I went through the same journey as a few other posters on this thread. Things I noted: Using Image.FromFile does seem unpredictable on when it releases the file handle. Calling the Image.Dispose() did not release the file handle in all cases. Using a FileStream and the Image.FromStream method works, and releases the handle on the … Read more
You don’t need to serialize the panel, a panel is not serializable. You can consider either of these options: You can draw on a bitmap and then save the bitmap, or draw your control to an image and save the image. This way you will flatten all shapes to a single image and after loading … Read more
These methods work correctly, you just have to take into account effects of anti-aliasing and rounding. First, turn on anti-aliasing to see everything (not only rounded result): graphics.SmoothingMode = SmoothingMode.AntiAlias; Now FillRectangle(10,10,10,10) will produce blurry result and DrawRectangle(10,10,10,10) will be sharp. The blurry result means that you have pixel coordinates off-grid. If you need to … Read more
You need to store lines in a List<List<Point>>. Each element of the list contains points of a drawing which you draw using a down, move and up. The next line which you draw, will store in the next element of list. Each undo, will remove the last drawing. Put an instance of this control on … Read more
Image is an abstract class: what you want to do depends on whether you are dealing with a Metafile or a Bitmap. Creating an image with GDI+ and saving it as an EMF is simple with Metafile. Per Mike’s post: var path = @”c:\foo.emf” var g = CreateGraphics(); // get a graphics object from your … Read more
Seems like we can do it using FreeImage (which is free) FIBITMAP dib = FreeImage.LoadEx(“test.jp2”); //save the image out to disk FreeImage.Save(FREE_IMAGE_FORMAT.FIF_JPEG, dib, “test.jpg”, FREE_IMAGE_SAVE_FLAGS.JPEG_QUALITYNORMAL); //or even turn it into a normal Bitmap for later use Bitmap bitmap = FreeImage.GetBitmap(dib);
I would use a function similar to this: public void RotateRectangle(Graphics g, Rectangle r, float angle) { using (Matrix m = new Matrix()) { m.RotateAt(angle, new PointF(r.Left + (r.Width / 2), r.Top + (r.Height / 2))); g.Transform = m; g.DrawRectangle(Pens.Black, r); g.ResetTransform(); } } It uses a matrix to perform the rotation at a certain … Read more
You can lock the bitmap data and use pointers to manually set the values. It’s much faster. Though you’ll have to use unsafe code. public override void PaintPoint(Layer layer, Point position) { // Rasterise the pencil tool // Assume it is square // Check the pixel to be set is witin the bounds of the … Read more
PNGs (and other formats) need to be saved to a seekable stream. Using an intermediate MemoryStream will do the trick: using (Bitmap image = new Bitmap(context.Server.MapPath(“images/stars_5.png”))) { using(MemoryStream ms = new MemoryStream()) { image.Save(ms, System.Drawing.Imaging.ImageFormat.Png); ms.WriteTo(context.Response.OutputStream); } }
Yes, it is too slow. I ran into this problem several years ago while developing Paint.NET (right from the start, actually, and it was rather frustrating!). Rendering performance was abysmal, as it was always proportional to the size of the bitmap and not the size of the area that it was told to redraw. That … Read more