本文实例讲述了Android编程实现简易弹幕效果。分享给大家供大家参考,具体如下:
首先上效果图,类似于360检测到骚扰电话页面:
布局很简单,上面是一个RelativeLayout,下面一个Button.
功能:
(1)弹幕生成后自动从右侧往左侧滚动(TranslateAnimation),弹幕消失后立刻被移除。
(2)弹幕位置随机出现,并且不重复(防止文字重叠)。
(3)字体大小在一定范围内随机改变,字体颜色也可以设置。
(4)自定义先减速,后加速的Interpolator,弹幕加速进入、减速停留、然后加速出去。
1.Activity代码:
public class MainActivity extends ActionBarActivity { private MyHandler handler; //弹幕内容 private TanmuBean tanmuBean; //放置弹幕内容的父组件 private RelativeLayout containerVG; //父组件的高度 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[]{"测试一下", "弹幕这东西真不好做啊", "总是出现各种问题~~", "也不知道都是为什么?麻烦!", "哪位大神可以帮帮我啊?", "I need your help.", "测试一下", "弹幕这东西真不好做啊", "总是出现各种问题~~", "也不知道都是为什么?麻烦!", "哪位大神可以帮帮我啊?", "I need your help.", "测试一下", "弹幕这东西真不好做啊", "总是出现各种问题~~", "也不知道都是为什么?麻烦!", "哪位大神可以帮帮我啊?", "I need your help."}); handler = new MyHandler(this); //开始弹幕 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自动添加一条弹幕 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); } } } //需要在主线城中添加组件 private static class MyHandler extends Handler { private WeakReferenceref; 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(); //计算本条弹幕的topMargin(随机值,但是与屏幕中已有的不重复) 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) { //移除该组件 containerVG.removeView(textView); //移除占位 int verticalMargin = (int) textView.getTag(); existMarginValues.remove(verticalMargin); } @Override public void onAnimationRepeat(Animation animation) { } }); textView.startAnimation(anim); containerVG.addView(textView); } //记录当前仍在显示状态的弹幕的位置(避免重复) private Set existMarginValues = new HashSet<>(); private int linesCount; private int getRandomTopMargin() { //计算用于弹幕显示的空间高度 if (validHeightSpace == 0) { validHeightSpace = containerVG.getBottom() - containerVG.getTop() - containerVG.getPaddingTop() - containerVG.getPaddingBottom(); } //计算可用的行数 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."); } } //检查重叠 while (true) { int randomIndex = (int) (Math.random() * linesCount); int marginValue = randomIndex * (validHeightSpace / linesCount); if (!existMarginValues.contains(marginValue)) { existMarginValues.add(marginValue); return marginValue; } } } }
2.平移动画生成工具:
public class AnimationHelper { public static Animation createTranslateAnim(Context context, int fromX, int toX) { TranslateAnimation tlAnim = new TranslateAnimation(fromX, toX, 0, 0); //自动计算时间 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是用来获取屏幕宽高、dp与px之间互转的工具类。
3.自定义的Interpolator,其实只有一行代码
public class DecelerateAccelerateInterpolator implements Interpolator { //input从0~1,返回值也从0~1.返回值的曲线表征速度加减趋势 @Override public float getInterpolation(float input) { return (float) (Math.tan((input * 2 - 1) / 4 * Math.PI)) / 2.0f + 0.5f; } }
4.TanmuBean是一个实体类
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; } 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; } }
完整实例代码点击此处本站下载。
更多关于Android相关内容感兴趣的读者可查看本站专题:《Android视图View技巧总结》、《Android开发动画技巧汇总》、《Android编程之activity操作技巧总结》、《Android布局layout技巧总结》、《Android开发入门与进阶教程》、《Android资源操作技巧汇总》及《Android控件用法总结》
希望本文所述对大家Android程序设计有所帮助。