Frames: what changed

Revision 1 to 2. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		[[TFrame\|TFrames]] are named containers for components and very similar to [[TForm\|forms]]. Their unique ability is that they can be embedded into forms or other frames in the designer. As forms they are stored in two files: the code is stored in .pas file and the design in the .lfm file.
2	2
3	3		## How to create a frame?
4	4
5	5		Press File-\>New... menu item and in the opened dialog select "Frame" item.
6	6
7		-	~~<figure>~~
8		-	~~<img src="Frame_new.PNG" title="Frame_new.PNG" />~~
9		-	~~<figcaption>Frame_new.PNG</figcaption>~~
10		-	~~</figure>~~
	7	+	![](/wiki-images/6/6d/Frame_new.PNG)
11	8
12	9		## How to place a frame to the form or another frame?
13	10
14	11		The [[Standard tab]] of the [[Component Palette]] has a special component item "[[TFrame]]". When you drop it to the form or frame the IDE asks you to choose one of project frames. You have to save the project and the the new frame first, only saved frames will appear in the choose from list. Frames in packages are not yet implemented. But you can create frames in code even in packages. You can't create frame circles - the IDE will forbid this, i.o.w. you can't place FrameA to FrameA and you can't place any frame which contains FrameA to FrameA.
15	12
16		-	~~<figure>~~
17		-	~~<img src="Frame_add.PNG" title="Frame_add.PNG" />~~
18		-	~~<figcaption>Frame_add.PNG</figcaption>~~
19		-	~~</figure>~~
	13	+	![](/wiki-images/3/35/Frame_add.PNG)
20	14
21	15		## What can they be used for?
22	16
23	17		They are needed when you have a group of components that you want to reuse on multiple forms. The group should have the same set of controls and logic between them at different windows (forms) of your application. You can group that repeated controls and logic into one frame and use that frame in different places. Therefore you don't need to repeat the work of control layouting and writing their logic.
24	18
25	19		For example, you have two listboxes and buttons to move items between them. So you can create a frame with two listboxes and needed buttons, write the logic for items moving and then use your frame on all forms where needed. Moreover, if you find an error in the frame code then you can fix it once in the frame code instead of fixing it n-times among all forms.
26	20
27	21		a frame in designer:
28	22
29		-	~~<figure>~~
30		-	~~<img src="Frame_example.PNG" title="Frame_example.PNG" />~~
31		-	~~<figcaption>Frame_example.PNG</figcaption>~~
32		-	~~</figure>~~
	23	+	![](/wiki-images/1/13/Frame_example.PNG)
33	24
34	25		the frame placed on a form:
35	26
36		-	~~<figure>~~
37		-	~~<img src="Frame_embedded.PNG‎" title="Frame_embedded.PNG‎" />~~
38		-	~~<figcaption>Frame_embedded.PNG‎</figcaption>~~
39		-	~~</figure>~~
	27	+	![](/wiki-images/d/d4/Frame_embedded.PNG%E2%80%8E)
40	28
41	29		the same frame placed on another form:
42	30
43		-	~~<figure>~~
44		-	~~<img src="Frame_embedded2.PNG‎" title="Frame_embedded2.PNG‎" />~~
45		-	~~<figcaption>Frame_embedded2.PNG‎</figcaption>~~
46		-	~~</figure>~~
	31	+	![](/wiki-images/3/36/Frame_embedded2.PNG%E2%80%8E)
47	32
48	33		## Initialising private variables
49	34
50	35		TFrame does not have OnCreate or OnDestroy events in which private variables can be initialised and released. [[Override]] the default [[Constructor\|constructor]] and [[Destructor\|destructor]] to do this.
51	36
52	37		``` pascal
53	38		TFrame1 = class(TFrame)
54	39		private
55	40		MyObj: TObject;
56	41		public
57	42		constructor Create(TheOwner: TComponent); override;
58	43		destructor Destroy; override;
59	44		end;
60	45
61	46		constructor TFrame1.Create(TheOwner: TComponent);
62	47		begin
63	48		inherited Create(TheOwner);
64	49		MyObj := TObject.Create;
65	50		end;
66	51
67	52		destructor TFrame1.Destroy;
68	53		begin
69	54		MyObj.Free
70	55		inherited Destroy;
71	56		end;
72	57		```
73	58
74	59		## Sample of dynamic creation
75	60
76	61		More easy. Because TFrame component in component palette is not required. And you can make a page change type application(like a smart phone application) with save resource.
77	62
78	63		``` pascal
79	64		unit Unit1;
80	65
81	66		{$mode objfpc}{$H+}
82	67
83	68		interface
84	69
85	70		uses
86	71		Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls;
87	72
88	73		type
89	74
90	75		{ TForm1 }
91	76
92	77		TForm1 = class(TForm)
93	78		Button1: TButton;
94	79		GroupBox1: TGroupBox;
95	80		procedure Button1Click(Sender: TObject);
96	81		procedure FormCreate(Sender: TObject);
97	82		private
98	83		{ private declarations }
99	84		Frame: TFrame;
100	85		public
101	86		{ public declarations }
102	87		end;
103	88
104	89		var
105	90		Form1: TForm1;
106	91
107	92		implementation
108	93		uses
109	94		Unit2{TFrame1}, Unit3{TFrame2}, Unit4{TFrame3};
110	95
111	96		{$R *.lfm}
112	97
113	98		{ TForm1 }
114	99
115	100		procedure TForm1.FormCreate(Sender: TObject);
116	101		begin
117	102		Frame := TFrame1.Create(GroupBox1);
118	103		Frame.Parent := GroupBox1;
119	104		end;
120	105
121	106		procedure TForm1.Button1Click(Sender: TObject);
122	107		begin
123	108		if not Assigned(Frame) then
124	109		begin
125	110		Frame := TFrame1.Create(GroupBox1);
126	111		Frame.Parent := GroupBox1;
127	112		end else if Frame is TFrame1 then begin
128	113		Frame.Free;
129	114		Frame := TFrame2.Create(GroupBox1);
130	115		Frame.Parent := GroupBox1;
131	116		end else if Frame is TFrame2 then begin
132	117		Frame.Free;
133	118		Frame := TFrame3.Create(GroupBox1);
134	119		Frame.Parent := GroupBox1;
135	120		end else begin
136	121		FreeAndNil(Frame);
137	122		end;
138	123		end;
139	124
140	125		end.
141	126		```
142	127
143	128		## See also
144	129
145	130		- [[TFrame]]
146	131
147	132		---
148	133		From the Free Pascal wiki, page "Frames", as it stood on 2020-05-12 after a change by Jesusrmx, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).

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