.NET Core中使用水印
在项目中，我需要给上传的图片添加水印，通过网上查找针对.NET Core 的找到两个方案：
- 使用
CoreCompat.System.Drawing及用于非Windows的runtime.osx.10.10-x64.CoreCompat.System.Drawing或runtime.linux-x64.CoreCompat.System.Drawing - 使用
System.Drawing.Common
遇到问题
经过尝试，发现方案1在.NET Core 2.2里面有类型冲突问题，如下：
The type 'Color' exists in both 'CoreCompat.System.Drawing, Version=1.0.0.0, Culture=neutral, PublicKeyToken=c0a7ed9c2333b592' and 'System.Drawing.Primitives, Version=4.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
故我采用了方案2，一开始很顺利：本地Windows上测试、debug都正常！
但当我把代码部署到CentOS服务器上的时候，出现问题， 得到错误消息如下：
ERROR:The type initializer for 'Gdip' threw an exception.
at System.Drawing.SafeNativeMethods.Gdip.GdipLoadImageFromDelegate_linux(StreamGetHeaderDelegate getHeader, StreamGetBytesDelegate getBytes, StreamPutBytesDelegate putBytes, StreamSeekDelegate doSeek, StreamCloseDelegate close, StreamSizeDelegate size, IntPtr& image)
at System.Drawing.Image.InitFromStream(Stream stream)
at System.Drawing.Image.LoadFromStream(Stream stream, Boolean keepAlive)
问题解决
很快在GitHub上找到接近答案的答案：ERROR:The type initializer for 'Gdip' threw an exception
但按照上面的步骤（我稍做整理）：
sudo yum install libgdiplus
cd /usr/lib
sudo ln -s libgdiplus.so gdiplus.dll
export LD_LIBRARY_PATH=/usr/lib
很遗憾，没有找到/usr/lib/libgdiplus.so，但我确实安装成功了。所以，经过摸索，我找到了，由于我的服务器是64位的，实际安装目录在/usr/lib64，且文件名是libgdiplus.so.0与libgdiplus.so.0.0.0，前者似乎是softlink。
OK到此成功解决，似乎都不需要重启服务，步骤如下：
sudo yum install libgdiplus
cd /usr/lib64
ln -s libgdiplus.so gdiplus.dll
export LD_LIBRARY_PATH=/usr/lib
参考文章
Watermark images on the fly in ASP.NET Core
在ASP.NET Core中给上传图片功能添加水印
ERROR:The type initializer for 'Gdip' threw an exception
其他
安装libgdiplus的成功输出：
[root@izuf****1agz ****]# yum install libgdiplus
Loaded plugins: fastestmirror
Determining fastest mirrors
base | 3.6 kB 00:00:00
epel | 5.3 kB 00:00:00
extras | 3.4 kB 00:00:00
nginx | 2.9 kB 00:00:00
packages-microsoft-com-prod | 2.9 kB 00:00:00
updates | 3.4 kB 00:00:00
(1/6): epel/x86_64/updateinfo | 974 kB 00:00:00
(2/6): extras/7/x86_64/primary_db | 200 kB 00:00:00
(3/6): updates/7/x86_64/primary_db | 5.0 MB 00:00:00
(4/6): epel/x86_64/primary_db | 6.7 MB 00:00:00
(5/6): packages-microsoft-com-prod/primary_db | 170 kB 00:00:00
(6/6): nginx/x86_64/primary_db | 46 kB 00:00:05
Resolving Dependencies
--> Running transaction check
---> Package libgdiplus.x86_64 0:2.10-10.el7 will be installed
--> Processing Dependency: libtiff.so.5(LIBTIFF_4.0)(64bit) for package: libgdiplus-2.10-10.el7.x86_64
--> Processing Dependency: libXrender.so.1()(64bit) for package: libgdiplus-2.10-10.el7.x86_64
--> Processing Dependency: libcairo.so.2()(64bit) for package: libgdiplus-2.10-10.el7.x86_64
--> Processing Dependency: libexif.so.12()(64bit) for package: libgdiplus-2.10-10.el7.x86_64
--> Processing Dependency: libgif.so.4()(64bit) for package: libgdiplus-2.10-10.el7.x86_64
--> Processing Dependency: libtiff.so.5()(64bit) for package: libgdiplus-2.10-10.el7.x86_64
--> Running transaction check
---> Package cairo.x86_64 0:1.15.12-3.el7 will be installed
