Android初级教程_图片混排效果和ViewPager的使用

前段时间公司需要实现图片混排的效果,类似"美丽说"那样,宽度一样,高度不一.总共有3列.每次加载更多的时候都是往最低的那列添加图片,这样就不会出现有的列非常多的图片,而有的列图片很少,效果如下图所示:

当滑倒底部的时候如果还有图片则自动加载下一页.
代码实现如下:
首先自定义布局:
[java]
public class MyLinearLayout extends LinearLayout {

    private Map<Integer, Integer> map;
    private ArrayList<LinearLayout> waterfall_items;
    private Context context;
    private Display display;
    private int itemWidth;

    public MyLinearLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    public MyLinearLayout(Context context) {
        super(context);
    }

    /**
     * 初始化容器
     * @param columnCount
     *            列数
     * @param paddingLeft
     * @param paddingTop
     * @param paddingRight
     * @param paddingBottom
     */
    public void initLayout(int columnCount, int paddingLeft, int paddingTop,
            int paddingRight, int paddingBottom) {

        if (columnCount < 1)
            columnCount = 3;

        Constans.COLUMN_COUNT = columnCount;

        waterfall_items = new ArrayList<LinearLayout>();
        map = new HashMap<Integer, Integer>();
        for (int i = 0; i < columnCount; i++) {
            map.put(i, 0);
        }
        context = getContext();
        WindowManager windowManager = (WindowManager) context
                .getSystemService(Context.WINDOW_SERVICE);
        display = windowManager.getDefaultDisplay();
        itemWidth = display.getWidth() / columnCount;// 根据屏幕大小计算每列大小
        for (int i = 0; i < columnCount; i++) {
            LinearLayout itemLayout = new LinearLayout(context);
            LinearLayout.LayoutParams itemParam = new LinearLayout.LayoutParams(
                    itemWidth, LayoutParams.WRAP_CONTENT);
            itemLayout.setPadding(1, 2, 1, 2);
            itemLayout.setOrientation(LinearLayout.VERTICAL);
            itemLayout.setLayoutParams(itemParam);
            waterfall_items.add(itemLayout);
            this.addView(itemLayout);
        }
    }
    /**
     * 贴图
     * @param article 文章实体
     * @param columnIndex 列索引
     */
    private void addImage(final Article article, int columnIndex) {
        ImageView item = (ImageView) LayoutInflater.from(context).inflate(
                R.layout.waterfallitem, null);
        waterfall_items.get(columnIndex).addView(item);
        //int inSampleSize = 1;
        int h = 0;
        // int originalWidth = article.getWidth();
         int originalHieght = article.getHeight();
        //
        // int screenHeight = display.getHeight() / 7;
        // int screenWidth = display.getWidth() / 7;
        // float heightRatio = (float) Math.ceil(article.getHeight()
        // / screenHeight);
        // float widthRatio = (float) (Math.ceil(originalWidth / screenWidth));
        // if (heightRatio >= 1 && widthRatio >= 1) {
        // if (heightRatio > widthRatio) {
        // inSampleSize = (int) heightRatio;
        // } else {
        // inSampleSize = (int) widthRatio;
        // }
        // h = originalHieght;// inSampleSize;
        // } else {
        // h = originalHieght;
        // }
        h = originalHieght;
        int value = map.get(columnIndex);
        map.put(columnIndex, value+h);

        TaskParam param = new TaskParam();
        param.setItemWidth(itemWidth);
        Bitmap defaultImage = BitmapFactory.decodeResource(getResources(),
                R.drawable.loading);
        ImageLoaderTask task = new ImageLoaderTask(item, display,
                article.getImage(), article, defaultImage, param);

补充：移动开发 , Android ,