使用應用程式時，新資訊會一併顯示在畫面上，不會改變 系統就會移除相關資訊您可以直接變更螢幕上顯示的內容 讓使用者可能錯過突然出現的新內容。動畫速度緩慢 套用變更，並用動作來勾勒出使用者的視角 更加醒目
有三種常見的動畫可用來顯示或隱藏檢視畫面：顯示 動畫、交叉漸變動畫和 CardFlip 動畫。
建立交叉漸變動畫
交叉漸變動畫 (又稱為溶解液) 逐漸淡出
一張 View 或
同時ViewGroup
或淡出淡出的火花如果您要在部分情況下
在應用程式中切換內容或檢視模式這裡顯示的交叉漸變動畫會使用
ViewPropertyAnimator、
適用於 Android 3.1 (API 級別 12) 以上版本。
以下是從進度指標到文字內容的交叉漸變範例：
建立檢視畫面
建立要交叉漸變的兩個檢視畫面。以下範例會建立 進度指標和可捲動的文字檢視區塊：
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/content"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView style="?android:textAppearanceMedium"
android:lineSpacingMultiplier="1.2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/lorem_ipsum"
android:padding="16dp" />
</ScrollView>
<ProgressBar android:id="@+id/loading_spinner"
style="?android:progressBarStyleLarge"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center" />
</FrameLayout>
設定交叉漸變動畫
如要設定交叉漸變動畫，請按照下列步驟操作：
- 為要交叉淡出的檢視畫面建立成員變數。您需要具備 稍後在動畫期間修改檢視畫面時，這些參照會成為參考資源。
- 設定主題檢視畫面的顯示設定
GONE。這可避免系統顯示 不會因為使用版面配置空間而省略了版面配置，所以在計算版面配置時 向上處理 - 快取
config_shortAnimTime系統屬性。此屬性定義標準的「短」 時間長度。這個時間長度適用於細微的動畫或 出現經常發生的動畫config_longAnimTime敬上 和config_mediumAnimTime。 您也可以使用
以下範例使用先前程式碼片段的版面配置， 活動內容檢視畫面：
class CrossfadeActivity : Activity() {
private lateinit var contentView: View
private lateinit var loadingView: View
private var shortAnimationDuration: Int = 0
...
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_crossfade)
contentView = findViewById(R.id.content)
loadingView = findViewById(R.id.loading_spinner)
// Initially hide the content view.
contentView.visibility = View.GONE
// Retrieve and cache the system's default "short" animation time.
shortAnimationDuration = resources.getInteger(android.R.integer.config_shortAnimTime)
}
...
}
public class CrossfadeActivity extends Activity {
private View contentView;
private View loadingView;
private int shortAnimationDuration;
...
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_crossfade);
contentView = findViewById(R.id.content);
loadingView = findViewById(R.id.loading_spinner);
// Initially hide the content view.
contentView.setVisibility(View.GONE);
// Retrieve and cache the system's default "short" animation time.
shortAnimationDuration = getResources().getInteger(
android.R.integer.config_shortAnimTime);
}
...
}
交叉淡出檢視畫面
正確設定檢視畫面後，如要交叉淡出，請按照下列步驟操作：
- 針對淡入效果的檢視畫面，將 Alpha 值設為 0，顯示設定
從初始的
VISIBLE開始 設定GONE。這樣一來，檢視區塊就會顯示，但會保持透明。 - 針對淡入效果的檢視區塊，為其 Alpha 值 0 到 1 加上動畫效果。對於 並以 1 到 0 的動畫方式設定 Alpha 值
- 使用
onAnimationEnd()敬上 風格Animator.AnimatorListener, 設定淡出至GONE的檢視畫面的顯示設定。雖然 Alpha 值為 0，將檢視畫面的瀏覽權限設為GONE會防止檢視畫面出現 不會因為使用版面配置空間而省略了版面配置，所以在計算版面配置時 後續處理作業
以下方法舉例說明相關做法：
class CrossfadeActivity : Activity() {
private lateinit var contentView: View
private lateinit var loadingView: View
private var shortAnimationDuration: Int = 0
...
private fun crossfade() {
contentView.apply {
// Set the content view to 0% opacity but visible, so that it is
// visible but fully transparent during the animation.
alpha = 0f
visibility = View.VISIBLE
// Animate the content view to 100% opacity and clear any animation
// listener set on the view.
animate()
.alpha(1f)
.setDuration(shortAnimationDuration.toLong())
.setListener(null)
}
// Animate the loading view to 0% opacity. After the animation ends,
// set its visibility to GONE as an optimization step so it doesn't
// participate in layout passes.
