Difference between revisions of "TRadioButton"

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(Added "Usage", "A simple Example", "Usage of a event")
(Added "Grouping")
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===Grouping===
 
===Grouping===
  
- in progress --[[User:Michl|Michl]] 12:51, 22 May 2014 (CEST)
+
If you add a radiobutton to your form is its [[Parent|parent]] (control, which includes the radio button) your form. By each setting (no matter whether via code or user button click) of a '''<code><RadioButton>.Checked:=True;</code>''' is checked whether a different radiobutton, with this parent, is selected and if yes, the property ''Checked'' of this would be changed to ''False''.<br>
 +
If you want to use multiple radiobuttons on your form, that are designed to provide different, independent choices, you must group the radio buttons. There are a finished component [[TRadioGroup]] or you group on a control (e.g. [[TPanel]], [[TGroupBox]], [[TNotebook]], [[TPageControl]] etc.).<br>
  
Fügen Sie Radiobuttons Ihrem Formular hinzu, ist der [[Parent/de|Parent]] (Steuerelement, welches den Radiobutton beinhaltet) Ihr Formular. Bei jedem Setzen (egal, ob per Code oder Nutzer per Buttonklick) eines '''<code><RadioButton>.Checked:=True;</code>''' wird geprüft, ob noch ein anderer Radiobutton, mit diesem Parent, ausgewählt ist und falls ja, dieser auf nicht ausgewählt gesetzt.<br>
+
The following example shows how you can group radio buttons:
Wollen Sie trotzdem mehrere Radiobuttons auf Ihrem Formular nutzen, die verschiedene, unabhängige Auswahlmöglichkeiten bieten sollen, müssen Sie die Radiobuttons gruppieren. Dazu gibt es eine fertige Komponente [[TRadioGroup/de|TRadioGroup]] oder sie gruppieren Sie selber auf einem Control (z.B. [[TPanel/de|TPanel]], [[TGroupBox/de|TGroupBox]], [[TNotebook/de|TNoteBook]], [[TPageControl/de|TPageControl]] etc.).<br>
 
  
Folgendes kleines Beispiel zeigt Ihnen, wie sie Radiobuttons selber gruppieren können:
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You can change the example [[TRadioButton#A simple example]] or create a new application:
 
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* As first you would need to place a [[TGroupBox]] of the standard component palette onto your form.
Sie können dazu das Beispiel [[TRadioButton/de#Ein einfaches Beispiel|Ein einfaches Beispiel]] umfunktionieren oder ein neues erstellen:
+
* You change its name to ''gbColor'' and its caption to ''Color''.
* Als erstes müssten Sie eine [[TGroupBox/de|TGroupBox]] von der Standard Komponentenpalette auf Ihr Formular platzieren.
+
* Now you subclass this GroupBox that radio buttons ''rbRed'', ''rbGreen'' and ''rbBlue'':
* Dieser GroupBox geben Sie den Namen ''gbColor'' und Caption ''Farbe''.
+
** In the modified project, you can sequentially move the radiobuttons '''in the Object Inspector''' by drag and drop to ''gbColor''.
* Nun ordnen Sie dieser Groupbox die Radiobuttons ''rbRed'', ''rbGreen'' und ''rbBlue'' unter:
+
** In a new project, you can insert the three radiobuttons one after the other, by clicking to insert in the GroupBox, then change the names to ''rbRed'', ''rbGreen'' and ''rbBlue'' and the captions to ''Red'', ''Green'' and ''Blue''.
** Im veränderten Projekt können Sie nacheinander die Radiobuttons '''im Objektinspektor''' per Drag and Drop auf ''gbColor'' verschieben.
+
* Now place a second TGroupBox on your form named ''gbBrightness'' with the caption ''Brightness''.
** In einem neuen Projekt können Sie nacheinander die drei Radiobuttons einfügen, indem Sie zum Einfügen in die Groupbox klicken, die Namen ''rbRed'', ''rbGreen'' und ''rbBlue'' vergeben und die Captions zu ''Rot'', ''Grün'' und ''Blau'' ändern.
+
* Add this GroupBox also three radio buttons and give it the name ''rbBrightDark'', ''rbBrightMedDark'' and ''rbBrightBright'' and the captions ''Dark'', ''MediumDark'' and ''Bright''.
* Nun platzieren Sie eine zweite TGroupBox auf Ihrem Formular mit dem Namen ''gbBrightness'' und der Caption ''Helligkeit''.
+
* If you have created a new application, you must add a button with name ''btnPaint'' and caption ''Draw new'' to the form.
* Fügen Sie dieser Groupbox ebenfalls drei Radiobuttons hinzu und geben diesen die Namen ''rbBrightDark'', ''rbBrightMedDark'' und ''rbBrightBright'' und die Captions ''Dunkel'', ''Halbdunkel'' und ''Hell''.
+
* In the ''OnClick'' event handler of ''btnPaint'' change the code to:
* Falls Sie eine neue Anwendung erstellt haben, müssen Sie dem Formular noch einen Button mit dem Namen ''btnPaint'' und Caption ''Neu Zeichnen'' hinzufügen.
 
