Android直播中弹幕效果实现

来源：互联网发布：时时彩源码大富豪编辑：程序博客网时间：2024/04/29 20:24

在B站或者其他视频网站看视频时，常常会打开弹幕效果，边看节目边看大家的吐槽。弹幕看起来很有意思，今天我们就来实现一个简单的弹幕效果。

从直观上，弹幕效果就是在一个ViewGroup上增加一些View，然后让这些View移动起来。所以，整体的实现思路大概是这样的：

1、定义一个RelativeLayout，在里面动态添加TextView。

2、这些TextView的字体大小、颜色、移动速度、初始位置都是随机的。

3、将TextView添加到RelativeLayout的右边缘，每隔一段时间添加一个。

4、对每个TextView做平移动画，使得TextView从右向左移动。

5、当TextView从左边移动出屏幕，将TextView从RelativeLayout中移除。

有了思路下面就来看具体的代码。

首先定义BarrageItem，用来存储每一个弹幕项的相关信息，包括字体内容、字体大小颜色、移动速度、垂直方向的位置、字体占据的宽度等。

[java] view plain copy

print?

public class BarrageItem {
public TextView textView;
public int textColor;
public String text;
public int textSize;
public int moveSpeed;//移动速度
public int verticalPos;//垂直方向显示的位置
public int textMeasuredWidth;//字体显示占据的宽度
}

public class BarrageItem {    public TextView textView;    public int textColor;    public String text;    public int textSize;    public int moveSpeed;//移动速度    public int verticalPos;//垂直方向显示的位置    public int textMeasuredWidth;//字体显示占据的宽度}

然后定义BarrageView，由于弹幕的字体颜色大小和移动速度都是随机的，需要定义最大最小值来限定它们的范围，然后通过产生随机数来设置它们在这个范围内的值。另外还需要定义弹幕的文本内容，这里是直接写死的一些固定值。

[java] view plain copy

print?

private Context mContext;
private BarrageHandler mHandler = new BarrageHandler();
private Random random = new Random(System.currentTimeMillis());
private static final long BARRAGE_GAP_MIN_DURATION = 1000;//两个弹幕的最小间隔时间
private static final long BARRAGE_GAP_MAX_DURATION = 2000;//两个弹幕的最大间隔时间
private int maxSpeed = 10000;//速度，ms
private int minSpeed = 5000;//速度，ms
private int maxSize = 30;//文字大小，dp
private int minSize = 15;//文字大小，dp
private int totalHeight = 0;
private int lineHeight = 0;//每一行弹幕的高度
private int totalLine = 0;//弹幕的行数
private String[] itemText = {“是否需要帮忙”, “what are you 弄啥来”, “哈哈哈哈哈哈哈”, “抢占沙发。。。。。。”, “************”, “是否需要帮忙”,“我不会轻易的狗带”, “嘿嘿”, “这是我见过的最长长长长长长长长长长长的评论”};
private int textCount;
// private List<BarrageItem> itemList = new ArrayList<BarrageItem>();
public BarrageView(Context context) {
this(context, null);
}
public BarrageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public BarrageView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mContext = context;
init();
}

    private Context mContext;    private BarrageHandler mHandler = new BarrageHandler();    private Random random = new Random(System.currentTimeMillis());    private static final long BARRAGE_GAP_MIN_DURATION = 1000;//两个弹幕的最小间隔时间    private static final long BARRAGE_GAP_MAX_DURATION = 2000;//两个弹幕的最大间隔时间    private int maxSpeed = 10000;//速度，ms    private int minSpeed = 5000;//速度，ms    private int maxSize = 30;//文字大小，dp    private int minSize = 15;//文字大小，dp    private int totalHeight = 0;    private int lineHeight = 0;//每一行弹幕的高度    private int totalLine = 0;//弹幕的行数    private String[] itemText = {"是否需要帮忙", "what are you 弄啥来", "哈哈哈哈哈哈哈", "抢占沙发。。。。。。", "************", "是否需要帮忙","我不会轻易的狗带", "嘿嘿", "这是我见过的最长长长长长长长长长长长的评论"};    private int textCount;//    private List<BarrageItem> itemList = new ArrayList<BarrageItem>();    public BarrageView(Context context) {        this(context, null);    }    public BarrageView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public BarrageView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        mContext = context;        init();    }

如果弹幕显示的垂直位置是随机的，就会出现垂直方向上弹幕重叠的情况，所以需要根据高度对垂直方向按照弹幕高度的最大值等分，然后让弹幕在这些指定的垂直位置随机分布。这个值在onWindowFocusChanged里计算，因为在这个方法中通过View的getMeasuredHeight()得到的高度不为空。

[java] view plain copy

print?

