基于Android R版本分析
应用场景：车载
Activity From To From需求分析
-
需求：需要实现Dock栏点击应用icon、Launcher点击桌面卡片开启、关闭相应的应用时，开关动画需要实现缩放效果，同时缩放位置为icon或者是卡片的中心位置；
-
场景：
- open animation：从dock或者是launcher界面中点击icon图标或者是桌面卡片；
- close animation：从应用侧返回到Launcher界面或者再次点击该应用对应dock栏中的icon图标时需要触发；
-
触发条件：
-
open：dock栏或者launcher点击对应的应用icon或卡片；
-
close：
- back key返回或者是手势back
- 在应用开启的状态下，再次点击dock栏中该应用程序对应的icon图标
-
-
中断场景：
- 从dock中开启对应的应用程序，然后dock栏进入编辑态，将对应的应用程序对应的icon移除，则该应用程序退出动画需要居中缩放，不需要再缩放至dock栏位置；
- 从dock栏或者是launcher开始应用程序之后，出现异常crash或者是主动kill，这种场景下，无退出动画的执行，因为是异常退出，无法执行正常的退出逻辑；
AOSP R工作流程分析
架构
整体的架构如上所示，这里需要明确一点核心点：
ActivityRecord和Animation之间不是强耦合的关系，即可以简单的理解为：ActivityRecord的加载和Animation的加载时序没有强关联，是两个独立的模块；
Activity Transit Type
| TRANSIT Type | value | desc |
|---|---|---|
| TRANSIT_UNSET | -1 | 初始值，未设置过渡动画 |
| TRANSIT_NONE | 0 | 没有过渡动画 |
| TRANSIT_ACTIVITY_OPEN | 6 | 新Activity的窗口正在同一任务中的现有窗口之上打开 |
| TRANSIT_ACTIVITY_CLOSE | 7 | 最顶层Activity的窗口正在关闭以显示同一任务中的前一个Activity |
| TRANSIT_TASK_OPEN | 8 | 新Activity的窗口正在另一个Activity所属的Task的现有窗口之上打开 |
| TRANSIT_TASK_CLOSE | 9 | 最顶层Activity的一个窗口正在关闭，以显示不同任务中的前一个Activity |
| TRANSIT_TASK_TO_FRONT | 10 | 将Task移至最顶端，即现有Task的窗口显示在另一个Activity所属Task的顶部 |
| TRANSIT_TASK_TO_BACK | 11 | 将Task移至最低端，即现有Task的窗口被放置在所有其他Task下方 |
| TRANSIT_WALLPAPER_CLOSE | 12 | 新Activity没有Wallpaper的窗口会在有Wallpaper的窗口之上打开，从而有效地关闭Wallpaper |
| TRANSIT_WALLPAPER_OPEN | 13 | 新Activity带有Wallpaper的窗口会在没有Wallpaper的窗口上打开，从而有效地打开Wallpaper |
| TRANSIT_WALLPAPER_INTRA_OPEN | 14 | 新Activity的一个窗口在现有Activity的顶部打开，并且两者都在Wallpaper的顶部 |
| TRANSIT_WALLPAPER_INTRA_CLOSE | 15 | 最顶部Activity的窗口正在关闭以显示之前的Activity，并且两者都位于Wallpaper的顶部 |
| TRANSIT_TASK_OPEN_BEHIND | 16 | 新Task中的一个窗口在另一个Activity的Task中的现有窗口后面打开 新窗口将短暂显示，然后消失 |
| TRANSIT_ACTIVITY_RELAUNCH | 18 | 正在重新启动Activity（例如，由于配置更改） |
| TRANSIT_DOCK_TASK_FROM_RECENTS | 19 | 正在对接最近的Task |
| TRANSIT_KEYGUARD_GOING_AWAY | 20 | Keyguard 即将消失 |
| TRANSIT_KEYGUARD_GOING_AWAY_ON_WALLPAPER | 21 | Keyguard 将消失，显示背后请求Wallpaper的Activity |
| TRANSIT_KEYGUARD_OCCLUDE | 22 | Keyguard 被遮挡 |
| TRANSIT_KEYGUARD_UNOCCLUDE | 23 | Keyguard 未被遮挡 |
| TRANSIT_TRANSLUCENT_ACTIVITY_OPEN | 24 | 正在打开一个半透明的Activity |
| TRANSIT_TRANSLUCENT_ACTIVITY_CLOSE | 25 | 一个半透明的Activity正在关闭 |
| TRANSIT_CRASHING_ACTIVITY_CLOSE | 26 | 正在关闭崩溃的Activity |
| TRANSIT_TASK_CHANGE_WINDOWING_MODE | 27 | 一项Task正在改变窗口模式 |
| TRANSIT_SHOW_SINGLE_TASK_DISPLAY | 28 | 由于第一个Activity已启动或正在打开，因此正在显示只能包含一个Task的显示 |
OpenAnimation & CloseAnimation 流程分析
参考：
其中有一个过称为：handleAppTransitionReady，这个过程中涉及几个模块概念；
动画类型
我们知道，在Framework中定义了两种类型的动画：
- RemoteAnimation
- LocalAnimation
同时还有一种动画定义类型，就是直接通过xml的方式定义的动画参数信息，通过loadAnimation的方式加载：
- xml Animation
/**
* Gets the {@link AnimationAdapter} according the given window layout properties in the window
* hierarchy.
