我一直在努力实现在Android中,当拖动项目的交换与它已被删除的项目位置非常简单的拖放操作。
我已经成功地实施了onLongClick和听众ondrag当。当我拖放一个项目它取代它已被删除的项目,但我不能想出如何使更换项目需要拖动选项的位置。
我花了一段时间寻找答案,但答案大多只是挂拖,涉及有很多很多代码文件拖放复杂的实现,我是无法理解他们足够的将其应用到我的代码。
我本来认为我没有得到的ImageView与真实副本
ImageView temp = (ImageView) event.getLocalState();
所以我尝试
ImageView dragged = (ImageView) findViewById(temp.getId());
但这并没有有所作为。
我几乎可以肯定的问题是在“OnDragListener”,在“案DragEvent.ACTION_DROP:”。这里是我的代码(从Main.java):
public class Main extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
findViewById(R.id.ball1).setOnLongClickListener(listenClick);
findViewById(R.id.ball1).setOnDragListener(listenDrag);
findViewById(R.id.target1).setOnLongClickListener(listenClick);
findViewById(R.id.target1).setOnDragListener(listenDrag);
findViewById(R.id.target2).setOnDragListener(listenDrag);
findViewById(R.id.target2).setOnLongClickListener(listenClick);
findViewById(R.id.target3).setOnDragListener(listenDrag);
findViewById(R.id.target3).setOnLongClickListener(listenClick);
View.OnLongClickListener listenClick = new View.OnLongClickListener()
{
@Override
public boolean onLongClick(View v)
{
ClipData data = ClipData.newPlainText("","");
DragShadow dragShadow = new DragShadow(v);
v.startDrag(data, dragShadow, v, 0);
return false;
}
};
private class DragShadow extends View.DragShadowBuilder
{
ColorDrawable greyBox;
public DragShadow(View view)
{
super(view);
greyBox = new ColorDrawable(Color.LTGRAY);
}
@Override
public void onDrawShadow(Canvas canvas)
{
greyBox.draw(canvas);
}
@Override
public void onProvideShadowMetrics(Point shadowSize,
Point shadowTouchPoint)
{
View v = getView();
int height = (int) v.getHeight();
int width = (int) v.getWidth();
greyBox.setBounds(0, 0, width, height);
shadowSize.set(width, height);
shadowTouchPoint.set((int)width/2, (int)height/2);
}
}
View.OnDragListener listenDrag = new View.OnDragListener() {
@Override
public boolean onDrag(View v, DragEvent event)
{
int dragEvent = event.getAction();
switch (dragEvent)
{
case DragEvent.ACTION_DRAG_ENTERED:
Log.i("Drag Event", "Entered");
break;
case DragEvent.ACTION_DRAG_EXITED:
Log.i("Drag Event", "Exited");
break;
case DragEvent.ACTION_DROP:
ImageView target = (ImageView) v;
ImageView temp = (ImageView) event.getLocalState();
ImageView dragged = (ImageView) findViewById(temp.getId());
target.setId(dragged.getId());
target.setImageDrawable(dragged.getDrawable());
dragged.setId(temp.getId());
dragged.setImageDrawable(temp.getDrawable());
break;
}
return true;
}
};
如果有人能告诉我为什么setImageDrawable工作目标,但不能在拖,我会非常感激。
一个计算机科学作为大乐趣是学习谦卑。至少90%的时候,答案的追求:“为什么不是这方面的工作?”是你告诉计算机做错误的事情。
在“情况DragEvent.ACTION_DROP:”我得到的这两个观点的引用。我并没有意识到由于某些原因,当我做
target.setImageDrawable(dragged.getDrawable());
我也改变温度的绘制,因为温度指的是实际的看法。正因为如此,当我做
dragged.setImageDrawable(temp.getDrawable());
我其实是只设置拖累的绘制到它原来是。下面是更正后的代码。
case DragEvent.ACTION_DROP:
ImageView target = (ImageView) v;
ImageView dragged = (ImageView) event.getLocalState();
Drawable target_draw = target.getDrawable();
Drawable dragged_draw = dragged.getDrawable();
dragged.setImageDrawable(target_draw);
target.setImageDrawable(dragged_draw);
break;
我更新的答案居然交换意见,而不是交换图像;
@RequiresApi(Build.VERSION_CODES.JELLY_BEAN)
private fun initView(view: View) {
view.setOnDragListener(View.OnDragListener { target, event ->
when (event.action) {
DragEvent.ACTION_DRAG_STARTED -> return@OnDragListener true
DragEvent.ACTION_DRAG_ENTERED -> {
target.setBackgroundColor(ContextCompat.getColor(this, R.color.colorAccent))
return@OnDragListener true
}
DragEvent.ACTION_DRAG_LOCATION -> return@OnDragListener true
DragEvent.ACTION_DRAG_EXITED -> {
target.setBackgroundColor(ContextCompat.getColor(this, R.color.colorPrimary))
return@OnDragListener true
}
DragEvent.ACTION_DROP -> {
target.setBackgroundColor(ContextCompat.getColor(this, R.color.colorPrimary))
val dragged = event.localState as ImageView
val targetView = target as ImageView
//Swap Image
// val target_draw = targetView!!.drawable
// val dragged_draw = dragged!!.drawable
// dragged.setImageDrawable(target_draw)
// targetView.setImageDrawable(dragged_draw)
val oldOwner = dragged.parent as ViewGroup
val newOwner = target.parent as ViewGroup
val draggedPosition = oldOwner.indexOfChild(dragged)
val targetPosition = oldOwner.indexOfChild(dragged)
oldOwner.removeView(dragged)
newOwner.addView(dragged,targetPosition)
newOwner.removeView(target)
oldOwner.addView(target,draggedPosition)
return@OnDragListener true
}
DragEvent.ACTION_DRAG_ENDED -> return@OnDragListener true
else -> {
}
}
false
})
view.setOnLongClickListener { v ->
val dummyData = ClipData.newPlainText("dummyData", "") // don't forget to pass empty String
val shadowBuilder = View.DragShadowBuilder(v)
v.startDrag(dummyData, shadowBuilder, v, 0)
//val data = ClipData.newPlainText("value", "1")
// view.startDrag(data, View.DragShadowBuilder(v), null, 0)
true
}
}