FMX.ImageRotation Sample

This sample uses the TGestureManager class to demonstrate how to rotate an image.

Location

You can find the ImageRotation sample project at:

• Start | Programs | Embarcadero RAD Studio Athens | Samples and then navigate to:
  • Object Pascal\Mobile Snippets\InteractiveGestures\ImageRotation
  • CPP\Mobile Snippets\InteractiveGestures\ImageRotation
• Subversion Repository:
  • You can find Delphi and C++ code samples in GitHub Repositories. Search by name into the samples repositories according to your RAD Studio version.

Description

The ImageRotation sample demonstrates how to rotate an image on an iOS or Android device. The sample provides a picture and the user can rotate the picture by pressing it with two fingers and rotating them. The image rotates in the direction of your fingers. If you rotate the fingers to the right, the image rotates to the right. If you rotate the fingers to the left, the image rotates to the left.

How to Use the Sample

1. Navigate to one of the locations given above and open:
   • Delphi: ImageRotation.dproj.
   • C++: ImageRotation.cbproj.
2. Select the target platform, iOS and Android supported.
3. Press F9 or choose Run > Run.
4. Press the picture with two fingers and rotate them to see how the image rotates.

Files

File in Delphi	File in C++	Contains
ImageRotation.dproj	ImageRotation.cbproj	The project itself.
ImageRotationU.fmx	ImageRotationU.fmx	The main form where the components are located.
ImageRotationU.pas	ImageRotationPCH.h, ImageRotation.cpp	Used to define and implement the sample.
Information.txt	Information.txt	Further information about the sample.

Implementation

• The sample uses TImage to display and define a 2D image component.
• The property RotationAngle is used to specify the amount (in degrees) by which the image is rotated from the x-axis.
• The sample uses the TGestureManager class to manage all the touch and gesturing functionalities of the application.
• The TGestureEventInfo describes a gesture event. It is a record that contains information about a gesture event. The TGestureEvent type passes a TGestureEventInfo record to the user code.

The sample shows a picture. When the user presses the picture with two fingers, the TGestureEventInfo detects a gesture event. If the user rotates the fingers, the sample calculates the rotation angle in order to rotate the image with the same angle.

Uses

• FMX.Objects.TImage
• FMX.Objects.TImage.RotationAngle
• FMX.Gestures.TGestureManager
• FMX.Types.TGestureEventInfo

See Also

• Images
• Mobile Tutorial: Taking and Sharing Pictures (iOS and Android)
• Gesturing Overview
• Using Gesturing in Your Applications

Samples

• VCL.ImageProc_Sample
• FMX.ImageZoom_Sample
• FMX.TapAndHold_Sample
• FMX.AccessCameraApp Sample