Take screenshot of WPF window with predefined image size without loss of quality
When I take a screenshot of the current WPF window, the image resolution is the image of my monitor (if the app is maxed out), which is fine. However, if I were to print this image in a much larger format, the image would look blurry. I found a way to grab the current window and save it as a png file, but that doesn't do the trick. The image is saved at the set resolution, but the actual wpf window only takes up a small portion of the saved image. The example is taken from:
var screen = System.Windows.Application.Current.Windows.OfType<Window>().SingleOrDefault(x => x.IsActive);
var rtb = new RenderTargetBitmap(4000, 4000, 96, 96, PixelFormats.Pbgra32);
rtb.Render(screen);
var enc = new System.Windows.Media.Imaging.PngBitmapEncoder();
enc.Frames.Add(System.Windows.Media.Imaging.BitmapFrame.Create(rtb));
using (var stm = System.IO.File.Create("ScreenShot.png"))
{
enc.Save(stm);
using (Image img = Image.FromStream(stm))
{
Rectangle dest = new Rectangle(0, 0, 6000, 4000);
using (Graphics imgG = Graphics.FromImage(img))
{
imgG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
imgG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
imgG.DrawImage(img, dest);
}
img.Save("NewScreenShot.png");
}
}
So basically, I would like to record a screenshot at 4000 x 4000 resolution, if possible, without losing quality. The above code creates a 4000 x 4000 image, however the screenshot only takes up a small part of its original resolution.
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To scale the image, you can use DrawingVisual
and ScaleTransform
:
var w = 4000;
var h = 4000;
var screen = System.Windows.Application.Current.Windows.OfType<Window>().SingleOrDefault(x => x.IsActive);
var visual = new DrawingVisual();
using (var context = visual.RenderOpen())
{
context.DrawRectangle(new VisualBrush(screen), null,
new Rect(new Point(),
new Size(screen.Width, screen.Height)));
}
visual.Transform = new ScaleTransform(w / screen.ActualWidth, h / screen.ActualHeight);
var rtb = new RenderTargetBitmap(w, h, 96, 96, PixelFormats.Pbgra32);
rtb.Render(visual);
var enc = new PngBitmapEncoder();
enc.Frames.Add(BitmapFrame.Create(rtb));
using (var stm = File.Create("ScreenShot.png"))
{
enc.Save(stm);
}
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