* Im ''OnClick''-Eventhandler von ''btnPaint'' ändern Sie den Code zu:
 
 
<syntaxhighlight>
 
<syntaxhighlight>
 
procedure TForm1.btnPaintClick(Sender: TObject);
 
procedure TForm1.btnPaintClick(Sender: TObject);
Line 95: Line 93:
 
end;
 
end;
 
</syntaxhighlight>
 
</syntaxhighlight>
* Nun erstellen Sie noch die Function ''Brightness'', indem Sie '''<code>function Brightness: TColor;</code>''' im ''private''-Abschnitt von TForm1 eingeben und [Ctrl]+[Shift]+[c] drücken (Codevervollständigung). Es wird die Function erstellt. Geben Sie dort folgenden Code ein:  
+
* Now create even the function Brightness, by enter the ''private'' section of TForm1, write '''<code>function Brightness: TColor;</code>''' and press the keys [CTRL] + [Shift] + [c] (code completion). The function is created. Enter there following code:
 
<syntaxhighlight>
 
<syntaxhighlight>
 
function TForm1.Brightness: TColor;
 
function TForm1.Brightness: TColor;
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end;
 
end;
 
</syntaxhighlight>
 
</syntaxhighlight>
* Starten Sie Ihr Programm, sie können die gruppierten Radiobuttons voneinader unabhängig einsetzen, so könnte es aussehen:
+
* Start your application, you can use the grouped radio buttons separate, so it could look like:
  
 
[[image:RadioButtonExample5.png]] -> [[image:RadioButtonExample6.png]]
 
[[image:RadioButtonExample5.png]] -> [[image:RadioButtonExample6.png]]

Revision as of 13:40, 22 May 2014

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>> LCL Components >> TRadioButton

This page explains how to use the TRadioButton component. When I mention to click on something, unless I explicitly say to right-click, you always left-click on the item in question.

Description

A selection button that works with other Radio Buttons in a mutually exclusive way - if one button is selected, none of the others in the group can be selected.

Comp Standard TRadioButton.png

Usage

To use a TRadioButtons on a Form, you can simply select it on the component palette Standard and place it, with one click on the form.
It usually does not make sense to use a single radiobutton, because radiobuttons are intended to select anything. Thus, you can instead of individual radiobuttons also a TRadioGroup use.
Anywhere in your source code, you can get the status of the radiobuttons, whether active or inactive, by query Status := <RadioButton>.Checked;. You can use Checked as a normal Boolean. Thus, the allocation <RadioButton>.Checked := True; is possible.

A simple Example

  • Create a new application and drop three TRadioButtons on the form.
  • In the Object Inspector tab properties change the name the RadioButton1...3 to rbRed, rbGreen and rbBlue.
  • Similarly, you change the captions of the radiobuttons to Red, Green and Blue there.
  • Add your form a TButton and change its caption to Draw new and its name to btnPaint.
  • Create the OnClick event handler for the TButton, by using the Object Inspector tab events, select the OnClick event and click the button [...] or double click the button in the form.
  • Add following code:
procedure TForm1.btnPaintClick(Sender: TObject);
begin
  if rbRed.Checked   then Color:=clRed;
  if rbGreen.Checked then Color:=clLime;
  if rbBlue.Checked  then Color:=clBlue;
end;
  • Open your application, it should look something like:

RadioButtonExample1.png -> RadioButtonExample2.png

Usage of a event

The difference to the previous example is, we repaint the form not by a button click, but already by clicking one of the radio buttons themselves.