loadingView.animate()
.alpha(0f)
.setDuration(shortAnimationDuration.toLong())
.setListener(object : AnimatorListenerAdapter() {
override fun onAnimationEnd(animation: Animator) {
loadingView.visibility = View.GONE
}
})
}
}
public class CrossfadeActivity extends Activity {
private View contentView;
private View loadingView;
private int shortAnimationDuration;
...
private void crossfade() {
// Set the content view to 0% opacity but visible, so that it is
// visible but fully transparent during the animation.
contentView.setAlpha(0f);
contentView.setVisibility(View.VISIBLE);
// Animate the content view to 100% opacity and clear any animation
// listener set on the view.
contentView.animate()
.alpha(1f)
.setDuration(shortAnimationDuration)
.setListener(null);
// Animate the loading view to 0% opacity. After the animation ends,
// set its visibility to GONE as an optimization step so it doesn't
// participate in layout passes.
loadingView.animate()
.alpha(0f)
.setDuration(shortAnimationDuration)
.setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
loadingView.setVisibility(View.GONE);
}
});
}
}
建立資訊卡翻轉動畫
資訊卡會顯示模擬內容的動畫，藉此切換內容檢視畫面
翻開卡片這裡顯示的資訊卡翻轉動畫會使用
FragmentTransaction。
卡片外觀如下：
建立動畫物件
如要建立資訊卡翻轉動畫，請備妥 4 個動畫。兩個動畫師 查看資訊卡正面動畫效果和左邊動畫的時機 從左側開始其他兩張動畫師適用於卡片背面 在動畫播放前以及從右側進入動畫，而當動畫往右移動時。
card_Flip_left_in.xml
<set xmlns:android="http://schemas.android.com/apk/res/android">
<!-- Before rotating, immediately set the alpha to 0. -->
<objectAnimator
android:valueFrom="1.0"
android:valueTo="0.0"
android:propertyName="alpha"
android:duration="0" />
<!-- Rotate. -->
<objectAnimator
android:valueFrom="-180"
android:valueTo="0"
android:propertyName="rotationY"
android:interpolator="@android:interpolator/accelerate_decelerate"
android:duration="@integer/card_flip_time_full" />
<!-- Halfway through the rotation, set the alpha to 1. See startOffset. -->
<objectAnimator
android:valueFrom="0.0"
android:valueTo="1.0"
android:propertyName="alpha"
android:startOffset="@integer/card_flip_time_half"
android:duration="1" />
</set>
card_Flip_left_out.xml
<set xmlns:android="http://schemas.android.com/apk/res/android">
<!-- Rotate. -->
<objectAnimator
android:valueFrom="0"
android:valueTo="180"
android:propertyName="rotationY"
android:interpolator="@android:interpolator/accelerate_decelerate"
android:duration="@integer/card_flip_time_full" />
<!-- Halfway through the rotation, set the alpha to 0. See startOffset. -->
<objectAnimator
android:valueFrom="1.0"
android:valueTo="0.0"
android:propertyName="alpha"
android:startOffset="@integer/card_flip_time_half"
android:duration="1" />
</set>
card_Flip_right_in.xml
<set xmlns:android="http://schemas.android.com/apk/res/android">
<!-- Before rotating, immediately set the alpha to 0. -->
<objectAnimator
android:valueFrom="1.0"
android:valueTo="0.0"
android:propertyName="alpha"
android:duration="0" />
<!-- Rotate. -->
<objectAnimator
android:valueFrom="180"
android:valueTo="0"
android:propertyName="rotationY"
android:interpolator="@android:interpolator/accelerate_decelerate"
android:duration="@integer/card_flip_time_full" />
<!-- Halfway through the rotation, set the alpha to 1. See startOffset. -->
<objectAnimator
android:valueFrom="0.0"
android:valueTo="1.0"
android:propertyName="alpha"
android:startOffset="@integer/card_flip_time_half"
android:duration="1" />
</set>
card_Flip_right_out.xml
<set xmlns:android="http://schemas.android.com/apk/res/android">
<!-- Rotate. -->
<objectAnimator
android:valueFrom="0"
android:valueTo="-180"
android:propertyName="rotationY"
android:interpolator="@android:interpolator/accelerate_decelerate"
android:duration="@integer/card_flip_time_full" />
<!-- Halfway through the rotation, set the alpha to 0. See startOffset. -->
<objectAnimator
android:valueFrom="1.0"
android:valueTo="0.0"
android:propertyName="alpha"
android:startOffset="@integer/card_flip_time_half"
android:duration="1" />
</set>
建立檢視畫面
資訊卡的每一面都是獨立的版面配置，可包含 例如兩個文字檢視區塊、兩張圖片，或是任意翻轉的組合 。稍後在製作動畫的片段中使用兩個版面配置。 下列版面配置會建立資訊卡的一側，顯示文字：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#a6c"
android:padding="16dp"
android:gravity="bottom">
<TextView android:id="@android:id/text1"
style="?android:textAppearanceLarge"
android:textStyle="bold"
android:textColor="#fff"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/card_back_title" />
<TextView style="?android:textAppearanceSmall"
android:textAllCaps="true"
android:textColor="#80ffffff"
android:textStyle="bold"
android:lineSpacingMultiplier="1.2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/card_back_description" />
</LinearLayout>
下一個版面配置會建立資訊卡的另一面
ImageView:
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:src="@drawable/image1"
android:scaleType="centerCrop"
android:contentDescription="@string/description_image_1" />
建立片段
為資訊卡正面和背面建立片段類別。片段
類別，會傳回您從
onCreateView()敬上
方法。接著，您就可以在父項活動中建立這個片段的例項
並在您要顯示資訊卡的時間點顯示資訊卡
以下範例顯示父項活動中的巢狀片段類別 使用 API
class CardFlipActivity : FragmentActivity() {
...