--> Processing Dependency: libpixman-1.so.0()(64bit) for package: cairo-1.15.12-3.el7.x86_64
--> Processing Dependency: libGL.so.1()(64bit) for package: cairo-1.15.12-3.el7.x86_64
--> Processing Dependency: libEGL.so.1()(64bit) for package: cairo-1.15.12-3.el7.x86_64
---> Package giflib.x86_64 0:4.1.6-9.el7 will be installed
---> Package libXrender.x86_64 0:0.9.10-1.el7 will be installed
---> Package libexif.x86_64 0:0.6.21-6.el7 will be installed
---> Package libtiff.x86_64 0:4.0.3-27.el7_3 will be installed
--> Processing Dependency: libjbig.so.2.0()(64bit) for package: libtiff-4.0.3-27.el7_3.x86_64
--> Running transaction check
---> Package jbigkit-libs.x86_64 0:2.0-11.el7 will be installed
---> Package libglvnd-egl.x86_64 1:1.0.1-0.8.git5baa1e5.el7 will be installed
--> Processing Dependency: libglvnd(x86-64) = 1:1.0.1-0.8.git5baa1e5.el7 for package: 1:libglvnd-egl-1.0.1-0.8.git5baa1e5.el7.x86_64
--> Processing Dependency: mesa-libEGL(x86-64) >= 13.0.4-1 for package: 1:libglvnd-egl-1.0.1-0.8.git5baa1e5.el7.x86_64
--> Processing Dependency: libGLdispatch.so.0()(64bit) for package: 1:libglvnd-egl-1.0.1-0.8.git5baa1e5.el7.x86_64
---> Package libglvnd-glx.x86_64 1:1.0.1-0.8.git5baa1e5.el7 will be installed
--> Processing Dependency: mesa-libGL(x86-64) >= 13.0.4-1 for package: 1:libglvnd-glx-1.0.1-0.8.git5baa1e5.el7.x86_64
---> Package pixman.x86_64 0:0.34.0-1.el7 will be installed
--> Running transaction check
---> Package libglvnd.x86_64 1:1.0.1-0.8.git5baa1e5.el7 will be installed
---> Package mesa-libEGL.x86_64 0:18.0.5-4.el7_6 will be installed
--> Processing Dependency: mesa-libgbm = 18.0.5-4.el7_6 for package: mesa-libEGL-18.0.5-4.el7_6.x86_64
--> Processing Dependency: libxshmfence.so.1()(64bit) for package: mesa-libEGL-18.0.5-4.el7_6.x86_64
--> Processing Dependency: libwayland-server.so.0()(64bit) for package: mesa-libEGL-18.0.5-4.el7_6.x86_64
--> Processing Dependency: libwayland-client.so.0()(64bit) for package: mesa-libEGL-18.0.5-4.el7_6.x86_64
--> Processing Dependency: libglapi.so.0()(64bit) for package: mesa-libEGL-18.0.5-4.el7_6.x86_64
--> Processing Dependency: libgbm.so.1()(64bit) for package: mesa-libEGL-18.0.5-4.el7_6.x86_64
---> Package mesa-libGL.x86_64 0:18.0.5-4.el7_6 will be installed
--> Processing Dependency: libXxf86vm.so.1()(64bit) for package: mesa-libGL-18.0.5-4.el7_6.x86_64
--> Processing Dependency: libXfixes.so.3()(64bit) for package: mesa-libGL-18.0.5-4.el7_6.x86_64
--> Processing Dependency: libXdamage.so.1()(64bit) for package: mesa-libGL-18.0.5-4.el7_6.x86_64
--> Running transaction check
---> Package libXdamage.x86_64 0:1.1.4-4.1.el7 will be installed
---> Package libXfixes.x86_64 0:5.0.3-1.el7 will be installed
---> Package libXxf86vm.x86_64 0:1.1.4-1.el7 will be installed
---> Package libwayland-client.x86_64 0:1.15.0-1.el7 will be installed
---> Package libwayland-server.x86_64 0:1.15.0-1.el7 will be installed
---> Package libxshmfence.x86_64 0:1.2-1.el7 will be installed
---> Package mesa-libgbm.x86_64 0:18.0.5-4.el7_6 will be installed
