我希望我的应用程序能够识别用户在手机屏幕上从右向左滑动。
如何做到这一点?
当前回答
@Mirek Rusin的回答很好。 但是，有一个小bug，需要修复
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
boolean result = false;
try {
float diffY = e2.getY() - e1.getY();
float diffX = e2.getX() - e1.getX();
if (Math.abs(diffX) > Math.abs(diffY)) {
if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
if (diffX > 0) {
if (getOnSwipeListener() != null) {
getOnSwipeListener().onSwipeRight();
}
} else {
if (getOnSwipeListener() != null) {
getOnSwipeListener().onSwipeLeft();
}
}
result = true;
}
}
else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
if (diffY > 0) {
if (getOnSwipeListener() != null) {
getOnSwipeListener().onSwipeBottom();
}
} else {
if (getOnSwipeListener() != null) {
getOnSwipeListener().onSwipeTop();
}
}
result = true;
}
有什么不同?我们设置result = true，仅当我们检查了所有的需求(SWIPE_THRESHOLD和SWIPE_VELOCITY_THRESHOLD都是Ok的)。这是重要的，如果我们放弃滑动，如果一些需求没有实现，我们必须做smth在OnSwipeTouchListener的onTouchEvent方法!
其他回答
OnSwipeTouchListener.java:
import android.content.Context;
import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
public class OnSwipeTouchListener implements OnTouchListener {
private final GestureDetector gestureDetector;
public OnSwipeTouchListener (Context ctx){
gestureDetector = new GestureDetector(ctx, new GestureListener());
}
@Override
public boolean onTouch(View v, MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
private final class GestureListener extends SimpleOnGestureListener {
private static final int SWIPE_THRESHOLD = 100;
private static final int SWIPE_VELOCITY_THRESHOLD = 100;
@Override
public boolean onDown(MotionEvent e) {
return true;
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
boolean result = false;
try {
float diffY = e2.getY() - e1.getY();
float diffX = e2.getX() - e1.getX();
if (Math.abs(diffX) > Math.abs(diffY)) {
if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
if (diffX > 0) {
onSwipeRight();
} else {
onSwipeLeft();
}
result = true;
}
}
else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
if (diffY > 0) {
onSwipeBottom();
} else {
onSwipeTop();
}
result = true;
}
} catch (Exception exception) {
exception.printStackTrace();
}
return result;
}
}
public void onSwipeRight() {
}
public void onSwipeLeft() {
}
public void onSwipeTop() {
}
public void onSwipeBottom() {
}
}
用法:
imageView.setOnTouchListener(new OnSwipeTouchListener(MyActivity.this) {
public void onSwipeTop() {
Toast.makeText(MyActivity.this, "top", Toast.LENGTH_SHORT).show();
}
public void onSwipeRight() {
Toast.makeText(MyActivity.this, "right", Toast.LENGTH_SHORT).show();
}
public void onSwipeLeft() {
Toast.makeText(MyActivity.this, "left", Toast.LENGTH_SHORT).show();
}
public void onSwipeBottom() {
Toast.makeText(MyActivity.this, "bottom", Toast.LENGTH_SHORT).show();
}
});
使用SwipeListView，让它为你处理手势检测。
这个问题仍然存在。添加以下类:
private class SwipeFirstTouchListener implements View.OnTouchListener {
private final DirtyOnSwipeTouchListener swipe;
private final View.OnTouchListener delegate;
private SwipeFirstTouchListener(DirtyOnSwipeTouchListener swipe, View.OnTouchListener delegate) {
this.swipe = swipe;
this.delegate = delegate;
}
@Override
public boolean onTouch(View v, MotionEvent event) {
if (!swipe.onTouch(v, event)) {
// no a swipe, so lets try with the rest of the events
return delegate.onTouch(v, event);
}
return false;
}
}
and
private class DirtyOnSwipeTouchListener extends OnSwipeTouchListener {
private boolean dirty = false;
private OnSwipeTouchListener delegate;
public DirtyOnSwipeTouchListener(Context ctx, OnSwipeTouchListener delegate) {
super(ctx);
this.delegate = delegate;
}
private void reset() {
dirty = false;
}
public void onSwipeTop() {
dirty = true;
delegate.onSwipeTop();
}
public void onSwipeRight() {
dirty = true;
delegate.onSwipeRight();
