转载请标明出处:http://blog.csdn.net/lmj623565791/article/details/38352503 ,本文出自【张鸿洋的博客】
1、概述
上一篇已经基本给大家介绍了如何自定义ViewGroup,如果你还不了解,请查看:Android 手把手教您自定ViewGroup ,本篇将使用上篇介绍的方法,给大家带来一个实例:实现FlowLayout,何为FlowLayout,如果对Java的Swing比较熟悉的话一定不会陌生,就是控件根据ViewGroup的宽,自动的往右添加,如果当前行剩余空间不足,则自动添加到下一行。有点所有的控件都往左飘的感觉,第一行满了,往第二行飘~所以也叫流式布局。Android并没有提供流式布局,但是某些场合中,流式布局还是非常适合使用的,比如关键字标签,搜索热词列表等,比如下图:
这些都特别适合使用FlowLayout,本篇博客会带领大家自己实现FlowLayout,然后使用我们自己定义的FlowLayout实现上面的标签效果。对了,github已经有了这样FlowLayout,但是我觉得丝毫不影响我们对其的学习,学会使用一个控件和学会写一个控件,我相信大家都明白,授人以鱼不如授人以渔。
2、简单的分析
1、对于FlowLayout,需要指定的LayoutParams,我们目前只需要能够识别margin即可,即使用MarginLayoutParams.
2、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)
3、onLayout中对所有的childView进行布局。
3、generateLayoutParams
因为我们只需要支持margin,所以直接使用系统的MarginLayoutParams
- @Override
- public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs)
- {
- return new MarginLayoutParams(getContext(), attrs);
- }
4、onMeasure
- /**
- * 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);
- // 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);
- Log.e(TAG, sizeWidth + "," + sizeHeight);
- // 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 cCount = getChildCount();
- // 遍历每个子元素
- for (int i = 0; i < cCount; i++)
- {
- View child = getChildAt(i);
- // 测量每一个child的宽和高
- measureChild(child, widthMeasureSpec, heightMeasureSpec);
- // 得到child的lp
- MarginLayoutParams lp = (MarginLayoutParams) child
- .getLayoutParams();
- // 当前子空间实际占据的宽度
- int childWidth = child.getMeasuredWidth() + lp.leftMargin
- + lp.rightMargin;
- // 当前子空间实际占据的高度
- int childHeight = child.getMeasuredHeight() + lp.topMargin
- + lp.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)
- {
- 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;
- } else
- // 否则累加值lineWidth,lineHeight取最大高度
- {
- lineWidth += childWidth;
- lineHeight = Math.max(lineHeight, childHeight);
- }
- // 如果是最后一个,则将当前记录的最大宽度和当前lineWidth做比较
- if (i == cCount - 1)
- {
- width = Math.max(width, lineWidth);
- height += lineHeight;
- }
- }
- setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth
- : width, (modeHeight == MeasureSpec.EXACTLY) ? sizeHeight
- : height);
- }
首先得到其父容器传入的测量模式和宽高的计算值,然后遍历所有的childView,使用measureChild方法对所有的childView进行测量。然后根据所有childView的测量得出的宽和高得到该ViewGroup如果设置为wrap_content时的宽和高。最后根据模式,如果是MeasureSpec.EXACTLY则直接使用父ViewGroup传入的宽和高,否则设置为自己计算的宽和高。
5、onLayout
onLayout中完成对所有childView的位置以及大小的指定
- /**
- * 存储所有的View,按行记录
- */
- private List<List<View>> mAllViews = new ArrayList<List<View>>();
- /**
- * 记录每一行的最大高度
- */
- private List<Integer> mLineHeight = new ArrayList<Integer>();
- @Override
- protected void onLayout(boolean changed, int l, int t, int r, int b)
- {
- mAllViews.clear();
- mLineHeight.clear();
- int width = getWidth();
- int lineWidth = 0;
- int lineHeight = 0;
- // 存储每一行所有的childView
- List<View> lineViews = new ArrayList<View>();
- int cCount = getChildCount();
- // 遍历所有的孩子
- for (int i = 0; i < cCount; i++)
- {
- View child = getChildAt(i);
- MarginLayoutParams lp = (MarginLayoutParams) child
- .getLayoutParams();
- int childWidth = child.getMeasuredWidth();
- int childHeight = child.getMeasuredHeight();
- // 如果已经需要换行
- if (childWidth + lp.leftMargin + lp.rightMargin + lineWidth > width)
- {
- // 记录这一行所有的View以及最大高度
- mLineHeight.add(lineHeight);
- // 将当前行的childView保存,然后开启新的ArrayList保存下一行的childView
- mAllViews.add(lineViews);
- lineWidth = 0;// 重置行宽
- lineViews = new ArrayList<View>();
- }
- /**
- * 如果不需要换行,则累加
- */
- lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
- lineHeight = Math.max(lineHeight, childHeight + lp.topMargin
- + lp.bottomMargin);
- lineViews.add(child);
- }
- // 记录最后一行
- mLineHeight.add(lineHeight);
- mAllViews.add(lineViews);
- int left = 0;
- int top = 0;
