Android自定义控件实现圆形进度CircleProgressBar的方法
这篇文章主要讲解了Android自定义控件实现圆形进度CircleProgressBar的方法,内容清晰明了,对此有兴趣的小伙伴可以学习一下,相信大家阅读完之后会有帮助。
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近日有朋友问我有没有如下图效果的开源控件
相信大家无论是用IOS还是Android,都对这种效果不陌生,很多主流APP都会有这样或类似的效果,之前也打算研究一下这类控件的代码,苦于一直不知道应该怎么搜索这种效果(就是关键词)或者所搜的结果不是自己想要的,所以就一直搁置了下来。
正好朋友需要这种效果,所以就忙里偷闲写了一个类似的、更加常见和适用范围更多的控件,效果如下图所示:
自定义上图所示效果的控件时,其实就是用Canvas绘制不同效果,比如渐变圆弧背景、圆周白色分割线、中间文字等,这篇博客也根据绘制的顺序依次阐述。
1.自定义CircleProgressBar,继承View,并实现响应的构造函数
代码如下:
/** * Created by WangChunLei on 2016.1.16 * E-mail:wcl_android@163.com */ public class GradientProgressBar extends View { public GradientProgressBar(Context context) { super(context); init(); } public GradientProgressBar(Context context, AttributeSet attrs) { super(context, attrs); init(); } public GradientProgressBar(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(); } }
其中init方法是对相关画笔进行初始化的方法,init方法代码如下:
private void init() { backCirclePaint = new Paint(); backCirclePaint.setStyle(Paint.Style.STROKE); backCirclePaint.setAntiAlias(true); backCirclePaint.setColor(Color.LTGRAY); backCirclePaint.setStrokeWidth(circleBorderWidth); // backCirclePaint.setMaskFilter(new BlurMaskFilter(20, BlurMaskFilter.Blur.OUTER)); gradientCirclePaint = new Paint(); gradientCirclePaint.setStyle(Paint.Style.STROKE); gradientCirclePaint.setAntiAlias(true); gradientCirclePaint.setColor(Color.LTGRAY); gradientCirclePaint.setStrokeWidth(circleBorderWidth); linePaint = new Paint(); linePaint.setColor(Color.WHITE); linePaint.setStrokeWidth(5); textPaint = new Paint(); textPaint.setAntiAlias(true); textPaint.setTextSize(textSize); textPaint.setColor(Color.BLACK); }
2.测量控件的宽高-onMeasure
onMeasure是自定义控件的第一步,目的就是测量得到该控件应该占有的宽高尺寸。其中onMeasure方法的代码如下:
@Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int measureWidth = MeasureSpec.getSize(widthMeasureSpec); int measureHeight = MeasureSpec.getSize(heightMeasureSpec); setMeasuredDimension(Math.min(measureWidth, measureHeight), Math.min(measureWidth, measureHeight)); }
贴上onMeasure的代码后,大家估计是很少见过测量过程这么简单的onMeasure,不要介意,有兴趣的同僚们可以细化一下这个测量过程,对不同的测量模式分别进行处理和测量,让控件适配效果更好更完善!
onMeasure方法中,分别获取期望的宽度和高度,并取其中较小的尺寸作为该控件的宽和高。
3.依次绘制不同的控件组成部分。
因为控件是直接继承自View,所以不需要再处理onLayout方法,这也是自定义View的难度远小于自定义ViewGroup的原因,但继承ViewGroup也并不一定要重写onMeasure。
要实现如图所示的效果,需要分以下步骤依次实现
(1)绘制灰色空心圆环
(2)绘制颜色渐变的圆环
(3)绘制圆环上分割的白色线条
(4)绘制百分比文字等。
绘制过程过,后绘制的内容如果与之前绘制的内容存在交集,则后绘制的内容会覆盖掉之前绘制的内容。
按照上述步骤依次介绍
在绘制过程中,会产生以下成员变量,下文中会用到:
/*圆弧线宽*/ private float circleBorderWidth = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 20, getResources().getDisplayMetrics()); /*内边距*/ private float circlePadding = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 20, getResources().getDisplayMetrics()); /*字体大小*/ private float textSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 50, getResources().getDisplayMetrics()); /*绘制圆周的画笔*/ private Paint backCirclePaint; /*绘制圆周白色分割线的画笔*/ private Paint linePaint; /*绘制文字的画笔*/ private Paint textPaint; /*百分比*/ private int percent = 0; /*渐变圆周颜色数组*/ private int[] gradientColorArray = new int[]{Color.GREEN, Color.parseColor("#fe751a"), Color.parseColor("#13be23"), Color.GREEN}; private Paint gradientCirclePaint;
3.1绘制灰色空心圆环
代码如下:
//1.绘制灰色背景圆环 canvas.drawArc( new RectF(circlePadding * 2, circlePadding * 2, getMeasuredWidth() - circlePadding * 2, getMeasuredHeight() - circlePadding * 2), -90, 360, false, backCirclePaint);
其中,-90为绘制圆弧的起始角度,360是圆弧绘制的角度,即sweepAngle.
