Write a piece of pseudo-code that override the onTouchEvent function in a View to perform “rotation” of the View content. You should use the appropriate event actions. No code needed for the object drawing
时间: 2023-07-16 19:17:03 浏览: 129
Here is an example of how to override the onTouchEvent function in a View to perform rotation of the View content:
```
public class MyView extends View {
private float mLastTouchX;
private float mLastTouchY;
public MyView(Context context) {
super(context);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mLastTouchX = event.getX();
mLastTouchY = event.getY();
break;
case MotionEvent.ACTION_MOVE:
float dx = event.getX() - mLastTouchX;
float dy = event.getY() - mLastTouchY;
float angle = (float) Math.atan2(dy, dx);
setRotation(angle * 180 / (float) Math.PI);
break;
}
return true;
}
}
```
This code creates a custom View called `MyView` and overrides its `onTouchEvent` function. When the user touches down on the view, the code saves the coordinates of the touch. When the user moves their finger across the screen, the code calculates the angle between the initial touch position and the current touch position, and uses that angle to set the rotation of the view. The `setRotation` method is a built-in method of the View class that sets the rotation of the view in degrees.
Note that this code assumes that the View already has content to rotate. No code is provided for drawing the object itself.
阅读全文