自定义控件学习之绘制刻度盘

本文主要是介绍自定义控件学习之绘制刻度盘，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

以前面试的时候面试官问过我会不会写标尺工具，我没做过呀，然后胡乱的说什么画布，ondraw绘制。。然后就没有然后了--！，现在想想真的有点囧。所以今天我试了下自己画刻度盘，不是很难，只有方法对了，轻轻松松。。大神勿喷，这是菜鸟的日常（高手退散退散。。巴拉巴拉能量>_<）

还是老样子，代码写到最后都是规律，就和学习一样，第一步在onMeasure方法中去计算控件的宽高，你也可以不写，但是在wrap_content的时候回很蛋疼····上代码

/**
 * 第一步
 */
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {int width =measureDim(widthMeasureSpec,150);
    int height = measureDim(heightMeasureSpec,150);
    if (width!=height){width=Math.max(width,height);
        height =width;
    }setMeasuredDimension(width,height);
    initView();
}public int measureDim(int Spec,int defultsize){int result;
    int mode = MeasureSpec.getMode(Spec);
    int size = MeasureSpec.getSize(Spec);
    if (mode==MeasureSpec.EXACTLY){result =size;
    }else {result =defultsize;
        if (mode==MeasureSpec.AT_MOST){result =Math.min(size,defultsize);
        }}return result;

}

public void initView(){cPaint = new Paint();
    cPaint.setAntiAlias(true);
    cPaint.setColor(Color.BLUE);
    cPaint.setStyle(Paint.Style.STROKE);
    cPaint.setStrokeWidth(2);
    cPaint.setTextSize(12);
    list = new ArrayList<>();

}

第二步画一个圆

@Override
protected void onDraw(Canvas canvas) {radio =getMeasuredWidth()/2-20;
    canvas.drawCircle(radio,radio,radio,cPaint);
    canvas.drawPoint(radio,radio,cPaint);
    scaleCount(canvas);
}

第三步就是对刻度坐标的计算，根据计算每个刻度是6度，那么就简单了

/**
 * 表盘刻度的计算,绘制
 */
private void scaleCount(Canvas canvas){double startx;
    double starty;
    double endx;
    double endy;
    for (int i=0;i<60;i++){if (i%5==0){endx= Math.sin( Math.toRadians(i*6))*(radio/2+10)+radio;
            endy = radio-Math.cos( Math.toRadians(i*6))*(radio/2+10);

            /*
            这段绘制刻度值有点问题字歪的 ，以后改善
             */
         /*
            double textX = Math.sin( Math.toRadians(i*6))*(radio/2+9)+radio;
            double textY = radio-Math.cos( Math.toRadians(i*6))*(radio/2+9);
            canvas.drawText((i/5==0?12:i/5)+"",(float) textX,(float)textY,cPaint);*/
        }else {endx= Math.sin( Math.toRadians(i*6))*(radio-10)+radio;
            endy = radio-Math.cos( Math.toRadians(i*6))*(radio-10);
        }startx  =Math.sin( Math.toRadians(i*6))*(radio)+radio;
        starty  = radio-Math.cos( Math.toRadians(i*6))*(radio);
        Line line = new Line(startx,starty,endx,endy);
        list.add(line);
    }drawLine(canvas);
}public void drawLine(Canvas canvas){cPaint.reset();
    cPaint.setColor(Color.BLACK);
    cPaint.setStyle(Paint.Style.FILL);
    cPaint.setAntiAlias(true);
    for (int i=0;i<list.size();i++){canvas.drawLine((float) list.get(i).getStartx(),(float)list.get(i).getStarty(),(float)list.get(i).getEndx(),
                (float)list.get(i).getEndy(),cPaint);
    }
}

大功告成