自定义控件（一）

1.在values文件夹下建立一个  attrs.xml文件

attrs.xml 中的format值如下

"reference" //引用  
"color" //颜色  
"boolean" //布尔值  
"dimension" //尺寸值  
"float" //浮点值  
"integer" //整型值  
"string" //字符串  
"fraction" //百分数,比如200%  

以下是构建的attrs.xml文件

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <attr name="wide" format="float"></attr>
    <attr name="height" format="float"></attr>
    <attr name="titletextcolor" format="color"></attr>
    <attr name="titletextsize" format="dimension"></attr>
    <attr name="titletext" format="string"></attr>
    
    <declare-styleable name="FirstView">
         <attr name="wide" />
         <attr name="height" />
         <attr name="titletextcolor" />
         <attr name="titletextsize" />
         <attr name="titletext" />
    </declare-styleable>
</resources>

由于在xml中的 attr是命名是不能重复的，所以一般定义在前面，而后  styleable再去调用，而这些属性，就是在调用自定义控件的时候，使用到的自定义属性，并且在自定义的类中进行调用使用

2.在布局文件中调用自定义的控件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
	xmlns:tw="http://schemas.android.com/apk/res/com.example.textmyview"
	android:layout_width="match_parent" 
	android:layout_height="match_parent" 
	android:paddingBottom="@dimen/activity_vertical_margin" 
	android:paddingLeft="@dimen/activity_horizontal_margin" 
	android:paddingRight="@dimen/activity_horizontal_margin" 
	android:paddingTop="@dimen/activity_vertical_margin" 
	android:orientation="vertical" > 
		<TextView 
			android:layout_width="wrap_content" 
			android:layout_height="wrap_content" 
			android:text="@string/hello_world" /> 
		<com.example.textmyview.myview.FirstView 
			android:layout_width="wrap_content" 
			android:layout_height="wrap_content" 
			tw:titletext="测试用的别认真" 
			tw:titletextcolor="@color/a_black" 
			tw:titletextsize="24sp" /> <!-- 这里的tw:titletextsize 就是自定义的属性 -->
</LinearLayout>

3.自定义类的编写

package com.example.textmyview.myview;

import com.example.textmyview.R;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.view.View;

public class FirstView extends View{

	private String titleText;//其中字体显示的值
	private int titleSize;//字体大小
	private int titleColor;//字体的颜色
	
	private Paint mPaint;//画笔对象
	private Rect mBound;//矩形框
	private int mCount=0;
	
	public FirstView(Context context){
		this(context,null);
	}
	
	public FirstView(Context context, AttributeSet attrs) {
		this(context, attrs,0);
		// TODO Auto-generated constructor stub
	}
	
	public FirstView(Context context, AttributeSet attrs,int defStyle){
		super(context, attrs, defStyle);
		
		TypedArray a=context.obtainStyledAttributes(attrs,R.styleable.FirstView, defStyle, 0);//获取用户在xml中使用到的自定义属性
		int count =a.getIndexCount();
		for (int i = 0; i < count; i++) {
			switch (a.getIndex(i)) {
			case R.styleable.FirstView_titletext:
				titleText=a.getString(R.styleable.FirstView_titletext);
				break;
			case R.styleable.FirstView_titletextsize:
				titleSize=a.getDimensionPixelSize(R.styleable.FirstView_titletextsize, (int) TypedValue.applyDimension(  
		                TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics())); 
				break;
			case R.styleable.FirstView_titletextcolor:
				titleColor=a.getColor(R.styleable.FirstView_titletextcolor, Color.BLUE);
				break;

			default:
				break;
			}
		}
		a.recycle();//  回收 TypedArray
		mPaint=new Paint();
		mPaint.setTextSize(titleSize);
		mBound=new Rect();
		mPaint.getTextBounds(titleText, 0, titleText.length(), mBound);
		
		this.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				titleText=titleText+" 很矮 "+mCount;
//				postInvalidate();  //postInvalidate()在工作者线程中被调用    刷新view 
				requestLayout();   //当被刷新的view需要重新刷新父类布局的时候进行调用
				mCount++;
			}
		});
	}
	
	@Override
	protected void onDraw(Canvas canvas) {
		// TODO Auto-generated method stub
		super.onDraw(canvas);
		mPaint.setColor(Color.DKGRAY);
		Log.e("", "getMeasuredWidth():"+getMeasuredWidth());//自定义view的宽度
		Log.e("", "getMeasuredHeight()"+getMeasuredHeight());//自定义view的高度
		canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint);
		mPaint.setColor(titleColor);
		Log.e("", "getWidth() :"+(getWidth() ));//自定义view的宽度  
		Log.e("", "mBound.width() :"+(mBound.width() )); //画出的矩形的宽度
		Log.e("", "getHeight() :"+(getHeight() ));//自定义view的高度
		Log.e("", "mBound.height() :"+(mBound.height() ));//画出的矩形的高度
		canvas.drawText(titleText, getWidth() / 2 - mBound.width() / 2, getHeight() / 2 + mBound.height() / 2, mPaint);
	}
	
	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		// TODO Auto-generated method stub
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		int wideMode=MeasureSpec.getMode(widthMeasureSpec);
		int wideSize=MeasureSpec.getSize(widthMeasureSpec);
		int heightMode=MeasureSpec.getMode(heightMeasureSpec);
		int heightSize=MeasureSpec.getSize(heightMeasureSpec);
		int wide;
		int height;
		if(wideMode==MeasureSpec.EXACTLY){//判断是否是给了确定的值，或是 match_parent 
			wide=wideSize;
		}else{
			mPaint.setTextSize(titleSize);
			mPaint.getTextBounds(titleText, 0, titleText.length(), mBound);//以 （0，0）为起点返回一个匹配当前的字符最小的矩形
			wide=(int)(getPaddingLeft()+mBound.width()+getPaddingRight());
		}
		if(heightMode==MeasureSpec.EXACTLY){
			height=heightSize;
		}else{
			mPaint.setTextSize(titleSize);
			mPaint.getTextBounds(titleText, 0, titleText.length(), mBound);
			height=(int)(getPaddingTop()+mBound.height()+getPaddingBottom());
		}
		setMeasuredDimension(wide, height);//设置view的宽高
	}
	
}

到这里一个简单的自定义的view算是完成了

参考  http://blog.youkuaiyun.com/lmj623565791/article/details/24252901