FW Activity跳转动画源码解析(一)

文章目录

- 跳转动画实际操作的是什么?
- 窗口怎么知道应该执行什么动画,是透明,还是平移,还是缩放,旋转?

跳转动画实际操作的是什么?

startActivity调用之后进行页面跳转,会有一系列的涉及到ActivitStar,ActivityTask,ActivityManager等类的操作,最终在执行动画会调用到SurfaceControl中去,相关代码如下

public final class SurfaceControl implements Parcelable {
//省略代码@NonNullpublic Transaction setAlpha(@NonNull SurfaceControl sc,@FloatRange(from = 0.0, to = 1.0) float alpha) {checkPreconditions(sc);nativeSetAlpha(mNativeObject, sc.mNativeObject, alpha);return this;}
//省略代码@UnsupportedAppUsagepublic Transaction setMatrix(SurfaceControl sc, Matrix matrix, float[] float9) {matrix.getValues(float9);setMatrix(sc, float9[MSCALE_X], float9[MSKEW_Y],float9[MSKEW_X], float9[MSCALE_Y]);setPosition(sc, float9[MTRANS_X], float9[MTRANS_Y]);return this;}
//这个是调用到native的函数        @UnsupportedAppUsagepublic Transaction setMatrix(SurfaceControl sc,float dsdx, float dtdx, float dtdy, float dsdy) {checkPreconditions(sc);nativeSetMatrix(mNativeObject, sc.mNativeObject,dsdx, dtdx, dtdy, dsdy);return this;}@UnsupportedAppUsagepublic Transaction setPosition(SurfaceControl sc, float x, float y) {checkPreconditions(sc);nativeSetPosition(mNativeObject, sc.mNativeObject, x, y);return this;}
//省略代码
}

以上函数就负责了窗口的透明度以及大小,还有位置的变换.
可以看到相应的设置函数,最终都会调用到native层去,我们选一个cpp的代码看一下

//android_view_SurfaceControl.cpp
static void nativeSetPosition(JNIEnv* env, jclass clazz, jlong transactionObj,jlong nativeObject, jfloat x, jfloat y) {auto transaction = reinterpret_cast<SurfaceComposerClient::Transaction*>(transactionObj);SurfaceControl* const ctrl = reinterpret_cast<SurfaceControl *>(nativeObject);transaction->setPosition(ctrl, x, y);
}//SurfaceComposerClient.cpp
SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::setPosition(const sp<SurfaceControl>& sc, float x, float y) {layer_state_t* s = getLayerState(sc);if (!s) {mStatus = BAD_INDEX;return *this;}s->what |= layer_state_t::ePositionChanged;s->x = x;s->y = y;registerSurfaceControlForCallback(sc);return *this;
}

以上代码调用到native去了之后会把相关设置的值赋值给layer,如果需要再cpp中定制动画相关的设置
可以修改这一块.

关于SurfaceControl 的调用链路如下图,WindowContainer,ActivityRecord大家应该都不陌生
在这里插入图片描述

窗口怎么知道应该执行什么动画,是透明,还是平移,还是缩放,旋转?

class WindowContainer<E extends WindowContainer> extends ConfigurationContainer<E>implements Comparable<WindowContainer>, Animatable, SurfaceFreezer.Freezable,BLASTSyncEngine.TransactionReadyListener {private Animation loadAnimation(WindowManager.LayoutParams lp, int transit, boolean enter,boolean isVoiceInteraction) {//省略代码//通过Transition获取动画对象final Animation a = getDisplayContent().mAppTransition.loadAnimation(lp, transit, enter,displayConfig.uiMode, displayConfig.orientation, frame, displayFrame, insets,surfaceInsets, stableInsets, isVoiceInteraction, inFreeformWindowingMode(), this);//省略代码}                   
}public class AppTransition implements Dump {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) {//这里面有一堆判定,但是普通应用的时候是不会通过的,会再调用到loadAnimationAttra = animAttr != 0 ? loadAnimationAttr(lp, animAttr, transit) : null;return a;}//调用getCachedAnimations获取EntryAnimation loadAnimationAttr(LayoutParams lp, int animAttr, int transit) {int resId = Resources.ID_NULL;Context context = mContext;if (animAttr >= 0) {AttributeCache.Entry ent = getCachedAnimations(lp);if (ent != null) {context = ent.context;resId = ent.array.getResourceId(animAttr, 0);}}resId = updateToTranslucentAnimIfNeeded(resId, transit);if (ResourceId.isValid(resId)) {return loadAnimationSafely(context, resId);}return null;}//获取Styleable中的动画主题private AttributeCache.Entry getCachedAnimations(LayoutParams lp) {if (DEBUG_ANIM) Slog.v(TAG, "Loading animations: layout params pkg="+ (lp != null ? lp.packageName : null)+ " resId=0x" + (lp != null ? Integer.toHexString(lp.windowAnimations) : null));if (lp != null && lp.windowAnimations != 0) {// If this is a system resource, don't try to load it from the// application resources.  It is nice to avoid loading application// resources if we can.String packageName = lp.packageName != null ? lp.packageName : "android";int resId = getAnimationStyleResId(lp);if ((resId&0xFF000000) == 0x01000000) {packageName = "android";}if (DEBUG_ANIM) Slog.v(TAG, "Loading animations: picked package="+ packageName);return AttributeCache.instance().get(packageName, resId,com.android.internal.R.styleable.WindowAnimation, mCurrentUserId);}return null;}
}

在执行以上代码以后,就会从主题中获取到定义的窗口切换动画资源了.
相关的调用栈如下:
在这里插入图片描述

获取到默认的启动动画资源,这个会对应一个anim的xml文件,以下文件位于frameworks/base/core/res/res/anim路径.
android:anim/activity_open_enter
退出的时候默认动画如下
android:anim/activity_close_enter

在获取到以上资源以后动画会调用到WindowAnimationSpec类中去执行如下代码

@Overridepublic void apply(Transaction t, SurfaceControl leash, long currentPlayTime) {final TmpValues tmp = mThreadLocalTmps.get();tmp.transformation.clear();mAnimation.getTransformation(currentPlayTime, tmp.transformation);tmp.transformation.getMatrix().postTranslate(mPosition.x, mPosition.y);t.setMatrix(leash, tmp.transformation.getMatrix(), tmp.floats);t.setAlpha(leash, tmp.transformation.getAlpha());boolean cropSet = false;if (mStackClipMode == STACK_CLIP_NONE) {if (tmp.transformation.hasClipRect()) {t.setWindowCrop(leash, tmp.transformation.getClipRect());cropSet = true;}} else {mTmpRect.set(mStackBounds);if (tmp.transformation.hasClipRect()) {mTmpRect.intersect(tmp.transformation.getClipRect());}t.setWindowCrop(leash, mTmpRect);cropSet = true;}// We can only apply rounded corner if a crop is set, as otherwise the value is meaningless,// since it doesn't have anything it's relative to.if (cropSet && mAnimation.hasRoundedCorners() && mWindowCornerRadius > 0) {t.setCornerRadius(leash, mWindowCornerRadius);}}

以上代码中 mAnimation.getTransformation(currentPlayTime, tmp.transformation);这一行就是通过之前得到的动画对象去计算应该设置的透明,平移等参数值,以用于去设置视图.
简单看一下这个计算吧,感兴趣的可以深入研究一下

public abstract class Animation implements Cloneable {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 durationnormalizedTime = 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;}}