Are you talking about a Windows GDI rectangle or drawing a rectangle on the screen with a pen?
Thank you but I want to explain . This function is used to transfer part of the image on another canvas to the image of the TCanvas object. Dest specifies the rectangle on the canvas where the source image will be copied. The Canvas parameter specifies the canvas with the source image. Source specifies a rectangle bounding the portion of the source canvas that will be copied.so I want to do the same thing in c#