using (Bitmap done = new Bitmap(original))
{
done.Save( Server.MapPath(saveas), ImageFormat.Jpeg );
}
Do i have to make some magic with g?
upd:
i tried:
Image original = Image.FromStream(fstream);
int w=original.Width, h=original.Height;
using(Bitmap b = new Bitmap(original)) //also tried new Bitmap(w,h)
using (Graphics g = Graphics.FromImage(b))
{
g.DrawImage(original, 0, 0, w, h); //also tried g.DrawImage(b, 0, 0, w, h)
using (Bitmap done = new Bitmap(w, h, g))
{
done.Save( Server.MapPath(saveas), ImageFormat.Jpeg );
}
}
same story - pure black of correct dimensions
