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
Solved

Restrict drawing on a canvas into a rectangle?

Posted on 2000-02-22
4
386 Views
Last Modified: 2010-04-04
I need to specify a rectangle on a canvas where drawing is enabled, and outside it is forbidden. For example, in Rect(25, 25, 200, 200) drawing is enabled, and anything drawn outside it is not displayed.

Please note, that the canvas in question is the canvas of a printer.

How can I do that?
Thank you for your help.
Levente
0
Comment
Question by:Levente
  • 2
  • 2
4 Comments
 
LVL 17

Expert Comment

by:inthe
ID: 2548194
Hi,
here an example of reading .lnk files:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls,shlobj,activex,comobj,commctrl,menus;

type
  TForm1 = class(TForm)
    Button1: TButton;
    OpenDialog1: TOpenDialog;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }

  public
    { Public declarations }
  end;

var
  Form1: TForm1;
   NeedToUninitialize : boolean = false;
implementation

{$R *.DFM}

function LoadShellLink(shellLinkFile: string;
                       var description, linkedObj, params: string;
                       var pidl: PItemIDList; var findData: TWin32FindData;
                       var iconPath: string; var iconIndex: integer;
                       var workingDir, hotKey: string;
                       var showCmd: integer) : boolean;
var sl  : IShellLink;
    w1  : word;
    s1  : string;
    wfd : TWin32FindData;
    i1  : integer;
begin
  NeedToUninitialize:=NeedToUninitialize or succeeded(CoInitialize(nil));
  sl:=CreateComObject(CLSID_ShellLink) as IShellLink;
  result:=(sl as IPersistFile).Load(PWideChar(wideString(ShellLinkFile)),0)=S_OK;
  if not result then exit;
  SetLength(description,MAX_PATH+1);
  if sl.GetDescription(PChar(description),MAX_PATH)=NOERROR then description:=string(PChar(description))
  else                                                           description:='';
  SetLength(s1,MAX_PATH+1);
  if sl.GetPath(PChar(s1),MAX_PATH,wfd,0)=NOERROR then begin
    linkedObj:=string(PChar(s1));
    findData :=wfd;
  end else begin
    linkedObj:='';
    ZeroMemory(@findData,sizeOf(TWin32FindData));
  end;
  SetLength(params,MAX_PATH+1);
  if sl.GetArguments(PChar(params),MAX_PATH)=NOERROR then params:=string(PChar(params))
  else                                                    params:='';
  if sl.GetIDList(pidl)<>NOERROR then pidl:=nil;
  SetLength(s1,MAX_PATH+1);
  if sl.GetIconLocation(pchar(s1),MAX_PATH,i1)=NOERROR then begin
    iconPath :=string(pchar(s1));
    iconIndex:=i1;
  end else begin
    iconPath :='';
    iconIndex:=-1;
  end;
  SetLength(workingDir,MAX_PATH+1);
  if sl.GetWorkingDirectory(PChar(workingDir),MAX_PATH)=NOERROR then workingDir:=string(PChar(workingDir))
  else                                                               workingDir:='';
  sl.GetHotKey(w1);
  if w1 and (HOTKEYF_ALT     shl 8)<>0 then w1:=(w1 and (not (HOTKEYF_ALT     shl 8))) or scAlt;
  if w1 and (HOTKEYF_CONTROL shl 8)<>0 then w1:=(w1 and (not (HOTKEYF_CONTROL shl 8))) or scCtrl;
  if w1 and (HOTKEYF_SHIFT   shl 8)<>0 then w1:=(w1 and (not (HOTKEYF_SHIFT   shl 8))) or scShift;
  hotKey:=ShortCutToText(w1);
  if sl.GetShowCmd(showCmd)<>NOERROR then showCmd:=-1;
end;

procedure FreePidl(var pidl: PItemIDList);
var malloc : IMalloc;
begin
  if (pidl<>nil) and (SHGetMalloc(malloc)=NOERROR) then begin
    malloc.Free(pidl);
    pidl:=nil;
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  pi:PItemIDList;
  s1,Desc,s2:String;
  icon,workdir,htkey:string;
  Data: TWin32FindData;
  i,ii : integer;
begin
  opendialog1.execute;
  loadshelllink(opendialog1.filename,desc,s1,s2,pi,Data,icon,i,workdir,htkey,ii);
  ShowMessage('File ShortCut : '+opendialog1.filename+#13#10+'File TruePath : '+s1+#13#10+'Working Dir : '+workdir+#13#10
              +'HotKey : '+htkey+#13#10+'Show Command : '+inttostr(ii));
 FreePidl(pi);
end;


initialization
finalization
  if NeedToUninitialize then CoUninitialize;

end.


Regards Barry
0
 
LVL 17

Expert Comment

by:inthe
ID: 2548208
opps silly me ,im sorry i pasted in wrong question :-)
0
 
LVL 8

Accepted Solution

by:
ZifNab earned 150 total points
ID: 2548286
Hi Levente,

This should do the trick (with TImage as example, but should be same for printer canvas)

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    Image1: TImage;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
  Var Region, OldRegion : HRgn;
      DC        : HDC;

begin
  DC:=Image1.Canvas.Handle;
  Region:=CreateRectRgn(10,10,50,50);
  GetClipRgn(DC,OldRegion);
  SelectClipRgn(DC,Region);
  DeleteObject(Region);
  with Image1 do
  begin
    Canvas.Pen.Color := Random(65535);
    Canvas.Pen.Style := psSolid;
    Canvas.Rectangle(5, 5, 20,20);
  end;
end;

end.

Regards, Zif.

0
 
LVL 8

Expert Comment

by:ZifNab
ID: 2548303
For TPrinter :

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    Image1: TImage;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation
uses printers;
{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
  Var Region, OldRegion : HRgn;
      DC        : HDC;

begin
  Printer.BeginDoc;
  DC:=Printer.Canvas.Handle;
  Region:=CreateRectRgn(10,10,50,50);
  GetClipRgn(DC,OldRegion);
  SelectClipRgn(DC,Region);
  DeleteObject(Region);
  with Printer do
  begin
    Canvas.Pen.Color := Random(65535);
    Canvas.Pen.Style := psSolid;
    Canvas.Rectangle(5, 5, 20,20);
  end;
  Printer.EndDoc;
  SelectClipRgn(DC,OldRegion);
end;

end.

What you see printed is just the right-bottom corner of the rectangle. The rest is clipped.


Regards, Zif.
0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

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

Suggested Solutions

Title # Comments Views Activity
How to call a form that is in a DLL  from an application? 13 80
Delphi selector screen 2 84
Delphi inherited method 6 76
Base1 Encode/Decode 3 81
Objective: - This article will help user in how to convert their numeric value become words. How to use 1. You can copy this code in your Unit as function 2. than you can perform your function by type this code The Code   (CODE) The Im…
Hello everybody This Article will show you how to validate number with TEdit control, What's the TEdit control? TEdit is a standard Windows edit control on a form, it allows to user to write, read and copy/paste single line of text. Usua…
With Secure Portal Encryption, the recipient is sent a link to their email address directing them to the email laundry delivery page. From there, the recipient will be required to enter a user name and password to enter the page. Once the recipient …
A short tutorial showing how to set up an email signature in Outlook on the Web (previously known as OWA). For free email signatures designs, visit https://www.mail-signatures.com/articles/signature-templates/?sts=6651 If you want to manage em…

839 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