編輯:關於Android編程
整理總結自鴻洋的博客:http://blog.csdn.net/lmj623565791/article/details/38352503/
一、FlowLayout介紹
所謂FlowLayout,就是控件根據ViewGroup的寬,自動的往右添加,如果當前行剩余空間不足,則自動添加到下一行。有點像所有的控件都往左飄的感覺,第一行滿了,往第二行飄~所以也叫流式布局。Android並沒有提供流式布局,但是某些場合中,流式布局還是非常適合使用的,比如關鍵字標簽,搜索熱詞列表等,比如下圖:
github上已有現成的FlowLayout,本文是從無到有去制作。
二、制作分析
1、對於FlowLayout,需要指定的LayoutParams,我們目前只需要能夠識別margin即可,即使用MarginLayoutParams.
2、onMeasure中計算所有childView的寬和高,然後根據childView的寬和高,計算自己的寬和高。(當然,如果不是wrap_content,直接使用父ViewGroup傳入的計算值即可)
3、onLayout中對所有的childView進行布局。
三、代碼
1、MainActivity.java
public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // setContentView(R.layout.activity_main2); // setContentView(R.layout.activity_main3); } }
2、CustomViewGroup.java
public class CustomViewGroup extends ViewGroup { private final String TAG = getClass().getSimpleName(); public CustomViewGroup(Context context) { super(context); } public CustomViewGroup(Context context, AttributeSet attrs) { super(context, attrs); } public CustomViewGroup(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } /** * 一、重寫generateLayoutParams,確定該ViewGroup的LayoutParams * 返回MarginLayoutParams的實例,這樣就為我們的ViewGroup指定了其LayoutParams為MarginLayoutParams */ @Override public LayoutParams generateLayoutParams(AttributeSet attrs) { return new MarginLayoutParams(getContext(), attrs); } /** * 二、計算所有ChildView的寬度和高度 然後根據ChildView的計算結果,設置自己的寬和高 */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //1、獲得此ViewGroup上級容器為其推薦的寬和高,以及計算模式 int widthMode = MeasureSpec.getMode(widthMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int sizeWidth = MeasureSpec.getSize(widthMeasureSpec); int sizeHeight = MeasureSpec.getSize(heightMeasureSpec); // 2、如果ViewGroup布局是wrap_content時,根據childView的尺寸,計算容器的寬和高 int width = 0;//ViewGroup的寬度 int height = 0;//ViewGroup的高度 int lineWidth = 0;//childView所占據的當前行總寬度 int lineHeight = 0;//childView所占據的各行總高度 int cCount = getChildCount();////childView的數量 for(int i=0; i<cCount; i++){//遍歷每個childView View childView = getChildAt(i); measureChild(childView, widthMeasureSpec, heightMeasureSpec);// 測量當前child的寬和高 MarginLayoutParams mlp = (MarginLayoutParams) childView.getLayoutParams(); int cWidth = childView.getMeasuredWidth() + mlp.leftMargin + mlp.rightMargin; int cHeight = childView.getMeasuredHeight() + mlp.topMargin + mlp.bottomMargin; if(lineWidth + cWidth > sizeWidth){//如果加入當前childView後超出最大寬度,width取最大高度,累加lineHeight,然後開啟新行 width = Math.max(lineWidth, cWidth); height += lineHeight; lineWidth = cWidth; }else{//如果加入當前childView後小於最大寬度,則累加lineWidthheight lineHeight取最大高度 lineWidth += cWidth; height = Math.max(lineHeight, cHeight); } if(i == cCount-1){// 如果是最後一個childView,則將當前記錄的最大寬度和當前lineWidth做比較 width = Math.max(lineWidth, cWidth); height += lineHeight; } } //3、如果是wrap_content設置為我們計算的值;否則直接設置為父容器計算的值 setMeasuredDimension( (widthMode == MeasureSpec.EXACTLY) ? sizeWidth : width, (heightMode == MeasureSpec.EXACTLY) ? sizeHeight : height ); } /** * 三、重寫onLayout,對其所有childView進行定位(設置childView的繪制區域) */ private List<List<View>> allChildViews = new ArrayList<List<View>>();//存儲所有的childView,按行記錄 private List<Integer> maxLineHeight = new ArrayList<Integer>();//存儲每行的最大高度值 @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { allChildViews.clear(); maxLineHeight.clear(); int width = getWidth();//每行的最大寬度 int lineWidth = 0;//每行的即時寬度 int lineHeight = 0;//每行的即時高度 List<View> lineChildViews = new ArrayList<View>();//存儲每行所有的childView int cCount = getChildCount(); for(int i=0; i<cCount; i++){//遍歷所有childView View childView = getChildAt(i); MarginLayoutParams mlp = (MarginLayoutParams) childView.getLayoutParams(); int cWidth = childView.getMeasuredWidth(); int cHeight = childView.getMeasuredHeight(); if(lineWidth + cWidth + mlp.leftMargin + mlp.rightMargin > width){//如果需要換行 maxLineHeight.add(lineHeight);// 存儲這一行最大高度 allChildViews.add(lineChildViews);// 將當前行的childView保存,然後開啟新的ArrayList保存下一行的childView lineChildViews = new ArrayList<View>(); lineWidth = 0;// 重置行寬 }else{//如果不需要換行 lineWidth += cWidth + mlp.leftMargin + mlp.rightMargin;//即時寬度累加 lineHeight = Math.max(lineHeight,cHeight + mlp.topMargin + mlp.bottomMargin );//即時高度取最大值 lineChildViews.add(childView);//把當前childView存入這一行的集合 } } // 記錄最後一行 maxLineHeight.add(lineHeight); allChildViews.add(lineChildViews); int left = 0;//左坐標 int top = 0;//上坐標 int lineNums = allChildViews.size();// 得到總行數 for (int i = 0; i < lineNums; i++) { lineChildViews = allChildViews.get(i);// 取得每一行的所有的views lineHeight = maxLineHeight.get(i);// 取得當前行的最大高度 Log.e(TAG, "第" + i + "行 :" + lineChildViews.size() + " , " + lineChildViews); Log.e(TAG, "第" + i + "行, :" + lineHeight); // 遍歷當前行所有的View for (int j = 0; j < lineChildViews.size(); j++) { View childView = lineChildViews.get(j);//取得childView if (childView.getVisibility() == View.GONE) { continue; } MarginLayoutParams mlp = (MarginLayoutParams) childView.getLayoutParams(); //計算childView的left,top,right,bottom int lc = left + mlp.leftMargin; int tc = top + mlp.topMargin; int rc = lc + childView.getMeasuredWidth(); int bc = tc + childView.getMeasuredHeight(); Log.e(TAG, childView + " , l = " + lc + " , t = " + t + " , r =" + rc + " , b = " + bc); childView.layout(lc, tc, rc, bc);//設置這個childView的位置 left += childView.getMeasuredWidth() + mlp.rightMargin + mlp.leftMargin;//左坐標累加 } left = 0;//開始新的一行,左坐標重置 top += lineHeight;//開始新的一行,上坐標累加 } } }
3、activity_main.xml
<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.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup android:layout_width="fill_parent" android:layout_height="wrap_content"> <TextView android:text="Welcome" /> <TextView android:text="IT工程師" /> <TextView android:text="學習ing" /> <TextView android:text="戀愛ing" /> <TextView android:text="掙錢ing" /> <TextView android:text="努力ing" /> <TextView android:text="I thick i can" /> </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup> </LinearLayout>
4、activity_main2.xml
<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.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup android:layout_width="fill_parent" android:layout_height="wrap_content"> <TextView android:text="Welcome" /> <TextView android:text="IT工程師" /> <TextView android:text="學習ing" /> <TextView android:text="戀愛ing" /> <TextView android:text="掙錢ing" /> <TextView android:text="努力ing" /> <TextView android:text="I thick i can" /> </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup> <com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_marginTop="20dp"> <TextView android:background="@drawable/flag_02" android:text="Welcome" android:textColor="#888888" /> <TextView android:background="@drawable/flag_02" android:text="IT工程師" android:textColor="#888888" /> <TextView android:background="@drawable/flag_02" android:text="學習ing" android:textColor="#888888" /> <TextView android:background="@drawable/flag_02" android:text="戀愛ing" android:textColor="#888888" /> <TextView android:background="@drawable/flag_02" android:text="掙錢ing" android:textColor="#888888" /> <TextView android:background="@drawable/flag_02" android:text="努力ing" android:textColor="#888888" /> <TextView android:background="@drawable/flag_02" android:text="I thick i can" android:textColor="#888888" /> </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup> <com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_marginTop="20dp"> <TextView android:background="@drawable/flag_03" android:text="Welcome" android:textColor="#43BBE7" /> <TextView android:background="@drawable/flag_03" android:text="IT工程師" android:textColor="#43BBE7" /> <TextView android:background="@drawable/flag_03" android:text="學習ing" android:textColor="#43BBE7" /> <TextView android:background="@drawable/flag_03" android:text="戀愛ing" android:textColor="#43BBE7" /> <TextView android:background="@drawable/flag_03" android:text="掙錢ing" android:textColor="#43BBE7" /> <TextView android:background="@drawable/flag_03" android:text="努力ing" android:textColor="#43BBE7" /> <TextView android:background="@drawable/flag_03" android:text="I thick i can" android:textColor="#43BBE7" /> </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup> </LinearLayout>
5、activity_main3.xml
<com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup 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 android:background="@drawable/flag_04" android:text="Welcome" android:textColor="#323232" /> <TextView android:background="@drawable/flag_04" android:text="IT工程師" android:textColor="#323232" /> <TextView android:background="@drawable/flag_04" android:text="學習ing" android:textColor="#323232" /> <TextView android:background="@drawable/flag_04" android:text="戀愛ing" android:textColor="#323232" /> <TextView android:background="@drawable/flag_04" android:text="掙錢ing" android:textColor="#323232" /> <TextView android:background="@drawable/flag_04" android:text="努力ing" android:textColor="#323232" /> <TextView android:background="@drawable/flag_04" android:text="I thick i can" android:textColor="#323232" /> </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup>
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