Drag and drop frame

Drag and drop Drag and drop frame

android11-release
Application and use Drag and drop Drag and drop

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Drag and drop Drag and drop launch

APP Call start

Drag and drop Drag and dropstartDragAndDrop start-up
frameworks/base/core/java/android/view/View.java

frameworks\base\services\core\java\com\android\server\wm\Session.java

initialization DragState And register InputChannel

• initialization DragState
• register drag InputChannel\DragInputEventReceiver
• Notify drag and drop to start mDragState.broadcastDragStartedLocked(touchX, touchY); Trigger DragEvent.ACTION_DRAG_STARTED

frameworks/base/services/core/java/com/android/server/wm/DragDropController.java

frameworks/base/services/core/java/com/android/server/wm/DragState.java
frameworks/base/services/core/java/com/android/server/wm/WindowManagerInternal.java
frameworks/base/services/core/java/com/android/server/wm/DragInputEventReceiver.java

Last notifyLocationLocked

• (touchedWin != mTargetWindow) && (mTargetWindow != null) Trigger when DragEvent.ACTION_DRAG_EXITED
• touchedWin != null Trigger when DragEvent.ACTION_DRAG_LOCATION
  
• adopt ViewRootImplmpl Layer upon layer ,result = mView.dispatchDragEvent(event) notice APP And accept the return value
• li.mOnDragListener.onDrag(this, event) Genuine notification APP
  frameworks/base/core/java/android/view/ViewRootImpl.java
  frameworks/base/core/java/android/view/View.java
  

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Drag and drop Drag and drop start summary ：

1. APP start-up startDragAndDrop, and View.OnDragListener monitor
2. initialization DragState And register drag InputChannel\DragInputEventReceiver;
4. ViewRootImpl in result = mView.dispatchDragEvent(event); Send to View, Notice the return value here result
5. View in li.mOnDragListener.onDrag(this, event) Notice to APP monitor
6. SurfaceControl Control display Surface, This display is similar to the general WMS Show different
   

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Drag and drop Drag and drop action Trigger problem

public static final int ACTION_DRAG_STARTED = 1;
public static final int ACTION_DRAG_LOCATION = 2;
public static final int ACTION_DROP = 3;
public static final int ACTION_DRAG_ENDED = 4;
public static final int ACTION_DRAG_ENTERED = 5;
public static final int ACTION_DRAG_EXITED = 6;

- ACTION_DRAG_STARTED

 When the application calls  startDragAndDrop\startDrag  And get after dragging the shadow , The drag event listener of the view object will immediately receive this event action type .

1 Trigger

You can also see initialization above registerInputChannel After completion mDragState.broadcastDragStartedLocked(touchX, touchY) Notification complete ：
performDrag -> broadcastDragStartedLocked -> sendDragStartedLocked -> newWin.mClient.dispatchDragEvent(event)\dispatchDragEvent(DragEvent event) -> handleDragEvent

2 notice APP Operation before listening

frameworks/base/core/java/android/view/ViewRootImpl.java
handleDragEvent Set in mCurrentDragView = null;mDragDescription preservation event.mClipDescription

3 result = mView.dispatchDragEvent(event) Return value

result No matter back to true or false No other treatment , All have no other effect .

- ACTION_DRAG_LOCATION

 When I received  ACTION_DRAG_ENTERED  Event and the drag shadow is still within the bounding box of the view , The drag event listener of the view object will receive this event action type .

