android 横向滚动条

/***
 * 横向滚动条，修改版，从左向右滚动，支持html代码和html里面的网络图片
 */
public class MarqueeView extends LinearLayout {

    private Context context ;

    private TextView mTextField;

    private ScrollView mScrollView;

    private static final int TEXT_VIEW_VIRTUAL_WIDTH = 2000;

    private Animation mMoveTextOut = null;
    //private Animation mMoveTextIn = null;

    private Paint mPaint;

    private boolean mMarqueeNeeded = false;

    private static final String TAG = MarqueeView.class.getSimpleName();

    private float mTextDifference;

    private  Drawable drawable ;

    /**
     * Control the speed. The lower this value, the faster it will scroll.
     */
    private static final int DEFAULT_SPEED = 60;

    /**
     * Control the pause between the animations. Also, after starting this activity.
     */
    private static final int DEFAULT_ANIMATION_PAUSE = 2000;

    private int mSpeed = DEFAULT_SPEED;

    private int mAnimationPause = DEFAULT_ANIMATION_PAUSE;

    private boolean mAutoStart = false;

    private Interpolator mInterpolator = new LinearInterpolator();

    private boolean mCancelled = false;
    private Runnable mAnimationStartRunnable;

    private boolean mStarted;

    private NetworkImageGetter mImageGetter;

    /**
     * Sets the animation speed.
     * The lower the value, the faster the animation will be displayed.
     *
     * @param speed Milliseconds per PX.
     */
    public void setSpeed(int speed) {
        this.mSpeed = speed;
    }

    /**
     * Sets the pause between animations
     *
     * @param pause In milliseconds.
     */
    public void setPauseBetweenAnimations(int pause) {
        this.mAnimationPause = pause;
    }

    /**
     * Sets a custom interpolator for the animation.
     *
     * @param interpolator Animation interpolator.
     */
    public void setInterpolator(Interpolator interpolator) {
        this.mInterpolator = interpolator;
    }

    @SuppressWarnings({"UnusedDeclaration"})
    public MarqueeView(Context context) {
        super(context);
        this.context = context ;
        init(context);
    }

    @SuppressWarnings({"UnusedDeclaration"})
    public MarqueeView(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context ;
        init(context);
        extractAttributes(attrs);
    }

    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public MarqueeView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        this.context = context ;
        init(context);
        extractAttributes(attrs);
    }

    private void extractAttributes(AttributeSet attrs) {
        if (getContext() == null) {
            return;
        }

        TypedArray a = getContext().obtainStyledAttributes(attrs, R.styleable.asia_ivity_android_marqueeview_MarqueeView);

        if (a == null) {
            return;
        }

        mSpeed = a.getInteger(R.styleable.asia_ivity_android_marqueeview_MarqueeView_speed, DEFAULT_SPEED);
        mAnimationPause = a.getInteger(R.styleable.asia_ivity_android_marqueeview_MarqueeView_pause, DEFAULT_ANIMATION_PAUSE);
        mAutoStart = a.getBoolean(R.styleable.asia_ivity_android_marqueeview_MarqueeView_autoStart, false);

        a.recycle();
    }

    private void init(Context context) {
        // init helper
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setStrokeWidth(1);
        mPaint.setStrokeCap(Paint.Cap.ROUND);

        mInterpolator = new LinearInterpolator();
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        super.onLayout(changed, l, t, r, b);

        if (getChildCount() == 0 || getChildCount() > 1) {
            throw new RuntimeException("MarqueeView must have exactly one child element.");
        }

        if (changed && mScrollView == null) {
            View v = getChildAt(0);
            // Fixes #1: Exception when using android:layout_width="fill_parent". There seems to be an additional ScrollView parent.
            if (v instanceof ScrollView && ((ScrollView) v).getChildCount() == 1) {
                v = ((ScrollView) v).getChildAt(0);
            }

            if (!(v instanceof TextView)) {
                throw new RuntimeException("The child view of this MarqueeView must be a TextView instance.");
            }

            initView(getContext());

            prepareAnimation();

            if (mAutoStart) {
                startMarquee();
            }
        }
    }

    private String message ;
    private boolean startScroll = true ;

    /***
     * 开始滚动
     * @param _message
     */
    public void startScrollView(String _message){

        if(message.equals(_message)) return;

        this.message = _message ;
        if(startScroll){
            mTextField.setText(Html.fromHtml(message ,mImageGetter ,null));
            startMarquee();
        }
    }

    /**
     * Starts the configured marquee effect.
     */
    public void startMarquee() {
        if (mMarqueeNeeded) {
            startScroll = false ;
            startTextFieldAnimation();
        }

        mCancelled = false;
        mStarted = true;
    }

    private void startTextFieldAnimation() {
        mAnimationStartRunnable = new Runnable() {
            public void run() {
                mTextField.startAnimation(mMoveTextOut);
            }
        };
        postDelayed(mAnimationStartRunnable, mAnimationPause);
    }

    /**
     * Disables the animations.
     */
    public void reset() {
        mCancelled = true;

        if (mAnimationStartRunnable != null) {
            removeCallbacks(mAnimationStartRunnable);
        }

        mTextField.clearAnimation();
        mStarted = false;
        mTextField.setVisibility(INVISIBLE);
        mMoveTextOut.reset();
        //   mMoveTextIn.reset();

