File: processmessagesunit1.pas

package info (click to toggle)
lazarus 0.9.28.2-12
  • links: PTS, VCS
  • area: main
  • in suites: squeeze
  • size: 93,096 kB
  • ctags: 89,312
  • sloc: pascal: 820,189; xml: 202,194; makefile: 110,323; sh: 2,460; perl: 395; sql: 174; ansic: 133
file content (138 lines) | stat: -rw-r--r-- 3,685 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
{
 ***************************************************************************
 *                                                                         *
 *   This source is free software; you can redistribute it and/or modify   *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This code is distributed in the hope that it will be useful, but      *
 *   WITHOUT ANY WARRANTY; without even the implied warranty of            *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU     *
 *   General Public License for more details.                              *
 *                                                                         *
 *   A copy of the GNU General Public License is available on the World    *
 *   Wide Web at <http://www.gnu.org/copyleft/gpl.html>. You can also      *
 *   obtain it by writing to the Free Software Foundation,                 *
 *   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.        *
 *                                                                         *
 ***************************************************************************

  Abstract:
    Demo to show, how to process a big file with the main thread.
}
unit ProcessMessagesUnit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, LResources, Forms, Controls, Graphics, Dialogs, Buttons,
  ComCtrls, FileUtil;

type

  { TForm1 }

  TForm1 = class(TForm)
    ProgressBar1: TProgressBar;
    StartStopButton: TButton;
    procedure FormCreate(Sender: TObject);
    procedure StartStopButtonClick(Sender: TObject);
  private
    procedure Run;
    procedure UpdateButton;
  public
    Running: boolean;
    Aborting: boolean;
    Filename: String;
  end;

var
  Form1: TForm1; 

implementation

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
begin
  Filename:='processmessagesunit1.pas';
end;

procedure TForm1.StartStopButtonClick(Sender: TObject);
begin
  if not Running then
    Run
  else
    Aborting:=true;
end;

procedure TForm1.Run;
var
  fs: TFileStream;
  Buffer: string;
  Count: LongInt;
  i: Integer;
  Last: TDateTime;
begin
  if Running then exit;
  Running:=true;
  UpdateButton;
  try
    // open a file
    fs:=TFileStream.Create(UTF8ToSys(Filename),fmOpenRead);
    try
      SetLength(Buffer,10);
      while true do begin

        // process all user events, like clicking on the button
        Application.ProcessMessages;
        if Aborting or Application.Terminated then break;

        // read some bytes
        Count:=fs.Read(Buffer[1],length(Buffer));
        if Count=0 then break;

        // process ...
        for i:=1 to Count do begin
          Last:=Now;
          repeat
          until Now-Last>(double(1)/fs.Size)/10000;
        end;

        // show progress
        ProgressBar1.Position:=ProgressBar1.Min
               +((ProgressBar1.Max-ProgressBar1.Min+1)*fs.Position) div fs.Size;
      end;
    finally
      fs.Free;
    end;
  except
    on E: Exception do begin
      MessageDlg('Error',E.Message,mtError,[mbCancel],0);
    end;
  end;
  Aborting:=false;
  Running:=false;
  UpdateButton;
end;

procedure TForm1.UpdateButton;
begin
  if Running then begin
    if Aborting then
      StartStopButton.Caption:='Aborting ...'
    else
      StartStopButton.Caption:='Running ...';
  end else begin
    StartStopButton.Caption:='Start';
  end;
end;

initialization
  {$I processmessagesunit1.lrs}

end.