}
public void onSwipeLeft() {
dirty = true;
delegate.onSwipeLeft();
}
public void onSwipeBottom() {
dirty = true;
delegate.onSwipeBottom();
}
@Override
public boolean onTouch(View v, MotionEvent event) {
try {
super.onTouch(v, event);
return dirty;
} finally {
dirty = false;
}
}
};
还有一个在网上找到的课程:
public class OnSwipeTouchListener implements OnTouchListener {
private static final String TAG = OnSwipeTouchListener.class.getName();
private final GestureDetector gestureDetector;
public OnSwipeTouchListener(Context ctx) {
gestureDetector = new GestureDetector(ctx, new GestureListener());
}
@Override
public boolean onTouch(View v, MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
private final class GestureListener extends GestureDetector.SimpleOnGestureListener {
private static final int SWIPE_THRESHOLD = 100;
private static final int SWIPE_VELOCITY_THRESHOLD = 100;
@Override
public boolean onDown(MotionEvent e) {
return true;
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
boolean result = false;
try {
float diffY = e2.getY() - e1.getY();
float diffX = e2.getX() - e1.getX();
if (Math.abs(diffX) > Math.abs(diffY)) {
if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
if (diffX > 0) {
onSwipeRight();
} else {
onSwipeLeft();
}
result = true;
}
} else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
if (diffY > 0) {
onSwipeBottom();
} else {
onSwipeTop();
}
result = true;
}
} catch (Exception exception) {
Log.d(TAG, "Unexpected problem handling swipes, ignoring.", exception);
}
return result;
}
}
public void onSwipeRight() {
// Do nothing
}
public void onSwipeLeft() {
// Do nothing
}
public void onSwipeTop() {
// Do nothing
}
public void onSwipeBottom() {
// Do nothing
}
}
然后添加你自己的OnTouchListener和OnSwipeTouchListener，如下所示:
DirtyOnSwipeTouchListener swipe = new DirtyOnSwipeTouchListener(this, new OnSwipeTouchListener(this) {
public void onSwipeTop() {
// your code here
}
public void onSwipeRight() {
// your code here
}
public void onSwipeLeft() {
// your code here
}
public void onSwipeBottom() {
// your code here
}
});
View.OnTouchListener toggleListener = new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_UP) {
// your code here
return true;
} else if (event.getAction() == MotionEvent.ACTION_DOWN) {
// your code here
return true;
}
return false;
}
};
SwipeFirstTouchListener swipeFirstTouchListener = new SwipeFirstTouchListener(swipe, toggleListener);
myView.setOnTouchListener(swipeFirstTouchListener);
扩展Mirek的回答，当你想在滚动视图中使用滑动手势时。默认情况下，滚动视图的触摸监听器被禁用，因此滚动动作不会发生。为了解决这个问题，您需要重写Activity的dispatchTouchEvent方法，并在您完成自己的侦听器后返回该方法的继承版本。
为了对Mirek的代码做一些修改: 我在OnSwipeTouchListener中添加了一个gestureDetector getter。
public GestureDetector getGestureDetector(){
return gestureDetector;
}
在Activity中声明OnSwipeTouchListener作为类范围的字段。
OnSwipeTouchListener onSwipeTouchListener;
相应修改用法代码:
onSwipeTouchListener = new OnSwipeTouchListener(MyActivity.this) {
public void onSwipeTop() {
Toast.makeText(MyActivity.this, "top", Toast.LENGTH_SHORT).show();
}
public void onSwipeRight() {
Toast.makeText(MyActivity.this, "right", Toast.LENGTH_SHORT).show();
}
public void onSwipeLeft() {
Toast.makeText(MyActivity.this, "left", Toast.LENGTH_SHORT).show();
}
public void onSwipeBottom() {
Toast.makeText(MyActivity.this, "bottom", Toast.LENGTH_SHORT).show();
}
});
imageView.setOnTouchListener(onSwipeTouchListener);
并覆盖活动内部的dispatchTouchEvent方法:
@Override
public boolean dispatchTouchEvent(MotionEvent ev){
swipeListener.getGestureDetector().onTouchEvent(ev);
return super.dispatchTouchEvent(ev);
}
现在滚动和滑动动作都可以工作了。
@Edward Brey的方法很有效。如果有人也想复制和粘贴导入的OnSwipeTouchListener，他们是:
import android.content.Context;
import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
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