做一个自定义View的小练习，效果如下
只需要画一个圆、一个圆弧、一个百分比文本，添加一个点击事件，传入百分比重绘
1、在res/values文件夹下新建attrs.xml文件，编写自定义属性：
<?xml version="1.0" encoding="utf-8"?> <resources> <declare-styleable name="CirclePercentView" > <attr name="circleBg" format="color"/> <attr name="arcColor" format="color"/> <attr name="arcWidth" format="dimension"/> <attr name="percentTextColor" format="color"/> <attr name="percentTextSize" format="dimension"/> <attr name="radius" format="dimension"/> </declare-styleable> </resources>
2、新建CirclePercentView继承View，重写构造方法：
public CirclePercentView(Context context) { this(context, null); } public CirclePercentView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public CirclePercentView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); }
3、在第三个构造方法中获取自定义属性的值：
TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.CirclePercentView, defStyleAttr, 0); mCircleColor = ta.getColor(R.styleable.CirclePercentView_circleBg, 0xff8e29fa); mArcColor = ta.getColor(R.styleable.CirclePercentView_arcColor, 0xffffee00); mArcWidth = ta.getDimensionPixelSize(R.styleable.CirclePercentView_arcWidth, DensityUtils.dp2px(context, 16)); mPercentTextColor = ta.getColor(R.styleable.CirclePercentView_arcColor, 0xffffee00); mPercentTextSize = ta.getDimensionPixelSize(R.styleable.CirclePercentView_percentTextSize, DensityUtils.sp2px(context, 16)); mRadius = ta.getDimensionPixelSize(R.styleable.CirclePercentView_radius, DensityUtils.dp2px(context, 100)); ta.recycle();
4、创建画图所使用的对象，如Paint、Rect、RectF：
mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG); mCirclePaint.setStyle(Paint.Style.FILL); mCirclePaint.setColor(mCircleColor); mArcPaint = new Paint(Paint.ANTI_ALIAS_FLAG); mArcPaint.setStyle(Paint.Style.STROKE); mArcPaint.setStrokeWidth(mArcWidth); mArcPaint.setColor(mArcColor); mArcPaint.setStrokeCap(Paint.Cap.ROUND);//使圆弧两头圆滑 mPercentTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG); mPercentTextPaint.setStyle(Paint.Style.STROKE); mPercentTextPaint.setColor(mPercentTextColor); mPercentTextPaint.setTextSize(mPercentTextSize); mArcRectF = new RectF();//圆弧的外接矩形 mTextBound = new Rect();//文本的范围矩形
5、重写onMeasure()方法，计算自定义View的宽高：
@Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { setMeasuredDimension(measureDimension(widthMeasureSpec), measureDimension(heightMeasureSpec)); } private int measureDimension(int measureSpec) { int result; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); if (specMode == MeasureSpec.EXACTLY) {//精确地，代表宽高为定值或者match_parent时 result = specSize; } else { result = 2 * mRadius; if (specMode == MeasureSpec.AT_MOST) {//最大地，代表宽高为wrap_content时 result = Math.min(result, specSize); } } return result; }
6、重写onDraw()方法，绘制圆、圆弧和百分比文本，注意坐标的计算：
@Override protected void onDraw(Canvas canvas) { //画圆 canvas.drawCircle(getWidth() / 2, getHeight() / 2, mRadius, mCirclePaint); //画圆弧 mArcRectF.set(getWidth() / 2 - mRadius + mArcWidth / 2, getHeight() / 2 - mRadius + mArcWidth / 2 , getWidth() / 2 + mRadius - mArcWidth / 2, getHeight() / 2 + mRadius - mArcWidth / 2); canvas.drawArc(mArcRectF, 270, 360 * mCurPercent / 100, false, mArcPaint); String text = mCurPercent + "%"; //计算文本宽高 mPercentTextPaint.getTextBounds(text, 0, String.valueOf(text).length(), mTextBound); //画百分比文本 canvas.drawText(text, getWidth() / 2 - mTextBound.width() / 2 , getHeight() / 2 + mTextBound.height() / 2, mPercentTextPaint); }
7、给这个view设置点击事件，暴露一个动态设置百分比的方法：
public void setCurPercent(float curPercent) { ValueAnimator anim = ValueAnimator.ofFloat(mCurPercent, curPercent); //动画时长由百分比大小决定 anim.setDuration((long) (Math.abs(mCurPercent - curPercent) * 20)); anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { float value = (float) animation.getAnimatedValue(); mCurPercent = (float) (Math.round(value * 10)) / 10;//四舍五入保留到小数点后两位 invalidate();//重绘，重走onDraw()方法，这也是不能再onDraw()中创建对象的原因 } }); anim.start(); } public void setOnCircleClickListener(OnClickListener onClickListener) { this.mOnClickListener = onClickListener; } //在构造方法中 setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if (mOnClickListener != null) { mOnClickListener.onClick(CirclePercentView.this); } } });
8、在activity_main.xml布局文件中使用该View：
<!-- 使用自定义命名空间namespace，cpv是该控件名的首字母缩写，可以随意取 --> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:cpv="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent"> <!-- cpv后面的属性名对应attrs.xml文件中的自定义属性名 --> <com.monkey.customviewdemo.view.CirclePercentView android:id="@+id/circlePercentView" android:layout_width="match_parent" android:layout_height="match_parent" cpv:arcColor="#ffee00" cpv:arcWidth="@dimen/activity_horizontal_margin" cpv:circleBg="#8e29fa" cpv:percentTextColor="#ffee00" cpv:percentTextSize="16sp" cpv:radius="100dp" /> </RelativeLayout>
9、在MainActivity.java中设置监听，传入百分比：
mCirclePercentView = (CirclePercentView) findViewById(R.id.circlePercentView); mCirclePercentView.setOnCircleClickListener(new View.OnClickListener() { @Override public void onClick(View v) { float percent = (float) (Math.random() * 99 + 1); mCirclePercentView.setCurPercent(percent); } });
代码下载地址：
https://github.com/MonkeyMushroom/CirclePercentView/tree/master
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。