我正在开发一个 Android 应用程序,我正在使用拖放 View 。
我在我的 View (屏幕截图中的圆圈)上实现了 onLongClick(实际上是使用具有 1.5 秒长点击阈值的 onTouch)。当检测到长按时,我会显示两个放置区域(分别附加 onDragListener 的 ImageView ,屏幕截图中的绿色框)。
当我的 View 被拖放到任何一个放置区域(ACTION_DROP 被调用)时,我的代码工作正常,但问题是,我还需要知道我的圆圈何时被放置在放置区域之外,以便我可以重置状态。在这种情况下,我没有从两个放置区域中的任何一个触发任何回调。我认为我也没有看到从我使用 startDrag 方法的 View 中调用的任何方法。
在将 View 放置在任何放置区域之外后,我从 logcat 获得的唯一信息是:
有什么方法可以从我的代码中检测到“丢弃结果:错误”?帮助将不胜感激!
截图链接如下:
---------- 更新 11/21 ----------
在我第一次发布这个问题时,我还在努力掌握高级概念,但现在我意识到我应该包含更多细节。
以下是目前在我的应用程序中使用的一些代码 fragment 。顺便说一下,我在服务中使用这些 View ——圆形( anchor )和绿色框(dropRegions)——在一个服务中,而不是一个 Activity 中,所以我使用 WindowManager 添加 View 。
我仍然有同样的问题,我不明白的主要问题是,从未调用 ACTION_DRAG_ENTERED 和 ACTION_DRAG_EXITED。到目前为止,只有 ACTION_DROP 对我有用。我还缺少什么吗?
下面是代码的相关部分。
长按圆圈时调用(在 Sandrstar 的响应后稍作修改):
private void anchorOnLongClick(View view) {
Log.d("####", "LONG CLICK");
showAnchorDropRegion();
ClipData.Item item = new ClipData.Item((String) view.getTag());
ClipData data = new ClipData((String) view.getTag(),
new String[]{ClipDescription.MIMETYPE_TEXT_PLAIN}, item);
View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
view.startDrag(data, shadowBuilder, null, 0);
setupAnchorDropRegion();
showAnchorDropRegion();
}
将拖动监听器附加到绿色框:
/* set up the region where anchor can be drag-and-dropped */
private void setupAnchorDropRegion() {
ivDropRight = new ImageView(this);
ivDropRight.setImageDrawable(getResources().getDrawable(R.drawable.dropregion_normal));
ivDropRight.setOnDragListener(new View.OnDragListener() {
@Override
public boolean onDrag(View v, DragEvent event) {
Log.d("####", "onDrag");
switch (event.getAction()) {
case DragEvent.ACTION_DRAG_STARTED:
// do nothing
return true;
case DragEvent.ACTION_DRAG_ENTERED:
Log.d("####", "DRAG_ENTERED");
break;
case DragEvent.ACTION_DRAG_EXITED:
Log.d("####", "DRAG_EXITED");
break;
case DragEvent.ACTION_DROP:
Log.d("####", "DROP ON: " + event.getX() + ", " + event.getY());
hideDropRegion();
// initialize anchor locations to the right
break;
case DragEvent.ACTION_DRAG_ENDED:
Log.d("####", "DRAG ENDED");
break;
default:
break;
}
return true;
}
});
// repeat for ivDropLeft
显示绿色框(放置区域):
/* display anchor drop region left and right */
private void showAnchorDropRegion() {
WindowManager.LayoutParams dropRegionParmas = new WindowManager.LayoutParams(
app.dropRegionSize, app.dropRegionSize, 0, 0,
WindowManager.LayoutParams.TYPE_PHONE,
WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
PixelFormat.TRANSLUCENT);
dropRegionParmas.gravity = Gravity.BOTTOM | Gravity.LEFT;
mWindowManager.addView(ivDropLeft, dropRegionParmas);
dropRegionParmas.gravity = Gravity.BOTTOM | Gravity.RIGHT;
mWindowManager.addView(ivDropRight, dropRegionParmas);
}
最佳答案
主要思想来自 DragEvent.getResult() 的这个文档:
因此,在 drop 之后,您可以通过 getResult()
获取结果:如果它返回 true
则它已被丢弃在某个接受 drop 的 View 中。请注意,接受 drop 的 View 将 true
返回到 ACTION_DROP
:
下面是一些小示例,类似于显示该方法的布局:
public class MainActivity extends Activity {
private static final String TAG = "MainActivity";
private View mCircleView = null;
private Boolean mDroppedIn = null;
private View.OnDragListener mLeftDragListener = new View.OnDragListener() {
private boolean mInView = false;
@Override
public boolean onDrag(final View v, final DragEvent event) {
