Android--Drag&&drop

ANDROID3.0 provides a Drag/drop framework that allows you to drag and drop a view into another view in the current layout using drag-and-drop.

steps to implement drag and drop

First, let's take a look at the drag-and-drop process, from the official documentation to know that the entire drag-and-drop process is divided into 4 steps, as follows:

1, Started: Start drag and drop, mainly call the StartDrag method that is dragged and dropped view. The prototype for this method is:

 Public Final boolean StartDrag (clipdata data, View.dragshadowbuilder Shadowbuilder, Object mylocalstate,  int flags)

After startup, the system generates drag-and-drop shadows and sends a drag-and-drop event with action action_drag_started to the current layout that has settings for the drag-and-drop listener view.

2, continuing: Keep dragging state. During this process, one or more drag events may be sent to the view where the drag-and-drop listener is set, such as action_drag_entered, Action_drag_location, and so on.

3. Dropped: The user releases the drag shadow within the target area, and the system sends an action-action_drop event to the view with the drag-and-drop listener set.

4, Ended: The user released the Drag shadow, the system will set the drag-and-drop listener view send action as action_drag_ended event, complete the drag and drop.

key interfaces and classes during drag and drop

Secondly, we need to understand clearly several key interfaces and classes in the drag-and-drop process, mainly Ondraglistener, Dragevent, Dragshadowbuilder, Clipdata, clipdescription and so on.

1, Ondraglistener: interface, drag and drop event listener. When drag occurs, the method in this interface is recalled. The interface contains only one method Ondrag, the method prototype is:

Boolean Ondrag (View V, dragevent event) // parameter V: Set the view of the listener // parameter event: Drag-and-drop event parameters that encapsulate drag-and-drop related data // return value: true-event handled; false event unhandled. 

2. Dragevent: Drag-and-drop event object that contains different event data depending on the action.

3. Dragshadowbuilder: Drag and Drop shadow constructor object to construct drag-and-drop shadows.

4, Clipdata, clipdescription: Mobile data for drag and drop.

Code

<?XML version= "1.0" encoding= "Utf-8"?><Relativelayoutxmlns:android= "Http://schemas.android.com/apk/res/android"Android:id= "@+id/topcontainer"Android:layout_width= "Match_parent"Android:layout_height= "Match_parent"android:orientation= "vertical" >    <ImageViewAndroid:id= "@+id/img"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"android:contentdescription= "@null"android:src= "@drawable/ic_launcher" />    <LinearLayoutAndroid:id= "@+id/container"Android:layout_width= "Match_parent"Android:layout_height= "100DP"Android:layout_alignparentbottom= "true"android:orientation= "vertical"Android:background= "#cccccc" >        <TextViewAndroid:id= "@+id/title"Android:layout_width= "Fill_parent"Android:layout_height= "Wrap_content"Android:textcolor= "#ff0000"android:textsize= "18SP" />    </LinearLayout></Relativelayout>

Bind long click events for ImageView

Imageview.setonlongclicklistener (NewOnlongclicklistener () {@Override Public BooleanOnlongclick (View v) {//Create mobile DataClipdata.item Item =NewClipdata.item (String) V.gettag ()); Clipdata Data=NewClipdata (Imageview_tag,Newstring[] {clipdescription.mimetype_text_plain}, item); //Call the StartDrag method, and the second argument is to create a drag-and-drop shadowV.startdrag (data,NewView.dragshadowbuilder (v),NULL, 0); return true; }        });

To target view bindings, drag-and-drop monitoring:

Container.setondraglistener (NewOndraglistener () {@Override Public BooleanOndrag (View V, dragevent event) {Final intAction =event.getaction (); Switch(action) { Casedragevent.action_drag_started://drag and Drop start event                    if(Event.getclipdescription (). Hasmimetype (Clipdescription.mimetype_text_plain)) { return true; }                    return false;  Casedragevent.action_drag_entered://drag and drop view into target viewContainer.setbackgroundcolor (Color.yellow); return true;  Casedragevent.action_drag_location:return true;  Casedragevent.action_drag_exited://drag and drop view away from Target viewContainer.setbackgroundcolor (Color.Blue); Title.settext (""); return true;  CaseDragevent.action_drop://release drag-and-drop shadows and get moving dataClipdata.item Item = Event.getclipdata (). Getitemat (0); String Dragdata=Item.gettext (). toString (); Title.settext (Dragdata+event.gety () + ":" +event.getx ()); return true;  Casedragevent.action_drag_ended://drag-and-drop event completion                    return true; default:                     Break; }                return false; }        });

Location of the ImageView

Topcontainer.setondraglistener (NewOndraglistener () {@Override Public BooleanOndrag (View V, dragevent event) {Final intAction =event.getaction (); Switch(action) { Casedragevent.action_drag_started:return true;  Casedragevent.action_drag_entered:return true;  Casedragevent.action_drag_location:return true;  Casedragevent.action_drag_exited:return true;  CaseDragEvent.ACTION_DROP:imageView.setX (Event.getx ()-imageview.getwidth ()/2); Imageview.sety (Event.gety ()-imageview.getheight ()/2); return true;  Casedragevent.action_drag_ended:return true; default:                     Break; }                return false; }        });

Effect

I'm the dividing line of the king of the Land Tiger.

Reprint: http://www.cnblogs.com/jerehedu/p/4427588.html

Android--Drag&&drop