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mfcvisual-c++-2012

MFC does not draw rectangular edges with LineTo

I have a Problem when drawing with the MFC CDC class and the LineTo and MoveTo function. The CDC Object doesn't begin at the point where I move the Pointer and leaves the first Pixel blanc like in the center of the image. When I draw around a corner like on the left side of the image it is clear that the CDC object leaves the outmost pixel free. I did try to load a custom brush but had no different results.

Edge example

    memDC.FillSolidRect(client, BACKGROUND_COLOR);
    CPen penBorder(PS_ENDCAP_SQUARE | PS_SOLID, BORDER_WIDTH, BORDER_COLOR);
    //Draw the Horizontal line for the Status Bar
    CPen* oldPen = memDC.SelectObject(&penBorder);
    memDC.MoveTo(client.left + 0.5f * BORDER_WIDTH, client.top + 0.5f * BORDER_WIDTH);
    memDC.LineTo(client.Width() - 0.5f * BORDER_WIDTH, client.top + 0.5f * BORDER_WIDTH);
    CPen penRecess(PS_ENDCAP_SQUARE | PS_SOLID, BORDER_WIDTH, RECESS_COLOR);
    //Draw the recess
    memDC.SelectObject(&penRecess);
    memDC.MoveTo(client.left + 1.5f * BORDER_WIDTH, client.top + 1.5f * BORDER_WIDTH);
    memDC.LineTo(client.Width() - 0.5f * BORDER_WIDTH, client.top + 1.5f * BORDER_WIDTH);
Solution

  • The problem has nothing to do with MFC but is inherent in the underlying Windows GDI function. The documentation for LineTo says:

    The LineTo function draws a line from the current position up to, but not including, the specified point.

    If you need the last point drawn, you should do a second LineTo one pixel away from the first.