欧美一级特黄大片做受成人-亚洲成人一区二区电影-激情熟女一区二区三区-日韩专区欧美专区国产专区

Android源碼解析之屬性動畫詳解

前言

創(chuàng)新互聯(lián)建站網(wǎng)絡公司擁有十余年的成都網(wǎng)站開發(fā)建設經(jīng)驗,千余家客戶的共同信賴。提供成都做網(wǎng)站、網(wǎng)站建設、網(wǎng)站開發(fā)、網(wǎng)站定制、賣友情鏈接、建網(wǎng)站、網(wǎng)站搭建、自適應網(wǎng)站建設、網(wǎng)頁設計師打造企業(yè)風格,提供周到的售前咨詢和貼心的售后服務

大家在日常開發(fā)中離不開動畫,屬性動畫更為強大,我們不僅要知道如何使用,更要知道他的原理。這樣,才能得心應手。那么,今天,就從最簡單的來說,了解下屬性動畫的原理。

ObjectAnimator
 .ofInt(mView,"width",100,500)
 .setDuration(1000)
 .start();

ObjectAnimator#ofInt

以這個為例,代碼如下。

public static ObjectAnimator ofInt(Object target, String propertyName, int... values) {
 ObjectAnimator anim = new ObjectAnimator(target, propertyName);
 anim.setIntValues(values);
 return anim;
}

在這個方法中,首先會new一個ObjectAnimator對象,然后通過setIntValues方法將值設置進去,然后返回。在ObjectAnimator的構(gòu)造方法中,會通過setTarget方法設置當前動畫的對象,通過setPropertyName設置當前的屬性名。我們重點說下setIntValues方法。

public void setIntValues(int... values) {
 if (mValues == null || mValues.length == 0) {
 // No values yet - this animator is being constructed piecemeal. Init the values with
 // whatever the current propertyName is
 if (mProperty != null) {
 setValues(PropertyValuesHolder.ofInt(mProperty, values));
 } else {
 setValues(PropertyValuesHolder.ofInt(mPropertyName, values));
 }
 } else {
 super.setIntValues(values);
 }
}

首先會判斷,mValues是不是null,我們這里是null,并且mProperty也是null,所以會調(diào)用
setValues(PropertyValuesHolder.ofInt(mPropertyName, values));方法。先看PropertyValuesHolder.ofInt方法,PropertyValuesHolder這個類是holds屬性和值的,在這個方法會構(gòu)造一個IntPropertyValuesHolder對象并返回。

public static PropertyValuesHolder ofInt(String propertyName, int... values) {
 return new IntPropertyValuesHolder(propertyName, values);
}

IntPropertyValuesHolder的構(gòu)造方法如下:

public IntPropertyValuesHolder(String propertyName, int... values) {
 super(propertyName);
 setIntValues(values);
}

在這里,首先會調(diào)用他的分類的構(gòu)造方法,然后調(diào)用setIntValues方法,在他父類的構(gòu)造方法中,只是設置了下propertyName。setIntValues內(nèi)容如下:

public void setIntValues(int... values) {
 super.setIntValues(values);
 mIntKeyframes = (Keyframes.IntKeyframes) mKeyframes;
}

在父類的setIntValues方法中,初始化了mValueType為int.class,mKeyframes為KeyframeSet.ofInt(values)。其中KeyframeSet為關鍵幀集合。然后將mKeyframes賦值給mIntKeyframes。

KeyframeSet

這個類是記錄關鍵幀的。我們看下他的ofInt方法。

public static KeyframeSet ofInt(int... values) {
 int numKeyframes = values.length;
 IntKeyframe keyframes[] = new IntKeyframe[Math.max(numKeyframes,2)];
 if (numKeyframes == 1) {
 keyframes[0] = (IntKeyframe) Keyframe.ofInt(0f);
 keyframes[1] = (IntKeyframe) Keyframe.ofInt(1f, values[0]);
 } else {
 keyframes[0] = (IntKeyframe) Keyframe.ofInt(0f, values[0]);
 for (int i = 1; i < numKeyframes; ++i) {
 keyframes[i] =
  (IntKeyframe) Keyframe.ofInt((float) i / (numKeyframes - 1), values[i]);
 }
 }
 return new IntKeyframeSet(keyframes);
}

