Android OnDragListener在快速拖动后未接收回调
首先,这个问题可能看起来像是重复的,看起来像是记录为问题,但仔细研究之后,你会发现它是完全不同的 设置 我正在尝试实现一个简单的拖放功能:当我将ImageView a拖动到ImageView B时,它们将交换其背景色 您可以下载这个小测试项目。下面描述的问题可以通过克隆并在手机上构建来重现 如果你只想看代码,请看 问题 如果您缓慢地执行拖放操作(例如,每次拖放0.5秒),则该操作将非常有效 但是,如果您尝试以最快的速度拖放(例如,每秒4到5次,无论如何是以最快的速度),很快您就会发现无法再执行拖放操作。通过查看日志,我发现没有触发拖动回调Android OnDragListener在快速拖动后未接收回调,android,drag-and-drop,touch,drag,Android,Drag And Drop,Touch,Drag,首先,这个问题可能看起来像是重复的,看起来像是记录为问题,但仔细研究之后,你会发现它是完全不同的 设置 我正在尝试实现一个简单的拖放功能:当我将ImageView a拖动到ImageView B时,它们将交换其背景色 您可以下载这个小测试项目。下面描述的问题可以通过克隆并在手机上构建来重现 如果你只想看代码,请看 问题 如果您缓慢地执行拖放操作(例如,每次拖放0.5秒),则该操作将非常有效 但是,如果您尝试以最快的速度拖放(例如,每秒4到5次,无论如何是以最快的速度),很快您就会发现无法再执行
03-12 10:41:53.782 (...) I/dragEvent: view.startDragAndDrop has been called
03-12 10:41:53.787 (...) I/dragEvent: ACTION_DRAG_STARTED received
03-12 10:41:53.787 (...) I/dragEvent: ACTION_DRAG_STARTED received
03-12 10:41:53.789 (...) I/dragEvent: ACTION_DRAG_ENTERED received
03-12 10:41:53.789 (...) I/dragEvent: ACTION_DRAG_LOCATION received
03-12 10:41:53.796 (...) I/dragEvent: ACTION_DRAG_LOCATION received
03-12 10:41:53.802 (...) I/dragEvent: ACTION_DROP received
03-12 10:41:53.815 (...) I/dragEvent: ACTION_DRAG_ENDED received
03-12 10:41:53.815 (...) I/dragEvent: ACTION_DRAG_ENDED received
03-12 10:41:54.014 (...) I/dragEvent: view.startDragAndDrop has been called //Since this call, no callbacks were received
此时,应用程序不会冻结。OnTouchListener仍在接收回调。拖放会冻结,因为我有一个标志来指示拖放是否正在进行,并且由于没有触发“拖放结束”操作,因此该标志会停留在
true
位置,因此无法执行更多的拖放操作
我真的不知道为什么,因为我已经记录了所有的东西,每一行代码都正常运行,我希望收到来自Android框架的回调,但它不是
为什么我认为这是可以解决的
实际上,这个小测试项目是我试图克隆应用程序中实现的拖放图像交换。我无法在他们的应用程序中重现这个问题。。。所以我认为我的代码中一定有错误;或者其他解决方法。查看下面的代码片段
private void setupTouchListeners () {
View.OnTouchListener listener = new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getActionMasked() == MotionEvent.ACTION_DOWN) {
return true;
}
if (event.getActionMasked() == MotionEvent.ACTION_MOVE) {
boolean beyondLeft = event.getX() <= 0;
boolean beyondRight = event.getX() >= v.getWidth();
boolean beyondTop = event.getY() <= 0;
boolean beyondBottom = event.getY() >= v.getHeight();
if (beyondLeft || beyondRight || beyondTop || beyondBottom) {
startDragAndDrop(v);
return true;
} else {
// done changes here, simply changed flag to false and return false
isDragging=false;
return false;
}
}
return false;
}
};
ivGrid1.setOnTouchListener(listener);
ivGrid2.setOnTouchListener(listener);
ivGrid3.setOnTouchListener(listener);
ivGrid4.setOnTouchListener(listener);
}
private void setupTouchListeners(){
View.OnTouchListener=新建View.OnTouchListener(){
@凌驾
公共布尔onTouch(视图v,运动事件){
if(event.getActionMasked()==MotionEvent.ACTION\u向下){
返回true;
}
if(event.getActionMasked()==MotionEvent.ACTION\u MOVE){
布尔beyondLeft=event.getX()=v.getWidth();
布尔beyondTop=event.getY()=v.getHeight();
if(beyondLeft | | beyondRight | | beyondTop | | beyondBottom){
起动制动(v);
返回true;
}否则{
//在这里做了更改,只需将标志更改为false并返回false
IsDraging=错误;
返回false;
}
}
