Android Open Source - Android-1 Gesture Image Activity

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License

The source code is released under:

MIT License

Java Source Code

package com.example.gestureimageview;
//  ww w.j  a v a 2  s  .  c  o  m
import java.util.ArrayList;
import java.util.List;

import android.animation.Animator;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.animation.PropertyValuesHolder;
import android.app.Activity;
import android.graphics.PointF;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.ImageView;

public class GestureImageActivity extends Activity implements OnTouchListener, OnClickListener {

  private View root;
  private Button btnFrame;
  private Button btnPlay;
  private ImageView image;
  
  List<Animator> animations;

  private PointF finger1;
  private PointF finger2;

  private float prevPanX;
  private float prevPanY;
  private float currPanX;
  private float currPanY;
  private float prevRotation;
  private float currRotation;
  private float prevScale;
  private float currScale;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.image_gestures);
    root = findViewById(R.id.root);
    root.setOnTouchListener(this);
    btnFrame = (Button) findViewById(R.id.frame);
    btnFrame.setOnClickListener(this);
    btnPlay = (Button) findViewById(R.id.play);
    btnPlay.setOnClickListener(this);
    image = (ImageView) findViewById(R.id.image);
    
    animations = new ArrayList<Animator>();
    
    finger1 = new PointF();
    finger2 = new PointF();
  }

  @Override
  public boolean onTouch(View v, MotionEvent event) {
    update(event);

    int pointerCount = event.getPointerCount();
    int action = event.getAction() & MotionEvent.ACTION_MASK;

    switch (action) {
    case MotionEvent.ACTION_DOWN:
    case MotionEvent.ACTION_POINTER_DOWN:
      if (pointerCount == 2) {
        prevPanX = getCenter(finger1.x, finger2.x);
        prevPanY = getCenter(finger1.y, finger2.y);
        prevRotation = getAngle(finger1, finger2);
        prevScale = getDistance(finger1, finger2);
      } else if (pointerCount == 1) {
        resetPan();
      }
      break;
    case MotionEvent.ACTION_UP:
    case MotionEvent.ACTION_POINTER_UP:
    case MotionEvent.ACTION_CANCEL:
      if (event.getPointerCount() == 2) {
        resetPan();
      }
      break;
    case MotionEvent.ACTION_MOVE:
      if (pointerCount == 2) {
        currPanX = getCenter(finger1.x, finger2.x);
        currPanY = getCenter(finger1.y, finger2.y);
        currRotation = getAngle(finger1, finger2);
        currScale = getDistance(finger1, finger2);

        float deltaRotation = currRotation - prevRotation;
        float deltaScale = currScale / prevScale;

        image.setRotation(image.getRotation() + deltaRotation);
        image.setScaleX(image.getScaleX() * deltaScale);
        image.setScaleY(image.getScaleY() * deltaScale);

        prevRotation = currRotation;
        prevScale = currScale;
      } else if (pointerCount == 1) {
        currPanX = finger1.x;
        currPanY = finger1.y;
      }

      float deltaPanX = currPanX - prevPanX;
      float deltaPanY = currPanY - prevPanY;

      image.setTranslationX(image.getTranslationX() + deltaPanX);
      image.setTranslationY(image.getTranslationY() + deltaPanY);

      prevPanX = currPanX;
      prevPanY = currPanY;

      break;
    }
    return true;
  }

  private void update(MotionEvent event) {
    for (int pointerIndex = 0; pointerIndex < event.getPointerCount(); pointerIndex++) {
      int pointerId = event.getPointerId(pointerIndex);
      if (pointerId == 0) {
        finger1.x = event.getX(pointerIndex);
        finger1.y = event.getY(pointerIndex);
      }
      if (pointerId == 1) {
        finger2.x = event.getX(pointerIndex);
        finger2.y = event.getY(pointerIndex);
      }
    }
  }

  private void resetPan() {
    prevPanX = finger1.x;
    prevPanY = finger1.y;
  }

  private float getCenter(float x1, float x2) {
    return (x1 + x2) / 2;
  }

  private float getAngle(PointF p1, PointF p2) {
    float xDiff = p2.x - p1.x;
    float yDiff = p2.y - p1.y;
    return (float) Math.toDegrees(Math.atan2(yDiff, xDiff));
  }

  private float getDistance(PointF p1, PointF p2) {
    float xDiff = p2.x - p1.x;
    float yDiff = p2.y - p1.y;
    return (float) Math.sqrt(xDiff * xDiff + yDiff * yDiff);
  }

  @Override
  public void onClick(View v) {
    if (v == btnFrame) {
      PropertyValuesHolder translationX = PropertyValuesHolder.ofFloat("translationX", image.getTranslationX());
      PropertyValuesHolder translationY = PropertyValuesHolder.ofFloat("translationY", image.getTranslationY());
      PropertyValuesHolder scaleX = PropertyValuesHolder.ofFloat("scaleX", image.getScaleX());
      PropertyValuesHolder scaleY = PropertyValuesHolder.ofFloat("scaleY", image.getScaleY());
      PropertyValuesHolder rotation = PropertyValuesHolder.ofFloat("rotation", image.getRotation());
      animations.add(ObjectAnimator.ofPropertyValuesHolder(image, translationX, translationY, scaleX, scaleY, rotation));
    } else if (v == btnPlay) {
      AnimatorSet as = new AnimatorSet();
      as.playSequentially(new ArrayList<Animator>(animations));
      as.start();
      animations.clear();
    }
  }
}

Java Source Code List

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