macOS Gestures

(macOS only)

Overview

The Gestures unit provides convenient Free Pascal classes for handling macOS gestures.

Currently only the magnification gesture is implemented, but others can be implemented easily in a similar way.

Usage Example

Let's assume your scalable control has a Scale property and you want to allow an end user to scale it by using the typical trackpad gesture. Here is the code:

uses
  Gestures;

type
  TForm_Main = class(TForm)
  private
    Gesture: TMagnificationGesture;
    InitialScale: Double;
  end;

procedure TForm_Main.FormCreate(Sender: TObject);
begin
  Gesture := TMagnificationGesture.Create(Self);
  Gesture.Control := MyScalableControl;
  Gesture.OnGesture := @MagnificationGestureGesture;
end;

procedure TForm_Main.MagnificationGestureGesture(Sender: TMagnificationGesture;
  State: TGestureState; Magnification: Double);
begin
  case State of
    gsBegan:
      InitialScale := MyScalableControl.Scale;

    gsChanged:
      if Magnification > 0 then
        MyScalableControl.Scale := InitialScale * (1 + Magnification)
      else
        MyScalableControl.Scale := InitialScale / (1 - Magnification);
  end;
end;

Author

Yuri Plashenkov

License

This package is licensed under the MIT license.

Download

The Gestures unit may be downloaded from GitHub.

External links

• Apple: Trackpad gestures
• Apple: Gestures

From the Free Pascal wiki, page "macOS Gestures", as it stood on 2020-11-29 after a change by Trev, 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.