.NetCore如何使用ImageSharp进行图片的生成

    ImageSharp是对NetCore平台扩展的一个图像处理方案,以往网上的案例多以生成文字及画出简单图形、验证码等方式进行探讨和实践。

    今天我分享一下所在公司项目的实际应用案例,导出微信二维码图片,圆形头像等等。

一、源码获取

    Git项目地址:https://github.com/SixLabors/ImageSharp

    安装这两个包即可:

    Install-Package SixLabors.ImageSharp -Version 1.0.0-beta0001 

    Install-Package SixLabors.ImageSharp.Drawing -Version 1.0.0-beta0001 

二、应用

    1.在图片中画出文字

     首先要注意字体问题,Windows自带的字体一般存储于 C:\Windows\Fonts 文件夹内,如果是部署在Linux系统的应用程序,则存储于 usr/share/fonts 文件夹内。以黑体为例,我们找到对应的字体文件 SIMHEI.TTF ,将其放入项目的根目录内方便调用。

 

 1   var path = "Image/Mud.png"                                  //图片路径
 2   FontCollection fonts = new FontCollection();
 3   FontFamily fontfamily = fonts.Install("Source/SIMHEI.TTF"); //字体的路径
var font = new Font(fontfamily,50); 4 using (Image<Rgba32> image = Image.Load(path)) 5 { 6 image.Mutate(x => x.
DrawText (
8 "陆家嘴旗舰店", //文字内容 9 font, 10 Rgba32.Black, //文字颜色 11 new PointF(100,100)) //坐标位置(浮点) 12 ); 13 image.Save(path); 14 }

 

       关于Image.Load()获取图片方法的使用,可以直接读取Stream类型的流,也可以根据图片的本地路径获取。

//线上地址的图片,通过获取流的方式读取   
WebRequest imgRequest = WebRequest.Create(url);
var res = (HttpWebResponse)imgRequest.GetResponse();
var image  = Image.Load(res.GetResponseStream());

      获取文字的像素宽度,可以使用:

  var str = "我是什么长度"  var size = TextMeasurer.Measure(str, new RendererOptions(new Font(fontfamily,50)));
var width = size.Width;

 

 

      2.在图片中画出圆形的头像

      我在ImageSharp的源码中,发现有画圆形的工具类可以使用,在这里直接copy出来。

 1 using SixLabors.ImageSharp;
 2 using SixLabors.ImageSharp.PixelFormats;
 3 using SixLabors.ImageSharp.Processing;
 4 using SixLabors.Primitives;
 5 using SixLabors.Shapes;
 6 using System;
 7 using System.Collections.Generic;
 8 using System.Text;
 9 
10 namespace CodePicDownload
11 {
12     public static class CupCircularHelper
13     {
14 
15         public static IImageProcessingContext<Rgba32> ConvertToAvatar(this IImageProcessingContext<Rgba32> processingContext, Size size, float cornerRadius)
16         {
17             return processingContext.Resize(new ResizeOptions
18             {
19                 Size = size,
20                 Mode = ResizeMode.Crop
21             }).Apply(i => ApplyRoundedCorners(i, cornerRadius));
22         }
23 
24 
25         // This method can be seen as an inline implementation of an `IImageProcessor`:
26         // (The combination of `IImageOperations.Apply()` + this could be replaced with an `IImageProcessor`)
27         private static void ApplyRoundedCorners(Image<Rgba32> img, float cornerRadius)
28         {
29             IPathCollection corners = BuildCorners(img.Width, img.Height, cornerRadius);
30 
31             var graphicOptions = new GraphicsOptions(true)
32             {
33                 AlphaCompositionMode = PixelAlphaCompositionMode.DestOut // enforces that any part of this shape that has color is punched out of the background
34             };
35             // mutating in here as we already have a cloned original
36             // use any color (not Transparent), so the corners will be clipped
37             img.Mutate(x => x.Fill(graphicOptions, Rgba32.LimeGreen, corners));
38         }
39 
40         private static IPathCollection BuildCorners(int imageWidth, int imageHeight, float cornerRadius)
41         {
42             // first create a square
43             var rect = new RectangularPolygon(-0.5f, -0.5f, cornerRadius, cornerRadius);
44 
45             // then cut out of the square a circle so we are left with a corner
46             IPath cornerTopLeft = rect.Clip(new EllipsePolygon(cornerRadius - 0.5f, cornerRadius - 0.5f, cornerRadius));
47 
48             // corner is now a corner shape positions top left
49             //lets make 3 more positioned correctly, we can do that by translating the orgional artound the center of the image
50 
51             float rightPos = imageWidth - cornerTopLeft.Bounds.Width + 1;
52             float bottomPos = imageHeight - cornerTopLeft.Bounds.Height + 1;
53 
54             // move it across the width of the image - the width of the shape
55             IPath cornerTopRight = cornerTopLeft.RotateDegree(90).Translate(rightPos, 0);
56             IPath cornerBottomLeft = cornerTopLeft.RotateDegree(-90).Translate(0, bottomPos);
57             IPath cornerBottomRight = cornerTopLeft.RotateDegree(180).Translate(rightPos, bottomPos);
58 
59             return new PathCollection(cornerTopLeft, cornerBottomLeft, cornerTopRight, cornerBottomRight);
60         }
61   }
62 }

