[游戏开发]Android动效实现——底部向上弹出滑动式弹幕

效果图：

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<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/white"
    android:orientation="vertical">
 
 
    <LinearLayout
        android:id="@+id/ll_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_gravity="bottom"
        android:divider="@drawable/divider"
        android:orientation="vertical"
        android:padding="15dp"
        android:showDividers="middle">
 
    </LinearLayout>
 
</RelativeLayout>

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public class Main2Activity extends AppCompatActivity {
 
    private LinearLayout llContainer;
    LayoutTransition transition;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        llContainer = (LinearLayout) findViewById(R.id.ll_container);
        transition = new LayoutTransition();
        //添加动画
        ObjectAnimator valueAnimator = ObjectAnimator.ofFloat(null, "alpha", 0, 1);
        valueAnimator.addListener(new Animator.AnimatorListener() {
            @Override
            public void onAnimationStart(Animator animation) {
                //当前展示超过四条，执行删除动画
                if (llContainer.getChildCount() == 4) {
                    handler.sendEmptyMessage(1);
                }
            }
 
            @Override
            public void onAnimationEnd(Animator animation) {
                if (llContainer.getChildCount() == 5)
                    //动画执行完毕，删除view
                    handler.sendEmptyMessage(2);
            }
 
            @Override
            public void onAnimationCancel(Animator animation) {
 
            }
 
            @Override
            public void onAnimationRepeat(Animator animation) {
 
            }
        });
        transition.setAnimator(LayoutTransition.APPEARING, valueAnimator);
        //删除动画
        PropertyValuesHolder alpha = PropertyValuesHolder.ofFloat("alpha", 0, 0);
        ObjectAnimator objectAnimator = ObjectAnimator.ofPropertyValuesHolder(null, new PropertyValuesHolder[]{alpha}).setDuration(transition.getDuration(LayoutTransition.DISAPPEARING));
 
        transition.setAnimator(LayoutTransition.DISAPPEARING, objectAnimator);
        llContainer.setLayoutTransition(transition);
    }
 
    private String[] texts = new String[]{
            "火来我在灰烬中等你",
            "我对这个世界没什么可说的。我对这个世界没什么可说的。我对这个世界没什么可说的。",
            "侠之大者，为国为民。",
            "为往圣而继绝学"};
   
 
    Pools.SimplePool<TextView> textViewPool = new Pools.SimplePool<>(texts.length);
 
    private TextView obtainTextView() {
        TextView textView = textViewPool.acquire();
        if (textView == null) {
            textView = new TextView(Main2Activity.this);
            textView.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT));
            textView.setPadding(dp2px(10), dp2px(5), dp2px(10), dp2px(5));
            textView.setTextColor(0xffffffff);
            textView.setMaxLines(1);
            textView.setEllipsize(TextUtils.TruncateAt.END);
            textView.setGravity(Gravity.CENTER);
            textView.setTextSize(15);
            textView.setTextColor(0xffffffff);
            Drawable drawable = getResources().getDrawable(R.mipmap.circle_head);
            drawable.setBounds(0, 0, 80, 80);
            textView.setCompoundDrawablesRelative(drawable, null, null, null);
            textView.setCompoundDrawablePadding(10);
            switch (index) {
                case 0:
                    textView.setBackgroundDrawable(ContextCompat.getDrawable(Main2Activity.this, R.drawable.rect_black));
                    break;
                case 1:
                    textView.setBackgroundDrawable(ContextCompat.getDrawable(Main2Activity.this, R.drawable.rect_blue));
 
                    break;
                case 2:
                    textView.setBackgroundDrawable(ContextCompat.getDrawable(Main2Activity.this, R.drawable.rect_green));
 
                    break;
                case 3:
                    textView.setBackgroundDrawable(ContextCompat.getDrawable(Main2Activity.this, R.drawable.rect_red));
 
                    break;
            }
        }
        textView.setText(texts[index]);
        return textView;
    }
 
    private int dp2px(float dp) {
        DisplayMetrics displayMetrics = new DisplayMetrics();
        this.getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, displayMetrics);
    }
 
 
    int index = 0;
    @SuppressLint("HandlerLeak")
    private Handler handler = new Handler() {
        @SuppressLint("ResourceAsColor")
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
                case 0:
                    TextView textView = obtainTextView();
                    llContainer.addView(textView);
                    sendEmptyMessageDelayed(0, 2000);
                    index++;
                    if (index == 4) {
                        index = 0;
                    }
                    break;
                case 1:
                    //给展示的第一个view增加渐变透明动画
                    llContainer.getChildAt(0).animate().alpha(0).setDuration(transition.getDuration(LayoutTransition.APPEARING)).start();
                    break;
                case 2:
                    //删除顶部view
                    llContainer.removeViewAt(0);
                    break;
            }
        }
    };
 
    @Override
    protected void onResume() {
        super.onResume();
        handler.sendEmptyMessage(0);
    }
 
    @Override
    protected void onPause() {
        super.onPause();
        handler.removeMessages(0);
    }
}