android.view.DragEvent#getClipDescription ( )源码实例Demo

@Override
public boolean onDrag(View view, DragEvent event) {
    // DragTarget is peeking into the MIME types of the dragged event in order to ignore
    // non-image drags completely.
    // DragSource does not do that but rejects non-image content once a drop has happened.
    ClipDescription clipDescription = event.getClipDescription();
    if (clipDescription != null && !clipDescription.hasMimeType("image/*")) {
        return false;
    }
    // Callback received when image is being dragged.
    return super.onDrag(view, event);
}
 

/**
 * DragEvents can contain additional data packaged in a {@link PersistableBundle}.
 * Extract the extras from the event and return the String stored for the
 * {@link #EXTRA_IMAGE_INFO} entry.
 */
private String getExtra(DragEvent event) {
    // The extras are contained in the ClipDescription in the DragEvent.
    ClipDescription clipDescription = event.getClipDescription();
    if (clipDescription != null) {
        PersistableBundle extras = clipDescription.getExtras();
        if (extras != null) {
            return extras.getString(EXTRA_IMAGE_INFO);
        }
    }
    return null;
}
 

@Override
public boolean onDrag(View view, DragEvent event) {
    // DragTarget is peeking into the MIME types of the dragged event in order to ignore
    // non-image drags completely.
    // DragSource does not do that but rejects non-image content once a drop has happened.
    ClipDescription clipDescription = event.getClipDescription();
    if (clipDescription != null && !clipDescription.hasMimeType("image/*")) {
        return false;
    }
    // Callback received when image is being dragged.
    return super.onDrag(view, event);
}
 

/**
 * DragEvents can contain additional data packaged in a {@link PersistableBundle}.
 * Extract the extras from the event and return the String stored for the
 * {@link #EXTRA_IMAGE_INFO} entry.
 */
private String getExtra(DragEvent event) {
    // The extras are contained in the ClipDescription in the DragEvent.
    ClipDescription clipDescription = event.getClipDescription();
    if (clipDescription != null) {
        PersistableBundle extras = clipDescription.getExtras();
        if (extras != null) {
            return extras.getString(EXTRA_IMAGE_INFO);
        }
    }
    return null;
}
 

boolean processDragStarted(DragEvent event) {
    // Determine whether to continue processing drag and drop based on the
    // plain text mime type.
    ClipDescription clipDesc = event.getClipDescription();
    if (clipDesc != null) {
        return clipDesc.hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN);
    }
    return false;
}
 

boolean processDragStarted(DragEvent event) {
    // Determine whether to continue processing drag and drop based on the
    // plain text mime type.
    ClipDescription clipDesc = event.getClipDescription();
    if (clipDesc != null) {
        return clipDesc.hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN);
    }
    return false;
}
 

boolean processDragStarted(DragEvent event) {
    // Determine whether to continue processing drag and drop based on the
    // plain text mime type.
    ClipDescription clipDesc = event.getClipDescription();
    if (clipDesc != null) {
        return clipDesc.hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN);
    }
    return false;
}
 

boolean processDragStarted(DragEvent event) {
    // Determine whether to continue processing drag and drop based on the
    // plain text mime type.
    ClipDescription clipDesc = event.getClipDescription();
    if (clipDesc != null) {
        return clipDesc.hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN);
    }
    return false;
}
 

boolean processDragStarted(DragEvent event) {
    // Determine whether to continue processing drag and drop based on the
    // plain text mime type.
    ClipDescription clipDesc = event.getClipDescription();
    if (clipDesc != null) {
        return clipDesc.hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN);
    }
    return false;
}
 

private boolean onDragStart(DragEvent event) {
    if (!mRequest.isValid()) {
        return false;
    }
    ClipDescription desc =  event.getClipDescription();
    if (desc == null || !desc.hasMimeType(getMimeType())) {
        return false;
    }

