AndroidonMeasure与onDraw及自定义属性使用示例

public TextView(Context context) {
        super(context);
    }

 public TextView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

<style name="defualt" > <item name="android:layout_width">wrap_content</item> <item name="android:layout_height">wrap_content</item> <item name="android:textColor">@color/colorAccent</item> </style>

 public TextView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

int widthSize = MeasureSpec.getMode(widthMeasureSpec); //获取前两位
int heightSize = MeasureSpec.getMode(heightMeasureSpec);

 int widthSize = MeasureSpec.getSize(widthMeasureSpec); //获取后面30位
 int heightSize = MeasureSpec.getSize(heightMeasureSpec);

 
    @Override
    protected void onDraw(canvas canvas) {
        super.onDraw(canvas);
        //画文本
        canvas.drawText();
        //画弧
        canvas.drawArc();
        //画圆
        canvas.drawCircle();
    }

    
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()){
            case MotionEvent.ACTION_DOWN:
                //手指按下
                Log.e("TAG","手指按下");
                break;
            case MotionEvent.ACTION_MOVE:
                //手指移动
                Log.e("TAG","手指移动");
                break;
            case MotionEvent.ACTION_UP:
                //手指抬起
                Log.e("TAG","手指抬起");
                break;
        }
        return super.onTouchEvent(event);
    }

<!-- name 属性名称
         fORMat 格式： string 文字  color:颜色
                       dimension 宽高 字体大小 integer 数字
                       reference 资源(drawable)
          -->
        <attr name="text" format="string"/>
        <attr name="textColor" format="color"/>
        <attr name="textSize" format="dimension"/>
        <attr name="maxLength" format="integer"/>
        <attr name="background" format="reference|color"/>
        <!-- 枚举 -->
        <attr name="inputType">
            <enum name="number" value="1"/>
            <enum name="text" value="2"/>
            <enum name="passWord" value="3"/>
        </attr>
    </declare-styleable>

xmlns:app="Http://schemas.android.com/apk/res-auto"

<com.zrc.view_java_demo_01.TextView
        app:text="Darren"
        app:textColor="@color/colorAccent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

 // 获取自定义属性
 TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.TextView);
 mText = array.getString(R.styleable.TextView_text);
 mTextColor = array.getColor(R.styleable.TextView_textColor,mTextColor);
  mTextSize = array.getDimensionPixelSize(R.styleable.TextView_textSize,mTextSize);
 // 回收
 array.recycle();