*
* @return The return value will always contain two elements, one for normal animations and the
* other for thumbnail animation, both can be {@code null}.
*
* @See com.android.server.wm.RemoteAnimationController.RemoteAnimationRecord
* @See LocalAnimationAdapter
*/
Pair<AnimationAdapter, AnimationAdapter> getAnimationAdapter(WindowManager.LayoutParams lp,
int transit, boolean enter, boolean isVoiceInteraction) {
final Pair<AnimationAdapter, AnimationAdapter> resultAdapters;
final int appStackClipMode = getDisplayContent().mAppTransition.getAppStackClipMode();
// Separate position and size for use in animators.
final Rect screenBounds = getAnimationBounds(appStackClipMode);
mTmpRect.set(screenBounds);
getAnimationPosition(mTmpPoint);
if (!sHierarchicalAnimations) {
// Non-hierarchical animation uses position in global coordinates.
mTmpPoint.set(mTmpRect.left, mTmpRect.top);
}
mTmpRect.offsetTo(0, 0);-
final RemoteAnimationController controller =
getDisplayContent().mAppTransition.getRemoteAnimationController();
final boolean isChanging = AppTransition.isChangeTransit(transit) && enter
&& isChangingAppTransition();
// Delaying animation start isn't compatible with remote animations at all.
if (controller != null && !mSurfaceAnimator.isAnimationStartDelayed()) {
final Rect localBounds = new Rect(mTmpRect);
localBounds.offsetTo(mTmpPoint.x, mTmpPoint.y);
// Remote Animation类型
final RemoteAnimationController.RemoteAnimationRecord adapters =
controller.createRemoteAnimationRecord(this, mTmpPoint, localBounds,
screenBounds, (isChanging ? mSurfaceFreezer.mFreezeBounds : null));
resultAdapters = new Pair<>(adapters.mAdapter, adapters.mThumbnailAdapter);
} else if (isChanging) {
final float durationScale = mWmService.getTransitionAnimationScaleLocked();
final DisplayInfo displayInfo = getDisplayContent().getDisplayInfo();
mTmpRect.offsetTo(mTmpPoint.x, mTmpPoint.y);
final AnimationAdapter adapter = new LocalAnimationAdapter(
new WindowChangeAnimationSpec(mSurfaceFreezer.mFreezeBounds, mTmpRect,
displayInfo, durationScale, true /* isAppAnimation */,
false /* isThumbnail */),
getSurfaceAnimationRunner());
// Local Animation
final AnimationAdapter thumbnailAdapter = mSurfaceFreezer.mSnapshot != null
? new LocalAnimationAdapter(new WindowChangeAnimationSpec(
mSurfaceFreezer.mFreezeBounds, mTmpRect, displayInfo, durationScale,
true /* isAppAnimation */, true /* isThumbnail */), getSurfaceAnimationRunner())
: null;
resultAdapters = new Pair<>(adapter, thumbnailAdapter);
mTransit = transit;
mTransitFlags = getDisplayContent().mAppTransition.getTransitFlags();
} else {
mNeedsAnimationBoundsLayer = (appStackClipMode == STACK_CLIP_AFTER_ANIM);
// load animation
final Animation a = loadAnimation(lp, transit, enter, isVoiceInteraction);
if (a != null) {
// Only apply corner radius to animation if we're not in multi window mode.
