Solved

Screensaver preview:

Posted on 1998-12-04
7
469 Views
Last Modified: 2010-04-04
How do I create a preview of my screensaver in the screensaver properties, I need some samples that aren't to hard to understand.
0
Comment
Question by:koger
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
7 Comments
 
LVL 20

Expert Comment

by:Madshi
ID: 1349328
Do you need a "little" preview in stamp size or is it ok to watch the preview in full-screen?
I don't know how to do a stamp preview. But a full-screen preview is very easy:

var si : TStartupInfo;
    pi : TProcessInformation;
begin
  ZeroMemory(@si,sizeOf(si)); si.cb:=sizeOf(si);
  if CreateProcess(nil,'c:\windows\system\marquee.scr',nil,nil,false,0,nil,nil,si,pi) then begin
    CloseHandle(pi.hThread); CloseHandle(pi.hProcess); // Never forget to close handles...
  end;

Regards, Madshi.
0
 
LVL 2

Expert Comment

by:trillo
ID: 1349329
When previewing, The preview window calls your program (with SCR extension) with two commandline parameters the first is a "p" and the second one is the handle of the preview window.

I'll paste here some code I used for a screensaver I made.

-----------------begin of code------------
unit Unit_InitProcs;

interface
uses Windows, extctrls, Classes, Graphics, SysUtils, Messages;

procedure ExecPreview;

var
  SaverMode:        Integer;  {one of the consts above}
  ParamHandle:      THandle;  {the Handle passed on command line as parameter}
  ConfigParent:     hWnd;     {the parent window for config-dialog}

  PrevRect:         TRect;
  MyBmp:        TBitmap;
  PreviewCanvas : TCanvas;
  R:    TRect;
implementation

{this is the window-proc for the preview window, it only implements 3 messages}
function MyWndProc (Wnd : HWnd; Msg : Integer; wParam : Word; lParam : Integer) : Integer; far; stdcall;
var
    x,y,cx,cy:  Integer;
begin {I don't know if it is ok to quit on WM_CLOSE, but I had no problems doing so}
    if (Msg = WM_DESTROY) or (Msg = WM_CLOSE) then
        PostMessage (Wnd, WM_QUIT, 0, 0);
    if Msg = WM_PAINT then begin
        x:=Round((PrevRect.Right-R.Right)/2);
        y:=Round((PrevRect.Bottom-R.Bottom)/2);
        cx:=x + R.Right-R.Left;
        cy:=y + R.Bottom-R.Top;
        PreviewCanvas.CopyRect(Rect(x,y,cx,cy),MyBmp.Canvas,R);
    end;
    DefWindowProc (Wnd, Msg, wParam, lParam);
end;
{This executes the preview window,
 and goes in a message loop to keep it running}
procedure ExecPreview;
var
  WndClass : TWndClass;
  Atom     : TAtom;
  DC       : hDC;
  MyWnd    : hWnd;
  Msg      : TMsg;
begin
  {create a new window class}
  with WndClass do begin
    style := CS_PARENTDC;
    lpfnWndProc := @MyWndProc;
    cbClsExtra := 0;
    cbWndExtra := 0;
    hIcon := 0;
    hCursor := 0;
    hbrBackground := 0;
    lpszMenuName := nil;
    lpszClassName := 'Delphi2ScreenSaverPreview';
  end;
  WndClass.hInstance := hInstance;
  Atom := Windows.RegisterClass (WndClass);
  {get some info on parent window}
  GetWindowRect (ParamHandle, PrevRect);
  PrevRect.Right := PrevRect.Right - PrevRect.Left;
  PrevRect.Bottom := PrevRect.Bottom - PrevREct.Top;
  PrevRect.Left := 0;
  PrevRect.Top := 0;
  {and now create the window as child of the window given in ParamHandle}
  MyWnd := CreateWindow ('Delphi2ScreenSaverPreview', 'FunSaver',
    WS_CHILD or WS_DISABLED or WS_VISIBLE, 0, 0, PrevRect.Right,
    PrevRect.Bottom, ParamHandle, 0, hInstance, nil);
  {get the DC for the new created window}
  DC := GetDC (MyWnd);
  PreviewCanvas := TCanvas.Create;
  PreviewCanvas.Handle := DC;
  MyBmp:=TBitmap.Create;
  MyBmp.LoadFromResourceName(hInstance,'INQUILINO');
  R:=Rect(0,0,MyBmp.Width,MyBmp.Height);
  {and now do the message loop, I think I cannot use any predifined loop here}
  while GetMessage(Msg, 0, 0, 0) do begin
    TranslateMessage(Msg);
    DispatchMessage(Msg);
  end;
  MyBmp.Free;
  PreviewCanvas.Free;
  ReleaseDC(0,DC);
  {I don't care about other resources here, as my app terminates immediately and
   Win95 cleans up after me}
end;

----------------end of code-------------
This block of code makes use of some unusual-in-Delphi functions and structures but it's not so hard to understand. In fact, we only create a new window and we make it a Child of the preview dialog box. Our window doesn't have a border and this is the window we will use to draw our screensaver.

Just tell me when you encounter any problem or if you have any question.

Trillo
0
 

Author Comment

by:koger
ID: 1349330
I have got this sample from somewhere (can't remember where) but I still don't get it, could you perhaps create a quick sample that would e.g. display an image.
0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 4

Expert Comment

by:dwwang
ID: 1349331
Supose you want to preview a screen saver in a panel named panel1:

var
   s:string;
begin
     s:='c:\windows\system\YourScrName.scr /P '+trim(IntToStr(panel1.handle));
      WinExec(pchar(s),0);
end;

0
 

Author Comment

by:koger
ID: 1349332
This is not what I'm looking for I don't have a preview in my screensaver.
0
 
LVL 4

Accepted Solution

by:
dwwang earned 200 total points
ID: 1349333
Oh, I see, so this site will help you for sure, it describe how to build screen savers as well as how to write the preview part. Full source is included.

http://www.inprise.com/devsupport/delphi/ti_list/TI3335.html
0
 

Author Comment

by:koger
ID: 1349334
just what I needed
0

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In this tutorial I will show you how to use the Windows Speech API in Delphi. I will only cover basic functions such as text to speech and controlling the speed of the speech. SAPI Installation First you need to install the SAPI type library, th…
In my programming career I have only very rarely run into situations where operator overloading would be of any use in my work.  Normally those situations involved math with either overly large numbers (hundreds of thousands of digits or accuracy re…
If you’ve ever visited a web page and noticed a cool font that you really liked the look of, but couldn’t figure out which font it was so that you could use it for your own work, then this video is for you! In this Micro Tutorial, you'll learn yo…
Visualize your data even better in Access queries. Given a date and a value, this lesson shows how to compare that value with the previous value, calculate the difference, and display a circle if the value is the same, an up triangle if it increased…
Suggested Courses
Course of the Month5 days, 2 hours left to enroll

635 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question