[移动开发]Android基础到进阶UI祖父级 ViewGroup介绍+实用

setWillNotDraw(false);

}

/**

• 负责设置子控件的测量模式和大小 根据所有子控件设置自己的宽和高

*/

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

MLog.e(getClass().getName(),“onMeasure”);

// 获得它的父容器为它设置的测量模式和大小

int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);

int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);

int modeWidth = MeasureSpec.getMode(widthMeasureSpec);

int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

// 如果是warp_content情况下，记录宽和高

int width = 0;

int height = 0;

//记录每一行的宽度，width不断取最大宽度

int lineWidth = 0;

//每一行的高度，累加至height

int lineHeight = 0;

int count = getChildCount();

int left = getPaddingLeft();

int top = getPaddingTop();

// 遍历每个子元素

for (int i = 0; i < count; i++) {

View child = getChildAt(i);

if (child.getVisibility() == GONE)

continue;

// 测量每一个child的宽和高

measureChild(child, widthMeasureSpec, heightMeasureSpec);

// 得到child的lp

ViewGroup.LayoutParams lp = child.getLayoutParams();

// 当前子空间实际占据的宽度

int childWidth = child.getMeasuredWidth() + childHorizontalSpace;

// 当前子空间实际占据的高度

int childHeight = child.getMeasuredHeight() + childVerticalSpace;

if (lp != null && lp instanceof MarginLayoutParams) {

MarginLayoutParams params = (MarginLayoutParams) lp;

childWidth += params.leftMargin + params.rightMargin;

childHeight += params.topMargin + params.bottomMargin;

}

//如果加入当前child，则超出最大宽度，则的到目前最大宽度给width，类加height 然后开启新行

if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {

width = Math.max(lineWidth, childWidth);// 取最大的

lineWidth = childWidth; // 重新开启新行，开始记录

// 叠加当前高度，

height += lineHeight;

// 开启记录下一行的高度

lineHeight = childHeight;

child.setTag(new Location(left, top + height, childWidth + left - childHorizontalSpace, height + child.getMeasuredHeight() + top));

} else {

// 否则累加值lineWidth,lineHeight取最大高度

child.setTag(new Location(lineWidth + left, top + height, lineWidth + childWidth - childHorizontalSpace + left, height + child.getMeasuredHeight() + top));

lineWidth += childWidth;

lineHeight = Math.max(lineHeight, childHeight);

}

}

width = Math.max(width, lineWidth) + getPaddingLeft() + getPaddingRight();

height += lineHeight;

sizeHeight += getPaddingTop() + getPaddingBottom();

height += getPaddingTop() + getPaddingBottom();

setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth : width, (modeHeight == MeasureSpec.EXACTLY) ? sizeHeight : height);

}

/**

• 记录子控件的坐标

*/

public class Location {

public Location(int left, int top, int right, int bottom) {

this.left = left;

this.top = top;

this.right = right;

this.bottom = bottom;

}

public int left;

public int top;

public int right;

public int bottom;

}

//计算当前View以及子View的位置

@Override

protected void onLayout(boolean changed, int l, int t, int r, int b) {

MLog.e(getClass().getName(),“onLayout”);

//获取子View个数

int count = getChildCount();

for (int i = 0; i < count; i++) {

//获取子View

View child = getChildAt(i);

//判断是否显示

if (child.getVisibility() == GONE)

continue;

//获取子View的坐标

Location location = (Location) child.getTag();

//设置子View位置

child.layout(location.left, location.top, location.right, location.bottom);

}

}

@Override

protected void onSizeChanged(int w, int h, int oldw, int oldh) {

super.onSizeChanged(w, h, oldw, oldh);

MLog.e(getClass().getName(),“onSizeChanged”);

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

MLog.e(getClass().getName(),“onDraw”);

}

}

2.使用自定义CustomLayout

<com.scc.demo.view.CustomLayout xmlns:android=“http://schemas.android.com/apk/res/android”

xmlns:custom=“http://schemas.android.com/apk/res-auto”

android:layout_width=“match_parent”

android:layout_height=“match_parent”

android:layout_margin="@dimen/dimen_20"

custom:horizontalSpace=“10dp”

custom:verticalSpace=“20dp”>

<TextView

style="@style/TvStyle"

android:text=“破阵子·为陈同甫赋壮词以寄” />

<TextView

style="@style/TvStyle"

android:text=“宋·辛弃疾” />

<TextView

style="@style/TvStyle"

android:text=“醉里挑灯看剑” />

<TextView

style="@style/TvStyle"

android:text=“梦回吹角连营” />

<TextView

style="@style/TvStyle"

android:text=“八百里分麾下炙” />

<TextView

style="@style/TvStyle"

android:text=“五十弦翻塞外声” />

<TextView

style="@style/TvStyle"

android:text=“沙场秋点兵” />

<TextView

style="@style/TvStyle"

android:text=“马作的卢飞快” />

<TextView

style="@style/TvStyle"

android:text=“弓如霹雳弦惊(增加点长度)” />

<TextView

style="@style/TvStyle"

android:text=“了却君王天下事” />

<TextView

style="@style/TvStyle"

android:text=“赢得生前身后名” />

<TextView

style="@style/TvStyle"

android:text=“可怜白发生！” />

</com.scc.demo.view.CustomLayout>

自定义属性

在app/src/main/res/values/attrs.xml中添加属性

使用自定义属性

• 在xml中使用

一定要添加：xmlns:test=”schemas.android.com/apk/res-aut…

<com.scc.demo.view.CustomLayout xmlns:android=“http://schemas.android.com/apk/res/android”

xmlns:custom=“http://schemas.android.com/apk/res-auto”

android:layout_width=“match_parent”

android:layout_height=“match_parent”

android:layout_margin="@dimen/dimen_20"

custom:horizontalSpace=“10dp”

custom:verticalSpace=“20dp”>

</com.scc.demo.view.CustomLayout>

• 在代码中使用

TypedArray attrArray = context.obtainStyledAttributes(attrs, R.styleable.CustomLayout);

if (attrArray != null) {

//参数1：获取xml中设置的参数；参数2：获取失败2使用参数作为默认值

childHorizontalSpace = attrArray.getDimensionPixelSize(R.styleable.CustomLayout_horizontalSpace, 12);

childVerticalSpace = attrArray.getDimensionPixelSize(R.styleable.CustomLayout_verticalSpace, 12);

MLog.e(getClass().getName(),“HorizontalSpace:”+childHorizontalSpace+"|VerticalSpace："+childVerticalSpace);

//TypedArray对象池的大小默认为5，使用时记得调用recyle()方法将不用的对象返回至对象池来达到重用的目的。

attrArray.recycle();

}

写到这里自定义ViewGroup基本完成。

ViewGroup属性

ViewGroup的XML属性以及相关方法