final int action = event.getAction();
switch (action) {
case DragEvent.ACTION_DRAG_STARTED:
mDroppedIn = null;
mCircleView.setVisibility(View.INVISIBLE);
v.setBackgroundResource(android.R.color.holo_green_dark);
break;
case DragEvent.ACTION_DRAG_ENTERED:
mInView = true;
v.setBackgroundResource(android.R.color.holo_green_light);
break;
case DragEvent.ACTION_DRAG_EXITED:
mInView = false;
v.setBackgroundResource(android.R.color.holo_green_dark);
break;
case DragEvent.ACTION_DRAG_ENDED:
mCircleView.post(new Runnable() {
@Override
public void run() {
if (mCircleView.getVisibility() != View.VISIBLE) {
mCircleView.setVisibility(View.VISIBLE);
}
}
});
reportResult(R.id.leftView, event.getResult());
break;
case DragEvent.ACTION_DROP:
return mInView;
}
return true;
}
};
private View.OnDragListener mRightDragListener = new View.OnDragListener() {
private boolean mInView = false;
@Override
public boolean onDrag(final View v, final DragEvent event) {
final int action = event.getAction();
switch (action) {
case DragEvent.ACTION_DRAG_STARTED:
mDroppedIn = null;
mCircleView.setVisibility(View.INVISIBLE);
v.setBackgroundResource(android.R.color.holo_green_dark);
break;
case DragEvent.ACTION_DRAG_ENTERED:
mInView = true;
v.setBackgroundResource(android.R.color.holo_green_light);
break;
case DragEvent.ACTION_DRAG_EXITED:
mInView = false;
v.setBackgroundResource(android.R.color.holo_green_dark);
break;
case DragEvent.ACTION_DRAG_ENDED:
mCircleView.post(new Runnable() {
@Override
public void run() {
if (mCircleView.getVisibility() != View.VISIBLE) {
mCircleView.setVisibility(View.VISIBLE);
}
}
});
reportResult(R.id.rightView, event.getResult());
break;
case DragEvent.ACTION_DROP:
return mInView;
}
return true;
}
};
private void reportResult(final int viewId, final boolean result) {
if (mDroppedIn == null) {
mDroppedIn = result;
Toast.makeText(this, "Dropped in: " + result, Toast.LENGTH_SHORT).show();
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mCircleView = findViewById(R.id.circleView);
mCircleView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(final View v) {
final ClipData.Item item = new ClipData.Item((String)v.getTag());
final ClipData dragData = new ClipData((String)v.getTag(),
new String[] {ClipDescription.MIMETYPE_TEXT_PLAIN}, item);
mCircleView.startDrag(dragData, new CircleShadowBuilder(v), null, 0);
findViewById(R.id.leftView).setOnDragListener(mLeftDragListener);
findViewById(R.id.rightView).setOnDragListener(mRightDragListener);
return true;
}
});
}
private class CircleShadowBuilder extends View.DragShadowBuilder {
private final Drawable mShadow;
CircleShadowBuilder(final View v) {
super(v);
mShadow = v.getResources().getDrawable(R.drawable.circle);
}
@Override
public void onProvideShadowMetrics(final Point shadowSize, final Point shadowTouchPoint) {
int width = getView().getWidth();
int height = getView().getHeight();
mShadow.setBounds(0, 0, width, height);
shadowSize.set(width, height);
shadowTouchPoint.set(width, height);
}
@Override
public void onDrawShadow(final Canvas canvas) {
mShadow.draw(canvas);
}
}
}
关于android - 如何检测 Android 中可拖动 View 外的放置,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/26911748/