99 lines
3.9 KiB
Markdown
99 lines
3.9 KiB
Markdown
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Android DragAndDropAcrossApps-new Sample
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===================================
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This sample contains two separate Android applications: DragSource and
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DropTarget. DragSource contains images and text that can be dropped into the DropTarget
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app. Images are shared between the two apps through a URI for which the receiving app
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must request permission first, before it can be used.
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It also demonstrates the use of the DragStartHelper from the v13 support library to easily
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handle drag and drop events.
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Introduction
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------------
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Android N introduces support for drag and drop between applications,
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augmenting the existing APIs that have enabled this within a single
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window before.
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To start a drag operation you need to call `View.startDragAndDrop`.
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Which gesture or action triggers this is up to you as an app developer.
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The API guide recommends doing this from
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`View.OnLongClickListener.onLongClick` and this seems to be the de-facto
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standard, but you are free to use other gestures (single tap, tap and drag
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etc).
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However, if you go for a unconventional drag start gesture, note that
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the framework implementation assumes that the pointer (touch or mouse)
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is down while the drag is starting, and the most recent touch/click
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position is used as the original position of the drag shadow.
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See also `android.support.v13.view.DragStartHelper` which uses different
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gestures for touch and mouse (click and drag works better for mouse
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than a long click).
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By default a drag and drop operation is constrained by the window
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containing the view that started the drag.
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To enable cross-window and cross-app drag and drop add
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`View.DRAG_FLAG_GLOBAL` to the flags passed to the `View.startDragAndDrop`
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call.
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If a Uri requiring permission grants is being sent, then the
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`android.view.View.DRAG_FLAG_GLOBAL_URI_READ` and/or the
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`android.view.View.DRAG_FLAG_GLOBAL_URI_WRITE` flags must be used also.
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To access content URIs requiring permissions on the receiving side, the target
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app needs to request the `android.view.DropPermissions` from the activity via
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`android.app.Activity.requestDropPermissions`. This permission will stay either
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until the activity is alive, or until the `release()` method is called on the
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`android.view.DropPermissions` object.
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Pre-requisites
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--------------
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- Android SDK 27
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- Android Build Tools v27.0.2
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- Android Support Repository
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Screenshots
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-------------
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<img src="screenshots/phone.png" height="400" alt="Screenshot"/> <img src="screenshots/tablet.png" height="400" alt="Screenshot"/>
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Getting Started
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---------------
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This sample uses the Gradle build system. To build this project, use the
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"gradlew build" command or use "Import Project" in Android Studio.
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Support
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-------
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- Google+ Community: https://plus.google.com/communities/105153134372062985968
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- Stack Overflow: http://stackoverflow.com/questions/tagged/android
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If you've found an error in this sample, please file an issue:
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https://github.com/googlesamples/android-DragAndDropAcrossApps-new
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Patches are encouraged, and may be submitted by forking this project and
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submitting a pull request through GitHub. Please see CONTRIBUTING.md for more details.
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License
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-------
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Copyright 2017 The Android Open Source Project, Inc.
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Licensed to the Apache Software Foundation (ASF) under one or more contributor
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license agreements. See the NOTICE file distributed with this work for
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additional information regarding copyright ownership. The ASF licenses this
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file to you under the Apache License, Version 2.0 (the "License"); you may not
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use this file except in compliance with the License. You may obtain a copy of
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the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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License for the specific language governing permissions and limitations under
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the License.
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