@Override
public void onWindowFocusChanged(boolean hasWindowFocus) {
super.onWindowFocusChanged(hasWindowFocus);
totalHeight = getMeasuredHeight();
lineHeight = getLineHeight();
totalLine = totalHeight / lineHeight;
}

    @Override    public void onWindowFocusChanged(boolean hasWindowFocus) {        super.onWindowFocusChanged(hasWindowFocus);        totalHeight = getMeasuredHeight();        lineHeight = getLineHeight();        totalLine = totalHeight / lineHeight;    }

通过Handler的sendEmptyMessageDelayed每隔随机的时间产生一个弹幕项。下面的代码设置弹幕项的属性。

[java] view plain copy

print?

class BarrageHandler extends Handler {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
generateItem();
//每个弹幕产生的间隔时间随机
int duration = (int) ((BARRAGE_GAP_MAX_DURATION - BARRAGE_GAP_MIN_DURATION) * Math.random());
this.sendEmptyMessageDelayed(0, duration);
}
}
private void generateItem() {
BarrageItem item = new BarrageItem();
String tx = itemText[(int) (Math.random() * textCount)];
int sz = (int) (minSize + (maxSize - minSize) * Math.random());
item.textView = new TextView(mContext);
item.textView.setText(tx);
item.textView.setTextSize(sz);
item.textView.setTextColor(Color.rgb(random.nextInt(256), random.nextInt(256), random.nextInt(256)));
item.textMeasuredWidth = (int) getTextWidth(item, tx, sz);
item.moveSpeed = (int) (minSpeed + (maxSpeed - minSpeed) * Math.random());
if (totalLine == 0) {
totalHeight = getMeasuredHeight();
lineHeight = getLineHeight();
totalLine = totalHeight / lineHeight;
}
item.verticalPos = random.nextInt(totalLine) * lineHeight;
showBarrageItem(item);
}

    class BarrageHandler extends Handler {        @Override        public void handleMessage(Message msg) {            super.handleMessage(msg);            generateItem();            //每个弹幕产生的间隔时间随机            int duration = (int) ((BARRAGE_GAP_MAX_DURATION - BARRAGE_GAP_MIN_DURATION) * Math.random());            this.sendEmptyMessageDelayed(0, duration);        }    }    private void generateItem() {        BarrageItem item = new BarrageItem();        String tx = itemText[(int) (Math.random() * textCount)];        int sz = (int) (minSize + (maxSize - minSize) * Math.random());        item.textView = new TextView(mContext);        item.textView.setText(tx);        item.textView.setTextSize(sz);        item.textView.setTextColor(Color.rgb(random.nextInt(256), random.nextInt(256), random.nextInt(256)));        item.textMeasuredWidth = (int) getTextWidth(item, tx, sz);        item.moveSpeed = (int) (minSpeed + (maxSpeed - minSpeed) * Math.random());        if (totalLine == 0) {            totalHeight = getMeasuredHeight();            lineHeight = getLineHeight();            totalLine = totalHeight / lineHeight;        }        item.verticalPos = random.nextInt(totalLine) * lineHeight;        showBarrageItem(item);    }

将每一个弹幕项添加到视图上，并给View添加一个TranslateAnimation动画，当动画结束时，将View从视图上移除。

[java] view plain copy

print?

private void showBarrageItem(final BarrageItem item) {
int leftMargin = this.getWidth();
LayoutParams params = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.ALIGN_PARENT_TOP);
params.topMargin = item.verticalPos;
this.addView(item.textView, params);
Animation anim = generateTranslateAnim(item, leftMargin);
anim.setAnimationListener(new Animation.AnimationListener() {
@Override
public void onAnimationStart(Animation animation) {
}
@Override
public void onAnimationEnd(Animation animation) {
item.textView.clearAnimation();
BarrageView.this.removeView(item.textView);
}
@Override
public void onAnimationRepeat(Animation animation) {
}
});
item.textView.startAnimation(anim);
}
private TranslateAnimation generateTranslateAnim(BarrageItem item, int leftMargin) {
TranslateAnimation anim = new TranslateAnimation(leftMargin, -item.textMeasuredWidth, 0, 0);
anim.setDuration(item.moveSpeed);
anim.setInterpolator(new AccelerateDecelerateInterpolator());
anim.setFillAfter(true);
return anim;
}

private void showBarrageItem(final BarrageItem item) {        int leftMargin = this.getWidth();        LayoutParams params = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);        params.addRule(RelativeLayout.ALIGN_PARENT_TOP);        params.topMargin = item.verticalPos;        this.addView(item.textView, params);        Animation anim = generateTranslateAnim(item, leftMargin);        anim.setAnimationListener(new Animation.AnimationListener() {            @Override            public void onAnimationStart(Animation animation) {            }            @Override            public void onAnimationEnd(Animation animation) {                item.textView.clearAnimation();                BarrageView.this.removeView(item.textView);            }            @Override            public void onAnimationRepeat(Animation animation) {            }        });        item.textView.startAnimation(anim);    }    private TranslateAnimation generateTranslateAnim(BarrageItem item, int leftMargin) {        TranslateAnimation anim = new TranslateAnimation(leftMargin, -item.textMeasuredWidth, 0, 0);        anim.setDuration(item.moveSpeed);        anim.setInterpolator(new AccelerateDecelerateInterpolator());        anim.setFillAfter(true);        return anim;    }

这样就完成了弹幕的功能，实现原理并不复杂。可以根据具体的需求来增加更多的控制，如控制每一行弹幕不重复，控制弹幕移动的Interpolator产生不同的滑动效果等等。

源码下载

0 0