---> Package mesa-libglapi.x86_64 0:18.0.5-4.el7_6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
=======================================================================================================
Package Arch Version Repository Size
=======================================================================================================
Installing:
libgdiplus x86_64 2.10-10.el7 epel 163 k
Installing for dependencies:
cairo x86_64 1.15.12-3.el7 base 741 k
giflib x86_64 4.1.6-9.el7 base 40 k
jbigkit-libs x86_64 2.0-11.el7 base 46 k
libXdamage x86_64 1.1.4-4.1.el7 base 20 k
libXfixes x86_64 5.0.3-1.el7 base 18 k
libXrender x86_64 0.9.10-1.el7 base 26 k
libXxf86vm x86_64 1.1.4-1.el7 base 18 k
libexif x86_64 0.6.21-6.el7 base 347 k
libglvnd x86_64 1:1.0.1-0.8.git5baa1e5.el7 base 89 k
libglvnd-egl x86_64 1:1.0.1-0.8.git5baa1e5.el7 base 44 k
libglvnd-glx x86_64 1:1.0.1-0.8.git5baa1e5.el7 base 125 k
libtiff x86_64 4.0.3-27.el7_3 base 170 k
libwayland-client x86_64 1.15.0-1.el7 base 33 k
libwayland-server x86_64 1.15.0-1.el7 base 39 k
libxshmfence x86_64 1.2-1.el7 base 7.2 k
mesa-libEGL x86_64 18.0.5-4.el7_6 updates 102 k
mesa-libGL x86_64 18.0.5-4.el7_6 updates 162 k
mesa-libgbm x86_64 18.0.5-4.el7_6 updates 38 k
mesa-libglapi x86_64 18.0.5-4.el7_6 updates 44 k
pixman x86_64 0.34.0-1.el7 base 248 k
Transaction Summary
=======================================================================================================
Install 1 Package (+20 Dependent packages)
Total download size: 2.5 M
Installed size: 8.0 M
Is this ok [y/d/N]: y
Downloading packages:
(1/21): giflib-4.1.6-9.el7.x86_64.rpm | 40 kB 00:00:00
(2/21): jbigkit-libs-2.0-11.el7.x86_64.rpm | 46 kB 00:00:00
(3/21): libXdamage-1.1.4-4.1.el7.x86_64.rpm | 20 kB 00:00:00
(4/21): libXfixes-5.0.3-1.el7.x86_64.rpm | 18 kB 00:00:00
(5/21): cairo-1.15.12-3.el7.x86_64.rpm | 741 kB 00:00:00
(6/21): libXrender-0.9.10-1.el7.x86_64.rpm | 26 kB 00:00:00
(7/21): libXxf86vm-1.1.4-1.el7.x86_64.rpm | 18 kB 00:00:00
(8/21): libglvnd-1.0.1-0.8.git5baa1e5.el7.x86_64.rpm | 89 kB 00:00:00
(9/21): libglvnd-egl-1.0.1-0.8.git5baa1e5.el7.x86_64.rpm | 44 kB 00:00:00
(10/21): libglvnd-glx-1.0.1-0.8.git5baa1e5.el7.x86_64.rpm | 125 kB 00:00:00
(11/21): libtiff-4.0.3-27.el7_3.x86_64.rpm | 170 kB 00:00:00
(12/21): libwayland-client-1.15.0-1.el7.x86_64.rpm | 33 kB 00:00:00
(13/21): libgdiplus-2.10-10.el7.x86_64.rpm | 163 kB 00:00:00
(14/21): libwayland-server-1.15.0-1.el7.x86_64.rpm | 39 kB 00:00:00
(15/21): libexif-0.6.21-6.el7.x86_64.rpm | 347 kB 00:00:00
(16/21): libxshmfence-1.2-1.el7.x86_64.rpm | 7.2 kB 00:00:00
(17/21): mesa-libEGL-18.0.5-4.el7_6.x86_64.rpm | 102 kB 00:00:00
(18/21): mesa-libGL-18.0.5-4.el7_6.x86_64.rpm | 162 kB 00:00:00
(19/21): mesa-libgbm-18.0.5-4.el7_6.x86_64.rpm | 38 kB 00:00:00
(20/21): mesa-libglapi-18.0.5-4.el7_6.x86_64.rpm | 44 kB 00:00:00
(21/21): pixman-0.34.0-1.el7.x86_64.rpm | 248 kB 00:00:00
-------------------------------------------------------------------------------------------------------