// We don't want rounded corners when in pip or split screen.
final float windowCornerRadius = !inMultiWindowMode()
? getDisplayContent().getWindowCornerRadius()
: 0;
AnimationAdapter adapter = new LocalAnimationAdapter(
new WindowAnimationSpec(a, mTmpPoint, mTmpRect,
getDisplayContent().mAppTransition.canSkipFirstFrame(),
appStackClipMode, true /* isAppAnimation */, windowCornerRadius),
getSurfaceAnimationRunner());
resultAdapters = new Pair<>(adapter, null);
mNeedsZBoost = a.getZAdjustment() == Animation.ZORDER_TOP
|| AppTransition.isClosingTransit(transit);
mTransit = transit;
mTransitFlags = getDisplayContent().mAppTransition.getTransitFlags();
} else {
resultAdapters = new Pair<>(null, null);
}
}
return resultAdapters;
}
动画参数
这个方法就是用于设置应用开启和关闭的过渡动画的，其中包含了两个类型为ArraySet集合列表，其中保存的元素类型为ActivityRecord：
- openingApps：应用过渡动画的打开应用列表
- closingApps：应用程序过渡动画所应用的关闭应用程序列表
同时还包含一些关键的参数信息：
-
transit：描述动画的过渡类型，这个参考Activity Transit Type的定义类型；
-
enter：描述当前的动画类型为开启场景还是关闭场景；
- true：开启场景
- false：关闭场景
AppTransition
大致的工作流程：在open和close的时候，获取或者是应用层传入执行过渡动画需要的参数；
openingApps
针对open场景的过渡动画，Android原生提供了相应的功能；
/**
* Create an ActivityOptions specifying an animation where the new
* activity is scaled from a small originating area of the screen to
* its final full representation.
*
* <p>If the Intent this is being used with has not set its
* {@link android.content.Intent#setSourceBounds Intent.setSourceBounds},
* those bounds will be filled in for you based on the initial
* bounds passed in here.
*
* @param source The View that the new activity is animating from. This
* defines the coordinate space for <var>startX</var> and <var>startY</var>.
* @param startX The x starting location of the new activity, relative to <var>source</var>.
* @param startY The y starting location of the activity, relative to <var>source</var>.
* @param width The initial width of the new activity.
* @param height The initial height of the new activity.
* @return Returns a new ActivityOptions object that you can use to
* supply these options as the options Bundle when starting an activity.
*/
public static ActivityOptions makeScaleUpAnimation(View source,
int startX, int startY, int width, int height) {
ActivityOptions opts = new ActivityOptions();
opts.mPackageName = source.getContext().getPackageName();
opts.mAnimationType = ANIM_SCALE_UP;
int[] pts = new int[2];
source.getLocationOnScreen(pts);
opts.mStartX = pts[0] + startX;
opts.mStartY = pts[1] + startY;
opts.mWidth = width;
opts.mHeight = height;
return opts;
}
ActivityOptions向应用层提供了定制ScaleUpAnimation的接口；
- source：起始View
- startX / startY：拉伸开始的坐标，一般情况下为0
- width / height：初始的宽高，这里一般指的就是source的width和height；
上述的参数为应用层传入的参数含义，我们需要重点关注一下ActivityOptions内部定义的变量含义：
- opts.mPackageName：代表当前view所属的package；
- opts.mAnimationType：过渡动画类型，当前场景下为ANIM_SCALE_UP，这个变量会在后续getAnimationAdapter过程中会使用到，需要特别注意；
- opts.mStartX：拉伸开始的坐标，这里的startX和应用层中的startX含义是不同的，这里的startX = source.getX + app.startX的和，这里的opts.mStartX代表的其实就是实际view在屏幕的中真实坐标；
- opts.mStartY：拉伸开始的坐标，同理startY = source.getY + app.startY的和，这里的opts.mStartY代表的其实就是实际view在屏幕的中真实坐标；
- opts.mWidth / opts.mHeight：width和height和应用层传入的含义一致；
ScaleUpAnimation
/**
*
* @param frame These are the bounds of the window when it finishes the animation. This is where
* the animation must usually finish in entrance animation, as the next frame will
* display the window at these coordinates. In case of exit animation, this is
* where the animation must start, as the frame before the animation is displaying
* the window at these bounds.
* @param insets Knowing where the window will be positioned is not enough. Some parts of the
* window might be obscured, usually by the system windows (status bar and
* navigation bar) and we use content insets to convey that information. This
* usually affects the animation aspects vertically, as the system decoration is
* at the top and the bottom. For example when we animate from full screen to
* recents, we want to exclude the covered parts, because they won't match the
* thumbnail after the last frame is executed.
* @param surfaceInsets In rare situation the surface is larger than the content and we need to
* know about this to make the animation frames match. We currently use
* this for freeform windows, which have larger surfaces to display
* shadows. When we animate them from recents, we want to match the content
* to the recents thumbnail and hence need to account for the surface being
* bigger.
