自定义仪表盘PaneView

1、概述

最近学习自定义View，趁着周末做了一个仪表盘练练手，效果还可以，在此分享一下先上效果图（截图有点不清晰，凑合着看下吧）

项目在我的github上https://github.com/xsfelvis/PanelView

有图才能有真相，下面简要说一下如何实现的

2、实现

【分析有哪些属性需要】

在values/attr文件中进行声明，这些属性都是可以在xml中进行使用的，实现定制的，比如unit单位属性

<resources>
 
    <declare-styleable name="PanelView">
        <attr name="arcColor" format="color"/>
        <attr name="arcWidth" format="dimension"/>
        <attr name="secArcWidth" format="dimension"/>
        <attr name="android:text"/>
        <attr name="tikeCount" format="integer"/>
        <attr name="pointerColor" format="color"/>
        <attr name="Unit" format="string"/>
        <attr name="android:textSize"/>
        <attr name="AcrStartColor" format="color"/>
        <attr name="AcrEndColor" format="color"/>
        <attr name="textColor" format="color"/>
 
    </declare-styleable>
 
</resources>

然后为了结构上更加工整，推荐单独写一个文件来处理这些属性，最好不要和自定义控件混在一起

这里在PanelViewAttr.java中做了处理

package PanelView;
 
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
 
import com.xsf.panelview.R;
 
import util.PxUtils;
 
/**
 * Created by hzxushangfei on 2016/1/23.
 */
public class PanelViewAttr {
    private int mArcColor;
    private int mPointerColor;
    private int mTikeCount;
    private int mTextSize;
    private String mText = "";
    private int arcwidth;
    private int mScendArcWidth;
    private String unit;//单位
    private int acrStartColor;
    private int acrEndColor;
    private int textColor;
 
    public PanelViewAttr(Context context, AttributeSet attrs, int defStyleAttr) {
        TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.PanelView, defStyleAttr, 0);
        mArcColor = ta.getColor(R.styleable.PanelView_arcColor, context.getResources().getColor(R.color.colorPrimaryDark));
        mPointerColor = ta.getColor(R.styleable.PanelView_pointerColor, context.getResources().getColor(R.color.PointerColor));
        mTikeCount = ta.getInt(R.styleable.PanelView_tikeCount, 12);
        mTextSize = ta.getDimensionPixelSize(PxUtils.spToPx(R.styleable.PanelView_android_textSize, context), 24);
        mText = ta.getString(R.styleable.PanelView_android_text);
        arcwidth = ta.getInt(R.styleable.PanelView_arcWidth, 3);
        mScendArcWidth = ta.getInt(R.styleable.PanelView_secArcWidth, 50);
        unit = ta.getString(R.styleable.PanelView_Unit);
        acrStartColor = ta.getColor(R.styleable.PanelView_AcrStartColor, context.getResources().getColor(R.color.GREEN));
        acrEndColor = ta.getColor(R.styleable.PanelView_AcrEndColor, context.getResources().getColor(R.color.RED));
        textColor = ta.getColor(R.styleable.PanelView_textColor, context.getResources().getColor(R.color.Yellow));
        ta.recycle();
    }
 
    public int getAcrEndColor() {
        return acrEndColor;
    }
 
    public int getAcrStartColor() {
        return acrStartColor;
    }
 
    public int getArcwidth() {
        return arcwidth;
    }
 
    public int getmArcColor() {
        return mArcColor;
    }
 
    public int getmPointerColor() {
        return mPointerColor;
    }
 
    public int getmTikeCount() {
        return mTikeCount;
    }
 
    public int getmTextSize() {
        return mTextSize;
    }
 
    public String getmText() {
        return mText;
    }
 
    public int getmScendArcWidth() {
        return mScendArcWidth;
    }
 
    public String getUnit() {
        return unit;
    }
    public int getTextColor() {
        return textColor;
    }
 
}

再然后在自定义view实现类 PanelView.java中获取

 panelViewattr = new PanelViewAttr(context, attrs, defStyleAttr);

通过get方法获取

 mArcColor = panelViewattr.getmArcColor();
        mPointerColor = panelViewattr.getmPointerColor();
        mTikeCount = panelViewattr.getmTikeCount();
        mTextSize = panelViewattr.getmTextSize();
        mTextColor = panelViewattr.getTextColor();
        mText = panelViewattr.getmText();
        mArcWidth = panelViewattr.getArcwidth();
        mScendArcWidth = panelViewattr.getmScendArcWidth();
        unit = panelViewattr.getUnit();
        acrStartColor = panelViewattr.getAcrStartColor();
        acrEndColor = panelViewattr.getAcrEndColor();

OK，这些都是小儿科，主要看onMeasure和OnDraw()方法

这里主要对exactly做了处理，其余的按照统一处理onMeasure()方法如下，推荐用一个方法来处理measure，不要把宽和高都写一遍，这样代码看起来会有点冗杂

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int realWidth = startMeasure(widthMeasureSpec);
        int realHeight = startMeasure(heightMeasureSpec);
 
        setMeasuredDimension(realWidth, realHeight);
    }
 
    private int startMeasure(int msSpec) {
        int result = 0;
        int mode = MeasureSpec.getMode(msSpec);
        int size = MeasureSpec.getSize(msSpec);
        if (mode == MeasureSpec.EXACTLY) {
            result = size;
        } else {
            result = PxUtils.dpToPx(200, mContext);
        }
        //Log.d("xsf", "startMeasure " + result);
        return result;
    }

onMeasure之后决定了大小，重头戏在onDraw，直接看onraw方法

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        float percent = mPercent / 100f;
 
