Android自定义控件实现圆形进度CircleProgressBar

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:[e-mail]
 */
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:[e-mail]
 */
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

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。