轉載請標明出處:http://blog.csdn.net/lmj623565791/article/details/38352503 ,本文出自【張鴻洋的博客】
1、概述
上一篇已經基本給大家介紹瞭如何自定義ViewGroup,如果你還不瞭解,請查看:Android 手把手教您自定ViewGroup ,本篇將使用上篇介紹的方法,給大家帶來一個實例:實現FlowLayout,何爲FlowLayout,如果對Java的Swing比較熟悉的話一定不會陌生,就是控件根據ViewGroup的寬,自動的往右添加,如果當前行剩餘空間不足,則自動添加到下一行。有點所有的控件都往左飄的感覺,第一行滿了,往第二行飄~所以也叫流式佈局。Android並沒有提供流式佈局,但是某些場合中,流式佈局還是非常適合使用的,比如關鍵字標籤,搜索熱詞列表等,比如下圖:
這些都特別適合使用FlowLayout,本篇博客會帶領大家自己實現FlowLayout,然後使用我們自己定義的FlowLayout實現上面的標籤效果。對了,github已經有了這樣FlowLayout,但是我覺得絲毫不影響我們對其的學習,學會使用一個控件和學會寫一個控件,我相信大家都明白,授人以魚不如授人以漁。
2、簡單的分析
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進行佈局。
3、generateLayoutParams
因爲我們只需要支持margin,所以直接使用系統的MarginLayoutParams
- @Override
- public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs)
- {
- return new MarginLayoutParams(getContext(), attrs);
- }
4、onMeasure
- /**
- * 負責設置子控件的測量模式和大小 根據所有子控件設置自己的寬和高
- */
- @Override
- protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
- {
- super.onMeasure(widthMeasureSpec, heightMeasureSpec);
- // 獲得它的父容器爲它設置的測量模式和大小
- 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情況下,記錄寬和高
- int width = 0;
- int height = 0;
- /**
- * 記錄每一行的寬度,width不斷取最大寬度
- */
- int lineWidth = 0;
- /**
- * 每一行的高度,累加至height
- */
- int lineHeight = 0;
- int cCount = getChildCount();
- // 遍歷每個子元素
- for (int i = 0; i < cCount; i++)
- {
- View child = getChildAt(i);
- // 測量每一個child的寬和高
- measureChild(child, widthMeasureSpec, heightMeasureSpec);
- // 得到child的lp
- MarginLayoutParams lp = (MarginLayoutParams) child
- .getLayoutParams();
- // 當前子空間實際佔據的寬度
- int childWidth = child.getMeasuredWidth() + lp.leftMargin
- + lp.rightMargin;
- // 當前子空間實際佔據的高度
- int childHeight = child.getMeasuredHeight() + lp.topMargin
- + lp.bottomMargin;
- /**
- * 如果加入當前child,則超出最大寬度,則的到目前最大寬度給width,類加height 然後開啓新行
- */
- if (lineWidth + childWidth > sizeWidth)
- {
- width = Math.max(lineWidth, childWidth);// 取最大的
- lineWidth = childWidth; // 重新開啓新行,開始記錄
- // 疊加當前高度,
- height += lineHeight;
- // 開啓記錄下一行的高度
- lineHeight = childHeight;
- } else
- // 否則累加值lineWidth,lineHeight取最大高度
- {
- lineWidth += childWidth;
- lineHeight = Math.max(lineHeight, childHeight);
- }
- // 如果是最後一個,則將當前記錄的最大寬度和當前lineWidth做比較
- if (i == cCount - 1)
- {
- width = Math.max(width, lineWidth);
- height += lineHeight;
- }
- }
- setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth
- : width, (modeHeight == MeasureSpec.EXACTLY) ? sizeHeight
- : height);
- }
首先得到其父容器傳入的測量模式和寬高的計算值,然後遍歷所有的childView,使用measureChild方法對所有的childView進行測量。然後根據所有childView的測量得出的寬和高得到該ViewGroup如果設置爲wrap_content時的寬和高。最後根據模式,如果是MeasureSpec.EXACTLY則直接使用父ViewGroup傳入的寬和高,否則設置爲自己計算的寬和高。
5、onLayout
onLayout中完成對所有childView的位置以及大小的指定
- /**
- * 存儲所有的View,按行記錄
- */
- private List<List<View>> mAllViews = new ArrayList<List<View>>();
- /**
- * 記錄每一行的最大高度
- */
- 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;
- // 存儲每一行所有的childView
- List<View> lineViews = new ArrayList<View>();
- int cCount = getChildCount();
- // 遍歷所有的孩子
- for (int i = 0; i < cCount; i++)
- {
- View child = getChildAt(i);
- MarginLayoutParams lp = (MarginLayoutParams) child
- .getLayoutParams();
- int childWidth = child.getMeasuredWidth();
- int childHeight = child.getMeasuredHeight();
- // 如果已經需要換行
- if (childWidth + lp.leftMargin + lp.rightMargin + lineWidth > width)
- {
- // 記錄這一行所有的View以及最大高度
- mLineHeight.add(lineHeight);