3.2绘制颜色渐变的圆环
//2.绘制颜色渐变圆环 LinearGradient linearGradient = new LinearGradient(circlePadding, circlePadding, getMeasuredWidth() - circlePadding, getMeasuredHeight() - circlePadding, gradientColorArray, null, Shader.TileMode.MIRROR); gradientCirclePaint.setShader(linearGradient); gradientCirclePaint.setShadowLayer(10, 10, 10, Color.RED); canvas.drawArc( new RectF(circlePadding * 2, circlePadding * 2, getMeasuredWidth() - circlePadding * 2, getMeasuredHeight() - circlePadding * 2), -90, (float) (percent / 100.0) * 360, false, gradientCirclePaint);
其中,linearGradient是Paint的shadow,是为了圆弧的颜色渐变效果的而需要设置的,日常开发中应用频率不高,但的确是可以实现非常理想的颜色渐变效果。
3.3绘制圆环上分割的白色线条
绘制圆弧上的白色线条时,需要进行一些简单的运算,比如线条的起始坐标startX,startY和线条的终止坐标stopX,stopY等,利用简单的三角函数还是很容易去计算出来的。
效果中,将圆弧使用白色线条平分成100分,每一个的阶级为1,可以满足int类型的百分比与效果图比例的一致。
//半径 float radius = (getMeasuredWidth() - circlePadding * 3) / 2; //X轴中点坐标 int centerX = getMeasuredWidth() / 2; //3.绘制100份线段,切分空心圆弧 for (float i = 0; i < 360; i += 3.6) { double rad = i * Math.PI / 180; float startX = (float) (centerX + (radius - circleBorderWidth) * Math.sin(rad)); float startY = (float) (centerX + (radius - circleBorderWidth) * Math.cos(rad)); float stopX = (float) (centerX + radius * Math.sin(rad) + 1); float stopY = (float) (centerX + radius * Math.cos(rad) + 1); canvas.drawLine(startX, startY, stopX, stopY, linePaint); }
3.4绘制百分比文字等
最后绘制百分比文字。
绘制文字时,为了保持文字的中心点和圆弧的原点一致,需要先测量得到要显示文字的宽度和高度,然后再进行一些简单的运算,原理不再赘述,相信大家数学一定都比我好。
//4.绘制文字 float textWidth = textPaint.measureText(percent + "%"); int textHeight = (int) (Math.ceil(textPaint.getFontMetrics().descent - textPaint.getFontMetrics().ascent) + 2); canvas.drawText(percent + "%", centerX - textWidth / 2, centerX + textHeight / 4, textPaint);
最后,暴漏一个公共的方法供改变显示的百分比,代码如下:
/** * 设置百分比 * * @param percent */ public void setPercent(int percent) { if (percent < 0) { percent = 0; } else if (percent > 100) { percent = 100; } this.percent = percent; invalidate(); }
至此,所有绘制过程简述完毕,130行代码就能实现很炫酷的效果有木有?
