如何在 CreatePolygonRgn 之后释放 HRGN？

Question

我在下面完整地写了一个非常简单的方法，它在 TForm 上的所有组件周围创建了一个多边形。由于没有 HRGN.Free 方法，Delphi XE6 的编译器指出，我只是问我是否应该 Free，好吧，任何东西 里面有，我以前从没用过HRGN 类型，想确定一下。谢谢。

PS: 我只是代表正确释放内存而问，如果这里需要的话，没有别的。

procedure TFormZoom.SetVisibleFormRegion;

var
    VisibleRegionPoints: array[0..11] of TPoint;
    VisibleFormRegion: HRGN;

begin
    try
        // XY points around all components that we want to be visible on the FormZoom
        VisibleRegionPoints[0] := Point(0, 0);
        VisibleRegionPoints[1] := Point(ZoomBoxPanel.Left + ZoomBoxPanel.Width, 0);
        VisibleRegionPoints[2] := Point(ZoomBoxPanel.Left + ZoomBoxPanel.Width, ZoomBoxPanel.Height);
        VisibleRegionPoints[3] := Point(ZoomBoxPanel.Left, ZoomBoxPanel.Height);
        VisibleRegionPoints[4] := Point(ZoomBoxPanel.Left, 0);
        VisibleRegionPoints[5] := Point(ColorBoxPanel.Width, 0);
        VisibleRegionPoints[6] := Point(ColorBoxPanel.Width, InfoValuesPanel.Top + InfoValuesPanel.Height);
        VisibleRegionPoints[7] := Point(0, InfoValuesPanel.Top + InfoValuesPanel.Height);
        VisibleRegionPoints[8] := Point(0, InfoValuesPanel.Top);
        VisibleRegionPoints[9] := Point(InfoValuesPanel.Width, InfoValuesPanel.Top);
        VisibleRegionPoints[10] := Point(ColorBoxPanel.Width, ColorBoxPanel.Height);
        VisibleRegionPoints[11] := Point(0, ColorBoxPanel.Height);
        try
            // we create a polygon region from the above points
            VisibleFormRegion := CreatePolygonRgn(VisibleRegionPoints, Length(VisibleRegionPoints), ALTERNATE);
            // finally, we set the FormZoom window region to the created polygon
            SetWindowRgn(Self.Handle, VisibleFormRegion, True);
        finally
            VisibleFormRegion.Free;  // <-- There is no method called Free!
        end;
    except
        on E: Exception do
        begin
            // in case of error, we log the exception only
            FormMain.ErrorLog.Add('TFormZoom.SetVisibleFormRegion: ' + E.ClassName + ' - ' + E.Message);
        end;
    end;
end;

Answer 1

如 CreatePolygonRgn(), the returned handle must be freed with DeleteObject() 的文档中所述：

When you no longer need the HRGN object, call the DeleteObject function to delete it.

更新

As Remy pointed out: in your case, you're calling SetWindowRgn()，将区域的所有权转移给系统。这意味着你不需要释放它。

如何在 CreatePolygonRgn 之后释放 HRGN？

How to free HRGN after CreatePolygonRgn?

delphi

winapi

memory-management