I am writing a program similar to TeamViewer. But I have a problem that the screen resolution is too much. How can I reduce the quality of the incoming picture?
byte[] ScreenShut()
{
Bitmap bmp = new Bitmap(Screen.PrimaryScreen.Bounds.Width,Screen.PrimaryScreen.Bounds.Height);
Graphics gr = Graphics.FromImage(bmp);
bmp.SetResolution(96.0F,96.0F);
gr.CopyFromScreen(0, 0, 0, 0, new Size(bmp.Width, bmp.Height));
MemoryStream ms = new MemoryStream();
bmp.Save(ms, ImageFormat.Png);
return ms.GetBuffer();
}
Creating a bitmap from graphics.CopyFromScreen() then create another bitmap for scaling waste too much cpu.
[DllImport("user32")] static extern int GetDC(int hWnd);
[DllImport("user32")] static extern int ReleaseDC(int hwnd, int hDC)
[DllImport("gdi32")] static extern int StretchBlt(int hdc, int x, int y, int nWidth, int nHeight, int hSrcDC, int xSrc, int ySrc, int nSrcWidth, int nSrcHeight, int dwRop);
int W = Screen.PrimaryScreen.Bounds.Width;
int H = Screen.PrimaryScreen.Bounds.Height;
int dW = W * 2 / 3; // 66%
int dH = H * 2 / 3; // 66%
Bitmap img = new Bitmap(dW, dH);
Graphics g = Graphics.FromImage(img);
var dc = g.GetHdc();
var screen = GetDC(0);
StretchBlt(dc.ToInt32(), 0, 0, dW, dH, screen, 0, 0, W, H, 0xCC0020);
g.ReleaseHdc(dc) ;
ReleaseDC(0, screen)
img.Save(@"C:\123.png", ImageFormat.Jpeg);
After scaling an image, text will become too hard to read. Scaling should be around 75%, then use JPG compression format to reduce size see here .
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