Как поменять обои в Windows 98/Windows 2000, когда включен Active Desktop?

Олег Кулабухов приводит следующий код:

Да, в данном случае стандартное изменение через SystemParametersInfo не пройдет. Придется использовать IActiveDesktop. Но учтите, что для его применения библиотека Shell32.dll должна иметь версию старше 4.71. В этом FAQ есть пример того, как узнавать версию файла, можете им воспользоваться.

uses
ComObj, // For CreateComObject and Initialization/Finalization of COM
ShlObj; // For IActiveDesktop

{ The CLASS ID for ActiveDesktop is not defined in
ShlObj, while the IID is so we define it here. }
const
CLSID_ActiveDesktop: TGUID = '{75048700-EF1F-11D0-9888-006097DEACF9}';

{ Demonstrate getting the Wallpaper }
procedure TForm1.Button1Click(Sender: TObject);
var
ActiveDesktop: IActiveDesktop;
CurrentWallpaper: string;
CurrentPattern: string;
WallpaperOptions: TWallpaperOpt;
tmpBuffer: PWideChar;
begin
// Create the ActiveDesktop COM Object
ActiveDesktop := CreateComObject(CLSID_ActiveDesktop) as IActiveDesktop;

// We now need to allocate some memory to get the current Wallpaper.
// However, tmpBuffer is a PWideChar which means 2 bytes make>
// up one Char. In order to compenstate for the WideChar, we
// allocate enough memory for MAX_PATH*2
tmpBuffer := AllocMem(MAX_PATH*2);
try
ActiveDesktop.GetWallpaper(tmpBuffer, MAX_PATH*2, 0);
CurrentWallpaper := tmpBuffer;
finally
FreeMem(tmpBuffer);
end;
if CurrentWallpaper <> '' then
Label1.Caption := 'Current Wallpaper: ' + CurrentWallpaper
else
Label1.Caption := 'No Wallpaper set';

// Now get the current Wallpaper options.
// The second parameter is reserved and must be 0.
WallpaperOptions.dwSize := SizeOf(WallpaperOptions);
ActiveDesktop.GetWallpaperOptions(WallpaperOptions, 0);
case WallpaperOptions.dwStyle of
WPSTYLE_CENTER: Label2.Caption := 'Centered';
WPSTYLE_TILE: Label2.Caption := 'Tiled';
WPSTYLE_STRETCH: Label2.Caption := 'Stretched';
WPSTYLE_MAX: Label2.Caption := 'Maxed';
end;

// Now get the desktop pattern.
// The pattern is a string of decimals whose bit pattern
// represents a picture. Each decimal represents the on/off state
// of the 8 pixels in that row.
tmpBuffer := AllocMem(256);
try
ActiveDesktop.GetPattern(tmpBuffer, 256, 0);
CurrentPattern := tmpBuffer;
finally
FreeMem(tmpBuffer);
end;
if CurrentPattern <> '' then
Label3.Caption := CurrentPattern
else
Label3.Caption := 'No Pattern set';
end;

{ Demonstrate setting the wallpaper }

procedure TForm1.Button2Click(Sender: TObject);
var
ActiveDesktop: IActiveDesktop;
begin
ActiveDesktop := CreateComObject(CLSID_ActiveDesktop)
as IActiveDesktop;
ActiveDesktop.SetWallpaper('c:\downloads\images\test.bmp', 0);
ActiveDesktop.ApplyChanges(AD_APPLY_ALL or AD_APPLY_FORCE);
end;

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Содержание раздела