Author: Pieter Valentijn

Saving and loading Component Published Propertys to disk

Answer:

The TStreams Class has a nice feature Couse it can stream component propertys in 
just one line . 

So here's the complete unit where i Stream the component 
If your class is not in the same unit you will have to register it . 

1   {
2   procedure RegisterClasses(AClasses: array of TPersistentClass);
3   
4   Description
5   
6   Call RegisterClasses to register a set of custom classes in a single line. Each 
7   class is registered by calling RegisterClass. Unregistered classes can’t be loaded 
8   or saved by the VCL streaming system.
9   }
10  
11  unit Unit1;
12  
13  interface
14  
15  uses
16    Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
17    StdCtrls;
18  
19  type
20    // jus a enumeration
21    TSomeints = 1..10;
22    // set of the enumeration
23    TExampleSet = set of TSomeints;
24    TExampleComponent = class(TComponent)
25    private
26      FASet: TExampleSet;
27      FAString: string;
28      FAFloat: Double;
29      FAInteger: Integer;
30    published
31      // Anyting you want streamed and is streameble by Delphi you can publish
32      // as property
33      property AString: string read FAString write FAString;
34      property ASet: TExampleSet read FASet write FASet;
35      property AInteger: Integer read FAInteger write FAInteger;
36      property AFloat: Double read FAFloat write FAFloat;
37    end;
38  
39    TForm1 = class(TForm)
40      SaveToStream: TButton;
41      LoadFromStream: TButton;
42      OpenDialog1: TOpenDialog;
43      SaveDialog1: TSaveDialog;
44      EAFloat: TEdit;
45      EAstring: TEdit;
46      procedure SaveToStreamClick(Sender: TObject);
47      procedure FormCreate(Sender: TObject);
48      procedure FormDestroy(Sender: TObject);
49      procedure LoadFromStreamClick(Sender: TObject);
50    private
51      FExampleComponent: TExampleComponent;
52      procedure SetExampleComponent(const Value: TExampleComponent);
53      { Private declarations }
54    public
55      property ExampleComponent: TExampleComponent read FExampleComponent write
56        SetExampleComponent;
57      procedure ObjectToGui;
58      procedure GuiToObject;
59      { Public declarations }
60    end;
61  
62  var
63    Form1: TForm1;
64  
65  implementation
66  
67  {$R *.DFM}
68  
69  procedure TForm1.SaveToStreamClick(Sender: TObject);
70  var
71    AStream: TMemoryStream;
72  begin
73    if SaveDialog1.execute then
74    begin
75      GuiToObject;
76      AStream := TMemoryStream.Create;
77      try
78        AStream.WriteComponent(ExampleComponent);
79        AStream.SaveToFile(SaveDialog1.FileName);
80      finally
81        AStream.free;
82      end;
83    end;
84  end;
85  
86  procedure TForm1.SetExampleComponent(const Value: TExampleComponent);
87  begin
88    FExampleComponent := Value;
89  end;
90  
91  procedure TForm1.FormCreate(Sender: TObject);
92  begin
93    // this is the Procedure To Call if you want to Use components not defined
94    // in this unit ;
95    // RegisterClasses([TButton,TMemo,TEnz]);
96    FExampleComponent := TExampleComponent.Create(Self);
97  end;
98  
99  procedure TForm1.FormDestroy(Sender: TObject);
100 begin
101   FExampleComponent.free;
102 end;
103 
104 procedure TForm1.LoadFromStreamClick(Sender: TObject);
105 
106 var
107   AStream: TMemoryStream;
108 begin
109   if OpenDialog1.execute then
110   begin
111     AStream := TMemoryStream.Create;
112     try
113       AStream.LoadFromFile(OpenDialog1.FileName);
114       AStream.ReadComponent(ExampleComponent);
115       ObjectToGui;
116     finally
117       AStream.free;
118     end;
119   end;
120 end;
121 
122 procedure TForm1.GuiToObject;
123 begin
124   ExampleComponent.AString := EAstring.Text;
125   ExampleComponent.AFloat := StrToFloat(EAFloat.Text);
126 end;
127 
128 procedure TForm1.ObjectToGui;
129 begin
130   EAstring.Text := ExampleComponent.AString;
131   EAFloat.Text := FloatToStr(ExampleComponent.AFloat);
132 end;
133 
134 end.


Component Download: http://www.xs4all.nl/~suusie/Pieter/Programs/StreamingComponent.ziphttp://www.xs4all.nl/~suusie/Pieter/Programs/StreamingComponent.zip