我想做的是在一个视图上有 4 个 ImageButtons，然后当我将一个按钮拖到另一个按钮时，Logcat 中会打印一条消息。问题是即使 Drag 事件通过 START、ENTERED、LOCATION、EXITED、DROP、ENDED 都没有问题，但是 onLongClick() 的其余部分，v.startDrag() 之后的代码不起作用。先谢谢了。
public class HomeAcitivity extends Activity implements OnClickListener, OnLongClickListener
{
//int windowWidth = getWindowManager().getDefaultDisplay().getWidth();
//int windowHeight = getWindowManager().getDefaultDisplay().getHeight();
public static int action = 0; // what action to take:
// 0: nothing
// 1: song to album
// 2: song to genre
// 3: song to artist
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
initialization(savedInstanceState);
}
public void initialization(Bundle savedInstanceState)
{
ImageButton songsMap = (ImageButton) findViewById(R.id.songsmap);
songsMap.setContentDescription("none");
songsMap.setOnClickListener(this);
songsMap.setOnLongClickListener(this);
ImageButton albumsMap = (ImageButton) findViewById(R.id.albumsmap);
albumsMap.setContentDescription("none");
albumsMap.setOnClickListener(this);
albumsMap.setOnLongClickListener(this);
ImageButton artistsMap = (ImageButton) findViewById(R.id.artistsmap);
artistsMap.setOnClickListener(this);
artistsMap.setOnLongClickListener(this);
ImageButton genresMap = (ImageButton) findViewById(R.id.genresmap);
genresMap.setOnClickListener(this);
genresMap.setOnLongClickListener(this);
myDragEventListener mAlbumDragListener = new myDragEventListener();
albumsMap.setOnDragListener(mAlbumDragListener);
myDragEventListener mSongDragListener = new myDragEventListener();
songsMap.setOnDragListener(mSongDragListener);
myDragEventListener mArtistDragListener = new myDragEventListener();
artistsMap.setOnDragListener(mArtistDragListener);
myDragEventListener mGenreDragListener = new myDragEventListener();
genresMap.setOnDragListener(mGenreDragListener);
}
public boolean songtoalbum()
{
Log.d("Song to album:", "true");
return true;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_home, menu);
return true;
}
public void onClick(View arg0)
{
}
public boolean onLongClick(View v)
{
if (v.getId() == R.id.musicmapparent)
{
// here modify wallpaper
return true;
}
// Drag and drop
ClipData.Item item = new ClipData.Item((CharSequence) v.getTag());
// this part is different from the android dev:
String[] mimetype = new String[1];
mimetype[0] = ClipDescription.MIMETYPE_TEXT_PLAIN;
ClipData dragData = new ClipData((CharSequence) v.getTag(),
mimetype,
item);
View.DragShadowBuilder myShadow;
switch(v.getId())
{
case R.id.albumsmap:
myShadow =
new MyDragShadowBuilder (v, getResources().getDrawable(R.drawable.ic_launcher));
break;
case R.id.songsmap:
myShadow =
new MyDragShadowBuilder (v, getResources().getDrawable(R.drawable.ic_launcher));
break;
case R.id.artistsmap:
myShadow =
new MyDragShadowBuilder (v, getResources().getDrawable(R.drawable.ic_launcher));
break;
case R.id.genresmap:
myShadow =
new MyDragShadowBuilder (v, getResources().getDrawable(R.drawable.ic_launcher));
break;
default:
myShadow = null;
}
//---------------------------------------------------------------------------
//v.setOnDragListener(mDragListener);
v.startDrag(dragData, // the data to be dragged
myShadow, // the drag shadow builder
null, // no need to use local data
0 // flags (not currently used, set to 0)
);
// Stuck here >"<
Log.d("Out of Drag", "At least we get here");
switch (HomeAcitivity.action)
{
case 0:
break;
case 1:
Log.d("ACTION: ", "Song to album");
//songtoalbum();
break;
case 2:
Log.d("ACTION: ", "Song to genre");
//songtogenre();
break;
case 3:
Log.d("ACTION: ", "Song to artist");
//songtoartist();
break;
default:
Log.d("ACTION", "nothing");
break;
}
return true;
}
}
// To create the shadow for the object
class MyDragShadowBuilder extends View.DragShadowBuilder {
// The drag shadow image, defined as a drawable thing
private static Drawable shadow;
// Defines the constructor for myDragShadowBuilder
public MyDragShadowBuilder(View v, Drawable drawable) {
super(v);
shadow = drawable;
}
// Defines a callback that sends the drag shadow dimensions and touch point back to the
// system.
@Override
public void onProvideShadowMetrics (Point size, Point touch)
{
// Defines local variables
int width, height;
// Sets the width of the shadow to half the width of the original View
width = getView().getWidth();
// Sets the height of the shadow to half the height of the original View
height = getView().getHeight();
// The drag shadow is a ColorDrawable. This sets its dimensions to be the same as the
// Canvas that the system will provide. As a result, the drag shadow will fill the
// Canvas.
shadow.setBounds(0, 0, width, height);
// Sets the size parameter's width and height values. These get back to the system
// through the size parameter.
size.set(width, height);
// Sets the touch point's position to be in the middle of the drag shadow
touch.set(width / 2, height / 2);
}
// Defines a callback that draws the drag shadow in a Canvas that the system constructs
// from the dimensions passed in onProvideShadowMetrics().