        //最外面线条
        drawOutAcr(canvas);
        //绘制刻度
        drawerNum(canvas);
        //绘制粗圆弧
        drawInArc(canvas, percent);
        //绘制中间小圆和圆环
        drawInPoint(canvas);
        //绘制指针
        drawerPointer(canvas, percent);
        //绘制矩形和文字
        drawerRecAndText(canvas, percent);
 
    }

这样写是不是显得逻辑非常清楚，不要把细节都放在ondraw方法中，用一个个函数封装是最好不过的了

首先 drawOutAcr(canvas)

画最外面的弧

private void drawOutAcr(Canvas canvas) {
        //最外面线条
        rectF1 = new RectF(mArcWidth, mArcWidth, getWidth() - mArcWidth, getHeight() - mArcWidth);
        canvas.drawArc(rectF1, START_ARC, DURING_ARC, false, paintOuter_Arc);
    }

主要使用到canvas.drawArc方法，没啥好说的

执行完你会看到一个弧

然后是画刻度drawerNum(canvas);

这个函数开始画刻度和数字

   private void drawerNum(Canvas canvas) {
        canvas.save(); //记录画布状态
        canvas.rotate(-(180 - START_ARC + 90), getWidth() / 2, getHeight() / 2);
        float rAngle = DURING_ARC / mTikeCount;
        for (int i = 0; i < mTikeCount + 1; i++) {
            canvas.save(); //记录画布状态
            canvas.rotate(rAngle * i, getWidth() / 2, getHeight() / 2);
            canvas.drawLine(getWidth() / 2, mArcWidth, getWidth() / 2, 20, paintOuter_Arc);//画刻度线
            canvas.drawText("" + i * 10, getWidth() / 2 - mArcWidth * 2, 40, paintouter_Num);//画刻度
            canvas.restore();
        }
        canvas.restore();
    }

要点：canvas.save 和canvas.restore来记录和恢复画布的状态

结合canvas.ratate旋转画布，画布旋转固定角度，画笔此时不需要变化，大大方便，这个技巧需要掌握

此时画出

然后执行drawInArc(canvas, percent);画粗圆弧

 private void drawInArc(Canvas canvas, float percent) {
        rectF2 = new RectF(mArcWidth + OFFSET, mArcWidth + OFFSET, getWidth() - mArcWidth - OFFSET, getHeight() - mArcWidth - OFFSET);
 
        canvas.drawArc(rectF2, START_ARC, DURING_ARC, false, paintInerArc);
 
        rectF3 = new RectF(mArcWidth + OFFSET, mArcWidth + OFFSET, getWidth() - mArcWidth - OFFSET, getHeight() - mArcWidth - OFFSET);
        shader = new LinearGradient(mArcWidth + OFFSET, mArcWidth + OFFSET,
                getWidth() - mArcWidth - OFFSET, getHeight() - mArcWidth - OFFSET, acrStartColor, acrEndColor, Shader.TileMode.REPEAT);
        paintInerArc_tranform.setShader(shader);
        canvas.drawArc(rectF3, START_ARC, <span style="color:#000099;">percent * DURING_ARC</span>, false, paintInerArc_tranform);
    }

这个涉及到了粗圆弧颜色状态的变化，首先画一个白色的圆弧，画笔设置粗一点，为白色

然后使用shader来变色，在相同的圆弧上根据百分比再覆盖一层颜色，我们画弧是从150度（START_ARC）为开始位置，持续了240度（DURING_ARC）

此时状态为

然后开始画圆环和圆点这个比较简单，注意下圆环使用空心画笔，圆点使用实心画笔即可

private void drawInPoint(Canvas canvas) {
        canvas.drawCircle(getWidth() / 2, getHeight() / 2, mMinRingRadius, paintOuter_Arc);//中心小圆环
        canvas.drawCircle(getWidth() / 2, getHeight() / 2, mMinCircleRadius, paint_centerPoint_Pointer);//中心圆点
    }

圆弧颜色变化解决了，下面来解决指针跟随百分比变化

percent在0-1之间，实现-120- +120变化（DURING_ARC=240）,那么转化成数学关系就是，变化角度angle = DURING_ARC*(percent-0.5)，ok表达式搞定就好搞了

  private void drawerPointer(Canvas canvas, float percent) {
        canvas.save();
        float angel = DURING_ARC * (percent - 0.5f);
        canvas.rotate(angel, getWidth() / 2, getHeight() / 2);//指针与外弧边缘持平
        paint_centerPoint_Pointer.setStrokeWidth(mArcWidth);
        canvas.drawLine(getWidth() / 2, getHeight() / 2, getWidth() / 2, getHeight() / 2 - mArcWidth * 2 - OFFSET - mScendArcWidth, paint_centerPoint_Pointer);
        canvas.restore();
    }

根据百分比变化位置的指针也画出来了

最后画画文字和单位

    private void drawerRecAndText(Canvas canvas, float percent) {
        float length = 0;
        paint_text.setTextSize(mTextSize);
 
        length = paint_text.measureText(mText);
        canvas.drawText(mText, getWidth() / 2 - length / 2, (float) (getHeight() / 2 * (1 + Math.sqrt(2) / 3)), paint_text);
 
        paint_text.setTextSize(mTextSize * 1.5f);
        speed = StringUtil.floatFormat(120 * percent) +<span style="color:#336666;"> unit</span>;
        length = paint_text.measureText(speed);
 
        canvas.drawText(speed, getWidth() / 2 - length / 2, (float) (getHeight() / 2 * (1 + Math.sqrt(2) / 2)), paint_text);
    }

为了使文字画在中间需要使用path里面的measureText的方法，然后为了文字和速度字体有层次感，这里设置为文字的1.5倍大小

ok很简答吧！