Android中自動上下滾動的TextView

Android中自動上下滾動的TextView

最近在做彈幕組件，其中有許多中動畫和樣式，其中一種是文字內容滾動，左右滾動很簡單，設置好寬度，在onDraw中畫出來就行了，這裏介紹一下上下滾動的文本

AutoTextView：

public class AutoTextView extends TextSwitcher implements
        ViewSwitcher.ViewFactory {

    private float mHeight;
    private Context mContext;
    //mInUp,mOutUp,上進上出動畫
    private Rotate3dAnimation mInUp;
    private Rotate3dAnimation mOutUp;

    //mInDown,mOutDown，下進下出動畫
    private Rotate3dAnimation mInDown;
    private Rotate3dAnimation mOutDown;
    private TextView t;


    public AutoTextView(Context context) {
        this(context, null);
        // TODO Auto-generated constructor stub
    }

    public AutoTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.auto3d);
        mHeight = a.getDimension(R.styleable.auto3d_textSize, 24);
        a.recycle();
        mContext = context;
        init();
    }

    private void init() {
        // TODO Auto-generated method stub
        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);
        setInAnimation(mInUp);
        setOutAnimation(mOutUp);
    }

    //創建動畫
    private Rotate3dAnimation createAnim(float start, float end, boolean turnIn, boolean turnUp){
        final Rotate3dAnimation rotation = new Rotate3dAnimation(start, end, turnIn, turnUp);
        rotation.setDuration(800);
        rotation.setFillAfter(false);
        rotation.setInterpolator(new AccelerateInterpolator());
        return rotation;
    }

    //初始化textView屬性
    @Override
    public View makeView() {
        // TODO Auto-generated method stub
        t = new TextView(mContext);
        //t.setGravity(Gravity.CENTER);
        t.setGravity(Gravity.CENTER_VERTICAL);
        t.setTextSize(mHeight);
        t.setMaxLines(3);
        //t.setGravity(Gravity.LEFT|Gravity.CENTER_VERTICAL);
        return t;
    }

    //重寫setText方法，動態設置字體顏色
    @Override
    public void setText(CharSequence text) {
        super.setText(text);
    }
    public void setText(CharSequence text,int color) {
        super.setText(text);
        final TextView t = (TextView) getNextView();
        t.setText(text);
        t.setTextColor(color);
        showNext();
    }

    //開始下進下出動畫
    public void previous(){
        if(getInAnimation() != mInDown){
            setInAnimation(mInDown);
        }
        if(getOutAnimation() != mOutDown){
            setOutAnimation(mOutDown);
        }
    }
    //開始上進上出動畫
    public void next(){
        if(getInAnimation() != mInUp){
            setInAnimation(mInUp);
        }
        if(getOutAnimation() != mOutUp){
            setOutAnimation(mOutUp);
        }
    }
    //初始化動畫屬性
     class Rotate3dAnimation extends Animation {
            private final float mFromDegrees;
            private final float mToDegrees;
            private float mCenterX;
            private float mCenterY;
            private final boolean mTurnIn;
            private final boolean mTurnUp;
            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);
            }
     }
}

控件原本是網上找到的一個demo，但是無法動態設置textview的各種屬性，於是自己小小的修改了一下，主要是重寫源碼的setText方法，加入了動態自定義顏色的元素，根據需要可以添加其他參數自行使用，使用時next()爲向上翻滾，previous()爲向下翻滾。想自動翻滾可以在線程中處理。