GestureDetector和ScaleGestureDetector示例
/**
* 演示【單點觸摸手勢識別器】
* 演示【縮放手勢識別器】最簡單的使用
* @author 白乾濤
*/
public class FirstActivity extends Activity implements OnTouchListener {
private ImageView iv;
private GestureDetector mGestureDetector;//單擊和雙擊事件手勢識別器
private ScaleGestureDetector mScaleGestureDetector;//縮放事件手勢識別器
private Matrix matrix = new Matrix();
private DecimalFormat df = new DecimalFormat("0.00");//格式化float
private float lastScale = 1;//記錄上次的縮放比例，下次縮放時是在此基礎上進行的
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
iv = new ImageView(this);
iv.setImageResource(R.drawable.ic_launcher);
iv.setScaleType(ScaleType.MATRIX);//用矩陣來繪制
setContentView(iv);
mGestureDetector = new GestureDetector(this, new MyGestureListener());
mScaleGestureDetector = new ScaleGestureDetector(this, new SimpleOnScaleGestureListener() {
@Override
public boolean onScale(ScaleGestureDetector detector) {
float scale = detector.getScaleFactor(); //縮放因子，兩指靠攏時小於1
float x = detector.getFocusX(), y = detector.getFocusY();//中心點坐標
Log.i("bqt", "縮放手勢 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", "縮放手勢 onScaleBegin，" + df.format(detector.getScaleFactor()));//始終是1
return super.onScaleBegin(detector);
}
@Override
public void onScaleEnd(ScaleGestureDetector detector) {
super.onScaleEnd(detector);
lastScale *= detector.getScaleFactor();
Log.i("bqt", "縮放手勢 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;//設置OnTouchListener時，返回值要為false，或者在onTouch()中將MotionEvent事件傳給GestureDetector，才能使手勢識別器生效
}
class MyGestureListener extends SimpleOnGestureListener {
@Override
//雙擊的【第二下】Touch down時觸發（只執行一次）
public boolean onDoubleTap(MotionEvent e) {
Log.i("bqt", "onDoubleTap");
return super.onDoubleTap(e);
}
@Override
//雙擊的【第二下】Touch down和up都會觸發（執行次數不確定）。
public boolean onDoubleTapEvent(MotionEvent e) {
Log.i("bqt", "onDoubleTapEvent");
return super.onDoubleTapEvent(e);
}
@Override
//Touch down時觸發
public boolean onDown(MotionEvent e) {
Log.i("bqt", "onDown");
return super.onDown(e);
}
@Override
//onScroll一點距離后，【拋擲時】觸發（若是輕輕的、慢慢的停止活動，而非拋擲，則很可能不觸發）
//參數為手指接觸屏幕、離開屏幕一瞬間的動作事件，及手指水平、垂直方向移動的速度，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-從左到右滑");
return true;//消耗事件
}
return super.onFling(e1, e2, velocityX, velocityY);
}
@Override
//Touch了不移動一直Touch down時觸發
public void onLongPress(MotionEvent e) {
Log.i("bqt", "onLongPress");
super.onLongPress(e);
}
@Override
//Touch了滑動時觸發，e1代表觸摸時的事件，是不變的，e2代表滑動過程中的事件，是時刻變化的
//distance是當前event2與上次回調時的event2之間的距離，代表上次回調之后到這次回調之前移動的距離
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了還沒有滑動時觸發
public void onShowPress(MotionEvent e) {
Log.i("bqt", "onShowPress");
super.onShowPress(e);
}
@Override
//在touch down后又沒有滑動（onScroll），又沒有長按（onLongPress），然后Touchup時觸發。
public boolean onSingleTapConfirmed(MotionEvent e) {
Log.i("bqt", "onSingleTapConfirmed");
return super.onSingleTapConfirmed(e);
}
@Override
//在touch down后又沒有滑動（onScroll），又沒有長按（onLongPress），然后Touchup時觸發。
public boolean onSingleTapUp(MotionEvent e) {
Log.i("bqt", "onSingleTapUp");
return super.onSingleTapUp(e);
}
}
}
MotionEvent示例：縮放圖片
public class SecondActivity extends Activity implements OnTouchListener {
