Thread: MFC, CreateCompatibleDC question.

Code:

 	
                
                CDC twdc;
                twdc.CreateCompatibleDC(this->GetDC());

	//=== gen pattern ===//
	for(	 int x=0 ; x<99 ; x++ ){
		for( int y=0 ; y<99 ; y++ ){
			twdc.SetPixelV( x,y, x*x+y*y );
		}
	}
	TRACE( "%d", twdc.GetPixel(4,4) );  //  any number for the (4,4).

i do this in MFC, why it always TRACE out -1 ?? and alsoo , there is nothing printed when use BitBlt to print it out.

i think i have problem with the CreateCompatibleDC().

help me please.