Desktop en lecteur seule

Bonjour
Voici une liste de code susceptible de lire et modifier le desktop

procedure TForm1.Button1Click(Sender: TObject);
var h,h2,hc : hdc;
offscrbmp,hb,hbitmapold : hbitmap;
lpbi : BITMAPINFO;
v : integer;
xf,yf,BitmapInfoSize : word;
p4 : pointer;
begin
h := getDC(getdesktopwindow());
hc := CreateCompatibleDC(h);
hB := CreateCompatibleBitmap(h, 100, 100);
hBitmapOld := SelectObject(hc, hb);
BitBlt(hc, 0, 0, 100, 100, h, 0, 0, SRCCOPY);

FillChar(lpbi, BitmapInfoSize, #0);

{Fill in the BitmapInfo structure}
lpbi.bmiHeader.biSize := sizeof(TBitmapInfoHeader);
lpbi.bmiHeader.biWidth := 100;
lpbi.bmiHeader.biHeight := 100;
lpbi.bmiHeader.biPlanes := 1;
lpbi.bmiHeader.biBitCount := 24;
lpbi.bmiHeader.biCompression := BI_RGB;
lpbi.bmiHeader.biSizeImage :=
((lpbi.bmiHeader.biWidth *
longint(lpbi.bmiHeader.biBitCount)) div 8) *
lpbi.bmiHeader.biHeight;
lpbi.bmiHeader.biXPelsPerMeter := 0;
lpbi.bmiHeader.biYPelsPerMeter := 0;

lpbi.bmiHeader.biClrUsed := 0;
lpbi.bmiHeader.biClrImportant := 0;

fillchar(img,sizeof(img),255);
setpixel(hc,0,0,clwhite);
v := GetDiBits( hc, // handle of device context
hb, // handle of bitmap
0, // first scan line to set in destination bitmap
100, // number of scan lines to copy
@img, // address of array for bitmap bits
lpbi, // address of structure with bitmap data
DIB_RGB_COLORS // RGB or palette index
);
move(img,img2,sizeof(img));
for xf := 0 to 99 do
for yf := 0 to 99 do begin
dec(img2[xf,yf].r,100);
dec(img2[xf,yf].g,100);
dec(img2[xf,yf].b,100);
end;
//setdiBits(h,hb,0,100,@img2,lpbi,DIB_RGB_COLORS);
selectobject(hc,hbitmapold);
deleteobject(offscrbmp);
DeleteDC(hc);
v := StretchDIBits(

h, // handle of device context
0, // x-coordinate of upper-left corner of dest. rect.
0, // y-coordinate of upper-left corner of dest. rect.
100, // width of destination rectangle
100, // height of destination rectangle
0, // x-coordinate of upper-left corner of source rect.
0, // y-coordinate of upper-left corner of source rect.
100, // width of source rectangle
100, // height of source rectangle
@img2, // address of bitmap bits
lpbi, // address of bitmap data
DIB_RGB_COLORS , // usage
SRCCOPY // raster operation code
);


releaseDC(0,h);

end;

Ca lit mais ça n'écrit pas dessus ;
Avez vous des tuyaux ???????
Merci beaucoup.