clearAnimation的简要流程

clearAnimation的简要流程

自己做了一个关于Animation动画的小游戏,出现了一些小问题,所以稍微看了一下此流程:

  /**
     * Cancels any animations for this view.
     */
    public void clearAnimation() {
        if (mCurrentAnimation != null) {
            mCurrentAnimation.detach();      ===> ①触发onAnimationEnd()方法
        }
        mCurrentAnimation = null;       ===> 将Animation置为null
        invalidateParentIfNeeded();      ===> ④
    }

==> mCurrentAnimation == Animation

①将Animation状态设置为Ended,并执行fireAnimationEnd()==>用于触发onAnimationEnd()方法

 /**
     * @hide
     */
    @UnsupportedAppUsage
    public void detach() {
        if (mStarted && !mEnded) {
            mEnded = true;
            guard.close();
            fireAnimationEnd();       ===>②
        }
    }

==>设置状态

/**
     * Set by {@link #getTransformation(long, Transformation)} when the animation starts.
     */
==>    boolean mStarted = false;

 /**
     * Set by {@link #getTransformation(long, Transformation)} when the animation ends.
     */
==>    boolean mEnded = false;

==>  private final CloseGuard guard = CloseGuard.get();

②
  private void fireAnimationEnd() {
        if (hasAnimationListener()) {
            if (mListenerHandler == null) 
               dispatchAnimationEnd();          ===> ③
            else 
               mListenerHandler.postAtFrontOfQueue(mOnEnd);
        }
    }

==>是否设置了事件监听
private boolean hasAnimationListener() {
        return mListener != null;
    }

    /**
     * <p>Binds an animation listener to this animation. The animation listener
     * is notified of animation events such as the end of the animation or the
     * repetition of the animation.</p>
     *
     * @param listener the animation listener to be notified
     */
    public void setAnimationListener(AnimationListener listener) {
        mListener = listener;
    }


==>设置mListenerHandler
     /**
     * Sets the handler used to invoke listeners.
     *
     * @hide
     */
    public void setListenerHandler(Handler handler) {
        if (mListenerHandler == null) {
            mOnStart = new Runnable() {
                public void run() {
                    dispatchAnimationStart();
                }
            };
            mOnRepeat = new Runnable() {
                public void run() {
                    dispatchAnimationRepeat();
                }
            };
            mOnEnd = new Runnable() {
                public void run() {
                    dispatchAnimationEnd();
                }
            };
        }
        mListenerHandler = handler;
    }

③
==>Start() Repeat() End()   mListener==AnimationListener
void dispatchAnimationStart() {
        if (mListener != null) {
            mListener.onAnimationStart(this);
        }
    }

    void dispatchAnimationRepeat() {
        if (mListener != null) {
            mListener.onAnimationRepeat(this);
        }
    }

    void dispatchAnimationEnd() {
        if (mListener != null) {
            mListener.onAnimationEnd(this);
        }
    }

==>Start() Repeat() End() 接口
 /**
     * <p>An animation listener receives notifications from an animation.
     * Notifications indicate animation related events, such as the end or the
     * repetition of the animation.</p>
     */
    public static interface AnimationListener {
        /**
         * <p>Notifies the start of the animation.</p>
         *
         * @param animation The started animation.
         */
        void onAnimationStart(Animation animation);

        /**
         * <p>Notifies the end of the animation. This callback is not invoked
         * for animations with repeat count set to INFINITE.</p>
         *
         * @param animation The animation which reached its end.
         */
        void onAnimationEnd(Animation animation);

        /**
         * <p>Notifies the repetition of the animation.</p>
         *
         * @param animation The animation which was repeated.
         */
        void onAnimationRepeat(Animation animation);
    }


④
 /**
     * Used to indicate that the parent of this view should be invalidated. This functionality
     * is used to force the parent to rebuild its display list (when hardware-accelerated),
     * which is necessary when various parent-managed properties of the view change, such as
     * alpha, translationX/Y, scrollX/Y, scaleX/Y, and rotation/X/Y. This method will propagate
     * an invalidation event to the parent.
     *
     * @hide
     */
    @UnsupportedAppUsage
    protected void invalidateParentIfNeeded() {
        if (isHardwareAccelerated() && mParent instanceof View) {
            ((View) mParent).invalidate(true);          ===>⑤
        }
    }


⑤
==>
 /**
     * This is where the invalidate() work actually happens. A full invalidate()
     * causes the drawing cache to be invalidated, but this function can be
     * called with invalidateCache set to false to skip that invalidation step
     * for cases that do not need it (for example, a component that remains at
     * the same dimensions with the same content).
     *
     * @param invalidateCache Whether the drawing cache for this view should be
     *            invalidated as well. This is usually true for a full
     *            invalidate, but may be set to false if the View's contents or
     *            dimensions have not changed.
     * @hide
     */
    @UnsupportedAppUsage
    public void invalidate(boolean invalidateCache) {
        invalidateInternal(0, 0, mRight - mLeft, mBottom - mTop, invalidateCache, true); ===>⑥
    }

mTop：视图相对父容器坐标系的上侧边界坐标。
mLeft：视图相对父容器坐标系的左侧边界坐标。
mRight-mLeft：视图宽度。
mBottom-mTop：视图高度。