*/
Animation loadAnimation(LayoutParams lp, int transit, boolean enter, int uiMode,
int orientation, Rect frame, Rect displayFrame, Rect insets,
@Nullable Rect surfaceInsets, @Nullable Rect stableInsets, boolean isVoiceInteraction,
boolean freeform, WindowContainer container) {
ActivityRecord record = container.getTopActivity(true, true);
Animation a = null;
if (isKeyguardGoingAwayTransit(transit) && enter) {
a = loadKeyguardExitAnimation(transit);
} ……………………
} else if (mNextAppTransitionType == NEXT_TRANSIT_TYPE_SCALE_UP) {
a = createScaleUpAnimationLocked(transit, enter, frame);
ProtoLog.v(WM_DEBUG_APP_TRANSITIONS_ANIM,
"applyAnimation: anim=%s nextAppTransition=ANIM_SCALE_UP transit=%s "
+ "isEntrance=%s Callers=%s",
a, appTransitionToString(transit), enter, Debug.getCallers(3));
} ……………………
return a;
}
private Animation createScaleUpAnimationLocked(int transit, boolean enter,
Rect containingFrame) {
Animation a;
getDefaultNextAppTransitionStartRect(mTmpRect);
final int appWidth = containingFrame.width();
final int appHeight = containingFrame.height();
// true：代表进入动画
// false：代表退出动画
if (enter) {
// Entering app zooms out from the center of the initial rect.
float scaleW = mTmpRect.width() / (float) appWidth;
float scaleH = mTmpRect.height() / (float) appHeight;
// 针对ScaleUp类型的进入动画，使用ScaleAnimation的Animation
Animation scale = new ScaleAnimation(scaleW, 1, scaleH, 1,
computePivot(mTmpRect.left, scaleW),
computePivot(mTmpRect.top, scaleH));
scale.setInterpolator(mDecelerateInterpolator);
Animation alpha = new AlphaAnimation(0, 1);
alpha.setInterpolator(mThumbnailFadeOutInterpolator);
AnimationSet set = new AnimationSet(false);
set.addAnimation(scale);
set.addAnimation(alpha);
set.setDetachWallpaper(true);
a = set;
} else if (transit == TRANSIT_WALLPAPER_INTRA_OPEN ||
transit == TRANSIT_WALLPAPER_INTRA_CLOSE) {
// If we are on top of the wallpaper, we need an animation that
// correctly handles the wallpaper staying static behind all of
// the animated elements. To do this, will just have the existing
// element fade out.
a = new AlphaAnimation(1, 0);
a.setDetachWallpaper(true);
} else {
// For normal animations, the exiting element just holds in place.
a = new AlphaAnimation(1, 1);
}
// Pick the desired duration. If this is an inter-activity transition,
// it is the standard duration for that. Otherwise we use the longer
// task transition duration.
final long duration;
switch (transit) {
case TRANSIT_ACTIVITY_OPEN:
case TRANSIT_ACTIVITY_CLOSE:
duration = mConfigShortAnimTime;
break;
default:
duration = DEFAULT_APP_TRANSITION_DURATION;
break;
}
a.setDuration(duration);
a.setFillAfter(true);
a.setInterpolator(mDecelerateInterpolator);
a.initialize(appWidth, appHeight, appWidth, appHeight);
return a;
}
closingApps
针对close退回至Launcher场景，我们默认是使用xml Anim；
Animation loadAnimation(LayoutParams lp, int transit, boolean enter, int uiMode,
int orientation, Rect frame, Rect displayFrame, Rect insets,
@Nullable Rect surfaceInsets, @Nullable Rect stableInsets, boolean isVoiceInteraction,
boolean freeform, WindowContainer container) {
ActivityRecord record = container.getTopActivity(true, true);
Animation a = null;
if (isKeyguardGoingAwayTransit(transit) && enter) {
a = loadKeyguardExitAnimation(transit);
} ……………………
} else {
int animAttr = 0;
switch (transit) {
