首页 > 代码库 > 手势 触摸【缩放】GestureDetector MotionEvent 案例
手势 触摸【缩放】GestureDetector MotionEvent 案例
GestureDetector和ScaleGestureDetector示例
/**
* 演示【单点触摸手势识别器】
* 演示【缩放手势识别器】最简单的使用
* @author 白乾涛
*/
public class FirstActivity extends Activity implements OnTouchListener {
private ImageView iv;
private GestureDetector mGestureDetector;//单击和双击事件手势识别器
private ScaleGestureDetector mScaleGestureDetector;//缩放事件手势识别器
private Matrix matrix = new Matrix();
private DecimalFormat df = new DecimalFormat("0.00");//格式化float
private float lastScale = 1;//记录上次的缩放比例，下次缩放时是在此基础上进行的
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
iv = new ImageView(this);
iv.setImageResource(R.drawable.ic_launcher);
iv.setScaleType(ScaleType.MATRIX);//用矩阵来绘制
setContentView(iv);
mGestureDetector = new GestureDetector(this, new MyGestureListener());
mScaleGestureDetector = new ScaleGestureDetector(this, new SimpleOnScaleGestureListener() {
@Override
public boolean onScale(ScaleGestureDetector detector) {
float scale = detector.getScaleFactor(); //缩放因子，两指靠拢时小于1
float x = detector.getFocusX(), y = detector.getFocusY();//中心点坐标
Log.i("bqt", "缩放手势 onScale，" + df.format(scale) + "-" + df.format(x) + "-" + df.format(y));
matrix.setScale(lastScale * scale, lastScale * scale);
iv.setImageMatrix(matrix);
return super.onScale(detector);
}
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
Log.i("bqt", "缩放手势 onScaleBegin，" + df.format(detector.getScaleFactor()));//始终是1
return super.onScaleBegin(detector);
}
@Override
public void onScaleEnd(ScaleGestureDetector detector) {
super.onScaleEnd(detector);
lastScale *= detector.getScaleFactor();
Log.i("bqt", "缩放手势 onScaleEnd，" + df.format(detector.getScaleFactor()));
}
});
}
@Override
public boolean onTouchEvent(MotionEvent event) {
mGestureDetector.onTouchEvent(event);
mScaleGestureDetector.onTouchEvent(event);
return super.onTouchEvent(event);
}
@Override
public boolean onTouch(View v, MotionEvent event) {
return false;//设置OnTouchListener时，返回值要为false，或者在onTouch()中将MotionEvent事件传给GestureDetector，才能使手势识别器生效
}
class MyGestureListener extends SimpleOnGestureListener {
@Override
//双击的【第二下】Touch down时触发（只执行一次）
public boolean onDoubleTap(MotionEvent e) {
Log.i("bqt", "onDoubleTap");
return super.onDoubleTap(e);
}
@Override
//双击的【第二下】Touch down和up都会触发（执行次数不确定）。
public boolean onDoubleTapEvent(MotionEvent e) {
Log.i("bqt", "onDoubleTapEvent");
return super.onDoubleTapEvent(e);
}
@Override
//Touch down时触发
public boolean onDown(MotionEvent e) {
Log.i("bqt", "onDown");
return super.onDown(e);
}
@Override
//onScroll一点距离后，【抛掷时】触发（若是轻轻的、慢慢的停止活动，而非抛掷，则很可能不触发）
//参数为手指接触屏幕、离开屏幕一瞬间的动作事件，及手指水平、垂直方向移动的速度，像素/秒
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
Log.i("bqt", "onFling");
if ((e2.getRawX() - e1.getRawX()) > 100) {
Log.i("bqt", "onFling-从左到右滑");
return true;//消耗事件
}
return super.onFling(e1, e2, velocityX, velocityY);
}
@Override
//Touch了不移动一直Touch down时触发
public void onLongPress(MotionEvent e) {
Log.i("bqt", "onLongPress");
super.onLongPress(e);
}
@Override
//Touch了滑动时触发，e1代表触摸时的事件，是不变的，e2代表滑动过程中的事件，是时刻变化的
//distance是当前event2与上次回调时的event2之间的距离，代表上次回调之后到这次回调之前移动的距离
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
Log.i("bqt", "onScroll-" + (int) e1.getX() + "-" + (int) e2.getX() + "-" + (int) distanceX + "-" + (int) distanceY);
return super.onScroll(e1, e2, distanceX, distanceY);
}
@Override
//Touch了还没有滑动时触发
public void onShowPress(MotionEvent e) {
Log.i("bqt", "onShowPress");
super.onShowPress(e);
}
@Override
//在touch down后又没有滑动（onScroll），又没有长按（onLongPress），然后Touchup时触发。
public boolean onSingleTapConfirmed(MotionEvent e) {
Log.i("bqt", "onSingleTapConfirmed");
return super.onSingleTapConfirmed(e);
}
@Override
//在touch down后又没有滑动（onScroll），又没有长按（onLongPress），然后Touchup时触发。
public boolean onSingleTapUp(MotionEvent e) {
Log.i("bqt", "onSingleTapUp");
return super.onSingleTapUp(e);
}
}
}MotionEvent示例：缩放图片
public class SecondActivity extends Activity implements OnTouchListener {
private ImageView iv;
private float scale = 1;