//        mScrollView.removeView(mTextField);
//        mScrollView.addView(mTextField);

        invalidate();
    }

    private void prepareAnimation() {
        // Measure
        mPaint.setTextSize(mTextField.getTextSize());
        mPaint.setTypeface(mTextField.getTypeface());
        final float mTextWidth = mPaint.measureText(mTextField.getText().toString());

        // See how much functions are needed at all
        mMarqueeNeeded = mTextWidth > getMeasuredWidth();

        if(drawable != null){
            //当html有图片时，不能获取到图片长度，我这里滚动条有15长图片，所以需要单独加上
            mTextDifference = Math.abs(mTextWidth) + drawable.getIntrinsicWidth() * 15 + 5;
        }else {
            mTextDifference = Math.abs(mTextWidth) + 5;
        }//获取滚动条长度，根据滚动速度和长度计算滚动时间（滚动动画持续时间）

//        if (true) {
//            Log.d(TAG, "mTextWidth       : " + mTextWidth);
//            Log.d(TAG, "measuredWidth    : " + getMeasuredWidth());
//            Log.d(TAG, "mMarqueeNeeded   : " + mMarqueeNeeded);
//            Log.d(TAG, "mTextDifference  : " + mTextDifference);
//        }

        final int duration = (int) (mTextDifference * mSpeed);

        mMoveTextOut = new TranslateAnimation(getMeasuredWidth(), -mTextDifference, 0, 0);
        mMoveTextOut.setDuration(duration);
        mMoveTextOut.setInterpolator(mInterpolator);

        mMoveTextOut.setAnimationListener(new Animation.AnimationListener() {
            public void onAnimationStart(Animation animation) {
                expandTextView(mTextWidth);
                mTextField.setVisibility(VISIBLE);
            }

            public void onAnimationEnd(Animation animation) {
                //    mTextField.setText(Html.fromHtml(message));
                mTextField.setText(Html.fromHtml(message ,mImageGetter ,null));

                if (mCancelled) {
                    return;
                }
                mTextField.startAnimation(mMoveTextOut);
            }

            public void onAnimationRepeat(Animation animation) {
            }

        });

    }

    private void initView(Context context) {
        mImageGetter = new NetworkImageGetter();
        // Scroll View
        LayoutParams sv1lp = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        sv1lp.gravity = Gravity.CENTER_HORIZONTAL;
        mScrollView = new ScrollView(context);

        // Scroll View 1 - Text Field
        mTextField = (TextView) getChildAt(0);
        removeView(mTextField);

        mScrollView.addView(mTextField, new ScrollView.LayoutParams(TEXT_VIEW_VIRTUAL_WIDTH, LayoutParams.WRAP_CONTENT));

        mTextField.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i2, int i3) {

            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) {

            }

            @Override
            public void afterTextChanged(Editable editable) {
                final boolean continueAnimation = mStarted;
                reset();
                prepareAnimation();
                cutTextView();
                post(new Runnable() {
                    @Override
                    public void run() {
                        if (continueAnimation) {
                            startScroll = true ;
                            startMarquee();
                        }
                    }
                });
            }
        });

        addView(mScrollView, sv1lp);
    }

    private void expandTextView(float width) {
        ViewGroup.LayoutParams lp = mTextField.getLayoutParams();
        if(drawable != null){
            //当html有图片时，不能获取到图片长度，我这里滚动条有15长图片，所以需要单独加上
            lp.width =(int)width + drawable.getIntrinsicWidth() * 15 +1;
        }else {
            lp.width =(int)width +1;
        }//设置滚动长度，滚动的内部其实是一个textView，滚动其实是textView向左做移动
        mTextField.setLayoutParams(lp);
    }

    private void cutTextView() {
        if (mTextField.getWidth() != getMeasuredWidth()) {
            ViewGroup.LayoutParams lp = mTextField.getLayoutParams();
            lp.width = getMeasuredWidth();
            mTextField.setLayoutParams(lp);
        }
    }

    /***
     * 根据html里面的图片地址获取网络图片存储到本地
     */
    class NetworkImageGetter implements Html.ImageGetter{

        @Override
        public Drawable getDrawable(String source) {
            // 封装路径
            File file = StorageUtils.getCacheFile(context,"jpg" ,source);//获取图片是否在本地SD卡中

            final Uri uri = Uri.parse(file.getAbsolutePath());
            final String path = uri.getPath();

            drawable = Drawable.createFromPath(path);

            // 判断是否以http开头
            if(source.startsWith("http")) {
                // 判断路径是否存在
                if(file.exists() && file.length() > 0) {
                    // 存在即获取drawable
                    drawable = Drawable.createFromPath(file.getAbsolutePath());
                    drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
                } else {
                    // 不存在即开启异步任务加载网络图片
                    toastService(context,source ,"jpg");
                }
            }
            return drawable;
        }
    }

    /**
     * 本地的下载图片服务
     * @param context
     * @param url
     * @param extension
     */
    private  void toastService(Context context,String url,String extension) {
        Intent intent = new Intent(context,HtmlCacheService.class);
        intent.putExtra(HtmlCacheService.DOWN_URL,url);
        intent.putExtra(HtmlCacheService.EXTENSION,extension);
        context.startService(intent);

    }

}