启用 Vcl 样式时调整 bsNone 窗体的大小

Question

我正在尝试调整非无边框表单（bsNone 边框样式）的大小。它可以用下面的代码完成，但它只在应用程序没有启用 VCL 样式时起作用。

protected
   procedure WMNCHitTest(var message: TWMNCHitTest); message WM_NCHITTEST;
....

procedure TForm1.WMNCHitTest(var message: TWMNCHitTest);
const
  EDGEDETECT = 7;
var
  deltaRect: TRect;
begin
  inherited;
  if BorderStyle = bsNone then
    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;

我也试过这样做，结果也是一样的。那么当启用 VCL 样式时，我怎样才能使它可调整大小呢？

非常感谢。

procedure CreateParams(var params: TCreateParams); override;
    ...
    procedure TForm1.CreateParams(var params: TCreateParams);
          begin
            BorderStyle := bsNone;
            inherited;
            params.ExStyle := params.ExStyle or WS_EX_STATICEDGE;
            params.Style   := params.Style or WS_SIZEBOX;
          end;

Answer 1

VCL 样式破坏您的 WM_NCHITTEST 消息处理程序的原因是表单的样式钩子直接处理 WM_NCHITTEST。您可以覆盖它并像这样重新获得控制权：

protected
  function DoHandleStyleMessage(var Message: TMessage): Boolean; override;

....

function TForm1.DoHandleStyleMessage(var Message: TMessage): Boolean;
begin
  if Message.Msg=WM_NCHITTEST then begin
    Result := False;
  end else begin
    Result := inherited;
  end;
end;

现在将再次调用 WM_NCHITTEST 的事件处理程序。当然，您将失去 WM_NCHITTEST 的 VCL 样式处理程序提供的任何功能，但我怀疑这正是您想要的。

启用 Vcl 样式时调整 bsNone 窗体的大小

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