@Override
public void onDrawShadow(Canvas canvas) {
// Draws the ColorDrawable in the Canvas passed in from the system.
shadow.draw(canvas);
}
}
class myDragEventListener implements OnDragListener {
// This is the method that the system calls when it dispatches a drag event to the
// listener.
public boolean onDrag(View v, DragEvent event) {
// Defines a variable to store the action type for the incoming event
final int action = event.getAction();
// Handles each of the expected events
CharSequence dragData = null;
switch(action) {
case DragEvent.ACTION_DRAG_STARTED:
// Determines if this View can accept the dragged data
if (event.getClipDescription().hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN)) {
switch(v.getId())
{
case R.id.albumsmap:
break;
case R.id.songsmap:
v.setContentDescription("songstart");
break;
case R.id.artistsmap:
break;
case R.id.genresmap:
break;
}
// As an example of what your application might do,
// applies a blue color tint to the View to indicate that it can accept
// data.
((ImageView) v).setColorFilter(Color.BLUE);
// Invalidate the view to force a redraw in the new tint
v.invalidate();
dragData = (CharSequence) v.getTag();
// returns true to indicate that the View can accept the dragged data.
return(true);
} else {
// Returns false. During the current drag and drop operation, this View will
// not receive events again until ACTION_DRAG_ENDED is sent.
return(false);
}
//break;
case DragEvent.ACTION_DRAG_ENTERED:
// Applies a green tint to the View. Return true; the return value is ignored.
((ImageView) v).setColorFilter(Color.GREEN);
// Invalidate the view to force a redraw in the new tint
v.invalidate();
return(true);
//break;
case DragEvent.ACTION_DRAG_LOCATION:
//
switch(v.getId())
{
case R.id.albumsmap:
((ImageView) v).setColorFilter(Color.RED);
break;
case R.id.songsmap:
((ImageView) v).setColorFilter(Color.YELLOW);
break;
case R.id.artistsmap:
((ImageView) v).setColorFilter(Color.WHITE);
break;
case R.id.genresmap:
((ImageView) v).setColorFilter(Color.BLACK);
break;
}
return(true);
//break;
case DragEvent.ACTION_DRAG_EXITED:
// Re-sets the color tint to blue. Returns true; the return value is ignored.
((ImageView) v).setColorFilter(Color.BLUE);
// Invalidate the view to force a redraw in the new tint
v.invalidate();
return(true);
//break;
case DragEvent.ACTION_DROP:
// Gets the item containing the dragged data
ClipData.Item item = event.getClipData().getItemAt(0);
// Gets the text data from the item.
dragData = item.getText();
Log.d("DRAGDATA = ", (String) dragData);
Log.d("V.ID = ", Integer.toString(v.getId()));
Log.d("Album.ID = ", Integer.toString(R.id.albumsmap));
// Displays a message containing the dragged data.
//Toast.makeText(this, "Dragged data is " + dragData, Toast.LENGTH_LONG);
// Turns off any color tints
((ImageView) v).clearColorFilter();
// Invalidates the view to force a redraw
v.invalidate();
String dragDataString = (String) dragData;
Log.d(dragDataString, dragDataString);
//
switch(v.getId())
{
case R.id.albumsmap:
((ImageView) v).setColorFilter(Color.RED);
if (dragDataString.equals("SONG_MAP_BUTTON"))
{
HomeAcitivity.action = 1;
v.invalidate();
}
break;
case R.id.songsmap:
((ImageView) v).setColorFilter(Color.YELLOW);
break;
case R.id.artistsmap:
if (dragDataString.equals("SONG_MAP_BUTTON"))
{
HomeAcitivity.action = 3;
Log.d("TAG: ", "This should be song to artist map");
v.invalidate();
}
break;
case R.id.genresmap:
if (dragDataString.equals("SONG_MAP_BUTTON"))
{
HomeAcitivity.action = 2;
Log.d("TAG: ", "This should be song to genre map");
v.invalidate();
}
break;
}
// Returns true. DragEvent.getResult() will return true.
return(true);
//break;
case DragEvent.ACTION_DRAG_ENDED:
// Turns off any color tinting
((ImageView) v).clearColorFilter();
// Invalidates the view to force a redraw
v.invalidate();
// Does a getResult(), and displays what happened.
if (event.getResult()) {
Log.d("End: ", "Well, end" + v.getId());
//Toast.makeText(this, "The drop was handled.", Toast.LENGTH_LONG);
} else {
//Toast.makeText(this, "The drop didn't work.", Toast.LENGTH_LONG);
};
// returns true; the value is ignored.
return(true);
//break;
// An unknown action type was received.
default:
Log.e("DragDrop Example","Unknown action type received by OnDragListener.");
break;
};
return true;
};
};