Lazarus Hacks: what changed

Revision 0 to 1. Removed lines have a minus sign; added lines have a plus sign.

Title: Lazarus Hacks

New		Line
1	+	Add here your hacks/modifications to the Lazarus IDE or LCL widgets. If a good idea arises and is good enough it may become part of the official distribution; if not it can be used by other people that need more handy functionality than standards.
2	+
3	+	> Note: Please post a patch to the bugtracker to get improvements into the Lazarus code. Just posting them here will not work.
4	+
5	+	## Exposing/Extending TCustomEdit
6	+
7	+	In some applications we need to constantly convert the Text property of TCustomEdit descendants from or to numeric values:
8	+
9	+	``` pascal
10	+	TCustomEditFilters = (cefNone, cefInteger, cefUnsigned, cefCurrency, cefFloat);
11	+
12	+	{ TCustomEdit }
13	+
14	+	TCustomEdit = class(TWinControl)
15	+	private
16	+	...
17	+	FTmpModified : Boolean;
18	+	FceFilter : TCustomEditFilters;
19	+	procedure SetceFilter(aCeFilter: TCustomEditFilters);
20	+	function GetAsInteger:Integer;
21	+	procedure SetAsInteger(aVal: Integer);
22	+	function GetAsFloat:Extended;
23	+	procedure SetAsFloat(aVal: Extended);
24	+	function GetAsCurrency:Currency;
25	+	procedure SetAsCurrency(aVal: Currency);
26	+
27	+	public
28	+	...
29	+	property TmpModified: Boolean read FTmpModified write FTmpModified;
30	+	property AsInteger: Integer read getAsInteger write setAsInteger;
31	+	property AsFloat: Extended read getAsFloat write setAsFloat;
32	+	property AsCurrency: Currency read getAsCurrency write setAsCurrency;
33	+	published
34	+	property Alignment: TAlignment read FAlignment write SetAlignment default taLeftJustify;
35	+	property ceFilter : TCustomEditFilters read FceFilter write SetceFilter default cefNone;
36	+	end;
37	+
38	+	//On the implementation part tcustomedit.inc:
39	+
40	+	resourcestring
41	+	rsInvalidNumbe = 'Invalid number !';
42	+
43	+	procedure TCustomEdit.Change;
44	+	begin
45	+	FTmpModified := True;
46	+	if Assigned(FOnChange) then FOnChange(Self);
47	+	end;
48	+
49	+	procedure TCustomEdit.DoExit;
50	+	begin
51	+	if FCeFilter <> cefNone then
52	+	begin
53	+	case FCeFilter of
54	+	cefInteger, cefUnsigned: AsInteger;
55	+	cefFloat: AsFloat;
56	+	cefCurrency: AsCurrency;
57	+	end;
58	+	end;
59	+	FAutoSelected := False;
60	+	inherited DoExit;
61	+	end;
62	+
63	+	procedure TCustomEdit.SetceFilter(aCeFilter: TCustomEditFilters);
64	+	begin
65	+	FCeFilter := aCeFilter;
66	+	if FCeFilter = cefNone then Alignment := taLeftJustify
67	+	else Alignment := taRightJustify;
68	+	end;
69	+
70	+	function TCustomEdit.GetAsInteger:Integer;
71	+	begin
72	+	TryStrToInt(Text, result);
73	+	end;
74	+
75	+	procedure TCustomEdit.SetAsInteger(aVal: Integer);
76	+	begin
77	+	Text := IntToStr(aVal);
78	+	end;
79	+
80	+	function TCustomEdit.GetAsFloat:Extended;
81	+	begin
82	+	if Text = '' then result := 0
83	+	else if not TryStrToFloat(Text, result) then
84	+	Raise Exception.Create(rsInvalidNumbe);
85	+	end;
86	+
87	+	procedure TCustomEdit.SetAsFloat(aVal: Extended);
88	+	begin
89	+	Text := FloatToStr(aVal);
90	+	end;
91	+
92	+	function TCustomEdit.GetAsCurrency:Currency;
93	+	begin
94	+	if Text = '' then result := 0
95	+	else if not TryStrToCurr(Text, result) then
96	+	raise Exception.Create(rsInvalidNumbe);
97	+	end;
98	+
99	+	procedure TCustomEdit.SetAsCurrency(aVal: Currency);
100	+	begin
101	+	Text := CurrToStr(aVal);
102	+	end;
103	+	```
104	+
105	+	## Replacing VK_DECIMAL keypad dot by comma
106	+
107	+	When writing Lazarus applications to non-US locales there is a problem with the keypad "." (dot) when the locale uses "," (comma) as decimal separator. I've been looking for a solution and ended up with this:
108	+
109	+	Form.KeyPreview := True; Form.OnKeyDown := @FormKeyDown; Form.OnKeyPress := @FormKeyPress;
110	+
111	+	``` pascal
112	+	{ TFormBase }
113	+
114	+	TFormBase = class(TForm)
115	+	...
116	+	protected
117	+	{ protected declarations }
118	+	fVK_Decimal : Boolean;
119	+	...
120	+	end;
121	+
122	+	procedure TFormBase.FormKeyPress(Sender: TObject; var Key: char);
123	+	begin
124	+	if fVK_Decimal and (key = '.') then key := DecimalSeparator;
125	+	end;
126	+
127	+	procedure TFormBase.FormKeyDown(Sender: TObject; var Key: word; Shift: TShiftState);
128	+	begin
129	+	if (Shift = []) and (key = VK_DECIMAL) then
130	+	fVK_Decimal := True;
131	+	end;
132	+	```
133	+
134	+	## See also
135	+
136	+	- [[Creating A Patch]] - How to get your modifications into the Lazarus codebase
137	+
138	+	---
139	+	From the Free Pascal wiki, page "Lazarus Hacks", as it stood on 2020-03-09 after a change by Minesadorada, 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).
140	+	Category: Code Snippets
141	+	Category: Lazarus

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