一、需求概述
多人聊天（群组，讨论组，聊天室，以下统称： “群组” ）生成一个拼接头像，需要把最先加入群组的几个人（最多4个人，以下简称：头部用户，A、B、C、D）的头像拼凑成在一起。
群组创建后，A、B、C、D其中任何一个修改了自己的头像，需要 "异步" 更新群组头像。
以上是简单的需求描述。
本文使用.net core实现了N张图片拼接算法。
完整代码点击：https://github.com/night-king/ImageMerge
二、方案实现探讨
本需求可以在服务端实现，也可以在客户端实现。
（1）服务端实现：
群组创建时，下载A、B、C、D的头像，然后合并即可；
头部用户修改头像后，后台任务刷新群组头像。
（2）客户端实现：客户端包括iOS，Android，React，Web。
情况有些复杂，所以最后决定直接采用服务端实现。
Github上搜索无果，只能自己动手完成了。
先看效果：
采用四位Github大神头像作为源图片：
结果如下：
三、解决方案
群组2个用户，3个用户，4个以及以上用户头像不一样，总结如下：
/// <summary>
/// 合并布局枚举
/// </summary>
public enum Merge2LayoutEnum
{
/// <summary>
/// 2张图片，上下各1个长方形
/// ———————————————————
/// | |
/// | R1 |
/// | |
/// ———————————————————
/// | |
/// | R2 |
/// | |
/// ———————————————————
/// </summary>
Merge2R1 = 1,
/// <summary>
/// 2张图片，左右各1个长方形
/// ———————————————————
/// | | |
/// | | |
/// | | |
/// | R1 | R2 |
/// | | |
/// | | |
/// | | |
/// ———————————————————
/// </summary>
Merge2R2 = 2
}
public enum Merge3LayoutEnum
{
/// <summary>
/// 3张图片， 上面一个长方形，下面2个正方形并排
/// ———————————————————
/// | |
/// | R1 |
/// | |
/// ———————————————————
/// | | |
/// | S1 | S2 |
/// | | |
/// ———————————————————
/// </summary>
Merge1R2S1 = 3,
/// <summary>
/// 3张图片，上面2个正方形并排，下面一个长方形
/// ———————————————————
/// | | |
/// | S1 | S2 |
/// | | |
/// ———————————————————
/// | |
/// | R1 |
/// | |
/// ———————————————————
/// </summary>
Merge1R2S2 = 4,
/// <summary>
/// 3张图片，上面2个正方形并排，下面一个长方形
/// ———————————————————
/// | | |
/// | | S1 |
/// | | |
/// | R1 |—————————
/// | | |
/// | | S2 |
/// | | |
/// ———————————————————
/// </summary>
Merge1R2S3 = 5,
/// <summary>
/// 3张图片，上面2个正方形并排，下面一个长方形
/// ———————————————————
/// | | |
/// | S2 | |
/// | | |
/// |—————————| R1 |
/// | | |
/// | S2 | |
/// | | |
/// ———————————————————
/// </summary>
Merge1R2S4 = 6
}
public enum Merge4LayoutEnum
{
/// <summary>
/// 4张图片，上面一个长方形，下面2个正方形并排
/// ———————————————————
/// | | |
/// | S1 | S2 |
/// | | |
/// ———————————————————
/// | | |
/// | S3 | S4 |
/// | | |
/// ———————————————————
/// </summary>
Merge4S = 7
}
以下是2张图片实现代码：
/// <summary>
/// 合并2张图片
/// </summary>
/// <param name="image1"></param>
/// <param name="image2"></param>
/// <param name="layout"></param>
/// <returns></returns>
public static Image Merge2Images(Image image1, Image image2, Merge2LayoutEnum layout = Merge2LayoutEnum.Merge2R1, int size = 250)
{
var width = size;
var height = size;
var pf = PixelFormat.Format32bppArgb;
using (var bg = new Bitmap(width, height, pf))
{
using (var g = Graphics.FromImage(bg))
{
g.FillRectangle((Brush)Brushes.White, 0, 0, width, height);//全幅背景为白色
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
switch (layout)
{
/// <summary>
/// 2张图片，上下各1个长方形
/// ———————————————————
/// | |
/// | R1 |
/// | |
/// ———————————————————
/// | |
/// | R2 |
/// | |
/// ———————————————————
/// </summary>
case Merge2LayoutEnum.Merge2R1:
{
using (var img1 = ZoomToSqure(image1, size))
{
var newHeight = height / 2;// =125
var newWidth = width;// =250
var srcWidth = img1.Width;// =250
var srcHeight = img1.Height * newHeight / newWidth;//=250*125/250=125
g.DrawImage(img1, new Rectangle(0, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img2 = ZoomToSqure(image2, size))
{
var newHeight = height / 2;// =125
var newWidth = width; // =250
var srcWidth = img2.Width;// =250
var srcHeight = img2.Height * newHeight / newWidth;//=250*125/250=125
g.DrawImage(img2, new Rectangle(0, height / 2, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
}
break;
/// <summary>
/// 2张图片，左右各1个长方形
/// ———————————————————
/// | | |
/// | | |
/// | | |
/// | R1 | R2 |
/// | | |
/// | | |
/// | | |
