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A library jar that provides APIs for Applications written for the Google Android Platform.

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/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.transition;

import android.content.Context;
import android.util.SparseArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * A scene represents the collection of values that various properties in the
 * View hierarchy will have when the scene is applied. A Scene can be
 * configured to automatically run a Transition when it is applied, which will
 * animate the various property changes that take place during the
 * scene change.
 */
public final class Scene {

    private Context mContext;
    private int mLayoutId = -1;
    private ViewGroup mSceneRoot;
    private View mLayout; // alternative to layoutId
    Runnable mEnterAction, mExitAction;

    /**
     * Returns a Scene described by the resource file associated with the given
     * layoutId parameter. If such a Scene has already been created for
     * the given sceneRoot, that same Scene will be returned.
     * This caching of layoutId-based scenes enables sharing of common scenes
     * between those created in code and those referenced by {@link TransitionManager}
     * XML resource files.
     *
     * @param sceneRoot The root of the hierarchy in which scene changes
     * and transitions will take place.
     * @param layoutId The id of a standard layout resource file.
     * @param context The context used in the process of inflating
     * the layout resource.
     * @return The scene for the given root and layout id
     */
    public static Scene getSceneForLayout(ViewGroup sceneRoot, int layoutId, Context context) {
        SparseArray scenes = (SparseArray) sceneRoot.getTag(
                com.android.internal.R.id.scene_layoutid_cache);
        if (scenes == null) {
            scenes = new SparseArray();
            sceneRoot.setTagInternal(com.android.internal.R.id.scene_layoutid_cache, scenes);
        }
        Scene scene = scenes.get(layoutId);
        if (scene != null) {
            return scene;
        } else {
            scene = new Scene(sceneRoot, layoutId, context);
            scenes.put(layoutId, scene);
            return scene;
        }
    }

    /**
     * Constructs a Scene with no information about how values will change
     * when this scene is applied. This constructor might be used when
     * a Scene is created with the intention of being dynamically configured,
     * through setting {@link #setEnterAction(Runnable)} and possibly
     * {@link #setExitAction(Runnable)}.
     *
     * @param sceneRoot The root of the hierarchy in which scene changes
     * and transitions will take place.
     */
    public Scene(ViewGroup sceneRoot) {
        mSceneRoot = sceneRoot;
    }

    /**
     * Constructs a Scene which, when entered, will remove any
     * children from the sceneRoot container and will inflate and add
     * the hierarchy specified by the layoutId resource file.
     *
     * 

This method is hidden because layoutId-based scenes should be * created by the caching factory method {@link Scene#getCurrentScene(View)}.