/**
* A fragment representing the front of the card.
*/
class CardFrontFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View = inflater.inflate(R.layout.fragment_card_front, container, false)
}
/**
* A fragment representing the back of the card.
*/
class CardBackFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View = inflater.inflate(R.layout.fragment_card_back, container, false)
}
}
public class CardFlipActivity extends FragmentActivity {
...
/**
* A fragment representing the front of the card.
*/
public class CardFrontFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_card_front, container, false);
}
}
/**
* A fragment representing the back of the card.
*/
public class CardBackFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_card_back, container, false);
}
}
}
為卡片翻轉動畫
顯示父項活動中的片段。方法是建立版面配置
。以下範例會建立
FrameLayout，你可以新增
執行階段的片段：
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
在活動程式碼中，將內容檢視畫面設為您建立的版面配置。 建議您在建立活動時顯示預設片段。 以下範例活動會說明如何按 預設：
class CardFlipActivity : FragmentActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_activity_card_flip)
if (savedInstanceState == null) {
supportFragmentManager.beginTransaction()
.add(R.id.container, CardFrontFragment())
.commit()
}
}
...
}
public class CardFlipActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_activity_card_flip);
if (savedInstanceState == null) {
getSupportFragmentManager()
.beginTransaction()
.add(R.id.container, new CardFrontFragment())
.commit();
}
}
...
}
卡片正面會顯示在卡片正面， 在適當時機翻轉動畫。建立顯示 執行以下作業的卡片：
- 設定您建立的自訂動畫，用於片段轉換功能。
- 將顯示的片段替換成新片段，並為此事件加上動畫效果 這部分就會顯示自訂動畫
- 將先前顯示的片段新增至片段返回堆疊， 使用者輕觸返回按鈕時，卡片就會翻回。
class CardFlipActivity : FragmentActivity() {
...
private fun flipCard() {
if (showingBack) {
supportFragmentManager.popBackStack()
return
}
// Flip to the back.
showingBack = true
// Create and commit a new fragment transaction that adds the fragment
// for the back of the card, uses custom animations, and is part of the
// fragment manager's back stack.
supportFragmentManager.beginTransaction()
// Replace the default fragment animations with animator
// resources representing rotations when switching to the back
// of the card, as well as animator resources representing
// rotations when flipping back to the front, such as when the
// system Back button is tapped.
.setCustomAnimations(
R.animator.card_flip_right_in,
R.animator.card_flip_right_out,
R.animator.card_flip_left_in,
R.animator.card_flip_left_out
)
// Replace any fragments in the container view with a fragment
// representing the next page, indicated by the just-incremented
// currentPage variable.
.replace(R.id.container, CardBackFragment())
// Add this transaction to the back stack, letting users press
// the Back button to get to the front of the card.
.addToBackStack(null)
// Commit the transaction.
.commit()
}
}
public class CardFlipActivity extends FragmentActivity {
...
private void flipCard() {
if (showingBack) {
getSupportFragmentManager().popBackStack();
return;
}
// Flip to the back.
showingBack = true;
// Create and commit a new fragment transaction that adds the fragment
// for the back of the card, uses custom animations, and is part of the
// fragment manager's back stack.
getSupportFragmentManager()
.beginTransaction()
// Replace the default fragment animations with animator
// resources representing rotations when switching to the back
// of the card, as well as animator resources representing
// rotations when flipping back to the front, such as when the
// system Back button is pressed.
.setCustomAnimations(
R.animator.card_flip_right_in,
R.animator.card_flip_right_out,
R.animator.card_flip_left_in,
R.animator.card_flip_left_out)
// Replace any fragments in the container view with a fragment
// representing the next page, indicated by the just-incremented
// currentPage variable.
.replace(R.id.container, new CardBackFragment())
// Add this transaction to the back stack, letting users press
// Back to get to the front of the card.
.addToBackStack(null)
// Commit the transaction.
