How to get the touch coordinates of a touch event in HarmonyOS?

In HarmonyOS, obtaining touch coordinates from user touch events can be achieved by listening to touch events and utilizing the TouchEvent class. The specific steps are as follows:

1. Create a touch listener:
   First, set up a touch event listener for your component or view. This is typically implemented within your AbilitySlice (equivalent to Android's Activity or Fragment).

2. Implement event handling logic:
   Within the touch event listener, you can process touch events using the onTouchEvent method, which receives a TouchEvent object containing all relevant information, including touch coordinates.

3. Retrieve touch coordinates:
   Within the TouchEvent object, you can call getPointerPosition(int pointerIndex) to get the position of a specific touch point. For single-point touch scenarios, directly retrieve the touch point with index 0.

Here is a simple code example demonstrating how to set up a touch listener and retrieve touch coordinates within a HarmonyOS AbilitySlice:

java
public class MainAbilitySlice extends AbilitySlice {
    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        Component mainComponent = findComponentById(ResourceTable.Id_main_component);
        mainComponent.setTouchEventListener(new Component.TouchEventListener() {
            @Override
            public boolean onTouchEvent(Component component, TouchEvent touchEvent) {
                int action = touchEvent.getAction();
                if (action == TouchEvent.PRIMARY_POINT_DOWN) {
                    // Retrieve coordinates of the first touch point
                    Point touchPoint = touchEvent.getPointerPosition(0);
                    float touchX = touchPoint.getX();
                    float touchY = touchPoint.getY();
                    System.out.println("Touch coordinates: (" + touchX + ", " + touchY + ")");
                }
                return true;
            }
        });
    }
}

In this example, when a user touches the component, the onTouchEvent method is triggered. You can obtain touch point coordinates using getPointerPosition(0) and extract the x and y values via getX() and getY() methods.

In summary, by implementing a touch event listener and leveraging methods of the TouchEvent class within the handling function, developers can efficiently capture and respond to user touch inputs in HarmonyOS.