Android自定义控件view(草稿版)

Ⅰ、继承现有控件，对其控件的功能进行拓展。(拓展功能)

Ⅱ、将现有控件进行组合，实现功能更加强大控件。(布局重用)

Ⅲ、重写View实现全新的控件(不规则效果控件)

本文来讨论最难的一种自定义控件形式，重写View来实现全新的控件。

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1.构造方法,1参,2参,3参(4参的一般不用)

onMeasure(int widthMeasureSpec, int heightMeasureSpec)测绘大小

onDraw(Canvas canvas)用Canvas和Paint绘制内容

onLayout(boolean changed,int left, int top, int right, int bottom)确定显示的位置

onTouchEvent(MotionEvent event)定义触摸事件

private int mColor01;
public CustomView01(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
//构造方法获取自定义属性的方法
    TypedArray a = context.obtainStyledAttributes(attrs,R.styleable.CustomView01);
//若第一个参数为null,默认值为RED
    mColor01=a.getColor(R.styleable.CustomView01_textColor,Color.RED);
//关闭资源
    a.recycle();
}

@Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        //先声明两个int值来表示最终的width和height并给定一个默认的大小
        int width_size  = 500;
        int height_size = 500;
        //使用MeasureSpec分别获取width和height的MODE和SIZE
        int HEIGHT_MODE = MeasureSpec.getMode(heightMeasureSpec);
        int HEIGHT_SIZE = MeasureSpec.getSize(heightMeasureSpec);
        int WIDTH_MODE = MeasureSpec.getMode(widthMeasureSpec);
        int WIDTH_SIZE = MeasureSpec.getSize(widthMeasureSpec);


//这个方法的用途是因为自定义view的wrap_content属性失效的使用方法
//setMeasuredDimension用于设置view的宽高
        if (getLayoutParams().width == ViewGroup.LayoutParams.WRAP_CONTENT && getLayoutParams().height == ViewGroup.LayoutParams.WRAP_CONTENT) {
            setMeasuredDimension(width_size, height_size);
        } else if (getLayoutParams().width == ViewGroup.LayoutParams.WRAP_CONTENT) {
            setMeasuredDimension(width_size, WIDTH_SIZE);
        } else if (getLayoutParams().height == ViewGroup.LayoutParams.WRAP_CONTENT) {
            setMeasuredDimension(HEIGHT_SIZE, height_size);
        }
    }

MeasureSpect三种模式

MeasureSpect是由LayoutParameter通过父容器的施加的规则产生的

MeasureSpec.EXACTLY MeasureSpec.AT_MOST MeasureSpec.UNSPECIFIED这三种模式

@Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
//        // 画文本
//        canvas.drawText();
//        // 画弧
//        canvas.drawArc();
//        // 画圆
//        canvas.drawCircle();
        canvas.drawColor(Color.RED);      //设置canvas的背景色
        float radius = 50;                //给定半径
        //给定圆心的的坐标
        float cx = 50;
        float cy = 50;
        Paint paint1 = new Paint();       //实例化一个Paint对象
        paint1.setColor(Color.BLUE);      //设置圆的颜色
        //通过canvas的drawCircle方法画一个圆圈.
//        canvas.drawCircle(cx, cy, radius, paint1);
        Paint paint2 = new Paint();       //实例化一个Paint对象
        paint2.setColor(Color.BLACK);
        paint2.setStrokeWidth(10);//因为默认实在是太细了 设定了一个宽度值
        canvas.drawLine(0, 0, 100, 100, paint2);

        Paint paint3 = new Paint();       //实例化一个Paint对象
        paint3.setColor(Color.BLACK);     //设置圆的颜色
        paint3.setAntiAlias(true);        //设置抗锯齿
        paint3.setStyle(Paint.Style.FILL);  //设置样式
        paint3.setStrokeWidth(3);          //设置宽度

        Paint paint4 = new Paint();      //实例化第二个paint对象
        paint4.setColor(Color.BLUE);     //设置颜色为蓝色
        paint4.setStyle(Paint.Style.STROKE);//设置样式
        paint4.setStrokeWidth(30);          //设定边框宽度

        //通过canvas的drawCircle方法画一个圆圈.
        canvas.drawCircle(cx, cy, radius, paint3);
        canvas.drawCircle(cx, cy, radius, paint4);
    }

Paint.setStyle三种样式,填充,填充和外轮廓,外轮廓

FILL，FILL_OR_STROKE，或STROKE

Paint的set和Canvas的set详细参考底下

https://www.cnblogs.com/itgungnir/p/6217447.html

@Override
    protected void onLayout(boolean changed,int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
    }

    @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;
            default:
                break;
        }
        return super.onTouchEvent(event);
    }

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <declare-styleable name="CustomView01">
        <attr name="textSize" format="dimension" />
        <attr name="text" format="string" />
        <attr name="circleColor" format="color" />
        <attr name="arcColor" format="color" />
        <attr name="textColor" format="color" />
        <attr name="startAngle" format="integer" />
        <attr name="sweepAngle" format="integer" />
    </declare-styleable>


</resources>

Android自定义控件view(草稿版)

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