最后,贴上项目完整代码,供懒得看实现过程的同僚们使用,O(∩_∩)O哈哈~
package com.example.myview; import android.content.Context; import android.graphics.*; import android.util.AttributeSet; import android.util.TypedValue; import android.view.View; /** * Created by WangChunLei on 2016.1.16 * e-mail:wcl_android@163.com */ public class GradientProgressBar extends View { /*圆弧线宽*/ private float circleBorderWidth = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 20, getResources().getDisplayMetrics()); /*内边距*/ private float circlePadding = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 20, getResources().getDisplayMetrics()); /*字体大小*/ private float textSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 50, getResources().getDisplayMetrics()); /*绘制圆周的画笔*/ private Paint backCirclePaint; /*绘制圆周白色分割线的画笔*/ private Paint linePaint; /*绘制文字的画笔*/ private Paint textPaint; /*百分比*/ private int percent = 0; /*渐变圆周颜色数组*/ private int[] gradientColorArray = new int[]{Color.GREEN, Color.parseColor("#fe751a"), Color.parseColor("#13be23"), Color.GREEN}; private Paint gradientCirclePaint; public GradientProgressBar(Context context) { super(context); init(); } public GradientProgressBar(Context context, AttributeSet attrs) { super(context, attrs); init(); } public GradientProgressBar(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(); } private void init() { backCirclePaint = new Paint(); backCirclePaint.setStyle(Paint.Style.STROKE); backCirclePaint.setAntiAlias(true); backCirclePaint.setColor(Color.LTGRAY); backCirclePaint.setStrokeWidth(circleBorderWidth); // backCirclePaint.setMaskFilter(new BlurMaskFilter(20, BlurMaskFilter.Blur.OUTER)); gradientCirclePaint = new Paint(); gradientCirclePaint.setStyle(Paint.Style.STROKE); gradientCirclePaint.setAntiAlias(true); gradientCirclePaint.setColor(Color.LTGRAY); gradientCirclePaint.setStrokeWidth(circleBorderWidth); linePaint = new Paint(); linePaint.setColor(Color.WHITE); linePaint.setStrokeWidth(5); textPaint = new Paint(); textPaint.setAntiAlias(true); textPaint.setTextSize(textSize); textPaint.setColor(Color.BLACK); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int measureWidth = MeasureSpec.getSize(widthMeasureSpec); int measureHeight = MeasureSpec.getSize(heightMeasureSpec); setMeasuredDimension(Math.min(measureWidth, measureHeight), Math.min(measureWidth, measureHeight)); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //1.绘制灰色背景圆环 canvas.drawArc( new RectF(circlePadding * 2, circlePadding * 2, getMeasuredWidth() - circlePadding * 2, getMeasuredHeight() - circlePadding * 2), -90, 360, false, backCirclePaint); //2.绘制颜色渐变圆环 LinearGradient linearGradient = new LinearGradient(circlePadding, circlePadding, getMeasuredWidth() - circlePadding, getMeasuredHeight() - circlePadding, gradientColorArray, null, Shader.TileMode.MIRROR); gradientCirclePaint.setShader(linearGradient); gradientCirclePaint.setShadowLayer(10, 10, 10, Color.RED); canvas.drawArc( new RectF(circlePadding * 2, circlePadding * 2, getMeasuredWidth() - circlePadding * 2, getMeasuredHeight() - circlePadding * 2), -90, (float) (percent / 100.0) * 360, false, gradientCirclePaint); //半径 float radius = (getMeasuredWidth() - circlePadding * 3) / 2; //X轴中点坐标 int centerX = getMeasuredWidth() / 2; //3.绘制100份线段,切分空心圆弧 for (float i = 0; i < 360; i += 3.6) { double rad = i * Math.PI / 180; float startX = (float) (centerX + (radius - circleBorderWidth) * Math.sin(rad)); float startY = (float) (centerX + (radius - circleBorderWidth) * Math.cos(rad)); float stopX = (float) (centerX + radius * Math.sin(rad) + 1); float stopY = (float) (centerX + radius * Math.cos(rad) + 1); canvas.drawLine(startX, startY, stopX, stopY, linePaint); } //4.绘制文字 float textWidth = textPaint.measureText(percent + "%"); int textHeight = (int) (Math.ceil(textPaint.getFontMetrics().descent - textPaint.getFontMetrics().ascent) + 2); canvas.drawText(percent + "%", centerX - textWidth / 2, centerX + textHeight / 4, textPaint); } /** * 设置百分比 * * @param percent */ public void setPercent(int percent) { if (percent < 0) { percent = 0; } else if (percent > 100) { percent = 100; } this.percent = percent; invalidate(); } }
最后,贴上自定义控件代码(自定义控件、Activity,布局文件)下载地址: Android圆形进度CircleProgressBar
看完上述内容,是不是对Android自定义控件实现圆形进度CircleProgressBar的方法有进一步的了解,如果还想学习更多内容,欢迎关注创新互联行业资讯频道。
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