/// ———————————————————
/// </summary>
case Merge2LayoutEnum.Merge2R2:
{
using (var img1 = ZoomToSqure(image1, size))
{
var newWidth = width / 2;// =125
var newHeight = height; // =250
var srcWidth = img1.Width * newWidth / newHeight;//=250*125/250=125
var srcHeight = img1.Height;// =250
g.DrawImage(img1, new Rectangle(0, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img2 = ZoomToSqure(image2, size))
{
var newWidth = width / 2;// =125
var newHeight = height; // =250
var srcWidth = img2.Width * newWidth / newHeight;//=500*125/250=250
var srcHeight = img2.Height;// =500
g.DrawImage(img2, new Rectangle(width / 2, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
}
break;
}
g.Save();
image1.Dispose();
image2.Dispose();
}
using (var ms = new MemoryStream())
{
bg.Save(ms, ImageFormat.Png);
var buffers = ms.ToArray();
return ConvertToImage(buffers);
}
}
}
View Code
以下是三种图片的生成算法
/// <summary>
/// 合并3张图片
/// </summary>
/// <param name="image1"></param>
/// <param name="image2"></param>
/// <param name="image3"></param>
/// <param name="layout"></param>
/// <returns></returns>
public static Image Merge3Images(Image image1, Image image2, Image image3, Merge3LayoutEnum layout = Merge3LayoutEnum.Merge1R2S1, int size = 250)
{
var width = size;
var height = size;
var pf = PixelFormat.Format32bppArgb;
using (var bg = new Bitmap(width, height, pf))
{
using (var g = Graphics.FromImage(bg))
{
g.FillRectangle((Brush)Brushes.White, 0, 0, width, height);//全幅背景为白色
switch (layout)
{
/// <summary>
/// 3张图片， 上面一个长方形，下面2个正方形并排
/// ———————————————————
/// | |
/// | R1 |
/// | |
/// ———————————————————
/// | | |
/// | S1 | S2 |
/// | | |
/// ———————————————————
/// </summary>
case Merge3LayoutEnum.Merge1R2S1:
{
using (var img1 = ZoomToSqure(image1, size))
{
var newHeight = height / 2;// =125
var newWidth = width;// =250
var srcWidth = img1.Width;// =250
var srcHeight = img1.Height * newHeight / newWidth;//=250*125/250=125
g.DrawImage(img1, new Rectangle(0, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img2 = ZoomToSqure(image2, size))
{
var newHeight = height / 2;// =125
var newWidth = width / 2; // =125
var srcWidth = img2.Width; // =250
var srcHeight = img2.Height;// =250
g.DrawImage(img2, new Rectangle(0, height / 2, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img3 = ZoomToSqure(image3, size))
{
var newHeight = height / 2; // =125
var newWidth = width / 2; // =125
var srcWidth = img3.Width; // =250
var srcHeight = img3.Height;// =250
g.DrawImage(img3, new Rectangle(width / 2, height / 2, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
}
break;
/// <summary>
/// 3张图片，上面2个正方形并排，下面一个长方形
/// ———————————————————
/// | | |
/// | S1 | S2 |
/// | | |
/// ———————————————————
/// | |
/// | R1 |
/// | |
/// ———————————————————
/// </summary>
case Merge3LayoutEnum.Merge1R2S2:
{
using (var img1 = ZoomToSqure(image1, size))
{
var newHeight = height / 2;// =125
var newWidth = width / 2; // =125
var srcWidth = img1.Width; // =250
var srcHeight = img1.Height;// =250
g.DrawImage(img1, new Rectangle(0, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img2 = ZoomToSqure(image2, size))
{
var newHeight = height / 2; // =125
var newWidth = width / 2; // =125
var srcWidth = img2.Width; // =250
var srcHeight = img2.Height;// =250
g.DrawImage(img2, new Rectangle(width / 2, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img3 = ZoomToSqure(image3, size))
{
var newHeight = height / 2;// =125
var newWidth = width;// =250
var srcWidth = img3.Width;// =250
var srcHeight = img3.Height * newHeight / newWidth;//=250*125/250=125
