https://source.android.com/ 
/*
 * Copyright (C) 2006 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.widget;


import android.annotation.AnimRes;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;


Base class for a FrameLayout container that will perform animations when switching between its views. 
@attrref android.R.styleable#ViewAnimator_inAnimation
@attrref android.R.styleable#ViewAnimator_outAnimation
@attrref android.R.styleable#ViewAnimator_animateFirstView
/**
 * Base class for a {@link FrameLayout} container that will perform animations
 * when switching between its views.
 *
 * @attr ref android.R.styleable#ViewAnimator_inAnimation
 * @attr ref android.R.styleable#ViewAnimator_outAnimation
 * @attr ref android.R.styleable#ViewAnimator_animateFirstView
 */
public class ViewAnimator extends FrameLayout {

    int mWhichChild = 0;
    boolean mFirstTime = true;

    boolean mAnimateFirstTime = true;

    Animation mInAnimation;
    Animation mOutAnimation;

    public ViewAnimator(Context context) {
        super(context);
        initViewAnimator(context, null);
    }

    public ViewAnimator(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray a = context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.ViewAnimator);
        int resource = a.getResourceId(com.android.internal.R.styleable.ViewAnimator_inAnimation, 0);
        if (resource > 0) {
            setInAnimation(context, resource);
        }

        resource = a.getResourceId(com.android.internal.R.styleable.ViewAnimator_outAnimation, 0);
        if (resource > 0) {
            setOutAnimation(context, resource);
        }

        boolean flag = a.getBoolean(com.android.internal.R.styleable.ViewAnimator_animateFirstView, true);
        setAnimateFirstView(flag);

        a.recycle();

        initViewAnimator(context, attrs);
    }

    
Initialize this ViewAnimator, possibly setting FrameLayout.setMeasureAllChildren(boolean) based on FrameLayout flags. 
/**
     * Initialize this {@link ViewAnimator}, possibly setting
     * {@link #setMeasureAllChildren(boolean)} based on {@link FrameLayout} flags.
     */
    private void initViewAnimator(Context context, AttributeSet attrs) {
        if (attrs == null) {
            // For compatibility, always measure children when undefined.
            mMeasureAllChildren = true;
            return;
        }

        // For compatibility, default to measure children, but allow XML
        // attribute to override.
        final TypedArray a = context.obtainStyledAttributes(attrs,
                com.android.internal.R.styleable.FrameLayout);
        final boolean measureAllChildren = a.getBoolean(
                com.android.internal.R.styleable.FrameLayout_measureAllChildren, true);
        setMeasureAllChildren(measureAllChildren);
        a.recycle();
    }

    
Sets which child view will be displayed.

Params:
  • whichChild – the index of the child view to display
/**
     * Sets which child view will be displayed.
     *
     * @param whichChild the index of the child view to display
     */
    @android.view.RemotableViewMethod
    public void setDisplayedChild(int whichChild) {
        mWhichChild = whichChild;
        if (whichChild >= getChildCount()) {
            mWhichChild = 0;
        } else if (whichChild < 0) {
            mWhichChild = getChildCount() - 1;
        }
        boolean hasFocus = getFocusedChild() != null;
        // This will clear old focus if we had it
        showOnly(mWhichChild);
        if (hasFocus) {
            // Try to retake focus if we had it
            requestFocus(FOCUS_FORWARD);
        }
    }

    
Returns the index of the currently displayed child view.

/**
     * Returns the index of the currently displayed child view.
     */
    public int getDisplayedChild() {
        return mWhichChild;
    }

    
Manually shows the next child.

/**
     * Manually shows the next child.
     */
    @android.view.RemotableViewMethod
    public void showNext() {
        setDisplayedChild(mWhichChild + 1);
    }

    
Manually shows the previous child.

