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Vista DWM thumbnail with Delphi 7 - how?

Hello!

Some days ago i did find an article "Programming the Windows Vista DWM in C#" You can read it under this link: http://bartdesmet.net/blogs/bart/archive/2006/10/05/4495.aspx

I decided that i'd like to realize this method with Delphi Win32 (Delphi 7). Delphi 7 is installed under my Vista Ultimate.

I linked a dwm.pas into my project (you can download it from this site:
http://www.box.net/index.php?rm=box_v2_download_shared_file&file_id=f_83304197
the zip file is containing the dwm unit...)

but i don't how can i apply it in my program...? I tried to "copy" the original source but...
Is there any way to show a live thumbnail in my form? What is the destination handle? An image canvas or bitmap handle? I don't know....

Any help will be appreciated! Thanks in advance!

My attampt is the following:

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, dwm, StdCtrls, ExtCtrls;
 
type
  TForm1 = class(TForm)
    Button1: TButton;
    Image1: TImage;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    thumb: ^integer;
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
function UpdateThumb():boolean;
var
 size: PSize;
 props: PDWM_THUMBNAIL_PROPERTIES;
begin
    result:=true;
    if form1.thumb <> nil then
    begin
      DwmQueryThumbnailSourceSize(form1.thumb^, size);
      props.dwFlags:=DWM_TNP_VISIBLE and DWM_TNP_RECTDESTINATION and DWM_TNP_OPACITY;
      props.fVisible:=true;
      props.opacity:=50;
      props.fSourceClientAreaOnly:=false;
      props.rcDestination:=Rect(form1.Image1.left,form1.image1.Top,form1.Image1.Left+form1.Image1.Width,form1.Image1.Top+form1.Image1.Height);
 
      if (size.cx<form1.Image1.Width) then props.rcDestination.Right:=props.rcDestination.Left+size.cx;
      if (size.cy<form1.Image1.Height) then props.rcDestination.Top:=props.rcDestination.Left+size.cy;
 
      DwmUpdateThumbnailProperties(form1.thumb^,Pointer(props));
    end;
 
end;
 
procedure TForm1.Button1Click(Sender: TObject);
var
 h: Hwnd;
 r: TRect;
 wwidth, wheight: integer;
 i: integer;
begin
 h:=FindWindow(nil,'Untitled - Notepad');
 
   if h<>0 then
   begin
   GetWindowRect(h,r);
   wwidth:=r.Right-r.Left;
   wheight:=r.Bottom-r.Top;
 
   if thumb <> nil then DwmUnregisterThumbnail(thumb^);
 
   i:=DwmRegisterThumbnail(image1.canvas.Handle,h,Ptr(thumb^));
   if i=0 then UpdateThumb();
   end;
 
end;
 
end.

Open in new window

Geert G

nice attempt ...

i would provide some parameters to your updatethumb (make it independant of form1)

if that don't work,
first assign a bitmap in the picture property, best is a ordinary white bitmap

or use a TPanel instead of a TImage

I don't have Vista, so can't test, just trying to help

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, dwm, StdCtrls, ExtCtrls;
 
type
  TForm1 = class(TForm)
    Button1: TButton;
    Image1: TImage;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    thumb: PHTHUMBNAIL;
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
function UpdateThumb(aThumb: PHTHUMBNAIL; aDestRect: TRect):boolean;
var
 size: PSize;
 props: PDWM_THUMBNAIL_PROPERTIES;
begin
    result:=true;
    if aThumb <> nil then
    begin
      DwmQueryThumbnailSourceSize(aThumb^, size);
      props.dwFlags:=DWM_TNP_VISIBLE and DWM_TNP_RECTDESTINATION and DWM_TNP_OPACITY;
      props.fVisible:=true;
      props.opacity:=50;
      props.fSourceClientAreaOnly:=false;
      props.rcDestination:=;
 
      if (size.cx < aDestRect.Right - aDestRect.Left) then props.rcDestination.Right:=props.rcDestination.Left+size.cx;
      if (size.cy < aDestRect.Bottom - aDestRect.Top) then props.rcDestination.Top:=props.rcDestination.Left+size.cy;
 
      DwmUpdateThumbnailProperties(aThumb^,Pointer(props));
    end;
 
end;
 
procedure TForm1.Button1Click(Sender: TObject);
var
 h: Hwnd;
 r: TRect;
 wwidth, wheight: integer;
 i: integer;
begin
 h:=FindWindow(nil,'Untitled - Notepad');
 
   if h<>0 then
   begin
   GetWindowRect(h,r);
   wwidth:=r.Right-r.Left;
   wheight:=r.Bottom-r.Top;
 
   if thumb <> nil then 
   begin
     DwmUnregisterThumbnail(thumb^);
     thumb := nil;
   end;
 
   i:=DwmRegisterThumbnail(image1.canvas.Handle,h,thumb);
   if i=0 then UpdateThumb(thumb, Rect(Image1.left,image1.Top, 
     Image1.Left  + Image1.Width, Image1.Top + Image1.Height));
   end;
 
end;
 
end.

Open in new window

Geert G

wouldn't it be more like this for the destination ?

UpdateThumb(thumb, Rect(0,0,Image1.Width, Image1.Height));

ASKER CERTIFIED SOLUTION

rogerrr

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Mike McCracken

This question has been classified as abandoned and is being closed as part of the Cleanup Program. See my comment at the end of the question for more details.