Android：簡易彈幕效果實現，android彈幕

Android：簡易彈幕效果實現，android彈幕

首先上，類似於360檢測到騷擾電話頁面：

布局很簡單，上面是一個RelativeLayout，下面一個Button.

功能：

（1）彈幕產生後自動從右側往左側滾動（TranslateAnimation），彈幕消失後立刻被移除。

（2）彈幕位置隨機出現，並且不重複（防止文字重疊）。

（3）字型大小在一定範圍內隨機改變，字型顏色也可以設定。

（4）自訂先減速，後加速的Interpolator，彈幕加速進入、減速停留、然後加速出去。

1.Activity代碼：

/** * 簡易彈幕效果實現 * Created by admin on 15-6-4. */public class MainActivity extends ActionBarActivity {    private MyHandler handler;    //彈幕內容    private TanmuBean tanmuBean;    //放置彈幕內容的父組件    private RelativeLayout containerVG;    //父組件的高度    private int validHeightSpace;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        containerVG = (RelativeLayout) findViewById(R.id.tanmu_container);        tanmuBean = new TanmuBean();        tanmuBean.setItems(new String[]{"測試一下", "彈幕這東西真不好做啊", "總是出現各種問題~~", "也不知道都是為什嗎？麻煩！", "哪位大神可以幫幫我啊？", "I need your help.",                "測試一下", "彈幕這東西真不好做啊", "總是出現各種問題~~", "也不知道都是為什嗎？麻煩！", "哪位大神可以幫幫我啊？", "I need your help.",                "測試一下", "彈幕這東西真不好做啊", "總是出現各種問題~~", "也不知道都是為什嗎？麻煩！", "哪位大神可以幫幫我啊？", "I need your help."});        handler = new MyHandler(this);        //開始彈幕        View startTanmuView = findViewById(R.id.startTanmu);        startTanmuView.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                if (containerVG.getChildCount() > 0) {                    return;                }                existMarginValues.clear();                new Thread(new CreateTanmuThread()).start();            }        });    }    //每2s自動添加一條彈幕    private class CreateTanmuThread implements Runnable {        @Override        public void run() {            int N = tanmuBean.getItems().length;            for (int i = 0; i < N; i++) {                handler.obtainMessage(1, i, 0).sendToTarget();                SystemClock.sleep(2000);            }        }    }    //需要在主線城中添加組件    private static class MyHandler extends Handler {        private WeakReference<MainActivity> ref;        MyHandler(MainActivity ac) {            ref = new WeakReference<>(ac);        }        @Override        public void handleMessage(Message msg) {            super.handleMessage(msg);            if (msg.what == 1) {                MainActivity ac = ref.get();                if (ac != null && ac.tanmuBean != null) {                    int index = msg.arg1;                    String content = ac.tanmuBean.getItems()[index];                    float textSize = (float) (ac.tanmuBean.getMinTextSize() * (1 + Math.random() * ac.tanmuBean.getRange()));                    int textColor = ac.tanmuBean.getColor();                    ac.showTanmu(content, textSize, textColor);                }            }        }    }    private void showTanmu(String content, float textSize, int textColor) {        final TextView textView = new TextView(this);        textView.setTextSize(textSize);        textView.setText(content);//        textView.setSingleLine();        textView.setTextColor(textColor);        int leftMargin = containerVG.getRight() - containerVG.getLeft() - containerVG.getPaddingLeft();        //計算本條彈幕的topMargin(隨機值，但是與螢幕中已有的不重複)        int verticalMargin = getRandomTopMargin();        textView.setTag(verticalMargin);        LayoutParams params = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);        params.addRule(RelativeLayout.ALIGN_PARENT_TOP);        params.topMargin = verticalMargin;        textView.setLayoutParams(params);        Animation anim = AnimationHelper.createTranslateAnim(this, leftMargin, -ScreenUtils.getScreenW(this));        anim.setAnimationListener(new Animation.AnimationListener() {            @Override            public void onAnimationStart(Animation animation) {            }            @Override            public void onAnimationEnd(Animation animation) {                //移除該組件                containerVG.removeView(textView);                //移除佔位                int verticalMargin = (int) textView.getTag();                existMarginValues.remove(verticalMargin);            }            @Override            public void onAnimationRepeat(Animation animation) {            }        });        textView.startAnimation(anim);        containerVG.addView(textView);    }    //記錄當前仍在顯示狀態的彈幕的位置（避免重複）    private Set<Integer> existMarginValues = new HashSet<>();    private int linesCount;    private int getRandomTopMargin() {        //計算用於彈幕顯示的空間高度        if (validHeightSpace == 0) {            validHeightSpace = containerVG.getBottom() - containerVG.getTop()                    - containerVG.getPaddingTop() - containerVG.getPaddingBottom();        }        //計算可用的行數        if (linesCount == 0) {            linesCount = validHeightSpace / ScreenUtils.dp2px(this, tanmuBean.getMinTextSize() * (1 + tanmuBean.getRange()));            if (linesCount == 0) {                throw new RuntimeException("Not enough space to show text.");            }        }        //檢查重疊        while (true) {            int randomIndex = (int) (Math.random() * linesCount);            int marginValue = randomIndex * (validHeightSpace / linesCount);            if (!existMarginValues.contains(marginValue)) {                existMarginValues.add(marginValue);                return marginValue;            }        }    }}

2.平移動畫產生工具：

public class AnimationHelper {    /**     * 建立平移動畫     */    public static Animation createTranslateAnim(Context context, int fromX, int toX) {        TranslateAnimation tlAnim = new TranslateAnimation(fromX, toX, 0, 0);        //自動計算時間        long duration = (long) (Math.abs(toX - fromX) * 1.0f / ScreenUtils.getScreenW(context) * 4000);        tlAnim.setDuration(duration);        tlAnim.setInterpolator(new DecelerateAccelerateInterpolator());        tlAnim.setFillAfter(true);        return tlAnim;    }}

ScreenUtils是用來擷取螢幕寬高、dp與px之間互轉的工具類。

3.自訂的Interpolator，其實只有一行代碼

public class DecelerateAccelerateInterpolator implements Interpolator {    //input從0～1，傳回值也從0～1.傳回值的曲線表徵速度加減趨勢    @Override    public float getInterpolation(float input) {        return (float) (Math.tan((input * 2 - 1) / 4 * Math.PI)) / 2.0f + 0.5f;    }}

4.TanmuBean是一個實體類

public class TanmuBean {    private String[] items;    private int color;    private int minTextSize;    private float range;    public TanmuBean() {        //init default value        color = Color.parseColor("#eeeeee");        minTextSize = 16;        range = 0.5f;    }    public String[] getItems() {        return items;    }    public void setItems(String[] items) {        this.items = items;    }    public int getColor() {        return color;    }    public void setColor(int color) {        this.color = color;    }    /**     * min textSize, in dp.     */    public int getMinTextSize() {        return minTextSize;    }    public void setMinTextSize(int minTextSize) {        this.minTextSize = minTextSize;    }    public float getRange() {        return range;    }    public void setRange(float range) {        this.range = range;    }}