一、前言
android是一种以linux与java为基础的开放源代码操作系统，主要使用于便携设备。中国大陆地区较多人使用“安卓”。android操作系统最初由andy rubin开发,被谷歌收购后则由google公司和开放手机联盟领导及开发,主要支持手机与平板。
二、实现
先看下实现的效果吧：
说下实现思路：圆点x轴会有个位移变化量，当位移达到圆点直径 圆点间距之和就回改变方向（改变方向就是通过变化量值不断增加和不断减少来实现），可能写的有点模糊，接下来看代码：
package com.kincai.testcustomview_dotalternatelyprogress;
import android.content.context;
import android.content.res.typedarray;
import android.graphics.canvas;
import android.graphics.paint;
import android.support.annotation.nullable;
import android.support.v4.content.contextcompat;
import android.util.attributeset;
import android.util.log;
import android.view.view;
/**
* 凯发娱发k8 copyright (c) 2015 the kincai open source project
* .
* create by kincai
* .
* time 2017-06-16 21:44
* .
* desc 两个源点来回移动
*/
public class dotalternatelyview extends view {
private final string tag = this.getclass().getsimplename();
private paint mpaint = new paint();
/**
* 可视为左边圆点颜色值
*/
private int mleftcolor;
/**
* 可视为右边圆点颜色值
*/
private int mrightcolor;
/**
* 圆点半径
*/
private int mdotradius;
/**
* 圆点间距
*/
private int mdotspacing;
/**
* 圆点位移量
*/
private float mmovedistance;
/**
* 圆点移动率
*/
private float mmoverate;
/**
* 以刚开始左边圆点为准 向右移
*/
private final int dot_status_right = 0x101;
/**
* 以刚开始左边圆点为准 圆点移动方向-向左移
*/
private final int dot_status_left = 0x102;
/**
* 以刚开始左边圆点为准，圆点移动方向
*/
private int mdotchangestatus = dot_status_right;
/**
* 圆点透明度变化最大(也就是透明度在255-malphachangetotal到255之间)
*/
private int malphachangetotal = 130;
/**
* 透明度变化率
*/
private float malphachangerate;
/**
* 透明度改变量
*/
private float malphachange;
public dotalternatelyview(context context) {
this(context, null);
}
public dotalternatelyview(context context, @nullable attributeset attrs) {
this(context, attrs, 0);
}
public dotalternatelyview(context context, @nullable attributeset attrs, int defstyleattr) {
super(context, attrs, defstyleattr);
typedarray typedarray = context.obtainstyledattributes(attrs, r.styleable.dotalternatelyview, defstyleattr, 0);
initattributes(typedarray);
typedarray.recycle();
init();
}
private void initattributes(typedarray attributes) {
mleftcolor = attributes.getcolor(r.styleable.dotalternatelyview_dot_dark_color, contextcompat.getcolor(getcontext(), r.color.colorprimary));
mrightcolor = attributes.getcolor(r.styleable.dotalternatelyview_dot_light_color, contextcompat.getcolor(getcontext(), r.color.coloraccent));
mdotradius = attributes.getdimensionpixelsize(r.styleable.dotalternatelyview_dot_radius, densityutils.dp2px(getcontext(), 3));
mdotspacing = attributes.getdimensionpixelsize(r.styleable.dotalternatelyview_dot_spacing, densityutils.dp2px(getcontext(), 6));
mmoverate = attributes.getfloat(r.styleable.dotalternatelyview_dot_move_rate, 1.2f);
}
/**
* 初始化
*/
private void init() {
//移动总距离/移动率 = alpha总变化/x
//x = 移动率 * alpha总变化 / 移动总距离
malphachangerate = mmoverate * malphachangetotal / (mdotradius * 2 mdotspacing);
mpaint.setcolor(mleftcolor);
mpaint.setantialias(true);
mpaint.setstyle(paint.style.fill);
log.e(tag, " aaaa " malphachangerate);
}
@override
protected void onmeasure(int widthmeasurespec, int heightmeasurespec) {
//测量宽高
int widthmode = measurespec.getmode(widthmeasurespec);
int widthsize = measurespec.getsize(widthmeasurespec);
int heightmode = measurespec.getmode(heightmeasurespec);
int heightsize = measurespec.getsize(heightmeasurespec);
int width;
int height;
if (widthmode == measurespec.exactly) {
width = widthsize;
log.e(tag, "onmeasure measurespec.exactly widthsize=" widthsize);
} else {
//指定最小宽度所有圆点加上间距的宽度, 以最小半径加上间距算总和再加上最左边和最右边变大后的距离
width = (mdotradius * 2) * 2 mdotspacing;
log.e(tag, "onmeasure no measurespec.exactly widthsize=" widthsize " width=" width);
if (widthmode == measurespec.at_most) {
width = math.min(width, widthsize);
log.e(tag, "onmeasure measurespec.at_most width=" width);
}
}
if (heightmode == measurespec.exactly) {
height = heightsize;
log.e(tag, "onmeasure measurespec.exactly heightsize=" heightsize);
} else {
height = mdotradius * 2;
log.e(tag, "onmeasure no measurespec.exactly heightsize=" heightsize " height=" height);
if (heightmode == measurespec.at_most) {
height = math.min(height, heightsize);
log.e(tag, "onmeasure measurespec.at_most height=" height);
}
}
setmeasureddimension(width, height);
}
@override
protected void ondraw(canvas canvas) {
//左边圆点起点x轴
int startpointx = getwidth() / 2 - (2 * mdotradius * 2 mdotspacing) / 2 mdotradius;
//左边圆点起点y轴
int startpointy = getheight() / 2;
//向右移 位移要增加对应透明度变化量也需要增加 反之都需要减小
if (mdotchangestatus == dot_status_right) {
mmovedistance = mmoverate;
malphachange = malphachangerate;
} else {
malphachange -= malphachangerate;
mmovedistance -= mmoverate;
}
log.e(tag, "malphachange " malphachange);
//当移动到最右 那么需要改变方向 反过来
if (mmovedistance >= mdotradius * 2 mdotspacing && mdotchangestatus == dot_status_right) {
mdotchangestatus = dot_status_left;
mmovedistance = mdotradius * 2 mdotspacing;
malphachange = malphachangetotal;
} else if (mmovedistance <= 0 && mdotchangestatus == dot_status_left) { //当移动到最座 那么需要改变方向 反过来
mdotchangestatus = dot_status_right;
mmovedistance = 0f;
malphachange = 0f;
}
//因为两个圆点可能会给定不同的颜色来显示 所以提供两种颜色设置mleftcolor和mrightcolor
mpaint.setcolor(mleftcolor);
mpaint.setalpha((int) (255 - malphachange));
canvas.drawcircle(startpointx mmovedistance, startpointy, mdotradius, mpaint);
mpaint.setcolor(mrightcolor);
mpaint.setalpha((int) (255 - malphachange));
canvas.drawcircle(startpointx mdotradius * 2 - mmovedistance mdotspacing, startpointy, mdotradius, mpaint);
invalidate();
}
}
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