从远边不同的约束中调整无边框形状的大小？

Question

我有一个自定义表单,没有任何类型的边框.我正在绘制一些自己的自定义边框,它不会延伸到窗体的远边缘.相反,通过使用表单的透明属性,此自定义绘制边框外的任何内容都是透明的.这使得形式的较小部分可用且可见.

我知道有很多解决方案可以实现这一目标,我已经找到了最合适的方法来实现这一目标.但是,此方法假定用户将鼠标指向窗体的远边缘.我需要限制它在不同的约束内作出反应(例如较小的矩形).

这是我发现的代码,它已经适用于下一个边缘约束:

procedure WMNCHitTest(var Message: TWMNCHitTest); message WM_NCHITTEST;

....

procedure TForm1.WMNCHitTest(var Message: TWMNCHitTest);
const
  EDGEDETECT = 7;  //adjust to suit yourself
var
  deltaRect: TRect;  //not really used as a rect, just a convenient structure
begin
  inherited;
  if BorderStyle = bsNone then begin
    with Message, deltaRect do begin
      Left := XPos - BoundsRect.Left;
      Right := BoundsRect.Right - XPos;
      Top := YPos - BoundsRect.Top;
      Bottom := BoundsRect.Bottom - YPos;
      if (Top<EDGEDETECT)and(Left<EDGEDETECT) then
        Result := HTTOPLEFT
      else if (Top<EDGEDETECT)and(Right<EDGEDETECT) then
        Result := HTTOPRIGHT
      else if (Bottom<EDGEDETECT)and(Left<EDGEDETECT) then
        Result := HTBOTTOMLEFT
      else if (Bottom<EDGEDETECT)and(Right<EDGEDETECT) then
        Result := HTBOTTOMRIGHT
      else if (Top<EDGEDETECT) then
        Result := HTTOP
      else if (Left<EDGEDETECT) then
        Result := HTLEFT
      else if (Bottom<EDGEDETECT) then
        Result := HTBOTTOM
      else if (Right<EDGEDETECT) then
        Result := HTRIGHT
    end; 
  end;
end;

我将如何改变这种反应的界限呢？例如,左边和右边应该在表单中反应10个像素.标准形式rect可能是,(0, 0, 100, 100)但我希望上面的这个方法在范围内工作(10, 3, 90, 97)

Answer 1

实际上,定义两个常量而不是唯一的常量是有意义的,EDGEDETECT因为你需要水平和垂直偏移是不同的并从头开始写,但这是一个快速补丁:

procedure TForm1.WMNCHitTest(var Message: TWMNCHitTest);
const
  EDGEDETECT = 17;  //adjust to suit yourself    // <- increased to suit outer offset
var
  deltaRect: TRect;  //not really used as a rect, just a convenient structure

  OuterRect: TRect;                              // used as a rect
begin
  inherited;
  if BorderStyle = bsNone then begin
    with Message, deltaRect do begin

     ..
      else if (Right<EDGEDETECT) then
        Result := HTRIGHT;
     ..

      OuterRect := BoundsRect;                    // patch
      InflateRect(OuterRect, -10, -3);
      if not PtInRect(OuterRect, SmallPointToPoint(Message.Pos)) then
        Message.Result := HTTRANSPARENT;

    end;
  end;
end;