* * @param sceneRoot The root of the hierarchy in which scene changes * and transitions will take place. * @param layoutId The id of a resource file that defines the view * hierarchy of this scene. * @param context The context used in the process of inflating * the layout resource. */ private Scene(ViewGroup sceneRoot, int layoutId, Context context) { mContext = context; mSceneRoot = sceneRoot; mLayoutId = layoutId; } /** * Constructs a Scene which, when entered, will remove any * children from the sceneRoot container and add the layout * object as a new child of that container. * * @param sceneRoot The root of the hierarchy in which scene changes * and transitions will take place. * @param layout The view hierarchy of this scene, added as a child * of sceneRoot when this scene is entered. */ public Scene(ViewGroup sceneRoot, View layout) { mSceneRoot = sceneRoot; mLayout = layout; } /** * @deprecated use {@link #Scene(ViewGroup, View)}. */ @Deprecated public Scene(ViewGroup sceneRoot, ViewGroup layout) { mSceneRoot = sceneRoot; mLayout = layout; } /** * Gets the root of the scene, which is the root of the view hierarchy * affected by changes due to this scene, and which will be animated * when this scene is entered. * * @return The root of the view hierarchy affected by this scene. */ public ViewGroup getSceneRoot() { return mSceneRoot; } /** * Exits this scene, if it is the current scene * on the scene's {@link #getSceneRoot() scene root}. The current scene is * set when {@link #enter() entering} a scene. * Exiting a scene runs the {@link #setExitAction(Runnable) exit action} * if there is one. */ public void exit() { if (getCurrentScene(mSceneRoot) == this) { if (mExitAction != null) { mExitAction.run(); } } } /** * Enters this scene, which entails changing all values that * are specified by this scene. These may be values associated * with a layout view group or layout resource file which will * now be added to the scene root, or it may be values changed by * an {@link #setEnterAction(Runnable)} enter action}, or a * combination of the these. No transition will be run when the * scene is entered. To get transition behavior in scene changes, * use one of the methods in {@link TransitionManager} instead. */ public void enter() { // Apply layout change, if any if (mLayoutId > 0 || mLayout != null) { // empty out parent container before adding to it getSceneRoot().removeAllViews(); if (mLayoutId > 0) { LayoutInflater.from(mContext).inflate(mLayoutId, mSceneRoot); } else { mSceneRoot.addView(mLayout); } } // Notify next scene that it is entering. Subclasses may override to configure scene. if (mEnterAction != null) { mEnterAction.run(); } setCurrentScene(mSceneRoot, this); } /** * Set the scene that the given view is in. The current scene is set only * on the root view of a scene, not for every view in that hierarchy. This * information is used by Scene to determine whether there is a previous * scene which should be exited before the new scene is entered. * * @param view The view on which the current scene is being set */ static void setCurrentScene(View view, Scene scene) { view.setTagInternal(com.android.internal.R.id.current_scene, scene); } /** * Gets the current {@link Scene} set on the given view. A scene is set on a view * only if that view is the scene root. * * @return The current Scene set on this view. A value of null indicates that * no Scene is currently set. */ static Scene getCurrentScene(View view) { return (Scene) view.getTag(com.android.internal.R.id.current_scene); } /** * Scenes that are not defined with layout resources or * hierarchies, or which need to perform additional steps * after those hierarchies are changed to, should set an enter * action, and possibly an exit action as well. An enter action * will cause Scene to call back into application code to do * anything else the application needs after transitions have * captured pre-change values and after any other scene changes * have been applied, such as the layout (if any) being added to * the view hierarchy. After this method is called, Transitions will * be played. * * @param action The runnable whose {@link Runnable#run() run()} method will * be called when this scene is entered * @see #setExitAction(Runnable) * @see Scene#Scene(ViewGroup, int, Context) * @see Scene#Scene(ViewGroup, ViewGroup) */ public void setEnterAction(Runnable action) { mEnterAction = action; } /** * Scenes that are not defined with layout resources or * hierarchies, or which need to perform additional steps * after those hierarchies are changed to, should set an enter * action, and possibly an exit action as well. An exit action * will cause Scene to call back into application code to do * anything the application needs to do after applicable transitions have * captured pre-change values, but before any other scene changes * have been applied, such as the new layout (if any) being added to * the view hierarchy. After this method is called, the next scene * will be entered, including a call to {@link #setEnterAction(Runnable)} * if an enter action is set. * * @see #setEnterAction(Runnable) * @see Scene#Scene(ViewGroup, int, Context) * @see Scene#Scene(ViewGroup, ViewGroup) */ public void setExitAction(Runnable action) { mExitAction = action; } /** * Returns whether this Scene was created by a layout resource file, determined * by the layoutId passed into * {@link #getSceneForLayout(android.view.ViewGroup, int, android.content.Context)}. * This is called by TransitionManager to determine whether it is safe for views from * this scene to be removed from their parents when the scene is exited, which is * used by {@link Fade} to fade these views out (the views must be removed from * their parent in order to add them to the overlay for fading purposes). If a * Scene is not based on a resource file, then the impact of removing views * arbitrarily is unknown and should be avoided. */ boolean isCreatedFromLayoutResource() { return (mLayoutId > 0); } }




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