Total 5.2 MB/s | 2.5 MB 00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : mesa-libglapi-18.0.5-4.el7_6.x86_64 1/21
Installing : 1:libglvnd-1.0.1-0.8.git5baa1e5.el7.x86_64 2/21
Installing : libXfixes-5.0.3-1.el7.x86_64 3/21
Installing : libwayland-server-1.15.0-1.el7.x86_64 4/21
Installing : libXrender-0.9.10-1.el7.x86_64 5/21
Installing : libxshmfence-1.2-1.el7.x86_64 6/21
Installing : mesa-libgbm-18.0.5-4.el7_6.x86_64 7/21
Installing : libXdamage-1.1.4-4.1.el7.x86_64 8/21
Installing : jbigkit-libs-2.0-11.el7.x86_64 9/21
Installing : libtiff-4.0.3-27.el7_3.x86_64 10/21
Installing : pixman-0.34.0-1.el7.x86_64 11/21
Installing : libexif-0.6.21-6.el7.x86_64 12/21
Installing : libXxf86vm-1.1.4-1.el7.x86_64 13/21
Installing : 1:libglvnd-glx-1.0.1-0.8.git5baa1e5.el7.x86_64 14/21
Installing : mesa-libGL-18.0.5-4.el7_6.x86_64 15/21
Installing : giflib-4.1.6-9.el7.x86_64 16/21
Installing : libwayland-client-1.15.0-1.el7.x86_64 17/21
Installing : 1:libglvnd-egl-1.0.1-0.8.git5baa1e5.el7.x86_64 18/21
Installing : mesa-libEGL-18.0.5-4.el7_6.x86_64 19/21
Installing : cairo-1.15.12-3.el7.x86_64 20/21
Installing : libgdiplus-2.10-10.el7.x86_64 21/21
Verifying : libgdiplus-2.10-10.el7.x86_64 1/21
Verifying : mesa-libEGL-18.0.5-4.el7_6.x86_64 2/21
Verifying : libtiff-4.0.3-27.el7_3.x86_64 3/21
Verifying : libwayland-client-1.15.0-1.el7.x86_64 4/21
Verifying : libxshmfence-1.2-1.el7.x86_64 5/21
Verifying : giflib-4.1.6-9.el7.x86_64 6/21
Verifying : libXxf86vm-1.1.4-1.el7.x86_64 7/21
Verifying : libXrender-0.9.10-1.el7.x86_64 8/21
Verifying : mesa-libglapi-18.0.5-4.el7_6.x86_64 9/21
Verifying : 1:libglvnd-glx-1.0.1-0.8.git5baa1e5.el7.x86_64 10/21
Verifying : mesa-libgbm-18.0.5-4.el7_6.x86_64 11/21
Verifying : libXdamage-1.1.4-4.1.el7.x86_64 12/21
Verifying : libwayland-server-1.15.0-1.el7.x86_64 13/21
Verifying : libexif-0.6.21-6.el7.x86_64 14/21
Verifying : pixman-0.34.0-1.el7.x86_64 15/21
Verifying : mesa-libGL-18.0.5-4.el7_6.x86_64 16/21
Verifying : libXfixes-5.0.3-1.el7.x86_64 17/21
Verifying : 1:libglvnd-1.0.1-0.8.git5baa1e5.el7.x86_64 18/21
Verifying : jbigkit-libs-2.0-11.el7.x86_64 19/21
Verifying : 1:libglvnd-egl-1.0.1-0.8.git5baa1e5.el7.x86_64 20/21
Verifying : cairo-1.15.12-3.el7.x86_64 21/21
Installed:
libgdiplus.x86_64 0:2.10-10.el7
Dependency Installed:
cairo.x86_64 0:1.15.12-3.el7 giflib.x86_64 0:4.1.6-9.el7
jbigkit-libs.x86_64 0:2.0-11.el7 libXdamage.x86_64 0:1.1.4-4.1.el7
libXfixes.x86_64 0:5.0.3-1.el7 libXrender.x86_64 0:0.9.10-1.el7
libXxf86vm.x86_64 0:1.1.4-1.el7 libexif.x86_64 0:0.6.21-6.el7
libglvnd.x86_64 1:1.0.1-0.8.git5baa1e5.el7 libglvnd-egl.x86_64 1:1.0.1-0.8.git5baa1e5.el7
libglvnd-glx.x86_64 1:1.0.1-0.8.git5baa1e5.el7 libtiff.x86_64 0:4.0.3-27.el7_3
libwayland-client.x86_64 0:1.15.0-1.el7 libwayland-server.x86_64 0:1.15.0-1.el7
libxshmfence.x86_64 0:1.2-1.el7 mesa-libEGL.x86_64 0:18.0.5-4.el7_6
mesa-libGL.x86_64 0:18.0.5-4.el7_6 mesa-libgbm.x86_64 0:18.0.5-4.el7_6
mesa-libglapi.x86_64 0:18.0.5-4.el7_6 pixman.x86_64 0:0.34.0-1.el7
Complete!