首先上效果圖,類似於360檢測到騷擾電話頁面:
佈局很簡單,上面是一個RelativeLayout,下面一個Button.
功能:
(1)彈幕生成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)字體大小在一定範圍內隨機改變,字體顏色也可以設置。
(4)自定義先減速,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~~", "也不知道都是爲什麼?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~~", "也不知道都是爲什麼?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~~", "也不知道都是爲什麼?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,但是與屏幕中已有的不重複)
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.平移動畫生成工具:
public class AnimationHelper {
/**
* 創建平移動畫
*/
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是用來獲取屏幕寬高、dp與px之間互轉的工具類。
3.自定義的Interpolator,其實只有一行代碼
public class DecelerateAccelerateInterpolator implements Interpolator {
//input從0~1,返回值也從0~1.返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;
}
}
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源碼下載:http://download.csdn.net/detail/books1958/9005279