1 Trigger

Registered here drag InputChannel\DragInputEventReceiver, received ACTION_MOVE Event call mDragDropController.handleMotionEvent(Android 12 beta4 There is no operation here ),!mMuteInput Finally call to mDragState.notifyMoveLocked.

frameworks/base/services/core/java/com/android/server/wm/DragInputEventReceiver.java
frameworks/base/services/core/java/com/android/server/wm/DragDropController.java
frameworks/base/services/core/java/com/android/server/wm/DragState.java

stay DragState in notifyLocationLocked adopt touchedWin.mClient.dispatchDragEvent(evt) Call to ViewRootImpl in handleDragEvent

Summary of process ：drag InputChannel\DragInputEventReceiver -> handleMotionEvent -> notifyMoveLocked\notifyLocationLocked -> touchedWin.mClient.dispatchDragEvent(evt)\dispatchDragEvent(DragEvent event) -> handleDragEvent

2 notice APP Operation before listening

frameworks/base/core/java/android/view/ViewRootImpl.java

3 result = mView.dispatchDragEvent(event) Return value

result No matter back to true or false,!event.mEventHandlerWasCalled Judgment execution setDragFocus.

- ACTION_DROP

 When the user releases the drag shadow onto the view object , The drag event listener of the view object will receive this event action type . Only if the listener of the view object is responding  ACTION_DRAG_STARTED  Returns a Boolean value when dragging an event  true  when , The system will send the operation type to the listener . If the user releases the drag shadow on a view that does not have a registered listener or on any view that does not belong to the current layout , The system will not send this operation type .
 If the drop operation is successfully handled , The listener should return a Boolean value  true. otherwise , It should return  false.

1 Trigger

Registered here drag InputChannel\DragInputEventReceiver, received ACTION_UP\ACTION_CANCEL Event call mDragDropController.handleMotionEvent(Android 12 beta4 There is no operation here ),!mMuteInput Finally call to mDragState.notifyDropLocked.

stay DragState in notifyLocationLocked adopt touchedWin.mClient.dispatchDragEvent(evt) Call to ViewRootImpl in handleDragEvent

Summary of process ：drag InputChannel\DragInputEventReceiver -> handleMotionEvent -> notifyMoveLocked\notifyLocationLocked -> touchedWin.mClient.dispatchDragEvent(evt)\dispatchDragEvent(DragEvent event) -> handleDragEvent

And ACTION_DRAG_LOCATION The difference is the timeout here 5s perform mDragState.endDragLocked()

It may not trigger DragEvent.ACTION_DROP,closeLocked() End trigger DragEvent.ACTION_DRAG_ENDED

2 notice APP Operation before listening

frameworks/base/core/java/android/view/ViewRootImpl.java

3 result = mView.dispatchDragEvent(event) return true situation

APP return true End drag and drop closeLocked() End trigger DragEvent.ACTION_DRAG_ENDED

- ACTION_DRAG_ENDED

 When the system ends the drag operation , The drag event listener of the view object will receive this event action type .
 This operation type is not necessarily in  ACTION_DROP  After the event .
 If the system has sent  ACTION_DROP, received  ACTION_DRAG_ENDED  The operation type does not mean that the drop operation is successful .
 The listener must call  getResult()  To get a response  ACTION_DROP  The value returned when .
 If not sent  ACTION_DROP  event ,getResult()  Will return  false.

1 Trigger

Read here , You can see on it closeLocked() Methods the trigger DragEvent.ACTION_DRAG_ENDED

Log off here first drag input channel

2 notice APP Operation before listening

3 result = mView.dispatchDragEvent(event) Return value

result No matter back to true or false All reset

- ACTION_DRAG_ENTERED\ACTION_DRAG_EXITED

**ACTION_DRAG_ENTERED** When you drag the shadow just into the bounding box of the view , The drag event listener of the view object will receive this event action type . This is the first event action type that the listener receives when dragging a shadow into the bounding box . If the listener wants to continue receiving drag events for this operation , Boolean values must be returned to the system  true.
**ACTION_DRAG_EXITED** When I received  ACTION_DRAG_ENTERED  And at least one  ACTION_DRAG_LOCATION  event , And when the user has moved the drag shadow outside the bounding box of the view , The drag event listener of the view object will receive this event action type .

1 Trigger

See from above setDragFocus Setting refresh will trigger

2 Call directly callDragEventHandler

ACTION_DRAG_ENTERED Description returns true, I don't see why