.commit();
}
}
建立循環顯示動畫
顯示動畫可在您顯示或隱藏群組時，為使用者提供視覺上的連貫性
這三項重要工具
ViewAnimationUtils.createCircularReveal()敬上
方法 可讓您建立裁剪圓形的動畫，藉此顯示或隱藏檢視畫面。這個
範本中
ViewAnimationUtils 類別，
適用於 Android 5.0 (API 級別 21) 以上版本。
以下範例說明如何顯示先前隱藏的檢視畫面：
// A previously invisible view.
val myView: View = findViewById(R.id.my_view)
// Check whether the runtime version is at least Android 5.0.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
// Get the center for the clipping circle.
val cx = myView.width / 2
val cy = myView.height / 2
// Get the final radius for the clipping circle.
val finalRadius = Math.hypot(cx.toDouble(), cy.toDouble()).toFloat()
// Create the animator for this view. The start radius is 0.
val anim = ViewAnimationUtils.createCircularReveal(myView, cx, cy, 0f, finalRadius)
// Make the view visible and start the animation.
myView.visibility = View.VISIBLE
anim.start()
} else {
// Set the view to invisible without a circular reveal animation below
// Android 5.0.
myView.visibility = View.INVISIBLE
}
// A previously invisible view.
View myView = findViewById(R.id.my_view);
// Check whether the runtime version is at least Android 5.0.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
// Get the center for the clipping circle.
int cx = myView.getWidth() / 2;
int cy = myView.getHeight() / 2;
// Get the final radius for the clipping circle.
float finalRadius = (float) Math.hypot(cx, cy);
// Create the animator for this view. The start radius is 0.
Animator anim = ViewAnimationUtils.createCircularReveal(myView, cx, cy, 0f, finalRadius);
// Make the view visible and start the animation.
myView.setVisibility(View.VISIBLE);
anim.start();
} else {
// Set the view to invisible without a circular reveal animation below
// Android 5.0.
myView.setVisibility(View.INVISIBLE);
}
ViewAnimationUtils.createCircularReveal() 動畫採用五個參數。
第一個參數是您想要在畫面中隱藏或顯示的檢視畫面。
接下來的兩個參數是剪裁中心的 X 和 Y 座標
社交圈。通常是檢視畫面的中心，但您也可以使用
在使用者輕觸之後，動畫就會從他們選取的位置開始播放。
第四個參數是剪裁圓的起始半徑。
在上一個範例中，初始半徑設為 0，因此檢視畫面會顯示 目前由社交圈隱藏。最後一個參數是最終的半徑 圓圈。顯示檢視畫面時，最終半徑應大於 ，這樣檢視畫面就能在動畫結束前完整顯示。
如要隱藏之前可見的檢視畫面，請執行下列步驟：
// A previously visible view.
val myView: View = findViewById(R.id.my_view)
// Check whether the runtime version is at least Android 5.0.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
// Get the center for the clipping circle.
val cx = myView.width / 2
val cy = myView.height / 2
// Get the initial radius for the clipping circle.
val initialRadius = Math.hypot(cx.toDouble(), cy.toDouble()).toFloat()
// Create the animation. The final radius is 0.
val anim = ViewAnimationUtils.createCircularReveal(myView, cx, cy, initialRadius, 0f)
// Make the view invisible when the animation is done.
anim.addListener(object : AnimatorListenerAdapter() {
override fun onAnimationEnd(animation: Animator) {
super.onAnimationEnd(animation)
myView.visibility = View.INVISIBLE
}
})
// Start the animation.
anim.start()
} else {
// Set the view to visible without a circular reveal animation below
// Android 5.0.
myView.visibility = View.VISIBLE
}
// A previously visible view.
final View myView = findViewById(R.id.my_view);
// Check whether the runtime version is at least Android 5.0.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
// Get the center for the clipping circle.
int cx = myView.getWidth() / 2;
int cy = myView.getHeight() / 2;
// Get the initial radius for the clipping circle.
float initialRadius = (float) Math.hypot(cx, cy);
// Create the animation. The final radius is 0.
Animator anim = ViewAnimationUtils.createCircularReveal(myView, cx, cy, initialRadius, 0f);
// Make the view invisible when the animation is done.
anim.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
super.onAnimationEnd(animation);
myView.setVisibility(View.INVISIBLE);
}
});
// Start the animation.
anim.start();
} else {
// Set the view to visible without a circular reveal animation below Android
// 5.0.
myView.setVisibility(View.VISIBLE);
}
在這種情況下，剪裁圓形的初始半徑會設為大
讓畫面在動畫開始播放前顯示。最後一個
dp 設為 0，以便在動畫結束後隱藏檢視畫面。
在動畫中新增事件監聽器，以便將檢視畫面的顯示設定設為
動畫播放時為 INVISIBLE
完成。