image
一、概述：
在日常的app使用中趁舀，我們會在android 的app中看見 熱門標簽等自動換行的流式布局赖捌，今天，我們就來看看如何
自定義一個類似熱門標簽?zāi)菢拥牧魇讲季职桑ㄔ创a下載在下面最后給出）
類似的自定義布局矮烹。下面我們就來詳細介紹流式布局的應(yīng)用特點以及用的的技術(shù)點：
1.流式布局的特點以及應(yīng)用場景
特點：當上面一行的空間不夠容納新的TextView時候越庇，
才開辟下一行的空間
原理圖：
image
場景：主要用于關(guān)鍵詞搜索或者熱門標簽等場景
2.自定義ViewGroup,重點重寫下面兩個方法
1罩锐、onMeasure:測量子view的寬高，設(shè)置自己的寬和高
2卤唉、onLayout:設(shè)置子view的位置
onMeasure:根據(jù)子view的布局文件中屬性涩惑，來為子view設(shè)置測量模式和測量值
測量=測量模式+測量值；
測量模式有3種：
EXACTLY：表示設(shè)置了精確的值桑驱，一般當childView設(shè)置其寬竭恬、高為精確值、match_parent時熬的，ViewGroup會將其設(shè)置為EXACTLY痊硕；
AT_MOST：表示子布局被限制在一個最大值內(nèi)，一般當childView設(shè)置其寬悦析、高為wrap_content時寿桨，ViewGroup會將其設(shè)置為AT_MOST此衅；
UNSPECIFIED：表示子布局想要多大就多大强戴，一般出現(xiàn)在AadapterView的item的heightMode中、ScrollView的childView的heightMode中挡鞍；此種模式比較少見骑歹。
3.LayoutParams
ViewGroup LayoutParams :每個 ViewGroup 對應(yīng)一個 LayoutParams; 即 ViewGroup -> LayoutParams
getLayoutParams 不知道轉(zhuǎn)為哪個對應(yīng)的LayoutParams ,其實很簡單，就是如下：
子View.getLayoutParams 得到的LayoutParams對應(yīng)的就是 子View所在的父控件的LayoutParams;
例如墨微，LinearLayout 里面的子view.getLayoutParams ->LinearLayout.LayoutParams
所以 咱們的FlowLayout 也需要一個LayoutParams道媚，由于上面的效果圖是子View的 margin，
所以應(yīng)該使用MarginLayoutParams翘县。即FlowLayout->MarginLayoutParams
二最域、熱門標簽的流式布局的實現(xiàn)：
- 自定義熱門標簽的ViewGroup實現(xiàn)
根據(jù)上面的技術(shù)分析，自定義類繼承于ViewGroup锈麸，并重寫 onMeasure和onLayout等方法镀脂。具體實現(xiàn)代碼如下：
package com.czm.flowlayout;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
/**
*
* @author caizhiming
* @created on 2015-4-13
*/
public class XCFlowLayout extends ViewGroup{
//存儲所有子View
private List<List<View>> mAllChildViews = new ArrayList<>();
//每一行的高度
private List<Integer> mLineHeight = new ArrayList<>();
public XCFlowLayout(Context context) {
this(context, null);
// TODO Auto-generated constructor stub
}
public XCFlowLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
// TODO Auto-generated constructor stub
}
public XCFlowLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// TODO Auto-generated method stub
//父控件傳進來的寬度和高度以及對應(yīng)的測量模式
int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
//如果當前ViewGroup的寬高為wrap_content的情況
int width = 0;//自己測量的 寬度
int height = 0;//自己測量的高度
//記錄每一行的寬度和高度
int lineWidth = 0;
int lineHeight = 0;
//獲取子view的個數(shù)
int childCount = getChildCount();
for(int i = 0;i < childCount; i ++){
View child = getChildAt(i);
//測量子View的寬和高
measureChild(child, widthMeasureSpec, heightMeasureSpec);
//得到LayoutParams
MarginLayoutParams lp = (MarginLayoutParams) getLayoutParams();
//子View占據(jù)的寬度
int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
//子View占據(jù)的高度
int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
//換行時候
if(lineWidth + childWidth > sizeWidth){
//對比得到最大的寬度
width = Math.max(width, lineWidth);
//重置lineWidth
lineWidth = childWidth;
//記錄行高
height += lineHeight;
lineHeight = childHeight;
}else{//不換行情況
//疊加行寬
lineWidth += childWidth;
//得到最大行高
lineHeight = Math.max(lineHeight, childHeight);
}
//處理最后一個子View的情況
if(i == childCount -1){
width = Math.max(width, lineWidth);
height += lineHeight;
}
}
//wrap_content
setMeasuredDimension(modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width,
modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// TODO Auto-generated method stub
mAllChildViews.clear();
mLineHeight.clear();
//獲取當前ViewGroup的寬度
int width = getWidth();
int lineWidth = 0;
int lineHeight = 0;
//記錄當前行的view
List<View> lineViews = new ArrayList<View>();
