Android 动画框架代码分析

http://www.ibm.com/developerworks/cn/opensource/os-cn-android-anmt2/

Android学习：

http://www.ibm.com/developerworks/cn/opensource/theme/android/

Activity之间、不同窗口间的切换动画：

WindowManager

performLayoutAndPlaceSurfacesLockedInner()

调用的是StartActivity，是标准的系统切换动画。
看能否让动画在目标Activity准备好之后才开始计划动画的时间？
Activity.startActivity()
Instrumentation.execStartActivity()
ActivityManagerNative.startActivity()
IBinder.transact(START_ACTIVITY_TRANSACTION, data, reply, 0);

ActivityManagerService.ActivityStack.startActivityMayWait();

ActivityStack.startActivityLocked();

mService.mWindowManager.prepareAppTransition(WindowManagerPolicy.TRANSIT_ACTIVITY_OPEN)
WindowManagerService.prepareAppTransition(int transit)
WindowManagerService.executeAppTransition()
WindowManagerService.performLayoutAndPlaceSurfacesLocked()

ActivityStack.resumeTopActivityLocked(ActivityRecord prev)
mService.mWindowManager.executeAppTransition();
WindowManagerService.executeAppTransition();
mAppTransitionReady = true; //此变量表示已经作好准备，动画要开始了
WindowManagerService.performLayoutAndPlaceSurfacesLocked()
WindowManagerService.performLayoutAndPlaceSurfacesLockedInner(), //其中咐循环所有窗口，并实现动画
currentTime = SystemClock.uptimeMillis(); （当前时间）
performLayoutLockedInner(); // 先布局，再动画
mPolicy.beginAnimationLw(dw, dh);
WindowManagerPolicy.beginAnimationLw()
PhoneWindowManager.beginAnimationLw()
WindowState.stepAnimationLocked(currentTime, dw, dh); //开始动画（记录开始时间）
PhoneWindowManager.animatingWindowLw()
PhoneWindowManager.finishAnimationLw()
if (mAppTransitionReady) {
mAppTransitionReady = false;
mAppTransitionRunning = true; //动画已经在运行中
mAppTransitionTimeout = false;
mStartingIconInTransition = false;
mSkipAppTransitionAnimation = false;

WindowManagerService.prepareAppTransition(int transit)
mAppTransitionReady = false; //此变量表示已经作好准备，动画要开始了
mAppTransitionTimeout = false;
mStartingIconInTransition = false;
mSkipAppTransitionAnimation = false;
mH.removeMessages(H.APP_TRANSITION_TIMEOUT);
mH.sendMessageDelayed(mH.obtainMessage(H.APP_TRANSITION_TIMEOUT),5000);

WindowState.stepAnimationLocked(currentTime, dw, dh)
if (!mLocalAnimating) {
if (DEBUG_ANIM) Slog.v(
TAG, "Starting animation in " + this +
" @ " + currentTime + ": ww=" + mFrame.width() + " wh=" + mFrame.height() +
" dw=" + dw + " dh=" + dh + " scale=" + mWindowAnimationScale);
mAnimation.initialize(mFrame.width(), mFrame.height(), dw, dh);
mAnimation.setStartTime(currentTime); //动画正式开始计时！
mLocalAnimating = true;
mAnimating = true;
}

同一窗口内的View之间的动画机制：

View.getAnimation()
ViewGroup:
// Layout animation
private LayoutAnimationController mLayoutAnimationController;
private Animation.AnimationListener mAnimationListener;
drawChild(Canvas canvas, View child, long drawingTime); //绘制子控件

Animation:
getTransformation(long currentTime, Transformation outTransformation); //得到某时刻的运动结果

ViewGroup.drawChild(Canvas canvas, View child, long drawingTime):
final Animation a = child.getAnimation(); //获得子控件的动画对象
more = a.getTransformation(drawingTime, mChildTransformation); // 计算子控件在绘制时刻的运动结果transformation
transformToApply = mChildTransformation;
// 根据子控件的transformation对画布进行相应设置
// 如果控件有Drawing_Cache，则用canvas.drawBitmap(cache)进行绘制，否则直接child.draw(canvas)绘制

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