⑥
==>
void invalidateInternal(int l, int t, int r, int b, boolean invalidateCache,boolean fullInvalidate) {
        if (mGhostView != null) {
            mGhostView.invalidate(true);
            return;
        }

        if (skipInvalidate()) {                  ===>⑦
            return;
        }

        // Reset content capture caches
        mCachedContentCaptureSession = null;

        if ((mPrivateFlags & (PFLAG_DRAWN | PFLAG_HAS_BOUNDS)) == (PFLAG_DRAWN | PFLAG_HAS_BOUNDS)
                || (invalidateCache && (mPrivateFlags & PFLAG_DRAWING_CACHE_VALID) == PFLAG_DRAWING_CACHE_VALID)
                || (mPrivateFlags & PFLAG_INVALIDATED) != PFLAG_INVALIDATED
                || (fullInvalidate && isOpaque() != mLastIsOpaque)) {
            if (fullInvalidate) {
                mLastIsOpaque = isOpaque();
                mPrivateFlags &= ~PFLAG_DRAWN;
            }

            mPrivateFlags |= PFLAG_DIRTY;

            if (invalidateCache) {
                mPrivateFlags |= PFLAG_INVALIDATED;
                mPrivateFlags &= ~PFLAG_DRAWING_CACHE_VALID;
            }

            // Propagate the damage rectangle to the parent view.
            final AttachInfo ai = mAttachInfo;
            final ViewParent p = mParent;
            if (p != null && ai != null && l < r && t < b) {
                final Rect damage = ai.mTmpInvalRect;
                damage.set(l, t, r, b);
                p.invalidateChild(this, damage);
            }

            // Damage the entire projection receiver, if necessary.
            if (mBackground != null && mBackground.isProjected()) {
                final View receiver = getProjectionReceiver();
                if (receiver != null) {
                    receiver.damageInParent();
                }
            }
        }
    }

⑦跳过绘制
private boolean skipInvalidate() {
        return (mViewFlags & VISIBILITY_MASK) != VISIBLE && mCurrentAnimation == null &&
                (!(mParent instanceof ViewGroup) ||
                        !((ViewGroup) mParent).isViewTransitioning(this));
    }

     public static final int VISIBLE = 0x00000000;
     
public static final int INVISIBLE = 0x00000004; 
     public static final int GONE = 0x00000008; 
     static final int VISIBILITY_MASK = 0x0000000C; 
     ==>VISIBLE + INVISIBLE + GONE = VISIBILITY_MASK          

5. public static long currentAnimationTimeMillis() {
        AnimationState state = sAnimationState.get();
        if (state.animationClockLocked) {
            // It's important that time never rewinds
            return Math.max(state.currentVsyncTimeMillis,
                    state.lastReportedTimeMillis);
        }
        state.lastReportedTimeMillis = SystemClock.uptimeMillis();
        return state.lastReportedTimeMillis;
    }
6. /**
     * Gets the transformation to apply at a specified point in time. Implementations of this
     * method should always replace the specified Transformation or document they are doing
     * otherwise.
     *
     * @param currentTime Where we are in the animation. This is wall clock time.
     * @param outTransformation A transformation object that is provided by the
     *        caller and will be filled in by the animation.
     * @return True if the animation is still running
     */
    public boolean getTransformation(long currentTime, Transformation outTransformation) {
        if (mStartTime == -1) {
            mStartTime = currentTime;
        }

        final long startOffset = getStartOffset();
        final long duration = mDuration;
        float normalizedTime;
        if (duration != 0) {
            normalizedTime = ((float) (currentTime - (mStartTime + startOffset))) /
                    (float) duration;
        } else {
            // time is a step-change with a zero duration
            normalizedTime = currentTime < mStartTime ? 0.0f : 1.0f;
        }

        final boolean expired = normalizedTime >= 1.0f || isCanceled();
        mMore = !expired;

        if (!mFillEnabled) normalizedTime = Math.max(Math.min(normalizedTime, 1.0f), 0.0f);

        if ((normalizedTime >= 0.0f || mFillBefore) && (normalizedTime <= 1.0f || mFillAfter)) {
            if (!mStarted) {
                fireAnimationStart();
                mStarted = true;
                if (NoImagePreloadHolder.USE_CLOSEGUARD) {
                    guard.open("cancel or detach or getTransformation");
                }
            }

            if (mFillEnabled) normalizedTime = Math.max(Math.min(normalizedTime, 1.0f), 0.0f);

            if (mCycleFlip) {
                normalizedTime = 1.0f - normalizedTime;
            }

            final float interpolatedTime = mInterpolator.getInterpolation(normalizedTime);
            applyTransformation(interpolatedTime, outTransformation);
        }

        if (expired) {
            if (mRepeatCount == mRepeated || isCanceled()) {
                if (!mEnded) {
                    mEnded = true;
                    guard.close();
                    fireAnimationEnd();
                }
            } else {
                if (mRepeatCount > 0) {
                    mRepeated++;
                }

                if (mRepeatMode == REVERSE) {
                    mCycleFlip = !mCycleFlip;
                }

                mStartTime = -1;
                mMore = true;

                fireAnimationRepeat();
            }
        }

        if (!mMore && mOneMoreTime) {
            mOneMoreTime = false;
            return true;
        }

        return mMore;
    }

就只看到此处了,没有更深入的研究了.QWQ