int childCount = getChildCount();
for(int i = 0;i < childCount; i ++){
View child = getChildAt(i);
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
int childWidth = child.getMeasuredWidth();
int childHeight = child.getMeasuredHeight();
//如果需要換行
if(childWidth + lineWidth + lp.leftMargin + lp.rightMargin > width){
//記錄LineHeight
mLineHeight.add(lineHeight);
//記錄當前行的Views
mAllChildViews.add(lineViews);
//重置行的寬高
lineWidth = 0;
lineHeight = childHeight + lp.topMargin + lp.bottomMargin;
//重置view的集合
lineViews = new ArrayList();
}
lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
lineHeight = Math.max(lineHeight, childHeight + lp.topMargin + lp.bottomMargin);
lineViews.add(child);
}
//處理最后一行
mLineHeight.add(lineHeight);
mAllChildViews.add(lineViews);
//設(shè)置子View的位置
int left = 0;
int top = 0;
//獲取行數(shù)
int lineCount = mAllChildViews.size();
for(int i = 0; i < lineCount; i ++){
//當前行的views和高度
lineViews = mAllChildViews.get(i);
lineHeight = mLineHeight.get(i);
for(int j = 0; j < lineViews.size(); j ++){
View child = lineViews.get(j);
//判斷是否顯示
if(child.getVisibility() == View.GONE){
continue;
}
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
int cLeft = left + lp.leftMargin;
int cTop = top + lp.topMargin;
int cRight = cLeft + child.getMeasuredWidth();
int cBottom = cTop + child.getMeasuredHeight();
//進行子View進行布局
child.layout(cLeft, cTop, cRight, cBottom);
left += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
}
left = 0;
top += lineHeight;
}
}
/**
* 與當前ViewGroup對應(yīng)的LayoutParams
*/
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
// TODO Auto-generated method stub
return new MarginLayoutParams(getContext(), attrs);
}
}
2.相關(guān)的布局文件：
引用自定義控件：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<com.czm.flowlayout.XCFlowLayout
android:id="@+id/flowlayout"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</com.czm.flowlayout.XCFlowLayout>
</RelativeLayout>
TextView的樣式文件：
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
<solid android:color="#666666" />
<corners android:radius="10dp" />
<padding
android:left="5dp"
android:right="5dp"
android:top="5dp"
android:bottom="5dp"
/>
</shape>
三、使用該自定義布局控件類
最后忘伞，如何使用該自定義的熱門標簽控件類呢薄翅？很簡單，請看下面實例代碼：
package com.czm.flowlayout;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.ViewGroup.LayoutParams;
import android.view.ViewGroup.MarginLayoutParams;
import android.widget.TextView;
/**
*
* @author caizhiming
* @created on 2015-4-13
*/
public class MainActivity extends Activity {
private String mNames[] = {
"welcome","android","TextView",
"apple","jamy","kobe bryant",
"jordan","layout","viewgroup",
"margin","padding","text",
"name","type","search","logcat"
};
private XCFlowLayout mFlowLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initChildViews();
}
private void initChildViews() {
// TODO Auto-generated method stub
mFlowLayout = (XCFlowLayout) findViewById(R.id.flowlayout);
MarginLayoutParams lp = new MarginLayoutParams(
LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
lp.leftMargin = 5;
lp.rightMargin = 5;
lp.topMargin = 5;
lp.bottomMargin = 5;
for(int i = 0; i < mNames.length; i ++){
TextView view = new TextView(this);
view.setText(mNames[i]);
view.setTextColor(Color.WHITE);
view.setBackgroundDrawable(getResources().getDrawable(R.drawable.textview_bg));
mFlowLayout.addView(view,lp);
}
}
}
