This interactive gestures example is designed for a touch screen interface. The example works on both Windows 8 and Windows 7. The Add Picture option makes an Open dialog appear, where you can select pictures (.jpg, .jpeg, .bmp, .png – more extensions can be added in the procedure TForm36.MenuItem1Click). The pictures are added as 200x200 images on the form (one on top of the other if more than one picture is selected). You can manipulate the picture(s) by using interactive gestures: Pan – moves picture around Zoom – makes picture smaller/bigger Rotate – rotates the picture Press and Tap – deletes the picture TGestureEventInfo is used by the interactive gesture procedures.
type TForm36 = class(TForm) MenuBar1: TMenuBar; MenuItem1: TMenuItem; OpenDialog1: TOpenDialog; Panel1: TPanel; procedure MenuItem1Click(Sender: TObject); procedure Panel1Gesture(Sender: TObject; const EventInfo: TGestureEventInfo; var Handled: Boolean); private FImages: TList<TImage>; FLastPosition: TPointF; FLastDistance: Integer; procedure AddPicture(files: TStrings); procedure handlePan(eventInfo: TGestureEventInfo); procedure handleZoom(eventInfo: TGestureEventInfo); procedure handleRotate(eventInfo: TGestureEventInfo); procedure handlePressAndTap(eventInfo: TGestureEventInfo); public end; var Form36: TForm36; //Here is the event handler for the Add Picture button (TForm36.MenuItem1Click calls the OpenDialog which in turn calls the AddPicture procedure): procedure TForm36.MenuItem1Click(Sender: TObject); begin OpenDialog1.Filter := 'Images|*.jpg;*.jpeg;*.bmp;*.png'; if OpenDialog1.Execute then begin AddPicture(OpenDialog1.files); end; // Panel1Gesture //For the TPanel, a TForm36.Panel1Gesture is the event handler for the Pan, Zoom, Rotate, and PressAndTap gestures: procedure TForm36.Panel1Gesture(Sender: TObject; const EventInfo: TGestureEventInfo; var Handled: Boolean); begin if EventInfo.GestureID = igiPan then handlePan(EventInfo) else if EventInfo.GestureID = igiZoom then handleZoom(EventInfo) else if EventInfo.GestureID = igiRotate then handleRotate(EventInfo) else if EventInfo.GestureID = igiPressAndTap then hand // handlePan //Here is the event handler when the GestureID = igiPan: procedure TForm36.handlePan(EventInfo: TGestureEventInfo); var LObj: IControl; image: TImage; begin LObj := Self.ObjectAtPoint(ClientToScreen(EventInfo.Location)); if LObj is TImage then begin if not(TInteractiveGestureFlag.gfBegin in EventInfo.Flags) then begin image := TImage(LObj.GetObject); //Set the X coordinate. image.Position.X := image.Position.X (EventInfo.Location.X - FLastPosition.X); if image.Position.X < 0 then image.Position.X := 0; if image.Position.X > (Panel1.Width - image.Width) then image.Position.X := Panel1.Width - image.Width; //Set the Y coordinate. image.Position.Y := image.Position.Y (EventInfo.Location.Y - FLastPosition.Y); if image.Position.Y < 0 then image.Position.Y := 0; if image.Position.Y > (Panel1.Height - image.Height) then image.Position.Y := Panel1.Height - image.Height; end; FLastPosition := EventInfo.Location; end; // handleRotate //Here is the event handler when GestureID = igiRotate: procedure TForm36.handleRotate(eventInfo: TGestureEventInfo); 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; // handleZoom //Here is the event handler when GestureID = igiZoom: procedure TForm36.handleZoom(EventInfo: TGestureEventInfo); var LObj: IControl; image: TImage; begin LObj := Self.ObjectAtPoint(ClientToScreen(EventInfo.Location)); if LObj is TImage then begin if not(TInteractiveGestureFlag.gfBegin in EventInfo.Flags) then begin image := TImage(LObj.GetObject); image.Width := image.Width (EventInfo.Distance - FLastDIstance)/2; image.Height := image.Height (EventInfo.Distance - FLastDIstance)/2; image.Position.X := image.Position.X - (EventInfo.Distance - FLastDIstance)/2; image.Position.Y := image.Position.Y - (EventInfo.Distance - FLastDIstance)/2; end; end; FLastDIstance := EventInfo.Distance; end; // handlePressAndTap //Here is the event handler when GestureID = igiPressAndTap: procedure TForm36.handlePressAndTap(EventInfo: TGestureEventInfo); var LObj: IControl; image: TImage; begin LObj := Self.ObjectAtPoint(ClientToScreen(EventInfo.Location)); if LObj is TImage then begin image := TImage(LObj.GetObject); FImages.Remove(image); FreeAndNil(image); end; end;
Comments (1)
Kubilay
good
2/6/2017