在這里呢?根據(jù)傳入的values來計算關鍵幀,最后返回IntKeyframeSet。

回到ObjectAnimator里面,這里的setValues用的是父類ValueAnimator的

ValueAnimator#setValues

public void setValues(PropertyValuesHolder... values) {
 int numValues = values.length;
 mValues = values;
 mValuesMap = new HashMap<String, PropertyValuesHolder>(numValues);
 for (int i = 0; i < numValues; ++i) {
 PropertyValuesHolder valuesHolder = values[i];
 mValuesMap.put(valuesHolder.getPropertyName(), valuesHolder);
 }
 // New property/values/target should cause re-initialization prior to starting
 mInitialized = false;
}

這里的操作就簡單了,就是把PropertyValuesHolder放入到mValuesMap中。

ObjectAnimator#start

這個方法就是動畫開始的地方。

public void start() {
 // See if any of the current active/pending animators need to be canceled
 AnimationHandler handler = sAnimationHandler.get();
 if (handler != null) {
 int numAnims = handler.mAnimations.size();
 for (int i = numAnims - 1; i >= 0; i--) {
 if (handler.mAnimations.get(i) instanceof ObjectAnimator) {
 ObjectAnimator anim = (ObjectAnimator) handler.mAnimations.get(i);
 if (anim.mAutoCancel && hasSameTargetAndProperties(anim)) {
  anim.cancel();
 }
 }
 }
 numAnims = handler.mPendingAnimations.size();
 for (int i = numAnims - 1; i >= 0; i--) {
 if (handler.mPendingAnimations.get(i) instanceof ObjectAnimator) {
 ObjectAnimator anim = (ObjectAnimator) handler.mPendingAnimations.get(i);
 if (anim.mAutoCancel && hasSameTargetAndProperties(anim)) {
  anim.cancel();
 }
 }
 }
 numAnims = handler.mDelayedAnims.size();
 for (int i = numAnims - 1; i >= 0; i--) {
 if (handler.mDelayedAnims.get(i) instanceof ObjectAnimator) {
 ObjectAnimator anim = (ObjectAnimator) handler.mDelayedAnims.get(i);
 if (anim.mAutoCancel && hasSameTargetAndProperties(anim)) {
  anim.cancel();
 }
 }
 }
 }
 if (DBG) {
 Log.d(LOG_TAG, "Anim target, duration: " + getTarget() + ", " + getDuration());
 for (int i = 0; i < mValues.length; ++i) {
 PropertyValuesHolder pvh = mValues[i];
 Log.d(LOG_TAG, " Values[" + i + "]: " +
 pvh.getPropertyName() + ", " + pvh.mKeyframes.getValue(0) + ", " +
 pvh.mKeyframes.getValue(1));
 }
 }
 super.start();
}

首先呢,會獲取AnimationHandler對象,如果不為空的話,就會判斷是mAnimations、mPendingAnimations、mDelayedAnims中的動畫,并且取消。最后調(diào)用父類的start方法。

ValueAnimator#start

private void start(boolean playBackwards) {
 if (Looper.myLooper() == null) {
 throw new AndroidRuntimeException("Animators may only be run on Looper threads");
 }
 mReversing = playBackwards;
 mPlayingBackwards = playBackwards;
 if (playBackwards && mSeekFraction != -1) {
 if (mSeekFraction == 0 && mCurrentIteration == 0) {
 // special case: reversing from seek-to-0 should act as if not seeked at all
 mSeekFraction = 0;
 } else if (mRepeatCount == INFINITE) {
 mSeekFraction = 1 - (mSeekFraction % 1);
 } else {
 mSeekFraction = 1 + mRepeatCount - (mCurrentIteration + mSeekFraction);
 }
 mCurrentIteration = (int) mSeekFraction;
 mSeekFraction = mSeekFraction % 1;
 }
 if (mCurrentIteration > 0 && mRepeatMode == REVERSE &&
 (mCurrentIteration < (mRepeatCount + 1) || mRepeatCount == INFINITE)) {
 // if we were seeked to some other iteration in a reversing animator,
 // figure out the correct direction to start playing based on the iteration
 if (playBackwards) {
 mPlayingBackwards = (mCurrentIteration % 2) == 0;
 } else {
 mPlayingBackwards = (mCurrentIteration % 2) != 0;
 }
 }
 int prevPlayingState = mPlayingState;
 mPlayingState = STOPPED;
 mStarted = true;
 mStartedDelay = false;
 mPaused = false;
 updateScaledDuration(); // in case the scale factor has changed since creation time
 AnimationHandler animationHandler = getOrCreateAnimationHandler();
 animationHandler.mPendingAnimations.add(this);
 if (mStartDelay == 0) {
 // This sets the initial value of the animation, prior to actually starting it running
 if (prevPlayingState != SEEKED) {
 setCurrentPlayTime(0);
 }
 mPlayingState = STOPPED;
 mRunning = true;
 notifyStartListeners();
 }
 animationHandler.start();
}
  • 先初始化一些值
  • updateScaledDuration 縮放時間,默認為1.0f
  • 獲取或者創(chuàng)建AnimationHandler,將動畫加入到mPendingAnimations列表中,
  • 如果沒延遲,通知監(jiān)聽器
  • animationHandler.start

