Android 学习笔记 初学自定义viewgroup

转载自(http://blog.csdn.net/lmj623565791/article/details/38352503)

onMeasure中计算所有childView的宽和高，然后根据childView的宽和高，计算自己的宽和高。（当然，如果不是wrap_content，直接使用父ViewGroup传入的计算值即可）

onLayout中对所有的childView进行布局。

package lud.com.myviewgroup;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by win7 on 2016/9/2.
 */

public class MyViewGroup extends ViewGroup {
    //用来保存所有的view
    private List<List<View>> mViews = new ArrayList<>();
     //用来保存每行的高度
    private List<Integer> mLineHeight = new ArrayList<>();

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

    @Override
    protected ViewGroup.LayoutParams generateLayoutParams(
            ViewGroup.LayoutParams p) {
        return new MarginLayoutParams(p);
    }

    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        Log.e("generateLayoutParams", "generateLayoutParams");
        return new MarginLayoutParams(getContext(), attrs);

    }

    @Override
    protected ViewGroup.LayoutParams generateDefaultLayoutParams() {
        return new MarginLayoutParams(LayoutParams.MATCH_PARENT,
                LayoutParams.MATCH_PARENT);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        Log.e("onMeasure", "onMeasure");
        int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
        int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
        int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
        int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

        //记录warp_content情况下的宽高
        int width = ;
        int height = ;

        int lineWidth = ;
        int lineHeight = ;

        int cCount = getChildCount();
        for (int i = ; i < cCount; i++) {
            View child = getChildAt(i);
            measureChild(child, widthMeasureSpec, heightMeasureSpec);
            MarginLayoutParams layoutParams = (MarginLayoutParams) child.getLayoutParams();
            int childWidth = child.getMeasuredWidth() + layoutParams.leftMargin + layoutParams.rightMargin;
            int childHeight = child.getMeasuredHeight() + layoutParams.topMargin + layoutParams.bottomMargin;

            if (lineWidth + childWidth > sizeWidth) {
                width = Math.max(lineWidth, childWidth);
                lineWidth = childWidth;
                height += lineHeight;
                lineHeight = childHeight;
            } else {
                lineWidth += childWidth;
                lineHeight = Math.max(lineHeight, childHeight);

            }
            if (i == cCount - ) {
                width = Math.max(width, lineWidth);
                height += lineHeight;
            }

        }
        //存储宽高
        setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth
                : width, (modeHeight == MeasureSpec.EXACTLY) ? sizeHeight
                : height);
    }


    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        Log.e("onLayout", "onLayout");
        mLineHeight.clear();
        mViews.clear();

        int width = getWidth();

        int lineWidth = ;
        int lineHeight = ;

        List<View> lineViews = new ArrayList<View>();//存放每行的view
        int cCount = getChildCount();

        for (int i = ; i < cCount; i++) {
            View child = getChildAt(i);
            MarginLayoutParams layoutParams = (MarginLayoutParams) child.getLayoutParams();
            int childWidth = child.getMeasuredWidth();
            int childHeight = child.getMeasuredHeight();
            if (childWidth + layoutParams.leftMargin + layoutParams.rightMargin + lineWidth > width) {
                mViews.add(lineViews);
                mLineHeight.add(lineHeight);
                lineWidth = ;
                lineViews = new ArrayList<View>();
            }
            lineWidth += childWidth + layoutParams.leftMargin + layoutParams.rightMargin;
            lineHeight = Math.max(lineHeight, childHeight + layoutParams.topMargin
                    + layoutParams.bottomMargin);
            lineViews.add(child);
        }
        mLineHeight.add(lineHeight);
        mViews.add(lineViews);

        int left = ;
        int top = ;

        int linesNum = mViews.size();
        for (int i = ; i < linesNum; i++) {
            lineViews = mViews.get(i);
            lineHeight = mLineHeight.get(i);
            for (int j = ; j < lineViews.size(); j++) {
                View child = lineViews.get(j);
                if (child.getVisibility() == View.GONE) {
                    continue;
                }
                MarginLayoutParams layoutParams = (MarginLayoutParams) child.getLayoutParams();
                int lc = left + layoutParams.leftMargin;
                int tc = top + layoutParams.topMargin;
                int rc = lc + child.getMeasuredWidth();
                int bc = tc + child.getMeasuredHeight();

                child.layout(lc, tc, rc, bc);
                left += child.getMeasuredWidth() + layoutParams.rightMargin
                        + layoutParams.leftMargin;
            }
            left = ;
            top += lineHeight;
        }
    }
}
           

布局代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#E1E6F6"
    android:orientation="vertical">

    <lud.com.myviewgroup.MyViewGroup
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            style="@style/text_style"
            android:text="Welcome" />

        <TextView
            style="@style/text_style"
            android:text="Welcome" />

        <TextView
            style="@style/text_style"
            android:text="呵呵呵" />

        <TextView
            style="@style/text_style"
            android:text="哈哈哈哈哈哈" />

        <TextView
            style="@style/text_style"
            android:text="诶诶诶诶诶诶诶" />

        <TextView
            style="@style/text_style"
            android:text="Welcome" />

        <TextView
            style="@style/text_style"
            android:text="Welcome" />

        <TextView
            style="@style/text_style"
            android:text="Welcome" />

        <TextView
            style="@style/text_style"
            android:text="哀伤的合法地方" />


    </lud.com.myviewgroup.MyViewGroup>
</LinearLayout>
           

效果图