delphi透明背景组件

Question

有关Delphi XE的快速问题。

我正在尝试制作具有透明背景的自定义圆形组件，以便在窗体上添加时，组件可以与其他组件重叠。我试过Brush.Style:=bsTransparent;或ellipse()等......但仍然找不到使边缘区域透明的方法。

是否有反正我可以使组件的边缘区域透明而不使用其他lib或api？

Answer 1

那么这里有一个快速的答案，应该让你去。

type 
    TEllipticPanel = class(Vcl.ExtCtrls.TPanel) 
    procedure CreateWnd; override; 
    procedure Paint; override; 
    procedure Resize; override; 
    procedure RecreateHRGN; 
end; 

    TForm1 = class(TForm) 
    Button1: TButton; 
    procedure Button1Click(Sender: TObject); 
    procedure FormCreate(Sender: TObject); 
    private 
    { Private declarations } 
    panl: TEllipticPanel; 
    public 
    { Public declarations } 
    end; 

implementation 

procedure TForm1.FormCreate(Sender: TObject); 
begin 
    panl := TEllipticPanel.Create(self); 
    panl.Left := 10; 
    panl.Top := 10; 
    panl.Width := 100; 
    panl.Height := 50; 
    panl.ParentBackground := False; 
    panl.ParentColor := False; 
    panl.Color := clYellow; 
    panl.Parent := self; 
end; 

{ TEllipticPanel } 

procedure TEllipticPanel.RecreateHRGN; 
var 
    hr: hRgn; 
begin 
    inherited; 
    hr := CreateEllipticRgn(0,0,Width,Height); 
    SetWindowRgn(Handle, hr, True); 
end; 

procedure TEllipticPanel.CreateWnd; 
begin 
    inherited; 
    RecreateHRGN; 
end; 

procedure TEllipticPanel.Paint; 
begin 
    inherited; 
    Canvas.Brush.Style := bsClear; 
    Canvas.Pen.Style := TPenStyle(psSolid); 
    Canvas.Pen.Width := 1; 
    Canvas.Pen.Color := clGray; 
    Canvas.Ellipse(1,1,Width-2,Height-2); 
end; 

procedure TEllipticPanel.Resize; 
begin 
    inherited; 
    RecreateHRGN; 
end; 

的关键是Windows CreateEllipticRgn和GDI函数的SetWindowRgn。

有关窗口区域的更多信息，请参阅Regions。