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..
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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);
}
}
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demo：progressviewdemo.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。