Android TextView上下滚动

我们经常看到一个软件的首页会有上下循环滚动的TextView，我们可以用来作为标题，或者活动信息展示，那么怎么实现的呢，废话不说，请看代码:

第一步，我们先写一个自定义view来继承TextSwitcher

public class AutoTextView extends TextSwitcher implements ViewFactory {

private float mHeight;
private Context mContext;
//mInUp,mOutUp分别构成向下翻页的进出动
private Rotate3dAnimation mInUp;
private Rotate3dAnimation mOutUp;
final int[] auto3d = {
0x7f010000
};
//mInDown,mOutDown分别构成向下翻页的进出动
private Rotate3dAnimation mInDown;
private Rotate3dAnimation mOutDown;

public AutoTextView(Context context) {
this(context, null);
}

public AutoTextView(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray a = context.obtainStyledAttributes(attrs, auto3d);
mHeight = a.getDimension(0, 15);
a.recycle();
mContext = context;
init();
}

private void init() {
setFactory(this);
mInUp = createAnim(-90, 0, true, true);
mOutUp = createAnim(0, 90, false, true);
mInDown = createAnim(90, 0, true, false);
mOutDown = createAnim(0, -90, false, false);
//TextSwitcher主要用于文件切换，比�? 从文字A 切换�? 文字 B�?
//setInAnimation()后，A将执行inAnimation�?
//setOutAnimation()后，B将执行OutAnimation
setInAnimation(mInUp);
setOutAnimation(mOutUp);
}

private Rotate3dAnimation createAnim(float start, float end, boolean turnIn, boolean turnUp) {
final Rotate3dAnimation rotation = new Rotate3dAnimation(start, end, turnIn, turnUp);
rotation.setDuration(300);
rotation.setFillAfter(false);
rotation.setInterpolator(new AccelerateInterpolator());
return rotation;
}

//这里返回的TextView，就是我们看到的View
@Override
public View makeView() {
TextView t = new TextView(mContext);
t.setGravity(Gravity.CENTER);
t.setTextSize(mHeight);
t.setSingleLine(true);
t.setTextColor(R.color.black);
return t;
}

//定义动作，向下滚动翻�?
public void previous() {
if (getInAnimation() != mInDown) {
setInAnimation(mInDown);
}
if (getOutAnimation() != mOutDown) {
setOutAnimation(mOutDown);
}
}

//定义动作，向上滚动翻�?
public void next() {
if (getInAnimation() != mInUp) {
setInAnimation(mInUp);
}
if (getOutAnimation() != mOutUp) {
setOutAnimation(mOutUp);
}
}

class Rotate3dAnimation extends Animation {
private final float mFromDegrees;
private final float mToDegrees;
private final boolean mTurnIn;
private final boolean mTurnUp;
private float mCenterX;
private float mCenterY;
private Camera mCamera;

public Rotate3dAnimation(float fromDegrees, float toDegrees, boolean turnIn, boolean turnUp) {
mFromDegrees = fromDegrees;
mToDegrees = toDegrees;
mTurnIn = turnIn;
mTurnUp = turnUp;
}

@Override
public void initialize(int width, int height, int parentWidth, int parentHeight) {
super.initialize(width, height, parentWidth, parentHeight);
mCamera = new Camera();
mCenterY = getHeight() / 2;
mCenterX = getWidth() / 2;
}

@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
final float fromDegrees = mFromDegrees;
float degrees = fromDegrees + ((mToDegrees - fromDegrees) * interpolatedTime);

final float centerX = mCenterX;
final float centerY = mCenterY;
final Camera camera = mCamera;
final int derection = mTurnUp ? 1 : -1;

final Matrix matrix = t.getMatrix();

camera.save();
if (mTurnIn) {
camera.translate(0.0f, derection * mCenterY * (interpolatedTime - 1.0f), 0.0f);
} else {
camera.translate(0.0f, derection * mCenterY * (interpolatedTime), 0.0f);
}
camera.rotateX(degrees);
camera.getMatrix(matrix);
camera.restore();

matrix.preTranslate(-centerX, -centerY);
matrix.postTranslate(centerX, centerY);
}
}
}

第二步，这里写个Handler来循环滚动TextView内容

private Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {

switch (msg.what) {
case 1001:
handler.sendEmptyMessageDelayed(1001, 4000);
mStringArray = new ArrayList<>();
mStringArray.add("滚动字体一");
mStringArray.add("滚动字体二");
if (mStringArray.size() != 0) {
int i = mLoopCount % mStringArray.size();
tv_main_inform.next();
tv_main_inform.setText(mStringArray.get(i));
mLoopCount++;
// handler.sendEmptyMessageDelayed(FLAG, 5000);
}
break;
}
};
};

这里写的这个handler有点麻烦了，后面我用了一个新写法：

mStringArray = new ArrayList<>();
mStringArray.add("滚动字体一");
mStringArray.add("滚动字体二");
Observable.interval(0, 4, TimeUnit.SECONDS).subscribe {

if (mStringArray.size() != 0) {
int i = mLoopCount % mStringArray.size();
tv_main_inform.next();
tv_main_inform.setText(mStringArray.get(i));
mLoopCount++;
// handler.sendEmptyMessageDelayed(FLAG, 5000);
}}

以上就是到这里了，不当之处还望大家指教，不明白的地方可以留言