- // 將當前行的childView保存,然後開啓新的ArrayList保存下一行的childView
- mAllViews.add(lineViews);
- lineWidth = 0;// 重置行寬
- lineViews = new ArrayList<View>();
- }
- /**
- * 如果不需要換行,則累加
- */
- lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
- lineHeight = Math.max(lineHeight, childHeight + lp.topMargin
- + lp.bottomMargin);
- lineViews.add(child);
- }
- // 記錄最後一行
- mLineHeight.add(lineHeight);
- mAllViews.add(lineViews);
- int left = 0;
- int top = 0;
- // 得到總行數
- int lineNums = mAllViews.size();
- for (int i = 0; i < lineNums; i++)
- {
- // 每一行的所有的views
- lineViews = mAllViews.get(i);
- // 當前行的最大高度
- lineHeight = mLineHeight.get(i);
- Log.e(TAG, "第" + i + "行 :" + lineViews.size() + " , " + lineViews);
- Log.e(TAG, "第" + i + "行, :" + lineHeight);
- // 遍歷當前行所有的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();
- //計算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的每個Item爲每行所有View的List集合。
mLineHeight記錄的爲每行的最大高度。
23-48行,遍歷所有的childView,用於設置allViews的值,以及mLineHeight的值。
57行,根據allViews的長度,遍歷所有的行數
67-91行,遍歷每一行的中所有的childView,對childView的left , top , right , bottom 進行計算,和定位。
92-93行,重置left和top,準備計算下一行的childView的位置。
好了,到此完成了所有的childView的繪製區域的確定,到此,我們的FlowLayout的代碼也結束了~~靜下心來看一看是不是也不難~
6、測試
我準備使用TextView作爲我們的標籤,所以爲其簡單寫了一點樣式:
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>
佈局文件:
- <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工程師" />
- <TextView
- style="@style/text_flag_01"
- android:text="學習ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="戀愛ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="掙錢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>
效果圖:
是不是還不錯,下面繼續簡單自定義幾個背景:
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>
佈局文件:
- <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工程師" />
- <TextView
- style="@style/text_flag_01"
- android:text="學習ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="戀愛ing" />
- <TextView
- style="@style/text_flag_01"
- android:text="掙錢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工程師"
- android:textColor="#888888" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_02"
- android:text="學習ing"
- android:textColor="#888888" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_02"
- android:text="戀愛ing"
- android:textColor="#888888" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_02"
- android:text="掙錢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工程師"
- android:textColor="#43BBE7" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_03"
- android:text="學習ing"
- android:textColor="#43BBE7" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_03"
- android:text="戀愛ing"
- android:textColor="#43BBE7" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_03"
- android:text="掙錢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>
效果圖:
暫不讚~~上面都是match_parent~~下面固定下寬度,實現文章最開始的移動開發熱門標籤:
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>
佈局文件:
- <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工程師"
- android:textColor="#323232" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_04"
- android:text="學習ing"
- android:textColor="#323232" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_04"
- android:text="戀愛ing"
- android:textColor="#323232" />
- <TextView
- style="@style/text_flag_01"
- android:background="@drawable/flag_04"
- android:text="掙錢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>
效果圖:
是不是完全相同~~o了~
如果你覺得本篇博客對你有用,那麼就留個言或者頂一個~~