- // 得到总行数
- int lineNums = mAllViews.size();
- for (int i = 0; i < lineNums; i++)
- {
- // 每一行的所有的views
- lineViews = mAllViews.get(i);
- // 当前行的最大高度
- lineHeight = mLineHeight.get(i);
- Log.e(TAG, "第" + i + "行 :" + lineViews.size() + " , " + lineViews);
- Log.e(TAG, "第" + i + "行, :" + lineHeight);
- // 遍历当前行所有的View
- for (int j = 0; j < lineViews.size(); j++)
- {
- View child = lineViews.get(j);
- if (child.getVisibility() == View.GONE)
- {
- continue;
- }
- MarginLayoutParams lp = (MarginLayoutParams) child
- .getLayoutParams();
- //计算childView的left,top,right,bottom
- int lc = left + lp.leftMargin;
- int tc = top + lp.topMargin;
- int rc =lc + child.getMeasuredWidth();
- int bc = tc + child.getMeasuredHeight();
- Log.e(TAG, child + " , l = " + lc + " , t = " + t + " , r ="
- + rc + " , b = " + bc);
- child.layout(lc, tc, rc, bc);
- left += child.getMeasuredWidth() + lp.rightMargin
- + lp.leftMargin;
- }
- left = 0;
- top += lineHeight;
- }
- }
allViews的每个Item为每行所有View的List集合。
mLineHeight记录的为每行的最大高度。
23-48行,遍历所有的childView,用于设置allViews的值,以及mLineHeight的值。
57行,根据allViews的长度,遍历所有的行数
67-91行,遍历每一行的中所有的childView,对childView的left , top , right , bottom 进行计算,和定位。
92-93行,重置left和top,准备计算下一行的childView的位置。
好了,到此完成了所有的childView的绘制区域的确定,到此,我们的FlowLayout的代码也结束了~~静下心来看一看是不是也不难~
6、测试
我准备使用TextView作为我们的标签,所以为其简单写了一点样式:
res/values/styles.xml中:
- <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:background">@drawable/flag_01</item>
- <item name="android:textColor">#ffffff</item>
- </style>
flag_01.xml
- <?xml version="1.0" encoding="utf-8"?>
- <shape xmlns:android="http://schemas.android.com/apk/res/android" >
- <solid android:color="#7690A5" >
- </solid>
- <corners android:radius="5dp"/>
- <padding
- android:bottom="2dp"
- android:left="10dp"
- android:right="10dp"
- android:top="2dp" />
- </shape>
布局文件:
- <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:tools="http://schemas.android.com/tools"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent"
- android:background="#E1E6F6"
- android:orientation="vertical" >
- <com.zhy.zhy_flowlayout02.FlowLayout
- android:layout_width="fill_parent"
- android:layout_height="wrap_content" >
- <TextView
- style="@style/text_flag_01"
- android:text="Welcome" />
- <TextView
- style="@style/text_flag_01"
- android:text="IT工程师" />
- <TextView
- style="@style/text_flag_01"
- android:text="学习ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="恋爱ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="挣钱ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="努力ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="I thick i can" />
- </com.zhy.zhy_flowlayout02.FlowLayout>
- </LinearLayout>
效果图:
是不是还不错,下面继续简单自定义几个背景:
res/drawble/flog_02.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"/>
- <stroke android:color="#C9C9C9" android:width="2dp"/>
- <padding
- android:bottom="2dp"
- android:left="10dp"
- android:right="10dp"
- android:top="2dp" />
- </shape>
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"/>
- <padding
- android:bottom="2dp"
- android:left="10dp"
- android:right="10dp"
- android:top="2dp" />
- </shape>
布局文件:
- <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:tools="http://schemas.android.com/tools"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent"
- android:background="#E1E6F6"
- android:orientation="vertical" >
- <com.zhy.zhy_flowlayout02.FlowLayout
- android:layout_width="fill_parent"
- android:layout_height="wrap_content" >
- <TextView
- style="@style/text_flag_01"
- android:text="Welcome" />
- <TextView
- style="@style/text_flag_01"
- android:text="IT工程师" />
- <TextView
- style="@style/text_flag_01"