You can modify the previous example, by deleting the button and its OnClick event handler in the source code. You can create a new example but also easy:

  • Create a new application and drop three TRadioButtons on the form.
  • In the Object Inspector tab properties change the name the RadioButton1...3 to rbRed, rbGreen and rbBlue.
  • Similarly, you change the captions of the radiobuttons to Red, Green and Blue there.
  • Now you can create the OnChange event handlers for the radiobuttons. For every radiobutton, you can use the Object Inspector tab events, select the Onchange event and click the button [...], but you can also doubleclick on it.
  • Let the event handler OnChange of the radio buttons change the colors of the form, according to clicked radio button:
procedure TForm1.rbRedChange(Sender: TObject);
begin
  Self.Color:=clRed;    //with "Self", you select the object in which the method exists (method: rbRedChange / object: Form1)
end;

procedure TForm1.rbGreenChange(Sender: TObject);
begin
  Form1.Color:=clLime;  //You can directly select the object ''Form1'', but poor, 
                        //because then no other object of class 'TForm1' can be created
end;

procedure TForm1.rbBlueChange(Sender: TObject);
begin
  Color:=clBlue;        //or you leave out "Self" and the compiler will automatically detect its own object
end;
  • Open your application, it should look something like:

RadioButtonExample3.png -> RadioButtonExample4.png

Grouping

If you add a radiobutton to your form is its parent (control, which includes the radio button) your form. By each setting (no matter whether via code or user button click) of a <RadioButton>.Checked:=True; is checked whether a different radiobutton, with this parent, is selected and if yes, the property Checked of this would be changed to False.
If you want to use multiple radiobuttons on your form, that are designed to provide different, independent choices, you must group the radio buttons. There are a finished component TRadioGroup or you group on a control (e.g. TPanel, TGroupBox, TNotebook, TPageControl etc.).

The following example shows how you can group radio buttons:

You can change the example TRadioButton#A simple example or create a new application:

  • As first you would need to place a TGroupBox of the standard component palette onto your form.
  • You change its name to gbColor and its caption to Color.
  • Now you subclass this GroupBox that radio buttons rbRed, rbGreen and rbBlue:
    • In the modified project, you can sequentially move the radiobuttons in the Object Inspector by drag and drop to gbColor.
    • In a new project, you can insert the three radiobuttons one after the other, by clicking to insert in the GroupBox, then change the names to rbRed, rbGreen and rbBlue and the captions to Red, Green and Blue.
  • Now place a second TGroupBox on your form named gbBrightness with the caption Brightness.
  • Add this GroupBox also three radio buttons and give it the name rbBrightDark, rbBrightMedDark and rbBrightBright and the captions Dark, MediumDark and Bright.
  • If you have created a new application, you must add a button with name btnPaint and caption Draw new to the form.
  • In the OnClick event handler of btnPaint change the code to:
procedure TForm1.btnPaintClick(Sender: TObject);
begin
  if rbRed.Checked   then Color:=Brightness or clRed;
  if rbGreen.Checked then Color:=Brightness or clLime;
  if rbBlue.Checked  then Color:=Brightness or clBlue;  
end;
  • Now create even the function Brightness, by enter the private section of TForm1, write function Brightness: TColor; and press the keys [CTRL] + [Shift] + [c] (code completion). The function is created. Enter there following code:
function TForm1.Brightness: TColor;
begin
  Result:=0;
  if rbBrightMedDark.Checked then Result:=$888888;
  if rbBrightBright.Checked  then Result:=$DDDDDD;
end;
  • Start your application, you can use the grouped radio buttons separate, so it could look like:

RadioButtonExample5.png -> RadioButtonExample6.png

Siehe auch

TRadioGroup - Verwendung von RadioGroups
TToggleBox - Verwendung von Toggleboxen
TCheckBox - Verwendung von CheckBoxen



Return To: LCL Components  — Previous: TCheckBox Next: TListBox


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--Michl 12:51, 22 May 2014 (CEST)