Drawing a rectangle to the screen-CodePudding

Is there a way to make the resulting rectangle from the FillRect() function stay on the screen? I am calling this function but it only remains up on the screen for a fraction of a second before disappearing. The only way to keep it on the screen is to run this in a while (true) loop which seems very inefficient.

void DrawRect(int x, int y, int w, int h, HBRUSH brushColor)
{
   RECT rect = { x, y, x   w, y   h };
   FillRect(HDC_Desktop, &rect, brushColor);
}

I have to ask what makes the resulting box from this function disappear? I notice it still sometimes flashes even when ran inside a while (true) loop. Does it disappear when your monitor refreshes or is disappearing not inherent to this function? My goal is to make a rectangle that stays on the screen for a set amount of time. Whether that be me setting a time period for it to last or having to manually delete it but either way running a while (true) loop to continuously print a rectangle to my screen is terribly inefficient.

CodePudding user response：

You should not paint directly on the screen DC! This has not worked properly since Vista (DWM) and even before that it was not a great thing to do.

You should create a window with the WS_POPUP style and draw there when you get the WM_PAINT message (don't forget to call BeginPaint/EndPaint)...