animationHandler.start中,會調(diào)用scheduleAnimation方法,在這個種,會用mChoreographerpost一個callback,最終會執(zhí)行mAnimate的run方法。mChoreographerpost涉及到VSYNC,這里不多介紹。

mAnimate#run

doAnimationFrame(mChoreographer.getFrameTime());

在這里會用過doAnimationFrame設置動畫幀,我們看下這個方法的代碼。

void doAnimationFrame(long frameTime) {
 mLastFrameTime = frameTime;
 // mPendingAnimations holds any animations that have requested to be started
 // We're going to clear mPendingAnimations, but starting animation may
 // cause more to be added to the pending list (for example, if one animation
 // starting triggers another starting). So we loop until mPendingAnimations
 // is empty.
 while (mPendingAnimations.size() > 0) {
 ArrayList<ValueAnimator> pendingCopy =
 (ArrayList<ValueAnimator>) mPendingAnimations.clone();
 mPendingAnimations.clear();
 int count = pendingCopy.size();
 for (int i = 0; i < count; ++i) {
 ValueAnimator anim = pendingCopy.get(i);
 // If the animation has a startDelay, place it on the delayed list
 if (anim.mStartDelay == 0) {
 anim.startAnimation(this);
 } else {
 mDelayedAnims.add(anim);
 }
 }
 }
 // Next, process animations currently sitting on the delayed queue, adding
 // them to the active animations if they are ready
 int numDelayedAnims = mDelayedAnims.size();
 for (int i = 0; i < numDelayedAnims; ++i) {
 ValueAnimator anim = mDelayedAnims.get(i);
 if (anim.delayedAnimationFrame(frameTime)) {
 mReadyAnims.add(anim);
 }
 }
 int numReadyAnims = mReadyAnims.size();
 if (numReadyAnims > 0) {
 for (int i = 0; i < numReadyAnims; ++i) {
 ValueAnimator anim = mReadyAnims.get(i);
 anim.startAnimation(this);
 anim.mRunning = true;
 mDelayedAnims.remove(anim);
 }
 mReadyAnims.clear();
 }
 // Now process all active animations. The return value from animationFrame()
 // tells the handler whether it should now be ended
 int numAnims = mAnimations.size();
 for (int i = 0; i < numAnims; ++i) {
 mTmpAnimations.add(mAnimations.get(i));
 }
 for (int i = 0; i < numAnims; ++i) {
 ValueAnimator anim = mTmpAnimations.get(i);
 if (mAnimations.contains(anim) && anim.doAnimationFrame(frameTime)) {
 mEndingAnims.add(anim);
 }
 }
 mTmpAnimations.clear();
 if (mEndingAnims.size() > 0) {
 for (int i = 0; i < mEndingAnims.size(); ++i) {
 mEndingAnims.get(i).endAnimation(this);
 }
 mEndingAnims.clear();
 }
 // Schedule final commit for the frame.
 mChoreographer.postCallback(Choreographer.CALLBACK_COMMIT, mCommit, null);
 // If there are still active or delayed animations, schedule a future call to
 // onAnimate to process the next frame of the animations.
 if (!mAnimations.isEmpty() || !mDelayedAnims.isEmpty()) {
 scheduleAnimation();
 }
}