- android:text="学习ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="恋爱ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="挣钱ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="努力ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="I thick i can" />
- </com.zhy.zhy_flowlayout02.FlowLayout>
- <com.zhy.zhy_flowlayout02.FlowLayout
- android:layout_width="fill_parent"
- android:layout_height="wrap_content"
- android:layout_marginTop="20dp" >
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_02"
- android:text="Welcome"
- android:textColor="#888888" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_02"
- android:text="IT工程师"
- android:textColor="#888888" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_02"
- android:text="学习ing"
- android:textColor="#888888" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_02"
- android:text="恋爱ing"
- android:textColor="#888888" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_02"
- android:text="挣钱ing"
- android:textColor="#888888" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_02"
- android:text="努力ing"
- android:textColor="#888888" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_02"
- android:text="I thick i can"
- android:textColor="#888888" />
- </com.zhy.zhy_flowlayout02.FlowLayout>
- <com.zhy.zhy_flowlayout02.FlowLayout
- android:layout_width="fill_parent"
- android:layout_height="wrap_content"
- android:layout_marginTop="20dp" >
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_03"
- android:text="Welcome"
- android:textColor="#43BBE7" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_03"
- android:text="IT工程师"
- android:textColor="#43BBE7" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_03"
- android:text="学习ing"
- android:textColor="#43BBE7" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_03"
- android:text="恋爱ing"
- android:textColor="#43BBE7" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_03"
- android:text="挣钱ing"
- android:textColor="#43BBE7" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_03"
- android:text="努力ing"
- android:textColor="#43BBE7" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_03"
- android:text="I thick i can"
- android:textColor="#43BBE7" />
- </com.zhy.zhy_flowlayout02.FlowLayout>
- </LinearLayout>
效果图:
暂不赞~~上面都是match_parent~~下面固定下宽度,实现文章最开始的移动开发热门标签:
flag_04.xml
- <?xml version="1.0" encoding="utf-8"?>
- <shape xmlns:android="http://schemas.android.com/apk/res/android" >
- <solid android:color="#E7E7E7" >
- </solid>
- <corners
- android:radius="30dp"
- />
- <padding
- android:bottom="2dp"
- android:left="10dp"
- android:right="10dp"
- android:top="2dp" />
- </shape>
布局文件:
- <com.zhy.zhy_flowlayout02.FlowLayout xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:tools="http://schemas.android.com/tools"
- android:layout_width="200dp"
- android:layout_height="wrap_content"
- android:background="#FFFFFF" >
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_04"
- android:text="Welcome"
- android:textColor="#323232" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_04"
- android:text="IT工程师"
- android:textColor="#323232" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_04"
- android:text="学习ing"
- android:textColor="#323232" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_04"
- android:text="恋爱ing"
- android:textColor="#323232" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_04"
- android:text="挣钱ing"
- android:textColor="#323232" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_04"
- android:text="努力ing"
- android:textColor="#323232" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_04"
- android:text="I thick i can"
- android:textColor="#323232" />
- </com.zhy.zhy_flowlayout02.FlowLayout>
效果图:
是不是完全相同~~o了~
如果你觉得本篇博客对你有用,那么就留个言或者顶一个~~