/**
     * Manually shows the previous child.
     */
    @android.view.RemotableViewMethod
    public void showPrevious() {
        setDisplayedChild(mWhichChild - 1);
    }

    
Shows only the specified child. The other displays Views exit the screen, optionally with the with the out animation and the specified child enters the screen, optionally with the in animation. 
Params:
  • childIndex – The index of the child to be shown.
  • animate – Whether or not to use the in and out animations, defaults
           to true.
/**
     * Shows only the specified child. The other displays Views exit the screen,
     * optionally with the with the {@link #getOutAnimation() out animation} and
     * the specified child enters the screen, optionally with the
     * {@link #getInAnimation() in animation}.
     *
     * @param childIndex The index of the child to be shown.
     * @param animate Whether or not to use the in and out animations, defaults
     *            to true.
     */
    void showOnly(int childIndex, boolean animate) {
        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (i == childIndex) {
                if (animate && mInAnimation != null) {
                    child.startAnimation(mInAnimation);
                }
                child.setVisibility(View.VISIBLE);
                mFirstTime = false;
            } else {
                if (animate && mOutAnimation != null && child.getVisibility() == View.VISIBLE) {
                    child.startAnimation(mOutAnimation);
                } else if (child.getAnimation() == mInAnimation)
                    child.clearAnimation();
                child.setVisibility(View.GONE);
            }
        }
    }
    
Shows only the specified child. The other displays Views exit the screen with the out animation and the specified child enters the screen with the in animation. 
Params:
  • childIndex – The index of the child to be shown.
/**
     * Shows only the specified child. The other displays Views exit the screen
     * with the {@link #getOutAnimation() out animation} and the specified child
     * enters the screen with the {@link #getInAnimation() in animation}.
     *
     * @param childIndex The index of the child to be shown.
     */
    void showOnly(int childIndex) {
        final boolean animate = (!mFirstTime || mAnimateFirstTime);
        showOnly(childIndex, animate);
    }

    @Override
    public void addView(View child, int index, ViewGroup.LayoutParams params) {
        super.addView(child, index, params);
        if (getChildCount() == 1) {
            child.setVisibility(View.VISIBLE);
        } else {
            child.setVisibility(View.GONE);
        }
        if (index >= 0 && mWhichChild >= index) {
            // Added item above current one, increment the index of the displayed child
            setDisplayedChild(mWhichChild + 1);
        }
    }

    @Override
    public void removeAllViews() {
        super.removeAllViews();
        mWhichChild = 0;
        mFirstTime = true;
    }

    @Override
    public void removeView(View view) {
        final int index = indexOfChild(view);
        if (index >= 0) {
            removeViewAt(index);
        }
    }

    @Override
    public void removeViewAt(int index) {
        super.removeViewAt(index);
        final int childCount = getChildCount();
        if (childCount == 0) {
            mWhichChild = 0;
            mFirstTime = true;
        } else if (mWhichChild >= childCount) {
            // Displayed is above child count, so float down to top of stack
            setDisplayedChild(childCount - 1);
        } else if (mWhichChild == index) {
            // Displayed was removed, so show the new child living in its place
            setDisplayedChild(mWhichChild);
        }
    }

    public void removeViewInLayout(View view) {
        removeView(view);
    }

    public void removeViews(int start, int count) {
        super.removeViews(start, count);
        if (getChildCount() == 0) {
            mWhichChild = 0;
            mFirstTime = true;
        } else if (mWhichChild >= start && mWhichChild < start + count) {
            // Try showing new displayed child, wrapping if needed
            setDisplayedChild(mWhichChild);
        }
    }

    public void removeViewsInLayout(int start, int count) {
        removeViews(start, count);
    }

    
Returns the View corresponding to the currently displayed child.

See Also:
Returns:The View currently displayed.
/**
     * Returns the View corresponding to the currently displayed child.
     *
     * @return The View currently displayed.
     *
     * @see #getDisplayedChild()
     */
    public View getCurrentView() {
        return getChildAt(mWhichChild);
    }

    
Returns the current animation used to animate a View that enters the screen.