方法較長,邏輯如下:

  1. 從mPendingAnimations中取出動畫,根據(jù)事先選擇startAnimation還是加入到mDelayedAnims列表。
  2. 如果mDelayedAnims列表中的動畫準備好了,就加入到mReadyAnims列表中
  3. 從mAnimations列表中取出要執(zhí)行的動畫,加入到mTmpAnimations列表
  4. 通過doAnimationFrame方法執(zhí)行動畫幀
  5. 繼續(xù)執(zhí)行scheduleAnimation

從上面我們能看出,執(zhí)行動畫的關鍵是doAnimationFrame方法。在這個方法中,會調(diào)用animationFrame方法。

ValueAniator#animationFrame

boolean animationFrame(long currentTime) {
 boolean done = false;
 switch (mPlayingState) {
 case RUNNING:
 case SEEKED:
 float fraction = mDuration > 0 ? (float)(currentTime - mStartTime) / mDuration : 1f;
 if (mDuration == 0 && mRepeatCount != INFINITE) {
 // Skip to the end
 mCurrentIteration = mRepeatCount;
 if (!mReversing) {
  mPlayingBackwards = false;
 }
 }
 if (fraction >= 1f) {
 if (mCurrentIteration < mRepeatCount || mRepeatCount == INFINITE) {
  // Time to repeat
  if (mListeners != null) {
  int numListeners = mListeners.size();
  for (int i = 0; i < numListeners; ++i) {
  mListeners.get(i).onAnimationRepeat(this);
  }
  }
  if (mRepeatMode == REVERSE) {
  mPlayingBackwards = !mPlayingBackwards;
  }
  mCurrentIteration += (int) fraction;
  fraction = fraction % 1f;
  mStartTime += mDuration;
  // Note: We do not need to update the value of mStartTimeCommitted here
  // since we just added a duration offset.
 } else {
  done = true;
  fraction = Math.min(fraction, 1.0f);
 }
 }
 if (mPlayingBackwards) {
 fraction = 1f - fraction;
 }
 animateValue(fraction);
 break;
 }
 return done;
 }
  • 計算fraction
  • 調(diào)用animateValue方法

根據(jù)虛擬機執(zhí)行引擎動態(tài)分派原則,這里會調(diào)用ObjectAnimator的animateValue方法。

ObjectAnimator#animateValue

void animateValue(float fraction) {
 final Object target = getTarget();
 if (mTarget != null && target == null) {
 // We lost the target reference, cancel and clean up.
 cancel();
 return;
 }
 super.animateValue(fraction);
 int numValues = mValues.length;
 for (int i = 0; i < numValues; ++i) {
 mValues[i].setAnimatedValue(target);
 }
}

這里主要干了兩件事,

  1. 調(diào)用父類的animateValue方法
  2. 通過setAnimatedValue設置屬性

其父類的方法如下:

void animateValue(float fraction) {
 fraction = mInterpolator.getInterpolation(fraction);
 mCurrentFraction = fraction;
 int numValues = mValues.length;
 for (int i = 0; i < numValues; ++i) {
 mValues[i].calculateValue(fraction);
 }
 if (mUpdateListeners != null) {
 int numListeners = mUpdateListeners.size();
 for (int i = 0; i < numListeners; ++i) {
 mUpdateListeners.get(i).onAnimationUpdate(this);
 }
 }
}

在這個方法中,會通過Interpolator得到出當前的fraction,并通過calculateValue來計算當前應該的值,這里會調(diào)用IntPropertyValuesHolder的calculateValue

void calculateValue(float fraction) {
 mIntAnimatedValue = mIntKeyframes.getIntValue(fraction);
}

我們知道,mIntKeyframes對應的是IntKeyframeSet。在這個類的getIntValue中,會通過TypeEvaluator來計算當前對應的值。不多說了。

