Author: William Gerbert 

Answer:

This canvas allows you to access the desktop:


1   type
2     TDesktopCanvas = class(TCanvas)
3     private
4       DC: hDC;
5       function GetWidth: Integer;
6       function GetHeight: Integer;
7     public
8       constructor Create;
9       destructor Destroy; override;
10    published
11      property Width: Integer read GetWidth;
12      property Height: Integer read GetHeight;
13    end;
14  
15    { TDesktopCanvas object }
16  
17  function TDesktopCanvas.GetWidth: Integer;
18  begin
19    Result := GetDeviceCaps(Handle, HORZRES);
20  end;
21  
22  function TDesktopCanvas.GetHeight: Integer;
23  begin
24    Result := GetDeviceCaps(Handle, VERTRES);
25  end;
26  
27  constructor TDesktopCanvas.Create;
28  begin
29    inherited Create;
30    DC := GetDC(0);
31    Handle := DC;
32  end;
33  
34  destructor TDesktopCanvas.Destroy;
35  begin
36    Handle := 0;
37    ReleaseDC(0, DC);
38    inherited Destroy;
39  end;