4.4 View的示例(二)

1. 继承ViewGroup派生特殊的Layout

实现类似ViewPager的View

public class HorizontalScrollViewEx extends ViewGroup {
    public HorizontalScrollViewEx(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int measureWidth = 0;
        int measuredHeight = 0;
        final int childCount = getChildCount();
        measureChildren(widthMeasureSpec, heightMeasureSpec);

        int widthSpaceSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightSpaceSize = MeasureSpec.getSize(heightMeasureSpec);
        int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);

        if (childCount == 0) {
            setMeasuredDimension(getLayoutParams().width, getLayoutParams().height);
        } else if (widthSpecMode == MeasureSpec.AT_MOST && heightSpecMode == MeasureSpec.AT_MOST) {
            View childView = getChildAt(0);
            measureWidth = childView.getMeasuredWidth() * childCount;
            measuredHeight = childView.getMeasuredHeight();
            setMeasuredDimension(measureWidth, measuredHeight);
        } else if (heightSpecMode == MeasureSpec.AT_MOST) {
            View childView = getChildAt(0);
            measureWidth = widthSpaceSize;
            measuredHeight = childView.getMeasuredHeight();
            setMeasuredDimension(measureWidth, measuredHeight);
        } else if (widthSpecMode == MeasureSpec.AT_MOST) {
            View childView = getChildAt(0);
            measureWidth = childView.getMeasuredWidth() * childCount;
            measuredHeight = heightSpaceSize;
            setMeasuredDimension(measureWidth, measuredHeight);
        }
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int childLeft = 0;
        int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            View childView = getChildAt(i);
            if (childView.getVisibility() != View.GONE) {
                int childWidth = childView.getMeasuredWidth();
                childView.layout(childLeft, 0, childLeft + childWidth, childView.getMeasuredHeight());
                childLeft += childWidth;
            }
        }
    }
}

2. Activity中的代码

public class ViewActivity extends AppCompatActivity {
    HorizontalScrollViewEx mListContainer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view);

        LayoutInflater inflater = getLayoutInflater();
        mListContainer = (HorizontalScrollViewEx) findViewById(R.id.horizontalScrollViewEx);
        final int screenWidth = MyUtils.getScreenMetrics(this).widthPixels;
        final int screenHeight = MyUtils.getScreenMetrics(this).heightPixels;
        for (int i = 0; i < 3; i++) {
            ViewGroup layout = (ViewGroup) inflater.inflate(
                    R.layout.content_layout, mListContainer, false);
            layout.getLayoutParams().width = screenWidth;
            TextView textView = (TextView) layout.findViewById(R.id.title);
            textView.setText("page " + (i + 1));
            layout.setBackgroundColor(Color.rgb(255 / (i + 1), 255 / (i + 1), 0));
            createList(layout);
            mListContainer.addView(layout);
        }
    }

    private void createList(ViewGroup layout) {
        ListView listView = (ListView) layout.findViewById(R.id.list);
        ArrayList<String> datas = new ArrayList<String>();
        for (int i = 0; i < 50; i++) {
            datas.add("name " + i);
        }

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                R.layout.content_list_item, R.id.name, datas);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                                    int position, long id) {
                Toast.makeText(ViewActivity.this, "click item",
                        Toast.LENGTH_SHORT).show();

            }
        });
    }
}

3. 几个布局文件

activity_view.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="qingfengmy.developmentofart._4view.ViewActivity">

    <qingfengmy.developmentofart._4view.HorizontalScrollViewEx
        android:id="@+id/horizontalScrollViewEx"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</RelativeLayout>

content_layout.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        android:layout_marginBottom="5dp"
        android:text="TextView" />

    <ListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#fff4f7f9"
        android:cacheColorHint="#00000000"
        android:divider="#dddbdb"
        android:dividerHeight="1.0px"
        android:listSelector="@android:color/transparent" />

</LinearLayout>

content_list_item.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:gravity="center_vertical"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView" />

</LinearLayout>

之后的滑动冲突处理请看
3.5 View的滑动冲突(二)