返回false;
}
};
ivGrid1.setOnTouchListener(listener);
ivGrid2.setOnTouchListener(listener);
ivGrid3.setOnTouchListener(listener);
ivGrid4.setOnTouchListener(listener);
}
无论如何,它有逻辑问题的颜色,这不是这个问题的一部分,通过做上述改变,你将能够以任何速度拖动你想要的
快乐编码:)您的快速拖拽会导致您未处理的拖拽,拖放设施不会通过正式结束拖拽来通知您它未继续进行。以下更新的
MainActivity.java
有以下更改:
GestureDetectorCompat
以检测何时发生放纵行为。我对这件事什么都不做,只是记录它的发生。您可能需要考虑在您的代码中触摸手势检测器的设备。isDraging==true
),则选中ACTION\u UP
事件以重置布局public class MainActivity extends AppCompatActivity {
ImageView ivGrid1, ivGrid2, ivGrid3, ivGrid4;
private GestureDetectorCompat mDetector;
//Drag and Drop
View dragOriginView;
Drawable whiteDrawable;
Drawable tempDrawableStorage;
boolean isDragging = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDetector = new GestureDetectorCompat(this, new MyGestureListener());
ivGrid1 = findViewById(R.id.grid_1);
ivGrid2 = findViewById(R.id.grid_2);
ivGrid3 = findViewById(R.id.grid_3);
ivGrid4 = findViewById(R.id.grid_4);
setupTouchListeners();
setupDragListeners();
whiteDrawable = new ColorDrawable(ContextCompat.getColor(this, android.R.color.white));
}
private void setupTouchListeners() {
View.OnTouchListener listener = new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
int action = event.getActionMasked();
switch (action) {
case MotionEvent.ACTION_DOWN:
return true;
case MotionEvent.ACTION_MOVE:
boolean beyondLeft = event.getX() <= 0;
boolean beyondRight = event.getX() >= v.getWidth();
boolean beyondTop = event.getY() <= 0;
boolean beyondBottom = event.getY() >= v.getHeight();
if (beyondLeft || beyondRight || beyondTop || beyondBottom) {
startDragAndDrop(v);
return true;
}
isDragging = false;
break;
case MotionEvent.ACTION_UP:
if (isDragging) {
dragOriginView.setBackground(tempDrawableStorage);
tempDrawableStorage = null;
v.setAlpha(1.0f);
isDragging = false;
}
}
return false;
}
};
ivGrid1.setOnTouchListener(listener);
ivGrid2.setOnTouchListener(listener);
ivGrid3.setOnTouchListener(listener);
ivGrid4.setOnTouchListener(listener);
}
private void startDragAndDrop(View view) {
if (isDragging) return;
isDragging = true;
dragOriginView = view;
view.setAlpha(0.5f);
ClipData.Item item = new ClipData.Item((String) view.getTag());
ClipData dragData = new ClipData((String) view.getTag(), new String[]{ClipDescription.MIMETYPE_TEXT_PLAIN},
item);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
view.startDragAndDrop(dragData, new View.DragShadowBuilder(view), null, 0);
} else {
view.startDrag(dragData, new View.DragShadowBuilder(view), null, 0);
}
Log.i("dragEvent", "view.startDragAndDrop has been called");
tempDrawableStorage = view.getBackground();
view.setBackground(whiteDrawable);
}
private void setupDragListeners() {
View.OnDragListener listener = new View.OnDragListener() {
@Override
public boolean onDrag(View v, DragEvent event) {
Log.i("dragEvent", "<<<<<<<<<<<<<<called");
switch (event.getAction()) {
case ACTION_DRAG_STARTED:
Log.i("dragEvent", "ACTION_DRAG_STARTED received");
