Refinements to drag/drop
Thumbnail measurement & drawing has been moved out into a delegate
class called View.DragThumbnailBuilder. This consolidates the
thumbnail-related code as well as ensuring that the drag initiator
does not have to know a priori where to place the thumbnail relative
to the touch point *before* the thumbnail measurement step, as was
previously the case.
startDrag() no longer needs to be told where the current touch point
is at the time the drag is launched.
Drag events are now dispatched only to VISIBLE views.
Dispatch shouldn't double-recycle events any more when the target
window is local to the system process.
Change-Id: I49419103765a0cad2e18ddfcdd6dacb94daf1ff1
diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index 1dfd2bf..8b1fc4e 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -615,7 +615,6 @@
*/
public class View implements Drawable.Callback, KeyEvent.Callback, AccessibilityEventSource {
private static final boolean DBG = false;
- static final boolean DEBUG_DRAG = true;
/**
* The logging tag used by this class with android.util.Log.
@@ -3957,6 +3956,12 @@
return true;
}
+ /** Gets the ViewRoot, or null if not attached. */
+ /*package*/ ViewRoot getViewRoot() {
+ View root = getRootView();
+ return root != null ? (ViewRoot)root.getParent() : null;
+ }
+
/**
* Call this to try to give focus to a specific view or to one of its descendants. This is a
* special variant of {@link #requestFocus() } that will allow views that are not focuable in
@@ -3970,12 +3975,9 @@
public final boolean requestFocusFromTouch() {
// Leave touch mode if we need to
if (isInTouchMode()) {
- View root = getRootView();
- if (root != null) {
- ViewRoot viewRoot = (ViewRoot)root.getParent();
- if (viewRoot != null) {
- viewRoot.ensureTouchMode(false);
- }
+ ViewRoot viewRoot = getViewRoot();
+ if (viewRoot != null) {
+ viewRoot.ensureTouchMode(false);
}
}
return requestFocus(View.FOCUS_DOWN);
@@ -9833,40 +9835,99 @@
}
/**
+ * !!! TODO: real docs
+ *
+ * The base class implementation makes the thumbnail the same size and appearance
+ * as the view itself, and positions it with its center at the touch point.
+ */
+ public class DragThumbnailBuilder {
+ private View mView;
+
+ /**
+ * Construct a thumbnail builder object for use with the given view.
+ * @param view
+ */
+ public DragThumbnailBuilder(View view) {
+ mView = view;
+ }
+
+ /**
+ * Provide the draggable-thumbnail metrics for the operation: the dimensions of
+ * the thumbnail image itself, and the point within that thumbnail that should
+ * be centered under the touch location while dragging.
+ * <p>
+ * The default implementation sets the dimensions of the thumbnail to be the
+ * same as the dimensions of the View itself and centers the thumbnail under
+ * the touch point.
+ *
+ * @param thumbnailSize The application should set the {@code x} member of this
+ * parameter to the desired thumbnail width, and the {@code y} member to
+ * the desired height.
+ * @param thumbnailTouchPoint The application should set this point to be the
+ * location within the thumbnail that should track directly underneath
+ * the touch point on the screen during a drag.
+ */
+ public void onProvideThumbnailMetrics(Point thumbnailSize, Point thumbnailTouchPoint) {
+ thumbnailSize.set(mView.getWidth(), mView.getHeight());
+ thumbnailTouchPoint.set(thumbnailSize.x / 2, thumbnailSize.y / 2);
+ }
+
+ /**
+ * Draw the thumbnail image for the upcoming drag. The thumbnail canvas was
+ * created with the dimensions supplied by the onProvideThumbnailMetrics()
+ * callback.
+ *
+ * @param canvas
+ */
+ public void onDrawThumbnail(Canvas canvas) {
+ mView.draw(canvas);
+ }
+ }
+
+ /**
* Drag and drop. App calls startDrag(), then callbacks to onMeasureDragThumbnail()
* and onDrawDragThumbnail() happen, then the drag operation is handed over to the
* OS.
* !!! TODO: real docs
* @hide
*/
- public final boolean startDrag(ClipData data, float touchX, float touchY,
- float thumbnailTouchX, float thumbnailTouchY, boolean myWindowOnly) {
- if (DEBUG_DRAG) {
- Log.d(VIEW_LOG_TAG, "startDrag: touch=(" + touchX + "," + touchY
- + ") thumb=(" + thumbnailTouchX + "," + thumbnailTouchY
- + ") data=" + data + " local=" + myWindowOnly);
+ public final boolean startDrag(ClipData data, DragThumbnailBuilder thumbBuilder,
+ boolean myWindowOnly) {
+ if (ViewDebug.DEBUG_DRAG) {
+ Log.d(VIEW_LOG_TAG, "startDrag: data=" + data + " local=" + myWindowOnly);
}
boolean okay = false;
- measureThumbnail(); // throws if the view fails to specify dimensions
+ Point thumbSize = new Point();
+ Point thumbTouchPoint = new Point();
+ thumbBuilder.onProvideThumbnailMetrics(thumbSize, thumbTouchPoint);
+
+ if ((thumbSize.x < 0) || (thumbSize.y < 0) ||
+ (thumbTouchPoint.x < 0) || (thumbTouchPoint.y < 0)) {
+ throw new IllegalStateException("Drag thumb dimensions must not be negative");
+ }
Surface surface = new Surface();
try {
IBinder token = mAttachInfo.mSession.prepareDrag(mAttachInfo.mWindow,
myWindowOnly, mThumbnailWidth, mThumbnailHeight, surface);
- if (DEBUG_DRAG) Log.d(VIEW_LOG_TAG, "prepareDrag returned token=" + token
+ if (ViewDebug.DEBUG_DRAG) Log.d(VIEW_LOG_TAG, "prepareDrag returned token=" + token
+ " surface=" + surface);
if (token != null) {
Canvas canvas = surface.lockCanvas(null);
try {
- onDrawDragThumbnail(canvas);
+ thumbBuilder.onDrawThumbnail(canvas);
} finally {
surface.unlockCanvasAndPost(canvas);
}
+ // repurpose 'thumbSize' for the last touch point
+ getViewRoot().getLastTouchPoint(thumbSize);
+
okay = mAttachInfo.mSession.performDrag(mAttachInfo.mWindow, token,
- touchX, touchY, thumbnailTouchX, thumbnailTouchY, data);
- if (DEBUG_DRAG) Log.d(VIEW_LOG_TAG, "performDrag returned " + okay);
+ (float) thumbSize.x, (float) thumbSize.y,
+ (float) thumbTouchPoint.x, (float) thumbTouchPoint.y, data);
+ if (ViewDebug.DEBUG_DRAG) Log.d(VIEW_LOG_TAG, "performDrag returned " + okay);
}
} catch (Exception e) {
Log.e(VIEW_LOG_TAG, "Unable to initiate drag", e);
@@ -9888,7 +9949,7 @@
+ " measured dimension by calling setDragThumbnailDimension()");
}
- if (DEBUG_DRAG) {
+ if (ViewDebug.DEBUG_DRAG) {
Log.d(VIEW_LOG_TAG, "Drag thumb measured: w=" + mThumbnailWidth
+ " h=" + mThumbnailHeight);
}