How to rotate a RoundRect on click

[Linuxuser1234 1]

I made a RoundRect to look like a tune Knob and i would like the knob to rotate on click  so how can i write a Onclick procedure to rotate the round rect at different angles 

[Rollo62 536]

In FMX you have RotationAngle and RotationCenter, that should be doing it.

[Linuxuser1234 1]

 

procedure TForm7.KnobClick(Sender: TObject);
begin
//Knob
property RotationAngle: Single read GetRotationAngle write SetRotationAngle;

end;

@Rollo62 this causes Expected END but received Property 

Edited November 8, 2022 by Linuxuser1234

[Rollo62 536]

procedure TForm7.FormCreate(Sender: TObject);
begin
    MyRoundRect.RotationCenter.Point( Pointf( MyRoundRect.Position.X + MyRoundRect.Width / 2.0,  MyRoundRect.Position.Y + MyRoundRect.Height / 2.0 ) ); 
end;

procedure TForm7.KnobLeftClick(Sender: TObject);
begin
    MyRoundRect.RotationAngle := MyRoundRect.RotationAngle - 15.0; 
end;

procedure TForm7.KnobRightClick(Sender: TObject);
begin
    MyRoundRect.RotationAngle := MyRoundRect.RotationAngle + 15.0; 
end;

Something similar like this (Untested) ?

Or even adding some smooth animation by TFloatAnimation, like this.

Edited November 8, 2022 by Rollo62

[Linuxuser1234 1]

@Rollo62  ignore this comment 

Edited November 8, 2022 by Linuxuser1234

[Linuxuser1234 1]

@Rollo62  also how would i change   a tlabel text based on what angle the knob is set to for example if the angle is at 15deg

the tlabel would  display another text and i do know how to set the text just not sure how to set the text based off the knob angle 

Edited November 8, 2022 by Linuxuser1234

[Rollo62 536]

function TForm7.GetMyStationNameFromAngleMethod( const AAngle : Single ) : String;
const
    CStations : array[0..24-1] of String = (  'New York, 'Honolulu', 'Tokyo' ... 'Paris' );
var
    LIdx : Integer;
begin
    LIdx := AAngle div 15.0;	// 0 ... 360 to 0 ... 23

    Result := CStations[ LIdx ];
end;

function TForm7.GetMyStationFreqFromAngleMethod( const AAngle : Single ) : Single;
begin
    Result := (AAngle / 360.0) * 200.0;   // 0 ... 360 to 0 ... 200.0 MHz
end;


procedure TForm7.KnobLeftClick(Sender: TObject);
begin
    MyRoundRect.RotationAngle := MyRoundRect.RotationAngle - 15.0; 

    Label1.Text := Format( 'My station is %s at %4.0f MHz, 
                           [ GetMyStationNameFromAngleMethod( MyRoundRect.RotationAngle ), GetMyStationFreqFromAngleMethod( MyRoundRect.RotationAngle ) ] );
end;

procedure TForm7.KnobRightClick(Sender: TObject);
begin
    MyRoundRect.RotationAngle := MyRoundRect.RotationAngle + 15.0; 

    Label1.Text := Format( 'My station is %s at %4.0f MHz, 
                           [ GetMyStationNameFromAngleMethod( MyRoundRect.RotationAngle ), GetMyStationFreqFromAngleMethod( MyRoundRect.RotationAngle ) ] );
end;

I assume you want to display the station name and frequency, right ?

Just a rough idea, its already very late here ...

Since I don't know exactly what you need this is a wild guess 🙂

Edited November 8, 2022 by Rollo62

[Linuxuser1234 1]

@Rollo62 sorry if this question sounds basic but i cant figure out how to fix this error TForm7 does not contain a member  named KnobLabelStationAngle  i have put the function line under the procedure and in public/private nothing worked 

[Rollo62 536]

You can simply add your function declaration and definition in the code window, similar like this:

 

unit UMain_Form;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
  FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.Layouts
  ;

type
  TForm1 = class(TForm)
  private
    { Private declarations }
  public
    { Public declarations }

    function MakeANewFunction( const AParam : Single ) : String;
  end;

var
  Form1: TForm1;

implementation

{$R *.fmx}

{ TForm1 }

function TForm1.MakeANewFunction(const AParam: Single): String;
begin
    if AParam >  100.0 then
        Result := 'Large'
    else
    if AParam >=   0.0 then
        Result := 'Small'    
    else
        Result := 'Negative';
end;

end.

For these kind of questions you better look into a good, basic Delphi book, like this one from Marco Cantu.

Edited November 9, 2022 by Rollo62

[Linuxuser1234 1]

@Rollo62 i put the function under public still wont work 

  private
    { Private declarations }
  public
    { Public declarations }

   function TForm7.KnobLabelStationAngle(const AAngle : Single) : String; overload;
   function TForm7.KnobLabelFreqAngle(const AAngle : Single ) : Single; overload;
  end;

procedure TForm7.KnobClick(Sender: TObject);
begin
//Knob
Knob.RotationAngle := Knob.RotationAngle - 15.0;
Rectangle4.RotationAngle := Knob.RotationAngle - 15.0;
Label2.Text := Format ('%s',
                      [KnobLabelStationAngle(Knob.RotationAngle), KnobLabelFreqAngle(Knob.RotationAngle) ] );
end;
function TForm7.KnobLabelStationAngle(const AAngle : Single) : String;
const
CStationLabel : array[0..24-1] of String = ('KEC61', 'WXK30');
var
LIdx : Integer;
begin
LIdx := AAngle div 15.0;
Result := CStationLabel[LIdx];
end;
function TForm7.KnobLabelFreqAngle(const AAngle : Single ) : Single;
begin
  Result := (AAngle / 162.550 * 162.525 * 162.500  * 162.400 * 162.475)
end;

Edited November 9, 2022 by Linuxuser1234

[Rollo62 536]

What I spot without too much looking into details: Your inside TForm7 declaration, so don't write TForm7. here

private
    { Private declarations }
  public
    { Public declarations }

   //function TForm7.KnobLabelStationAngle(const AAngle : Single) : String; overload;
   function KnobLabelStationAngle(const AAngle : Single) : String; overload;
   //function TForm7.KnobLabelFreqAngle(const AAngle : Single ) : Single; overload;
   function KnobLabelFreqAngle(const AAngle : Single ) : Single; overload;
  end;

 

[Linuxuser1234 1]

@Rollo62 

now i get this and also when i click on the design tab i keep getting a error saying container form not set and i changed the name from ignore the first error i got it fixed but im still getting the second error 

//second error line  
LIdx := AAngle div 15.0;

Edited November 9, 2022 by Linuxuser1234

[Linuxuser1234 1]

@Rollo62 i just had to restart the ide to get rid of the container form not set message 

 

Edited November 9, 2022 by Linuxuser1234

[Rollo62 536]

Ok, ok, here is a short demo maybe what you are looking for, additionally with some mouse drag-and-drop for the knob..

I would really recommend that you look into some books and the help before continuing, as well as checking out all the samples.

Maybe that small demo helps for a start, but you should begin with the basics first.

 

T465_Rotation_001.zip

Edited November 9, 2022 by Rollo62