自定义ViewGroup实现view的自由布局

文章目录

1. 1. 自定义ViewGroup
   1. 1.1. CustomViewGroup.java
   2. 1.2. MainActivity.java
   3. 1.3. ViewSizeInfo.java
   4. 1.4. ScreenUtil.java
   5. 1.5. 效果图

前段时间有个需求是:

1. 给定一个list 数组，根据集合里面的数据来画View；
2. View的数目是小于等于手机横屏后的宽度。

传统的线性布局，相对布局都不能满足这个需求，所以我们只能自己来自定义一个ViewGroupl 。

自定义ViewGroup

我们知道ViewGroup就是View的容器类，我们经常用的LinearLayout，RelativeLayout等都是ViewGroup的子类。

CustomViewGroup.java

public class CustomViewGroup extends ViewGroup {

    private final static String TAG = "CustomViewGroup";

    // view 的间隔
    private final static int VIEW_MARGIN = 0;

    public CustomViewGroup(Context context) {
        super(context);
    }

    // 重写它的onMeasure() 在该方法中进行对子View的大小进行测量
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        Log.d(TAG, "widthMeasureSpec = " + widthMeasureSpec
                + " heightMeasureSpec" + heightMeasureSpec);
        for (int index = 0; index < getChildCount(); index++) {
            final View child = getChildAt(index);
            child.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
        }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    // 重写onLayout方法实现子View的定位
    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {

        Log.d(TAG, "changed = " + changed + " left = " + l + " top = " + t
                + " right = " + r + " botom = " + b);
        final int count = getChildCount();
        int row = 0;
        //当前宽度
        int lengthX = l;
        //当前高度
        int lengthY = t;
        for (int i = 0; i < count; i++) {
            final View child = this.getChildAt(i);
            int width = child.getMeasuredWidth();
            int height = child.getMeasuredHeight();
            lengthX += width + VIEW_MARGIN;
            lengthY = row * (height + VIEW_MARGIN) + VIEW_MARGIN + height
                    + t;
            if (lengthX > r) {
                lengthX = width + VIEW_MARGIN + l;
                row++;
                lengthY = row * (height + VIEW_MARGIN) + VIEW_MARGIN + height
                        + t;
            }
            child.layout(lengthX - width, lengthY - height, lengthX, lengthY);
        }
    }
}

MainActivity.java

public class MainActivity extends Activity {
    private CustomViewGroup mViewGroup;
    private ArrayList<ViewSizeInfo> mViewSizes;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //初始化数据
        mViewSizes = getViewSizes();
        mViewGroup = getViewGroup(mViewSizes);
        setContentView(mViewGroup);
    }

    private ArrayList<ViewSizeInfo> getViewSizes() {
        ArrayList<ViewSizeInfo> viewSizes = new ArrayList<>();

        viewSizes.add(new ViewSizeInfo(1, 1,R.color.colorAccent));
        viewSizes.add(new ViewSizeInfo(3, 2,R.color.colorDarkOrchid));
        viewSizes.add(new ViewSizeInfo(4, 4,R.color.colorPrimary));
        viewSizes.add(new ViewSizeInfo(1, 5,R.color.colorLightBLue));
        return viewSizes;
    }

    private CustomViewGroup getViewGroup(ArrayList<ViewSizeInfo> viewSizes) {
        CustomViewGroup myViewGroup = new CustomViewGroup(this);

        myViewGroup.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
        int width = ScreenUtil.getScreenWidth(this)/10;
        int height =ScreenUtil.getScreenHeight(this)/5;

        for (int i = 0; i <viewSizes.size() ; i++) {
            ViewSizeInfo viewSize =viewSizes.get(i);
            TextView textView = new TextView(this);
            textView.setText("TextView"+i);
            textView.setBackgroundColor(getResources().getColor(viewSize.getColor()));
            textView.setWidth(width* viewSize.getWidth());
            textView.setHeight(height* viewSize.getHeight());
            myViewGroup.addView(textView);
        }
        return myViewGroup;
    }
}

ViewSizeInfo.java

public class ViewSizeInfo {
    private int mWidth;
    private int mHeight;
    // 设置默认颜色
    private int color;

    public ViewSizeInfo(int width, int height) {
        this.mWidth = width;
        this.mHeight = height;
    }

    public ViewSizeInfo(int width, int height, int color) {
        this.mWidth = width;
        this.mHeight = height;
        this.color = color;
    }

    public int getWidth() {
        return mWidth;
    }

    public void setWidth(int width) {
        this.mWidth = width;
    }

    public int getHeight() {
        return mHeight;
    }

    public void setHeight(int height) {
        this.mHeight = height;
    }

    public int getColor() {
        return color;
    }

    public void setColor(int color) {
        this.color = color;
    }
}

ScreenUtil.java

public class ScreenUtil {
    private ScreenUtil() {
        /*cannot be instantiated*/
        throw new UnsupportedOperationException("cannot be instantiated");
    }

    /**
     * 获得屏幕宽度
     *
     * @param context
     * @return
     */
    public static int getScreenWidth(Context context) {
        WindowManager wm = (WindowManager) context
                .getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics outMetrics = new DisplayMetrics();
        wm.getDefaultDisplay().getMetrics(outMetrics);
        return outMetrics.widthPixels;
    }

    /**
     * 获得屏幕高度
     *
     * @param context
     * @return
     */
    public static int getScreenHeight(Context context) {
        WindowManager wm = (WindowManager) context
                .getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics outMetrics = new DisplayMetrics();
        wm.getDefaultDisplay().getMetrics(outMetrics);
        return outMetrics.heightPixels;
    }
}

效果图

完整代码已经上传到Github了：https://github.com/HJXANDHMR/CustomViewGroup