[英]Dragging button is going out of the screen?
我有一个按钮,可以将其拖动到屏幕上的任何位置,但是拖动时它在屏幕外,所以如何只在屏幕内拖动,这样它就不会超出屏幕
Button.setOnTouchListener(new TextView.OnTouchListener() {
public boolean onTouch(View view, MotionEvent event) {
X_button = (int) event.getRawX();
Y_button= (int) event.getRawY();
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
RelativeLayout.LayoutParams lParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
_xDelta = X_button - lParams.leftMargin;
_yDelta = Y_button - lParams.topMargin;
break;
case MotionEvent.ACTION_UP:
if(!isMoving)
{
view.performClick();
}
isMoving=false;
break;
case MotionEvent.ACTION_POINTER_DOWN:
break;
case MotionEvent.ACTION_POINTER_UP:
break;
case MotionEvent.ACTION_MOVE:
isMoving=true;
RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) view
.getLayoutParams();
layoutParams.leftMargin = X_button - _xDelta;
layoutParams.topMargin = Y_button - _yDelta;
layoutParams.rightMargin = -250;
layoutParams.bottomMargin = -250;
view.setLayoutParams(layoutParams);
break;
}
return true;
}
});
将OnTouch listerner部分修改为:
DisplayMetrics displaymetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
screenHight = displaymetrics.heightPixels;
screenWidth = displaymetrics.widthPixels;
@SuppressLint("NewApi") @Override
public boolean onTouch(View view, MotionEvent event) {
float newX, newY;
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
dX = view.getX() - event.getRawX();
dY = view.getY() - event.getRawY();
lastAction = MotionEvent.ACTION_DOWN;
break;
case MotionEvent.ACTION_MOVE:
newX = event.getRawX() + dX;
newY = event.getRawY() + dY;
// check if the view out of screen
if ((newX <= 0 || newX >= screenWidth-view.getWidth()) || (newY <= 0 || newY >= screenHight-view.getHeight()))
{
lastAction = MotionEvent.ACTION_MOVE;
break;
}
view.setX(newX);
view.setY(newY);
lastAction = MotionEvent.ACTION_MOVE;
break;
case MotionEvent.ACTION_UP:
if (lastAction == MotionEvent.ACTION_DOWN)
Toast.makeText(DraggableView.this, "Clicked!", Toast.LENGTH_SHORT).show();
break;
default:
return false;
}
return true;
}
当拖动图像停留在屏幕上时,请参考此解决方案。 https://stackoverflow.com/a/36417605/4324288
首先,使用View.setX()
, View.setY()
, View.setTranslateX()
, View.setTranslateY()
方法在屏幕上移动视图,而不是更新LayoutParams的边距。 我发现它们的执行方式更流畅。
其次,为了将视图限制为可用窗口,请使用以下函数获取可用窗口的大小:
DisplayMetrics metrics = getResources().getDisplayMetrics();
int windowWidth = metrics.widthPixels;
int windowHeight = metrics.heightPixels
接下来,在您的onTouch方法中,计算目标位置是否超过上述尺寸。 例如:
if( currentXLocation + deltaX > windowWidth ){
// this will ensure that target location
// is always <= windowHeight
deltaX = windowWidth - currentXLocation;
} else if( currentXLocation + deltaX < 0){
deltaX = -(currentXLocation);
} else if (...){
// perform similar calculations for the rest
}
仅仅为了回答这个问题而注册,是因为在互联网上找不到相同的(不幸的是错误的)答案而感到沮丧。
要处理在视图外部绘制的对象,请为该对象设置OnDragListener,然后从那里调用处理程序-如果不使用处理程序,则该处理程序将崩溃-并将视图ID传递给该处理程序。 除此之外,我发现您的用户还可以通过完全同时触摸两个按钮来制作作品,并且如果用户触摸屏幕时切换活动,那么您也可以那样丢失对象-因此,最有效的方法是处理程序是从拖动侦听器ACTION_DRAG_ENDED中调用的,而触摸侦听器ACTION_UP只是确保应显示的所有内容都是正确的。 这样,每次用户停止触摸屏幕时,它都会修复他/她所做的任何事情。
private final class MyTouchListener implements OnTouchListener {
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
switch (motionEvent.getAction()) {
case MotionEvent.ACTION_DOWN:
ClipData data = ClipData.newPlainText("", "");
DragShadowBuilder shadowBuilder = new DragShadowBuilder(view);
view.startDrag(data, shadowBuilder, view, 0);
view.setVisibility(View.INVISIBLE);
return true;
case MotionEvent.ACTION_UP:
drophandler.sendEmptyMessage(0);
case MotionEvent.ACTION_MOVE:
return true;
default:
break;
}
return true;
}
}
class MyDragListener implements OnDragListener {
@Override
public boolean onDrag(View v, DragEvent event) {
View view = (View) event.getLocalState();
Button drag = (Button) view;
int action = event.getAction();
switch (event.getAction()) {
case DragEvent.ACTION_DRAG_STARTED:
break;
case DragEvent.ACTION_DRAG_ENTERED:
break;
case DragEvent.ACTION_DRAG_EXITED:
break;
case DragEvent.ACTION_DROP:
Button target = (Button) v;
//do stuff
return true;
case DragEvent.ACTION_DRAG_ENDED:
drophandler.sendEmptyMessage(0);
return true;
default:
break;
}
return true;
}
}
private Handler drophandler = new Handler() {
public void handleMessage(android.os.Message msg) {
for(int x = 0; x < 3 + difficulty; x++){
for(int y = 0; y < 5 + difficulty; y++){
if (buttons[x][y] != null){
buttons[x][y].setVisibility(View.VISIBLE);
}
}
}
}
};
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