android自定义进度条渐变圆形

在安全卫生上，经常看到有圆形的进度条在转动，效果非常好看，于是就尝试去实现一下，具体实现过程不多说了，直接上效果图，先炫耀下。

效果图：

分析：比较常见于扫描结果、进度条等场景

利用canvas.drawarc(rectf oval, float startangle, float sweepangle, boolean usecenter, paint paint)绘制圆弧

paint的一些属性定义粗细、颜色、样式等

lineargradient实现颜色的线型渐变

同样的道理，可以画出长条进度条，扇图饼图等，感兴趣可以试下..

package com.liujing.progressviewdemo;
/***
 * 自定义圆弧进度条
 * 
 * @author liujing
 */
public class progressview extends view {
 //分段颜色 
 private static final int[] section_colors = { color.green, color.yellow,
 color.red };
 private static final string[] alarm_level = { "安全", "低危", "中危", "高危" };
 private float maxcount;
 private float currentcount;
 private int score;
 private string crrentlevel;
 private paint mpaint;
 private paint mtextpaint;
 private int mwidth, mheight;
 public progressview(context context, attributeset attrs, int defstyleattr) {
 super(context, attrs, defstyleattr);
 init(context);
 }
 public progressview(context context, attributeset attrs) {
 this(context, attrs, 0);
 }
 public progressview(context context) {
 this(context, null);
 }
 private void init(context context) {
 mpaint = new paint();
 mtextpaint = new paint();
 }
 @override
 protected void ondraw(canvas canvas) {
 super.ondraw(canvas);
 initpaint();
 rectf rectblackbg = new rectf(20, 20, mwidth - 20, mheight - 20);
 canvas.drawarc(rectblackbg, 0, 360, false, mpaint);
 mpaint.setcolor(color.black);
 canvas.drawtext(score + "分", mwidth / 2, mheight / 2, mtextpaint);
 mtextpaint.settextsize(40);
 if (crrentlevel != null) {
 canvas.drawtext(crrentlevel, mwidth / 2, mheight / 2 + 50,
  mtextpaint);
 }
 float section = currentcount / maxcount;
 if (section <= 1.0f / 3.0f) {
 if (section != 0.0f) {
 mpaint.setcolor(section_colors[0]);
 } else {
 mpaint.setcolor(color.transparent);
 }
 } else {
 int count = (section <= 1.0f / 3.0f * 2) ? 2 : 3;
 int[] colors = new int[count];
 system.arraycopy(section_colors, 0, colors, 0, count);
 float[] positions = new float[count];
 if (count == 2) {
 positions[0] = 0.0f;
 positions[1] = 1.0f - positions[0];
 } else {
 positions[0] = 0.0f;
 positions[1] = (maxcount / 3) / currentcount;
 positions[2] = 1.0f - positions[0] * 2;
 }
 positions[positions.length - 1] = 1.0f;
 lineargradient shader = new lineargradient(3, 3, (mwidth - 3)
  * section, mheight - 3, colors, null,
  shader.tilemode.mirror);
 mpaint.setshader(shader);
 }
 canvas.drawarc(rectblackbg, 180, section * 360, false, mpaint);
 }
 private void initpaint() {
 mpaint.setantialias(true);
 mpaint.setstrokewidth((float) 40.0);
 mpaint.setstyle(style.stroke);
 mpaint.setstrokecap(cap.round);
 mpaint.setcolor(color.transparent);
 mtextpaint.setantialias(true);
 mtextpaint.setstrokewidth((float) 3.0);
 mtextpaint.settextalign(paint.align.center);
 mtextpaint.settextsize(50);
 mtextpaint.setcolor(color.black);
 }
 private int diptopx(int dip) {
 float scale = getcontext().getresources().getdisplaymetrics().density;
 return (int) (dip * scale + 0.5f * (dip >= 0 ? 1 : -1));
 }
 public int getscore() {
 return score;
 }
 public string getcrrentlevel() {
 return crrentlevel;
 }
 public void setcrrentlevel(string crrentlevel) {
 this.crrentlevel = crrentlevel;
 }
 public float getmaxcount() {
 return maxcount;
 }
 public float getcurrentcount() {
 return currentcount;
 }
 public void setscore(int score) {
 this.score = score;
 if (score == 100) {
 this.crrentlevel = alarm_level[0];
 } else if (score >= 70 && score < 100) {
 this.crrentlevel = alarm_level[1];
 } else if (score >= 30 && score < 70) {
 this.crrentlevel = alarm_level[2];
 } else {
 this.crrentlevel = alarm_level[3];
 }
 invalidate();
 }
 /***
 * 设置最大的进度值
 * 
 * @param maxcount
 */
 public void setmaxcount(float maxcount) {
 this.maxcount = maxcount;
 }
 /***
 * 设置当前的进度值
 * 
 * @param currentcount
 */
 public void setcurrentcount(float currentcount) {
 this.currentcount = currentcount > maxcount ? maxcount : currentcount;
 invalidate();
 }
 @override
 protected void onmeasure(int widthmeasurespec, int heightmeasurespec) {
 int widthspecmode = measurespec.getmode(widthmeasurespec);
 int widthspecsize = measurespec.getsize(widthmeasurespec);
 int heightspecmode = measurespec.getmode(heightmeasurespec);
 int heightspecsize = measurespec.getsize(heightmeasurespec);
 if (widthspecmode == measurespec.exactly
 || widthspecmode == measurespec.at_most) {
 mwidth = widthspecsize;
 } else {
 mwidth = 0;
 }
 if (heightspecmode == measurespec.at_most
 || heightspecmode == measurespec.unspecified) {
 mheight = diptopx(15);
 } else {
 mheight = heightspecsize;
 }
 setmeasureddimension(mwidth, mheight);
 }
}

 demo：http://xiazai.jb51.net/201507/yuanma/progressviewdemo(jb51.net).rar 

以上内容就是实现android自定义进度条渐变圆形的代码，希望对大家有所帮助。