           有了画圆形的方法,我们只需要调用ConvertToAvatar() 方法把方形的图片转为圆形,画在图片上即可。

1 using (Image<Rgba32> image = Image.Load("Image/Mud.png"))
2 {
3     var logoWidth = 300;
4     var logo = Image.Load("Image/Logo.png")
5 logo.Mutate(x => x.ConvertToAvatar(new Size(logoWidth, logoWidth), logoWidth / 2)); 6 image.Mutate(x => x.DrawImage(logo, new Point(100, 100), 1)); 7 Image.Save("..");
8 }

 

 

  3.处理二维码的BitMatrix类型

   我以微信获取的二维码类型为例,因为我的项目中二维码是从微信公众号平台API获取,在这次获取图片中,将BitMatrix类型转换为流的格式从而可以通过Image.Load()方法获取图片信息成为了关键。在这里我还是引用到了System.Drawing,可以单独提取公用方法。

 

 1         public void WriteToStream(BitMatrix QrMatrix, ImageFormat imageFormat, Stream stream)
 2         {
 3             if (imageFormat != ImageFormat.Exif && imageFormat != ImageFormat.Icon && imageFormat != ImageFormat.MemoryBmp)
 4             {
 5                 DrawingSize size = m_iSize.GetSize(QrMatrix?.Width ?? 21);
 6                 using (Bitmap bitmap = new Bitmap(size.CodeWidth, size.CodeWidth))
 7                 {
 8                     using (Graphics graphics = Graphics.FromImage(bitmap))
 9                     {
10                         Draw(graphics, QrMatrix);
11                         bitmap.Save(stream, imageFormat);
12                     }
13                 }
14             }
15         }

 

       这样数据就存入了stream中,但直接用ImageSharp去Load处理过的流可能会有些问题,为了保险,我将数据流中的byte取出,实例化了一个新的MemoryStream类型。这样,就可以获取到二维码的图片了。

1 //Matrix为BitMatrix类型数据,ImageFormat我选择了png类型
2 MemoryStream ms = new MemoryStream();   
3 WriteToStream(Matrix,System.Drawing.Imaging.ImageFormat.Png, ms);
4 byte[] data = new byte[ms.Length];
5 ms.Seek(0, SeekOrigin.Begin);
6 ms.Read(data, 0, Convert.ToInt32(ms.Length));
7 var image =  Image.Load(new MemoryStream(data));

 

      最后附上保存后图片的效果:

 

      本篇内容到此就结束了,非常感谢您的观看,有机会的话,希望能够一起讨论技术,一起成长!

 

.NetCore如何使用ImageSharp进行图片的生成

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