private float lastScale = 1;//记录手指全部离开时的缩放比例，下次缩放时是在此基础上进行的
private float oldDist;//记录第二个触摸点和第一个触摸点之间的距离
private Matrix mMatrix = new Matrix();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
iv = new ImageView(this);
iv.setImageResource(R.drawable.ic_launcher);
iv.setBackgroundColor(0x8822ffff);//从背景可以看出，此ImageView 是占用整个屏幕大小的
iv.setScaleType(ScaleType.MATRIX);
iv.setOnTouchListener(this);
setContentView(iv);
}
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
Log.i("bqt", "ACTION_DOWN，第一个触摸点，所以肯定为【1】" + event.getPointerCount());
break;
case MotionEvent.ACTION_UP://当屏幕上唯一的点被放开时触发
lastScale = scale;//记录手指全部离开时的缩放比例，下次缩放时是在此基础上进行的
Log.i("bqt", "ACTION_UP，最后一个触摸点，之前触摸点数肯定为【1】" + event.getPointerCount());
break;
case MotionEvent.ACTION_POINTER_UP://当屏幕上有多个点被按住，松开其中一个点时触发
Log.i("bqt", "ACTION_POINTER_UP，少一个触摸点，少之前的触摸点数为" + event.getPointerCount());
break;
case MotionEvent.ACTION_POINTER_DOWN://当屏幕上已经有一个点被按住，此时再按下其他点时触发
if (event.getPointerCount() == 2) oldDist = spacing(event);//记录第二个触摸点和第一个触摸点之间的距离
Log.i("bqt", "ACTION_POINTER_DOWN，又一个触摸点，目前触摸点数为" + event.getPointerCount());
break;
case MotionEvent.ACTION_MOVE://当有点在屏幕上移动时触发
if (event.getPointerCount() == 2) {
float newDist = spacing(event);//移动过程中，第二个点和第一个点的距离
if (Math.abs(newDist - oldDist) > 10) {//减小灵敏度
scale = lastScale * newDist / oldDist;
Log.i("bqt", "ACTION_MOVE，缩放比例为" + scale);
mMatrix.setScale(scale, scale);
iv.setImageMatrix(mMatrix);
}
}
break;
}
return true;
}
/**
* 返回两个点之间的距离
*/
private float spacing(MotionEvent event) {
if (event.getPointerCount() >= 2) {
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return (float) Math.sqrt(x * x + y * y);
} else return 0;
}
}MotionEvent示例：功能增强
public class ThirdActivity extends Activity implements OnTouchListener {
private ImageView imageView;
private Matrix startMatrix = new Matrix();//ImageView初始矩阵
private Matrix matrix = new Matrix();//要给ImageView设置的矩阵
private float startDis;//两个手指的按下时的初始距离
private PointF midPoint;//两个手指的按下时中间点
private PointF startPoint = new PointF();//第一个手指按下时的坐标位置
private boolean isPointerUp;//当有手指放开时，如果不停止缩放，会导致图片位置错乱。后续可以优化
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
imageView = new ImageView(this);
imageView.setImageResource(R.drawable.ic_launcher);
imageView.setOnTouchListener(this);
imageView.setScaleType(ScaleType.MATRIX);
setContentView(imageView);
}
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
Log.i("bqt", "初始矩阵" + imageView.getImageMatrix());//值是会变的 {[1.0, 0.0, 0.0][0.0, 1.0, 0.0][0.0, 0.0, 1.0]}
startMatrix.set(imageView.getImageMatrix());//获取初始状态
startPoint.set(event.getX(), event.getY());//获取开始时候的坐标位置
isPointerUp = true;
break;
case MotionEvent.ACTION_MOVE:
if (isPointerUp) {
if (event.getPointerCount() == 1) { //移动图片
float dx = event.getX() - startPoint.x; // 得到X轴的移动距离
float dy = event.getY() - startPoint.y; // 得到Y轴的移动距离
Log.i("bqt", "移动距离" + (int) dx + "---" + (int) dy);
matrix.set(startMatrix);//先置为初始状态
matrix.postTranslate(dx, dy);
} else if (event.getPointerCount() == 2) { // 放大缩小图片
float endDis = distance(event);// 距离
float scale = endDis / startDis;//ImageView缩放的比例
Log.i("bqt", "缩放倍数" + scale);
matrix.set(startMatrix);
matrix.postScale(scale, scale, midPoint.x, midPoint.y);
}
imageView.setImageMatrix(matrix);
}
break;
case MotionEvent.ACTION_POINTER_DOWN:
startDis = distance(event);
midPoint = mid(event);
startMatrix.set(imageView.getImageMatrix());//重置为目前的初始状态
break;
case MotionEvent.ACTION_UP:
break;
case MotionEvent.ACTION_POINTER_UP:
isPointerUp = false;
break;
}
return true;
}
/** 计算两个手指间的距离 */
private float distance(MotionEvent event) {
float dx = event.getX(1) - event.getX(0);
float dy = event.getY(1) - event.getY(0);
/** 使用勾股定理返回两点之间的距离 */
return (float) Math.sqrt(dx * dx + dy * dy);
}
/** 计算两个手指间的中间点 */
private PointF mid(MotionEvent event) {
float midX = (event.getX(1) + event.getX(0)) / 2;
float midY = (event.getY(1) + event.getY(0)) / 2;
return new PointF(midX, midY);
}
}附件列表
手势 触摸【缩放】GestureDetector MotionEvent 案例
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