Question

I’m working on a simple application that draws an alpha-blended picture on the screen’s Device Context every 2 secs, I want to refresh the screen contents before the drawing operation (To erase the drawn pic),

I have used many many trick but unfortunately, the screen won’t refresh correctly, some regions still keep portions of the drawn pic

I’m really frustrated from this issue 🙁

These are the sources codes I have used, I’m using C#

SendMessage(HWND_BROADCAST, WM_SYSCOLORCHANGE, IntPtr.Zero, IntPtr.Zero); // wasted time in the refreshing process is enough to keep this.

UpdateWindow(HWND_BROADCAST);// does not work at all!

InvalidateRect(IntPtr.Zero,IntPtr.Zero,true); // the same goes here.

SendMessage(HWND_BROADCAST, WM_PAINT, IntPtr.Zero, IntPtr.Zero); // pfffff !

SendMessage(HWND_BROADCAST, WM_SETTINGCHANGE, new IntPtr(SPI_SETNONCLIENTMETRICS), IntPtr.Zero); // trying to refresh the explorer, no resutl

I used also EnumWindows and call back , very slow and does not fit my case.

I wanna refresh the whole screen

Help please!

Regards

Waleed

Answer 1

Could you instead copy the screen image before you draw anything, allowing you to take advantage of off-screen composition; and you wouldn’t need to ask everything else to redraw first.