g.DrawImage(img3, new Rectangle(0, height / 2, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
}
break;
/// <summary>
/// 3张图片，上面2个正方形并排，下面一个长方形
/// ———————————————————
/// | | |
/// | | S1 |
/// | | |
/// | R1 |—————————
/// | | |
/// | | S2 |
/// | | |
/// ———————————————————
/// </summary>
case Merge3LayoutEnum.Merge1R2S3:
{
using (var img1 = ZoomToSqure(image1, size))
{
var newHeight = height;// =250
var newWidth = width / 2;// =125
var srcHeight = img1.Height;//=250
var srcWidth = img1.Width * newWidth / newHeight;// =250*125/250=125;
g.DrawImage(img1, new Rectangle(0, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img2 = ZoomToSqure(image2, size))
{
var newHeight = height / 2;// =125
var newWidth = width / 2; // =125
var srcWidth = img2.Width; // =250
var srcHeight = img2.Height;// = 250
g.DrawImage(img2, new Rectangle(width / 2, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img3 = ZoomToSqure(image3, size))
{
var newHeight = height / 2; // =125
var newWidth = width / 2; // =125
var srcWidth = img3.Width; // =250
var srcHeight = img3.Height;// =250
g.DrawImage(img3, new Rectangle(width / 2, height / 2, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
}
break;
/// <summary>
/// 3张图片，上面2个正方形并排，下面一个长方形
/// ———————————————————
/// | | |
/// | S2 | |
/// | | |
/// |—————————| R1 |
/// | | |
/// | S2 | |
/// | | |
/// ———————————————————
/// </summary>
case Merge3LayoutEnum.Merge1R2S4:
{
using (var img1 = ZoomToSqure(image1, size))
{
var newHeight = height / 2;// =125
var newWidth = width / 2; // =125
var srcWidth = img1.Width; // =250
var srcHeight = img1.Height;// =250
g.DrawImage(img1, new Rectangle(0, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img2 = ZoomToSqure(image2, size))
{
var newHeight = height / 2; // =125
var newWidth = width / 2; // =125
var srcWidth = img2.Width; // =250
var srcHeight = img2.Height;// =250
g.DrawImage(img2, new Rectangle(0, height / 2, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img3 = ZoomToSqure(image3, size))
{
var newHeight = height;// =250
var newWidth = width / 2;// =125
var srcHeight = img3.Height;//=250
var srcWidth = img3.Width * newWidth / newHeight;// =250*125/250=125;
g.DrawImage(img3, new Rectangle(width / 2, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
}
break;
}
g.Save();
image1.Dispose();
image2.Dispose();
image3.Dispose();
}
using (var ms = new MemoryStream())
{
bg.Save(ms, ImageFormat.Png);
var buffers = ms.ToArray();
return ConvertToImage(buffers);
}
}
}
View Code
以下是4张图片的生成是算法：
/// <summary>
/// 合并4张图片
/// </summary>
/// <param name="image1"></param>
/// <param name="image2"></param>
/// <param name="image3"></param>
/// <param name="image4"></param>
/// <param name="layout"></param>
/// <returns></returns>
public static Image Merge4Images(Image image1, Image image2, Image image3, Image image4, Merge4LayoutEnum layout = Merge4LayoutEnum.Merge4S, int size = 250)
{
var width = size;
var height = size;
var pf = PixelFormat.Format32bppArgb;
using (var bg = new Bitmap(width, height, pf))
{
using (var g = Graphics.FromImage(bg))
{
g.FillRectangle((Brush)Brushes.White, 0, 0, width, height);//全幅背景为白色
switch (layout)
{
/// <summary>
/// 4张图片，上面一个长方形，下面2个正方形并排
/// ———————————————————
/// | | |
/// | S1 | S2 |
/// | | |
/// ———————————————————
/// | | |
/// | S3 | S4 |
/// | | |
/// ———————————————————
/// </summary>
case Merge4LayoutEnum.Merge4S:
{
using (var img1 = ZoomToSqure(image1, size))
{
var newHeight = height / 2;// =125
var newWidth = width / 2; // =125
var srcWidth = img1.Width; // =250
var srcHeight = img1.Height;// =250
g.DrawImage(img1, new Rectangle(0, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img2 = ZoomToSqure(image2, size))