    final PendingAddItemInfo item;
    if (mRequest.getRequestType() == PinItemRequestCompat.REQUEST_TYPE_SHORTCUT) {
        item = new PendingAddShortcutInfo(
                new PinShortcutRequestActivityInfo(mRequest, mLauncher));
    } else {
        // mRequest.getRequestType() == PinItemRequestCompat.REQUEST_TYPE_APPWIDGET
        LauncherAppWidgetProviderInfo providerInfo =
                LauncherAppWidgetProviderInfo.fromProviderInfo(
                        mLauncher, mRequest.getAppWidgetProviderInfo(mLauncher));
        final PinWidgetFlowHandler flowHandler =
                new PinWidgetFlowHandler(providerInfo, mRequest);
        item = new PendingAddWidgetInfo(providerInfo) {
            @Override
            public WidgetAddFlowHandler getHandler() {
                return flowHandler;
            }
        };
    }
    View view = new View(mLauncher);
    view.setTag(item);

    Point downPos = new Point((int) event.getX(), (int) event.getY());
    DragOptions options = new DragOptions();
    options.systemDndStartPoint = downPos;
    options.preDragCondition = this;

    // We use drag event position as the screenPos for the preview image. Since mPreviewRect
    // already includes the view position relative to the drag event on the source window,
    // and the absolute position (position relative to the screen) of drag event is same
    // across windows, using drag position here give a good estimate for relative position
    // to source window.
    PendingItemDragHelper dragHelper = new PendingItemDragHelper(view);
    if (mRequest.getRequestType() == PinItemRequestCompat.REQUEST_TYPE_APPWIDGET) {
        dragHelper.setPreview(getPreview(mRequest));
    }

    dragHelper.startDrag(new Rect(mPreviewRect),
            mPreviewBitmapWidth, mPreviewViewWidth, downPos,  this, options);
    mDragStartTime = SystemClock.uptimeMillis();
    return true;
}
 

/**
 * @see View#onDragEvent(DragEvent)
 */
@TargetApi(Build.VERSION_CODES.N)
public boolean onDragEvent(DragEvent event) {
    if (mNativeContentViewCore == 0 || Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
        return false;
    }

    ClipDescription clipDescription = event.getClipDescription();

    // text/* will match text/uri-list, text/html, text/plain.
    String[] mimeTypes =
            clipDescription == null ? new String[0] : clipDescription.filterMimeTypes("text/*");

    if (event.getAction() == DragEvent.ACTION_DRAG_STARTED) {
        // TODO(hush): support dragging more than just text.
        return mimeTypes != null && mimeTypes.length > 0
                && nativeIsTouchDragDropEnabled(mNativeContentViewCore);
    }

    StringBuilder content = new StringBuilder("");
    if (event.getAction() == DragEvent.ACTION_DROP) {
        // TODO(hush): obtain dragdrop permissions, when dragging files into Chrome/WebView is
        // supported. Not necessary to do so for now, because only text dragging is supported.
        ClipData clipData = event.getClipData();
        final int itemCount = clipData.getItemCount();
        for (int i = 0; i < itemCount; i++) {
            ClipData.Item item = clipData.getItemAt(i);
            content.append(item.coerceToStyledText(mContainerView.getContext()));
        }
    }

    int[] locationOnScreen = new int[2];
    mContainerView.getLocationOnScreen(locationOnScreen);

    float xPix = event.getX() + mCurrentTouchOffsetX;
    float yPix = event.getY() + mCurrentTouchOffsetY;

    int xCss = (int) mRenderCoordinates.fromPixToDip(xPix);
    int yCss = (int) mRenderCoordinates.fromPixToDip(yPix);
    int screenXCss = (int) mRenderCoordinates.fromPixToDip(xPix + locationOnScreen[0]);
    int screenYCss = (int) mRenderCoordinates.fromPixToDip(yPix + locationOnScreen[1]);

    nativeOnDragEvent(mNativeContentViewCore, event.getAction(), xCss, yCss, screenXCss,
            screenYCss, mimeTypes, content.toString());
    return true;
}