最后,回到animateValue。計算了值之后,會調(diào)用setAnimatedValue來設置值。我們看看他的實現(xiàn)。

IntPropertyValuesHolder#setAnimatedValue

void setAnimatedValue(Object target) {
 if (mIntProperty != null) {
 mIntProperty.setValue(target, mIntAnimatedValue);
 return;
 }
 if (mProperty != null) {
 mProperty.set(target, mIntAnimatedValue);
 return;
 }
 if (mJniSetter != 0) {
 nCallIntMethod(target, mJniSetter, mIntAnimatedValue);
 return;
 }
 if (mSetter != null) {
 try {
 mTmpValueArray[0] = mIntAnimatedValue;
 mSetter.invoke(target, mTmpValueArray);
 } catch (InvocationTargetException e) {
 Log.e("PropertyValuesHolder", e.toString());
 } catch (IllegalAccessException e) {
 Log.e("PropertyValuesHolder", e.toString());
 }
 }
}

恩,到這里就能看到修改屬性值得痕跡了,有以下四種情況

  1. mIntProperty不為null
  2. mProperty不為null
  3. mJniSetter不為null
  4. mSetter不為null

首先,我們通過String propertyName, int… values參數(shù)構(gòu)造的對象,mIntProperty為null,并且mProperty也為null。那其他兩個是怎么來的呢?似乎漏了什么?

還節(jié)的,在doAnimationFrame中,直接調(diào)用startAnimation么?沒錯,就是這里。

startAnimation

在這個方法中調(diào)用了initAnimation方法。還是根據(jù)動態(tài)分派規(guī)則,這里調(diào)用ObjectAnimator的initAnimation方法。在這里調(diào)用PropertyValuesHolder的setupSetterAndGetter方法,在這里對mSetter等進行了初始化,這里就不多說了,大家自己看代碼吧。

好了,以上就是關于Android中屬性動畫對的全部內(nèi)容,希望本文的內(nèi)容對各位Android開發(fā)者們能帶來一定的幫助,如果有疑問大家可以留言交流,謝謝大家對創(chuàng)新互聯(lián)的支持。

本文標題:Android源碼解析之屬性動畫詳解
文章網(wǎng)址:http://aaarwkj.com/article12/ihpggc.html

成都網(wǎng)站建設公司_創(chuàng)新互聯(lián),為您提供自適應網(wǎng)站、建站公司、云服務器手機網(wǎng)站建設品牌網(wǎng)站設計、網(wǎng)站營銷

廣告

聲明:本網(wǎng)站發(fā)布的內(nèi)容(圖片、視頻和文字)以用戶投稿、用戶轉(zhuǎn)載內(nèi)容為主,如果涉及侵權(quán)請盡快告知,我們將會在第一時間刪除。文章觀點不代表本網(wǎng)站立場,如需處理請聯(lián)系客服。電話:028-86922220;郵箱:631063699@qq.com。內(nèi)容未經(jīng)允許不得轉(zhuǎn)載,或轉(zhuǎn)載時需注明來源: 創(chuàng)新互聯(lián)

微信小程序開發(fā)
日日做日夜夜操天天搞| 成人黄色大片免费看| 日本爱爱一区二区三区| 美日韩黄色大片免费看| 麻豆资源视频在线观看| 男女互射视频在线观看| 亚洲精品紧身裙女教师av| 国产精品一区2区3区| 亚洲福利影院一区久久| 深夜释放自己污在线看| 日韩在线电影二区三区| 日本精品在线小视频| 韩国三级伦理中文字幕| dy888午夜福利精品国产97| 国产一区二区三区免费有码视频| 亚洲av少妇一区二区成年男人 | 欧美中日韩一区二区三区| 国产中文字幕婷婷丁香| 99久久伊人精品综合观看| 精品久久激情中文字幕| 日本在线观看成人大片| 精品人妻一区两区三区| 日本一级特黄大片做受在线观看| av大全网站免费一区二区| 高清在线一区二区在线| 熟年人妻一区二区三区| 色国产精品一区在线观看| 成年人免费观看黄色片| 亚洲精品成人免费电影| 岛国av有码高清在线观看| 中文字幕精品一区二区介绍| 视频一区日本视频二区| 蜜臀av网站在线播放| 国产一区二区黄色网页| 亚洲五月婷婷久久综合| 亚洲激情欧美日韩精品| 高清不卡av在线播放| 国产深夜福利在线观看| av在线免费观看不卡| 欧洲亚洲精品免费二区| 漂亮人妻少妇中文字幕|