.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 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!