Delphi:将 TImage 置于前面

Question

看下面的图片:

如您所见，我无法将按钮发送到后面。这仅适用于标签。

那么我怎样才能将TImage发送到前面并具有透明度。

顺便说一句，我读过 This related question但没有帮助我。因为运行 Andreas Rejbrand 的代码后您甚至无法单击按钮。不仅仅是按钮，所有东西(比如图中的滚动条)

编辑:我不想在将其发送回图像后使该按钮可访问。只是想将 TImage 带到所有内容的前面。

谢谢。

Answer 1

接近目标的一种方法是使用 TWincontrol 的插入器类，并在绘制完它们之后，使用 TControlCanvas 和“ Hook ”WM_PAINT 来绘制在其上移动的图像。
该代码使用半透明 PNG 图像显示原始草稿，并且可能会得到增强。

unit Unit2;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Buttons, dxGDIPlusClasses, ExtCtrls;

type
  TButton=Class (StdCtrls.TButton)
      Procedure WMPaint(var MSG:TMessage);Message WM_Paint;
  End;
  TEdit=Class (StdCtrls.TEdit)
      Procedure WMPaint(var MSG:TMessage);Message WM_Paint;
  End;

  TForm2 = class(TForm)
    Image1: TImage;
    SpeedButton1: TSpeedButton;
    Button1: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
  private
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

{ TButton }

procedure TButton.WMPaint(var MSG: TMessage);
var
  cc:TControlCanvas;
begin
   inherited;
    CC:=TControlCanvas.Create;
    CC.Control := TControl(Self);
    CC.Draw(-Left,-Top,Form2.Image1.Picture.Graphic);
    CC.Free;
end;

procedure TEdit.WMPaint(var MSG: TMessage);
var
  cc:TControlCanvas;
begin
   inherited;
    CC:=TControlCanvas.Create;
    CC.Control := TControl(Self);
    CC.Draw(-Left,-Top,Form2.Image1.Picture.Graphic);
    CC.Free;

end;

end.

另一个(更好的)“ Hook ”位置将覆盖PaintWindow

unit Unit2;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Buttons, dxGDIPlusClasses, ExtCtrls;

type
  TButton=Class (StdCtrls.TButton)
      procedure PaintWindow(DC: HDC);override;
  End;
  TEdit=Class (StdCtrls.TEdit)
      procedure PaintWindow(DC: HDC);override;
  End;

  TForm2 = class(TForm)
    Image1: TImage;
    SpeedButton1: TSpeedButton;
    Button1: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
  private
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

{ TButton }

procedure TButton.PaintWindow(DC: HDC);
var
  cc:TCanvas;
begin
   inherited;
    CC:=TCanvas.Create;
    CC.Handle := DC;
    CC.Draw(-Left,-Top,Form2.Image1.Picture.Graphic);
    CC.Free;
end;

procedure TEdit.PaintWindow(DC: HDC);
var
  cc:TCanvas;
begin
   inherited;
    CC:=TCanvas.Create;
    CC.Handle := DC;
    CC.Draw(-Left,-Top,Form2.Image1.Picture.Graphic);
    CC.Free;

end;

end.