…………
case TRANSIT_WALLPAPER_OPEN:
animAttr = enter
? WindowAnimation_wallpaperOpenEnterAnimation
: WindowAnimation_wallpaperOpenExitAnimation;
break;
case …………
}
return a;
}
判断条件：transit = TRANSIT_WALLPAPER_OPEN；
技术方案
根据上述的工作原理分析，我们可以分析出几个核心的关键点：
- mNextAppTransitionType：用于描述新开启的Activity的过渡动画类型
- transit：用于描述当前Activity的过渡动画类型
- ScaleAnimation：Scale类型Animation实例
我们需要注意mNextAppTransitionType和transit参数的区别；
mNextAppTransitionType
我们通过分析代码可知，这个变量是在开启新的Activity的时候，才需要关注的；
当应用层通过startActivity启动新的Activity时绑定了ScaleUpAnimation，则mNextAppTransitionType变量会被赋值为NEXT_TRANSIT_TYPE_SCALE_UP；当启动动画执行完成之后，这个mNextAppTransitionType参数又会被赋值为NEXT_TRANSIT_TYPE_NONE，即使用完毕之后需要复位；
针对从哪儿来回哪儿去的需求定义，如果Activity启动动画为SCALE_UP类型，则关闭时也需要执行Scale操作，我们暂且定义为SCALE_DOWN；
技术方案
针对NEXT_TRANSIT_TYPE_SCALE_UP变量的使用方式，我们需要在赋值之后以及其复位之前，我们需要记录一下当前所属的ActivityRecord，并给其设置一个flag保存其状态，为其后续close的时候使用做准备；
而当其执行close的时候，判断新定义的flag是否属于NEXT_TRANSIT_TYPE_SCALE_UP，如果属于的话，则执行我们自定义的逻辑，同时也需要复位该flag，代表本次open/close动画已经全部完成，清楚本次的record，等待下一次startActivity；
transit
针对transit参数，我们主要是在App返回至Launcher的时候需要特别关注，在App返回Launcher中，transit = TRANSIT_WALLPAPER_OPEN；
技术方案
针对close场景，我们需要新增一个判断条件，即在判断transit类型的基础上，我们需要再判断上述新增的flag是否属于NEXT_TRANSIT_TYPE_SCALE_UP类型，如果可以对应的上，则需要执行我们自定义的Animation；
ScaleAnimation
我们在创建ScaleAnimation的时候，传入的多个参数：
Animation scale = new ScaleAnimation(scaleW, 1, scaleH, 1,
computePivot(mTmpRect.left, scaleW),
computePivot(mTmpRect.top, scaleH));
/**
* Constructor to use when building a ScaleAnimation from code
*
* @param fromX Horizontal scaling factor to apply at the start of the
* animation
* @param toX Horizontal scaling factor to apply at the end of the animation
* @param fromY Vertical scaling factor to apply at the start of the
* animation
* @param toY Vertical scaling factor to apply at the end of the animation
* @param pivotX The X coordinate of the point about which the object is
* being scaled, specified as an absolute number where 0 is the left
* edge. (This point remains fixed while the object changes size.)
* @param pivotY The Y coordinate of the point about which the object is
* being scaled, specified as an absolute number where 0 is the top
* edge. (This point remains fixed while the object changes size.)
*/
public ScaleAnimation(float fromX, float toX, float fromY, float toY,
float pivotX, float pivotY) {
mResources = null;
mFromX = fromX;
mToX = toX;
mFromY = fromY;
mToY = toY;
mPivotXType = ABSOLUTE;
mPivotYType = ABSOLUTE;
mPivotXValue = pivotX;
mPivotYValue = pivotY;
initializePivotPoint();
}
- fromX：表示x坐标轴上动画的起始比例，比如fromX=0.5f，可以简单的理解为scale起始的比例大小；
- toX：表示动画结束时控件x轴方向的比例，比如toX = 1f，结合fromX参数，可以理解为，缩放比例大小是从0.5f放大至1f，1f代表的就是View的原始大小；
- fromY：同fromX；
- toY：同toY；
- pivotX：表示x坐标轴上动画的缩放位置；
- pivotY：表示y坐标轴上动画的缩放位置；
切记：pivotX和pivotY这两个参数代表的才是真正的缩放坐标，它的作用就是作为一个固定点，在动画播放的过程中，这个点保持不动，而周围的点围绕着这点进行缩放；
我们知道，在open场景下，上述的参数是通过应用层传入的，但是在close场景下，我们无法获取到对应的预期参数值；同时，针对dock栏可编辑态修改icon图标的位置信息时，底层也是无法获取到的；
技术方案
icon位置不变场景
针对icon位置不变的场景，我们可以按照上述保存NEXT_TRANSIT_TYPE_SCALE_UP的方式，新增几个变量，将ScaleAnimation所使用到的参数都一一保存，在后续close的时候，将根据我们保存的这些参数创建我们自己的SCALE_DOWN类型的ScaleAnimation实例；
icon位置changed场景
针对dock栏调整icon位置的场景，解决方案为：
当应用层icon坐标发生变化（包括：位置调整、icon新增、icon移除）时，需要将变化后的位置信息都一并传入底层，使其底层在执行close的时候，优先判断应用层icon是否发生变化，如果没有发生变化，执行上述的逻辑，如果发生变化的话，则需要重新获取最新的ScaleAnimation参数信息创建对应的SCALE_DOWN类型的ScaleAnimation实例；