return event.getClipDescription().hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN);
case ACTION_DRAG_ENTERED:
Log.i("dragEvent", "ACTION_DRAG_ENTERED received");
v.setAlpha(0.5f);
return true;
case ACTION_DRAG_LOCATION:
Log.i("dragEvent", "ACTION_DRAG_LOCATION received");
return true;
case ACTION_DRAG_EXITED:
Log.i("dragEvent", "ACTION_DRAG_EXITED received");
v.setAlpha(1f);
return true;
case ACTION_DROP:
Log.i("dragEvent", "ACTION_DROP received");
v.setAlpha(1f);
swapColor(v);
return true;
case ACTION_DRAG_ENDED:
Log.i("dragEvent", "ACTION_DRAG_ENDED received");
if (!event.getResult() && v == dragOriginView) {
dragOriginView.setBackground(tempDrawableStorage);
tempDrawableStorage = null;
}
v.setAlpha(1f);
isDragging = false;
default:
//Do nothing
}
return false;
}
};
ivGrid1.setOnDragListener(listener);
ivGrid2.setOnDragListener(listener);
ivGrid3.setOnDragListener(listener);
ivGrid4.setOnDragListener(listener);
}
private void swapColor(View dragTarget) {
if (dragOriginView == dragTarget) {
//Restore color
dragOriginView.setBackground(tempDrawableStorage);
tempDrawableStorage = null;
return;
}
Drawable targetBackground = dragTarget.getBackground();
dragOriginView.setBackground(targetBackground);
dragTarget.setBackground(tempDrawableStorage);
tempDrawableStorage = null;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
this.mDetector.onTouchEvent(event);
return super.onTouchEvent(event);
}
class MyGestureListener extends GestureDetector.SimpleOnGestureListener {
private static final String DEBUG_TAG = "Gestures";
@Override
public boolean onDown(MotionEvent event) {
Log.d(DEBUG_TAG, "onDown: " + event.toString());
return true;
}
@Override
public boolean onFling(MotionEvent event1, MotionEvent event2,
float velocityX, float velocityY) {
Log.d(DEBUG_TAG, "onFling: " + ((event1 != null) ? event1.toString() : "" + event2.toString()));
return true;
}
}
}
public类MainActivity扩展了AppCompatActivity{
ImageView ivGrid1、ivGrid2、ivGrid3、ivGrid4;
私人手势检测器;
//拖放
视图dragOriginView;
可拉拔的;可拉拔的;
可抽温可抽储存;
布尔IsDraging=false;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDetector=new GestureDetectorCompat(这个,new MyGestureListener());
ivGrid1=findViewById(R.id.grid_1);
ivGrid2=findViewById(R.id.grid_2);
ivGrid3=findViewById(R.id.grid_3);
ivGrid4=findViewById(R.id.grid_4);
setupTouchListeners();
设置dAglisteners();
whiteDrawable=newColorDrawable(ContextCompat.getColor(this,android.R.color.white));
}
私有void setupTouchListeners(){
View.OnTouchListener=新建View.OnTouchListener(){
@凌驾
公共布尔onTouch(视图v,运动事件){
int action=event.getActionMasked();
开关(动作){
case MotionEvent.ACTION\u DOWN:
返回true;
case MotionEvent.ACTION\u移动:
布尔beyondLeft=event.getX()=v.getWidth();
布尔beyondTop=event.getY()=v.getHeight();
if(beyondLeft | | beyondRight | | beyondTop | | beyondBottom){
起动制动(v);
返回true;
}
IsDraging=错误;
打破
case MotionEvent.ACTION\u UP:
if(ISDRAGING){
dragOriginView.后退地面(临时可拉伸存储);