See Also:
Returns:An Animation or null if none is set.
/**
     * Returns the current animation used to animate a View that enters the screen.
     *
     * @return An Animation or null if none is set.
     *
     * @see #setInAnimation(android.view.animation.Animation)
     * @see #setInAnimation(android.content.Context, int)
     */
    public Animation getInAnimation() {
        return mInAnimation;
    }

    
Specifies the animation used to animate a View that enters the screen.

Params:
  • inAnimation – The animation started when a View enters the screen.
See Also:
/**
     * Specifies the animation used to animate a View that enters the screen.
     *
     * @param inAnimation The animation started when a View enters the screen.
     *
     * @see #getInAnimation()
     * @see #setInAnimation(android.content.Context, int)
     */
    public void setInAnimation(Animation inAnimation) {
        mInAnimation = inAnimation;
    }

    
Returns the current animation used to animate a View that exits the screen.

See Also:
Returns:An Animation or null if none is set.
/**
     * Returns the current animation used to animate a View that exits the screen.
     *
     * @return An Animation or null if none is set.
     *
     * @see #setOutAnimation(android.view.animation.Animation)
     * @see #setOutAnimation(android.content.Context, int)
     */
    public Animation getOutAnimation() {
        return mOutAnimation;
    }

    
Specifies the animation used to animate a View that exit the screen.

Params:
  • outAnimation – The animation started when a View exit the screen.
See Also:
/**
     * Specifies the animation used to animate a View that exit the screen.
     *
     * @param outAnimation The animation started when a View exit the screen.
     *
     * @see #getOutAnimation()
     * @see #setOutAnimation(android.content.Context, int)
     */
    public void setOutAnimation(Animation outAnimation) {
        mOutAnimation = outAnimation;
    }

    
Specifies the animation used to animate a View that enters the screen.

Params:
  • context – The application's environment.
  • resourceID – The resource id of the animation.
See Also:
/**
     * Specifies the animation used to animate a View that enters the screen.
     *
     * @param context The application's environment.
     * @param resourceID The resource id of the animation.
     *
     * @see #getInAnimation()
     * @see #setInAnimation(android.view.animation.Animation)
     */
    public void setInAnimation(Context context, @AnimRes int resourceID) {
        setInAnimation(AnimationUtils.loadAnimation(context, resourceID));
    }

    
Specifies the animation used to animate a View that exit the screen.

Params:
  • context – The application's environment.
  • resourceID – The resource id of the animation.
See Also:
/**
     * Specifies the animation used to animate a View that exit the screen.
     *
     * @param context The application's environment.
     * @param resourceID The resource id of the animation.
     *
     * @see #getOutAnimation()
     * @see #setOutAnimation(android.view.animation.Animation)
     */
    public void setOutAnimation(Context context, @AnimRes int resourceID) {
        setOutAnimation(AnimationUtils.loadAnimation(context, resourceID));
    }

    
Returns whether the current View should be animated the first time the ViewAnimator
is displayed.

See Also:
Returns:true if the current View will be animated the first time it is displayed,
false otherwise.
/**
     * Returns whether the current View should be animated the first time the ViewAnimator
     * is displayed.
     *
     * @return true if the current View will be animated the first time it is displayed,
     * false otherwise.
     *
     * @see #setAnimateFirstView(boolean)
     */
    public boolean getAnimateFirstView() {
        return mAnimateFirstTime;
    }

    
Indicates whether the current View should be animated the first time
the ViewAnimator is displayed.

Params:
  • animate – True to animate the current View the first time it is displayed,
               false otherwise.
/**
     * Indicates whether the current View should be animated the first time
     * the ViewAnimator is displayed.
     *
     * @param animate True to animate the current View the first time it is displayed,
     *                false otherwise.
     */
    public void setAnimateFirstView(boolean animate) {
        mAnimateFirstTime = animate;
    }

    @Override
    public int getBaseline() {
        return (getCurrentView() != null) ? getCurrentView().getBaseline() : super.getBaseline();
    }

    @Override
    public CharSequence getAccessibilityClassName() {
        return ViewAnimator.class.getName();
    }
}