自定义控件一、

本文参考鸿神：http://blog.csdn.net/lmj623565791/article/category/2680591. 仅作个人动手总结.

1. 自定义View的属性.

2. 在View的构造方法中获取各个属性.

3. 重写onMesure()方法.

4. 重写onLayout()方法

5. 重写OnDraw()方法.

第一个简单自定义控件的实现

新建attrs.xml文件，在该文件中定义控件的各个属性

<?xml version="1.0" encoding="utf-8" ?>
<resources>
<!--format:string,color,demension,integer,enum,reference,float,boolean,fraction,flag-->
<attr name="titleText" format="string" />
<attr name="titleColor" format="color" />
<attr name="titleSize" format="dimension" />

<declare-styleable name="CatfaceTextView">
<attr name="titleText" />
<attr name="titleColor" />
<attr name="titleSize" />
</declare-styleable>
</resources>

自定义类继承目标控件，实现相关方法

public class CatfaceTextView extends TextView {

// 自定义控件的属性
private String titleText;
private int titleColor, titleSize;

// 初始化控件内容的范围
private Rect rect = new Rect();

// 初始化画笔
private Paint paint = new Paint();

public CatfaceTextView(Context context) {
this(context, null);
}

public CatfaceTextView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}

public CatfaceTextView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);

/** 获取自定义控件的属性 */
TypedArray typedArray = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CatfaceTextView, defStyleAttr, 0);
int indexCount = typedArray.getIndexCount();
for (int i = 0; i < indexCount; i++) {
int attr = typedArray.getIndex(i);
switch (attr) {
case R.styleable.CatfaceTextView_titleText:
titleText = typedArray.getString(attr);
break;
case R.styleable.CatfaceTextView_titleColor:
titleColor = typedArray.getColor(attr, Color.argb(255, 0, 0, 0)); // 默认字体颜色黑色
break;
case R.styleable.CatfaceTextView_titleSize:
titleSize = typedArray.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics())); // 默认大小16sp
break;
}

/** 给当前控件设置监听事件：点击更换控件内容 */
this.setOnClickListener(new OnClickListener() {
@Override public void onClick(View view) {
titleText = new Random().nextInt(1000) + "";
postInvalidate();
}
});
}
typedArray.recycle();

/** 获取控件内容的宽高 */
paint.setTextSize(titleSize);
paint.getTextBounds(titleText, 0, titleText.length(), rect);
}

// 以下介绍MeasureSpec的三个属性值
// EXACTLY：一般是设置了明确的值或者是MATCH_PARENT
// AT_MOST：表示子布局限制在一个最大值内，一般为WARP_CONTENT
// UNSPECIFIED：表示子布局想要多大就多大，很少使用
@Override /** 初始化执行一次 */
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
Log.d("sequency", "mesure");
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);

int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);

int width, height;

if (widthMode == MeasureSpec.EXACTLY) {
width = widthSize;
} else { // 当使用wrap_content包裹时重新确认控件宽高
paint.setTextSize(titleSize);
paint.getTextBounds(titleText, 0, titleText.length(), rect);
float textWidth = rect.width();
int desired = (int) (getPaddingLeft() + textWidth + getPaddingRight());
width = desired;
}

if (heightMode == MeasureSpec.EXACTLY) {
height = heightSize;
} else {
paint.setTextSize(titleSize);
paint.getTextBounds(titleText, 0, titleText.length(), rect);
float textHeight = rect.height();
int desired = (int) (getPaddingTop() + getPaddingBottom() + textHeight);
height = desired;
}

setMeasuredDimension(width, height);
}

@Override /** 初始化执行一次 */
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
Log.d("sequency", "layout");
}

@Override  /** 每次绘制都会执行 */
protected void onDraw(Canvas canvas) {
Log.d("sequency", "draw");

/** 填充控件背景 */
paint.setColor(Color.argb(255, 255, 0, 0));
canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), paint);

/** 绘制内容及确定文本相对控件的位置 */
paint.setColor(titleColor);
// 确定文本相对控件的左下角坐标
canvas.drawText(titleText, getWidth() / 2 - rect.width() / 2, getHeight() / 2 + rect.height() / 2, paint);
}
}

xml布局文件中定义

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
<!-- 必须声明命名空间！ -->
xmlns:catface="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">

<catface.myview01.view.CatfaceTextView
android:layout_centerInParent="true"
android:layout_width="150dp"
android:layout_height="100dp"
catface:titleText="999"
catface:titleColor="#ff0"
catface:titleSize="36sp"/>

</RelativeLayout>

效果