Android瀑布流的实现

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/** * Created by Venn on 2016/4/18. */1 WaterFallStream public class WaterFallStream extends ScrollView {    private Context mContext;    private LinearLayout llWaterPool;    private int columns;    private List<LinearLayout> subChildList;    private int childCounts;    private onReachBottomListener reachBottomListener;    public WaterFallStream(Context context) {        this(context, null);    }    public WaterFallStream(Context context, AttributeSet attrs) {        super(context, attrs);        this.mContext = context;        TypedArray ta = mContext.obtainStyledAttributes(attrs, R.styleable.WaterFallStream);        columns = ta.getInt(R.styleable.WaterFallStream_columns, 1);        init();    }    public void setReachBottomListener(onReachBottomListener reachBottomListener) {        this.reachBottomListener = reachBottomListener;    }    public int getColumns() {        return columns;    }    private void init() {        subChildList = new ArrayList<>();        llWaterPool = new LinearLayout(mContext);        llWaterPool.setOrientation(LinearLayout.HORIZONTAL);        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams                .MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);        llWaterPool.setLayoutParams(params);        this.addView(llWaterPool);        for (int i = 0; i < columns; i++) {            LinearLayout llChild = new LinearLayout(mContext);            LinearLayout.LayoutParams childParams = new LinearLayout.LayoutParams(0, ViewGroup                    .LayoutParams.WRAP_CONTENT, 1.0f);            llChild.setOrientation(LinearLayout.VERTICAL);            llChild.setLayoutParams(childParams);            llWaterPool.addView(llChild);            subChildList.add(llChild);        }    }    public void addSubView(View view) {        if (!subChildList.isEmpty()) {            int childIndex = childCounts % columns;            subChildList.get(childIndex).addView(view);            childCounts++;        }    }    @Override    public boolean onTouchEvent(MotionEvent ev) {        switch (ev.getAction()) {            case MotionEvent.ACTION_DOWN:                break;            case MotionEvent.ACTION_MOVE:                break;            case MotionEvent.ACTION_UP:                int height = getHeight();                int scrollY = getScrollY();                int mHeight = height + scrollY;                int contentHeight = llWaterPool.getHeight();                if (mHeight >= contentHeight) {                    if (reachBottomListener != null) {                        reachBottomListener.addMore(this);                    }                }                break;            default:                break;        }        return super.onTouchEvent(ev);    }    public interface onReachBottomListener {        void addMore(WaterFallStream stream);    }}

2 Style<declare-styleable name="WaterFallStream">    <attr name="columns" format="integer"></attr></declare-styleable>

3 Activitypublic class MainActivity extends Activity implements WaterFallStream.onReachBottomListener {    private WaterFallStream waterFallStream;    private int columns;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        waterFallStream = (WaterFallStream) this.findViewById(R.id.water_stream);        waterFallStream.setReachBottomListener(this);        columns = waterFallStream.getColumns();    }    @Override    public void addMore(WaterFallStream stream) {        for (int i = 0; i < columns; i++) {            ImageView imageView = new ImageView(this);            switch (i % columns) {                case 0:                    imageView.setImageResource(R.mipmap.image);                    break;                case 1:                    imageView.setImageResource(R.mipmap.head);                    break;                case 2:                    imageView.setImageResource(R.mipmap.image2);                    break;                default:                    break;            }            stream.addSubView(imageView);        }    }}

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