Android自定义控件实现一个带文本与数字的圆形进度条

实现的效果图如下所示：

第一步：绘制下方有缺口的空心圆，称为外围大弧吧

anvas.clipRect(0, 0, mWidth, mHeight / 2 + radius - textHeight * 3 / 4);

第二步：计算绘制圆弧进度条时的起始角度，设置为外围大弧的左端点为进度值得起点，扫过的角度所占外围大弧的百分比就是进度值

第三步：绘制数字、文字、百分号

第四步：使用Handler Runnable 和DecelerateInterpolator是进度条和数字动起来

测试代码：

final CustomCircleBar circle=(CustomCircleBar)findViewById(R.id.win_home);
circle.setPercent(10);
circle.setCustomText("呵呵");
circle.setProgessColor(getResources().getColor(R.color.blue));
final Random random=new Random();
circle.setOnClickListener(new View.OnClickListener(){
    @Override
    public void onClick(View v){
        circle.setPercent(random.nextInt(100));
    }
});

完成代码如下：

public class CustomCircleBar extends View {
    private Context context;
    /*进度值*/
    private int percent;
    /*颜色值*/
    private int mProgessColor;
    /*下边的文字名称*/
    private String mCustomText;
    /*外圈圆环的画笔*/
    private Paint paintBar = new Paint();
    /*下边文字的画笔*/
    private Paint paintText = new Paint();
    /*动态获取属性值*/
    private TypedValue typedValue;
    /*先加速后减速*/
    DecelerateInterpolator mDecelerateInterpolator = new DecelerateInterpolator();
    /*动画持续时间*/
    private int duration = 10;
    private int curTime = 0;
    public CustomCircleBar(Context context) {
        super(context);
        this.context=context;
        init();
    }

    public CustomCircleBar(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context=context;
        init();
    }

    public CustomCircleBar(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        this.context=context;
        init();
    }

    public void setPercent(int percent) {
        this.percent = percent;
        /*isShown()：Returns the visibility of this view and all of its ancestors*/
        if (isShown()) {
            /*设置进度后重新开始一次动画*/
            curTime=0;
            this.invalidate();
        }
    }

    public void setProgessColor(int mProgessColor) {
        this.mProgessColor = mProgessColor;
        if (isShown()) {
            this.invalidate();
        }
    }

    public void setCustomText(String mCustomText) {
        this.mCustomText = mCustomText;
    }

    private Handler mHandler = new Handler();
    private Runnable mAnimation = new Runnable() {
        @Override
        public void run() {
            if (curTime < duration) {
                curTime++;
                /*导致重绘，调用onDraw，onDraw最后调用
                *  mHandler.postDelayed(mAnimation, 20);更新进度条，界面重绘
                *  每次20毫秒，绘制10次，因此动画时间200毫秒*/
                CustomCircleBar.this.invalidate();
            }
        }
    };

    private void init() {
        /*数据初始化，没有设置属性时候的默认值*/
        percent = 0;
        mProgessColor=Color.rgb(95,112,72);
        mCustomText="Home";
        typedValue=new TypedValue();
        context.getTheme().resolveAttribute(R.attr.maintextclor,typedValue,true);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        float mWidth = getWidth();
        float mHeight = getHeight();
        /*下边是进度条画笔的设置*/
        /** Restores the paint to its default settings. */
        paintBar.reset();
        /*圆环宽度4个像素*/
        paintBar.setStrokeWidth(4);
        /*空心圆环而非填充的额扇形*/
        paintBar.setStyle(Paint.Style.STROKE);
        paintBar.setAntiAlias(true);
        paintBar.setColor(mProgessColor);
        /*调整下不透明度，使边框弧和进度条区分开*/
        paintBar.setAlpha(80);
        /*接下来是文字画笔的设置*/
        paintText.setTextSize(20);
        paintText.setColor(getResources().getColor(typedValue.resourceId));
        paintText.setStyle(Paint.Style.STROKE);
        paintText.setAntiAlias(true);
        /*从中间开始绘制文本*/
        paintText.setTextAlign(Paint.Align.CENTER);
        /*测量文字大小*/
        Paint.FontMetrics fontMetrics = paintText.getFontMetrics();
        /*计算文字高度*/
        float textHeight = fontMetrics.bottom - fontMetrics.top;
        /*计算圆的半径*/
        float radius = Math.min(mWidth, mHeight) / 2 - 10;
        /*  ? save：用来保存Canvas的状态。save之后，可以调用Canvas的平移、放缩、旋转、错切、裁剪等操作。
            ? restore：用来恢复Canvas之前保存的状态。防止save后对Canvas执行的操作对后续的绘制有影响。*/
        /*保存画布，绘制进度条*/
        canvas.save();
        /*clipRect：该方法用于裁剪画布，也就是设置画布的显示区域
        调用clipRect()方法后，只会显示被裁剪的区域，之外的区域将不会显示 */
        canvas.clipRect(0, 0, mWidth, mHeight / 2 + radius - textHeight * 3 / 4);
        /*因为clipRect的原因，外边的圆环下边留个缺口绘制文字*/
        canvas.drawCircle(mWidth / 2, mHeight / 2, radius, paintBar);

        /*三角函数计算，下方缺口扇形的角度的一半*/
        float theta_offset = (float) Math.acos((radius - textHeight / 2) / radius);
        /*大弧围成的扇形的角度*/
        float theta_full = 360 - 2 * theta_offset;
        /*进度值围成的弧对应的角度*/
        float thetaProcess = mDecelerateInterpolator.getInterpolation(1.0f * curTime / duration) * percent * theta_full / 100;
        /*设置进度值颜色完全不透明*/
        paintBar.setAlpha(255);
        paintBar.setColor(mProgessColor);
        /*注意弧形的起始角度，下边因显示文字导致圆环断开成一条弧，弧有左右两个端点，从左端点开始画弧*/
        canvas.drawArc(new RectF(mWidth / 2 - radius, mHeight / 2 - radius, mWidth / 2 + radius, mHeight / 2 + radius), theta_offset+90, thetaProcess, false, paintBar);
        /*恢复画布*/
        canvas.restore();
        /*开始绘制文字*/
        paintText.setTextSize(20);
        fontMetrics = paintText.getFontMetrics();
        float textBaseLineOffset = (fontMetrics.bottom - fontMetrics.top) / 2 - fontMetrics.bottom;
        canvas.drawText(mCustomText, mWidth / 2, mHeight / 2 + radius - textHeight / 2 + textBaseLineOffset, paintText);

        /*绘制百分号*/
        paintText.setTextSize(mHeight * 1 / 8);
        fontMetrics = paintText.getFontMetrics();
        textBaseLineOffset = (fontMetrics.bottom - fontMetrics.top) / 2 - fontMetrics.bottom;
        canvas.drawText("%", mWidth / 2, mHeight / 2 + radius / 3 + textBaseLineOffset, paintText);

        /*绘制百分比*/
        paintText.setTextSize(mHeight * 3 / 8);
        canvas.drawText("" + (int)(percent*mDecelerateInterpolator.getInterpolation(1.0f * curTime / duration)), mWidth / 2, mHeight / 2, paintText);
        /*20毫秒后执行动画*/
        mHandler.postDelayed(mAnimation, 20);
    }
}