{
var newHeight = height / 2; // =125
var newWidth = width / 2; // =125
var srcWidth = img2.Width; // =250
var srcHeight = img2.Height;// =250
g.DrawImage(img2, new Rectangle(width / 2, 0, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img3 = ZoomToSqure(image3, size))
{
var newHeight = height / 2; // =125
var newWidth = width / 2; // =125
var srcWidth = img3.Width; // =250
var srcHeight = img3.Height;// =250
g.DrawImage(img3, new Rectangle(0, height / 2, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
using (var img4 = ZoomToSqure(image4, size))
{
var newHeight = height / 2; // =125
var newWidth = width / 2; // =125
var srcWidth = img4.Width; // =250
var srcHeight = img4.Height;// =250
g.DrawImage(img4, new Rectangle(width / 2, height / 2, newWidth, newHeight), new Rectangle(0, 0, srcWidth, srcHeight), GraphicsUnit.Pixel);
}
}
break;
}
g.Save();
image1.Dispose();
image2.Dispose();
image3.Dispose();
image4.Dispose();
}
using (var ms = new MemoryStream())
{
bg.Save(ms, ImageFormat.Png);
var buffers = ms.ToArray();
return ConvertToImage(buffers);
}
}
}
View Code
以下是用到的Helper方法：
/// <summary>
/// 下载图片
/// </summary>
/// <param name="imageUrl"></param>
/// <returns></returns>
public static byte[] Download(string imageUrl)
{
if (imageUrl.StartsWith("http"))
{
using (var ms = new MemoryStream())
{
var request = (HttpWebRequest)HttpWebRequest.Create(imageUrl);// 打开网络连接
using (var rs = request.GetResponse().GetResponseStream())// 向服务器请求,获得服务器的回应数据流
{
byte[] btArray = new byte[512];// 定义一个字节数据,用来向readStream读取内容和向writeStream写入内容
int size = rs.Read(btArray, 0, btArray.Length);// 向远程文件读第一次
while (size > 0)// 如果读取长度大于零则继续读
{
ms.Write(btArray, 0, size);// 写入本地文件
size = rs.Read(btArray, 0, btArray.Length);// 继续向远程文件读取
}
return ms.ToArray();
}
}
}
else
{
using (var ms = new MemoryStream())
{
var img = Image.FromFile(imageUrl);
img.Save(ms, img.RawFormat);
return ms.ToArray();
}
}
}
/// <summary>
/// 将byte数组转化为Image
/// </summary>
/// <param name="buffer"></param>
/// <returns></returns>
public static Image ConvertToImage(byte[] buffer)
{
using (MemoryStream ms = new MemoryStream(buffer))
{
return Image.FromStream(ms);
}
}
/// <summary>
/// 将Image转化为byte数组
/// </summary>
/// <param name="image"></param>
/// <returns></returns>
public static byte[] ConvertToByte(Image image)
{
using (MemoryStream ms = new MemoryStream())
{
image.Save(ms, image.RawFormat);
return ms.ToArray();
}
}
/// <summary>
/// 等比缩放/放大成正方形图片
/// </summary>
/// <param name="orginal">原始图片</param>
/// <param name="size">目标宽高</param>
/// <param name="cute">超出部分是否剪裁</param>
/// <returns></returns>
public static Image ZoomToSqure(Image orginal, int size, bool cute = true)
{
var width = 0d;//图片宽度
var height = 0d;//图片高度
if (orginal.Width > orginal.Height)//原始图片宽度大于高度
{
height = size;
width = cute ? size : (orginal.Width * height / orginal.Height);
}
else if (orginal.Width < orginal.Height)//原始图片高度大于宽度
{
width = size;
height = cute ? size : (orginal.Height * width / orginal.Width);
}
else//原始图片是正方形，刚好
{
width = size;
height = size;
}
var board = new Bitmap((int)width, (int)height);
using (var g = Graphics.FromImage(board))
{
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;//设置质量
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;//设置质量
g.Clear(Color.White);//置背景色
g.DrawImage(orginal, new Rectangle(0, 0, board.Width, board.Height), new Rectangle(0, 0, orginal.Width, orginal.Height), System.Drawing.GraphicsUnit.Pixel); //画图
orginal.Dispose();//释放原图
return board;
}
}
View Code
完整代码点击：https://github.com/night-king/ImageMerge