Spinning image in Delphi - delphi

Question

I am testing how to spin image in Delphi (on Android). For some reason it works only if I move two fingers on the screen. And the rotation isn't smooth. Ideally on-clik on the image with one finger I would like to have the image spinning until it's stopped by another click. Also, is there a better more Delphi like way to achieve this? I have this code (RAD Delphi 10.4):
unit Unit1;
interface
uses
System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.Objects,
FMX.Colors, System.IOUtils, FMX.Gestures, System.Math, FMX.Media;
type
TForm1 = class(TForm)
ColorBox1: TColorBox;
ColorBox2: TColorBox;
ColorBox3: TColorBox;
ColorBox4: TColorBox;
ColorBox5: TColorBox;
ColorBox6: TColorBox;
Image1: TImage;
GestureManager1: TGestureManager;
MediaPlayer1: TMediaPlayer;
procedure ColorBox1Click(Sender: TObject);
procedure ColorBox2Click(Sender: TObject);
procedure ColorBox3Click(Sender: TObject);
procedure ColorBox4Click(Sender: TObject);
procedure ColorBox5Click(Sender: TObject);
procedure ColorBox6Click(Sender: TObject);
procedure Image1Gesture(Sender: TObject; const EventInfo: TGestureEventInfo;
var Handled: Boolean);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.fmx}
{$R *.LgXhdpiPh.fmx ANDROID}
procedure TForm1.ColorBox1Click(Sender: TObject);
var
number: Integer;
stop: Boolean;
begin
//Image1.Bitmap.LoadFromFile('../../images/black.png')
Image1.Bitmap.LoadFromFile(TPath.GetDocumentsPath + PathDelim + 'black.png');
MediaPlayer1.FileName := TPath.Combine(TPath.GetDocumentsPath, 'spinner.3gp');
MediaPlayer1.Play;
end;
procedure TForm1.ColorBox2Click(Sender: TObject);
begin
//Image1.Bitmap.LoadFromFile('../../images/blue.png')
Image1.Bitmap.LoadFromFile(TPath.GetDocumentsPath + PathDelim + 'blue.png');
end;
procedure TForm1.ColorBox3Click(Sender: TObject);
begin
//Image1.Bitmap.LoadFromFile('../../images/red.png')
Image1.Bitmap.LoadFromFile(TPath.GetDocumentsPath + PathDelim + 'red.png');
end;
procedure TForm1.ColorBox4Click(Sender: TObject);
begin
//Image1.Bitmap.LoadFromFile('../../images/green.png')
Image1.Bitmap.LoadFromFile(TPath.GetDocumentsPath + PathDelim + 'green.png');
end;
procedure TForm1.ColorBox5Click(Sender: TObject);
begin
//Image1.Bitmap.LoadFromFile('../../images/yellow.png')
Image1.Bitmap.LoadFromFile(TPath.GetDocumentsPath + PathDelim + 'yellow.png');
end;
procedure TForm1.ColorBox6Click(Sender: TObject);
begin
//Image1.Bitmap.LoadFromFile('../../images/pink.png')
Image1.Bitmap.LoadFromFile(TPath.GetDocumentsPath + PathDelim + 'pink.png');
end;
procedure TForm1.Image1Gesture(Sender: TObject;
const EventInfo: TGestureEventInfo; var Handled: Boolean);
var
LObj: IControl;
image: TImage;
begin
LObj := Self.ObjectAtPoint(ClientToScreen(EventInfo.Location));
if LObj is TImage then
begin
image := TImage(LObj.GetObject);
image.RotationAngle := RadToDeg(-EventInfo.Angle);
end;
end;
end.

Answer 1

It's better to use TImage's OnClick event instead of Gesture, I suppose.
const
RotationDelta = 0.5;
...
procedure TForm1.FormCreate(Sender: TObject);
begin
Timer1.Enabled := false; //to disable rotation
Timer1.Interval := 20;
end;
procedure TForm1.Image1Click(Sender: TObject);
begin
Timer1.Enabled := not Timer1.Enabled; //Timer.Interval should be 20-30 ms
end;
procedure TForm1.Timer1Timer(Sender: TObject);
begin
Image1.RotationAngle := Image1.RotationAngle + RotationDelta; //rotate image
end;
It's not very good implementation because TTimer is not very acurate, but it's good enough for general purpose. If you want slower or faster rotating you should change RotationDelta respectively.
But my advice will only work if you want to enable/disable rotation by clicking image, not while sliding.
P.S. Checked this solution on Delphi 10.1, but on Windows only.