自定义ViewGroup控件（三）-----流式布局进阶（三）

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activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="fill_parent"android:layout_height="fill_parent"android:orientation="vertical" ><com.example.flowlayout.FlowLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:background="#ff00ff" ><TextViewstyle="@style/text_flag_01"android:background="@drawable/flag_03"android:text="sfasfsfasfs"android:textColor="#43BBE7" /><TextViewstyle="@style/text_flag_01"android:background="@drawable/flag_03"android:text="sfas嗯啥哦 "android:textColor="#43BBE7" /><TextViewstyle="@style/text_flag_01"android:background="@drawable/flag_03"android:text="我真是我弄 可以的"android:textColor="#43BBE7" /><TextViewstyle="@style/text_flag_01"android:background="@drawable/flag_03"android:text="暗色捏你你呢你了 "android:textColor="#43BBE7" /><TextViewstyle="@style/text_flag_01"android:background="@drawable/flag_03"android:text="问候foe 接口就是"android:textColor="#43BBE7" /><TextViewstyle="@style/text_flag_01"android:background="@drawable/flag_03"android:text="暗色法俄万人 问啊"android:textColor="#43BBE7" /><TextViewstyle="@style/text_flag_01"android:background="@drawable/flag_03"android:text="为问啊 问问发我发"android:textColor="#43BBE7" /></com.example.flowlayout.FlowLayout></LinearLayout>

styles.xml

<resources><style name="text_flag_01"><item name="android:layout_width">wrap_content</item><item name="android:layout_height">wrap_content</item><item name="android:layout_margin">4dp</item><item name="android:textColor">#ffffff</item></style></resources>

flag_03.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" ><solid android:color="#FFFFFF" ></solid><corners android:radius="40dp" /><paddingandroid:bottom="2dp"android:left="10dp"android:right="10dp"android:top="2dp" /></shape>

MainActivity

package com.example.flowlayout;import android.app.Activity;
import android.os.Bundle;public class MainActivity extends Activity {@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);}
}

FlowLayout

package com.example.flowlayout;import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;public class FlowLayout extends ViewGroup {public FlowLayout(Context context) {super(context);}public FlowLayout(Context context, AttributeSet attrs) {super(context, attrs);}public FlowLayout(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);}/*** 父容器生成 子view 的布局LayoutParams;* 一句话道出LayoutParams的本质：LayoutParams是Layout提供给其中的Children使用的。* 如果要自定义ViewGroup支持子控件的layout_margin参数* ，则自定义的ViewGroup类必须重载generateLayoutParams()函数，* 并且在该函数中返回一个ViewGroup.MarginLayoutParams派生类对象，这样才能使用margin参数。*/@Overrideprotected LayoutParams generateLayoutParams(LayoutParams p) {return new MarginLayoutParams(p);}@Overridepublic LayoutParams generateLayoutParams(AttributeSet attrs) {return new MarginLayoutParams(getContext(), attrs);}@Overrideprotected LayoutParams generateDefaultLayoutParams() {return new MarginLayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);int measureWidth = MeasureSpec.getSize(widthMeasureSpec);int measureHeight = MeasureSpec.getSize(heightMeasureSpec);int measureWidthMode = MeasureSpec.getMode(widthMeasureSpec);int measureHeightMode = MeasureSpec.getMode(heightMeasureSpec);// 每行的宽度，每行的高度int lineWidth = 0;int lineHeight = 0;// 初始化容器的高度，宽地int viewGroupHeight = 0;int viewGroupWidth = 0;// 获取子view的数量int count = getChildCount();for (int i = 0; i < count; i++) {// 获取每一个子viewView child = getChildAt(i);// 测量子viewmeasureChild(child, widthMeasureSpec, heightMeasureSpec);// 如果忘记重写generateLayoutParams，则hild.getLayoutParams()将不是MarginLayoutParams的实例// 在强制转换时就会出错，此时我们把左右间距设置为0，但由于在计算布局宽高时没有加上间距值，就是计算出的宽高要比实际小，所以是onLayout时就会出错MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();// 每个子view的宽、高int childWidth = child.getMeasuredWidth() + lp.leftMargin+ lp.rightMargin;int childHeight = child.getMeasuredHeight() + lp.topMargin+ lp.bottomMargin;/*** 换行后：当在显示下一个子view的时候，之前累加 的宽度+下个子view的宽度>测量的viewGroup的宽度，就需要换行显示*/if (lineWidth + childWidth > measureWidth) {// 将容器的高度，进行累加，换行后viewGroupHeight += lineHeight;// 因为由于盛不下当前控件，而将此控件调到下一行，所以将此控件的高度和宽度初始化给lineHeight、lineWidthlineHeight = childHeight;lineWidth = childWidth;} else {// 每行的高度，需要在当前行的所有view取最大值lineHeight = Math.max(lineHeight, childHeight);// 拿第一行来说，在没有换行的情况下，每行的宽度，需要不断累加每个子view的宽度lineWidth += childWidth;}// 最后一行是不会超出width范围的，所以要单独处理if (i == count - 1) {viewGroupHeight += lineHeight;viewGroupWidth = Math.max(viewGroupWidth, lineWidth);}}// 当属性是MeasureSpec.EXACTLY时，那么它的高度就是确定的，// 只有当是wrap_content时，根据内部控件的大小来确定它的大小时，大小是不确定的，属性是AT_MOST,此时，就需要我们自己计算它的应当的大小，并设置进去setMeasuredDimension((measureWidthMode == MeasureSpec.EXACTLY) ? measureWidth: viewGroupWidth,(measureHeightMode == MeasureSpec.EXACTLY) ? measureHeight: viewGroupHeight);}@Overrideprotected void onLayout(boolean changed, int l, int t, int r, int b) {int count = getChildCount();int lineWidth = 0;int lineHeight = 0;int top = 0, left = 0;for (int i = 0; i < count; i++) {View child = getChildAt(i);MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();int childWidth = child.getMeasuredWidth() + lp.leftMargin+ lp.rightMargin;int childHeight = child.getMeasuredHeight() + lp.topMargin+ lp.bottomMargin;if (childWidth + lineWidth > getMeasuredWidth()) {// 如果换行,当前控件将跑到下一行，从最左边开始，所以left就是0，而top则需要加上上一行的行高，才是这个控件的top点;top += lineHeight;left = 0;// 同样，重新初始化lineHeight和lineWidthlineHeight = childHeight;lineWidth = childWidth;} else {lineHeight = Math.max(lineHeight, childHeight);lineWidth += childWidth;}// 计算childView的left,top,right,bottomint lc = left + lp.leftMargin;int tc = top + lp.topMargin;int rc = lc + child.getMeasuredWidth();int bc = tc + child.getMeasuredHeight();child.layout(lc, tc, rc, bc);// 将left置为下一子控件的起始点left += childWidth;}}}

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