private ImageView iv;
private float scale = 1;
private float lastScale = 1;//記錄手指全部離開時的縮放比例，下次縮放時是在此基礎上進行的
private float oldDist;//記錄第二個觸摸點和第一個觸摸點之間的距離
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);//從背景可以看出，此ImageView 是占用整個屏幕大小的
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，第一個觸摸點，所以肯定為【1】" + event.getPointerCount());
break;
case MotionEvent.ACTION_UP://當屏幕上唯一的點被放開時觸發
lastScale = scale;//記錄手指全部離開時的縮放比例，下次縮放時是在此基礎上進行的
Log.i("bqt", "ACTION_UP，最后一個觸摸點，之前觸摸點數肯定為【1】" + event.getPointerCount());
break;
case MotionEvent.ACTION_POINTER_UP://當屏幕上有多個點被按住，松開其中一個點時觸發
Log.i("bqt", "ACTION_POINTER_UP，少一個觸摸點，少之前的觸摸點數為" + event.getPointerCount());
break;
case MotionEvent.ACTION_POINTER_DOWN://當屏幕上已經有一個點被按住，此時再按下其他點時觸發
if (event.getPointerCount() == 2) oldDist = spacing(event);//記錄第二個觸摸點和第一個觸摸點之間的距離
Log.i("bqt", "ACTION_POINTER_DOWN，又一個觸摸點，目前觸摸點數為" + event.getPointerCount());
break;
case MotionEvent.ACTION_MOVE://當有點在屏幕上移動時觸發
if (event.getPointerCount() == 2) {
float newDist = spacing(event);//移動過程中，第二個點和第一個點的距離
if (Math.abs(newDist - oldDist) > 10) {//減小靈敏度
scale = lastScale * newDist / oldDist;
Log.i("bqt", "ACTION_MOVE，縮放比例為" + scale);
mMatrix.setScale(scale, scale);
iv.setImageMatrix(mMatrix);
}
}
break;
}
return true;
}
/**
* 返回兩個點之間的距離
*/
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：功能增強
public class ThirdActivity extends Activity implements OnTouchListener {
private ImageView imageView;
private Matrix startMatrix = new Matrix();//ImageView初始矩陣
private Matrix matrix = new Matrix();//要給ImageView設置的矩陣
private float startDis;//兩個手指的按下時的初始距離
private PointF midPoint;//兩個手指的按下時中間點
private PointF startPoint = new PointF();//第一個手指按下時的坐標位置
private boolean isPointerUp;//當有手指放開時，如果不停止縮放，會導致圖片位置錯亂。后續可以優化
@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", "初始矩陣" + imageView.getImageMatrix());//值是會變的 {[1.0, 0.0, 0.0][0.0, 1.0, 0.0][0.0, 0.0, 1.0]}
startMatrix.set(imageView.getImageMatrix());
//獲取初始狀態
startPoint.set(event.getX(), event.getY());//獲取開始時候的坐標位置
isPointerUp = true;
break;
case MotionEvent.ACTION_MOVE:
if (isPointerUp) {
if (event.getPointerCount() == 1) { //移動圖片
float dx = event.getX() - startPoint.x; // 得到X軸的移動距離
float dy = event.getY() - startPoint.y; // 得到Y軸的移動距離
Log.i("bqt", "移動距離" + (int) dx + "---" + (int) dy);
matrix.set(startMatrix);//先置為初始狀態
matrix.postTranslate(dx, dy);
} else if (event.getPointerCount() == 2) { // 放大縮小圖片
float endDis = distance(event);// 距離
float scale = endDis / startDis;//ImageView縮放的比例
Log.i("bqt", "縮放倍數" + 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());//重置為目前的初始狀態
break;
case MotionEvent.ACTION_UP:
break;
case MotionEvent.ACTION_POINTER_UP:
isPointerUp = false;
break;
}
return true;
}
/** 計算兩個手指間的距離 */
private float distance(MotionEvent event) {
float dx = event.getX(1) - event.getX(0);
float dy = event.getY(1) - event.getY(0);
/** 使用勾股定理返回兩點之間的距離 */
return (float) Math.sqrt(dx * dx + dy * dy);
}
/** 計算兩個手指間的中間點 */
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);
}
}
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