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Last Modified:<br>Mar 14, 2019</div></div><div id="main_text"><div id="main_text_body"><center><a name="Using%20dlib%20from%20Python"></a><h1>Using dlib from Python</h1></center><p> |
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Either run <tt>pip install dlib --verbose</tt> or grab the latest sources |
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from github, go to the base folder of the dlib repository, |
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and run <tt>python setup.py install</tt>. Once either of these commands |
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finishes running you are ready to use dlib from Python. Note |
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that you need to have CMake and a working C++ compiler |
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installed for this to work. |
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</p><p> |
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Also note that various optional features like GUI support (e.g. |
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dlib.image_window) and CUDA acceleration will be automatically |
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enabled or disabled based on what is available on your computer. |
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When you run the install command it will print messages telling |
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you what it is using. Read those messages and take appropriate |
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action if you don't like the results. For example, Linux and |
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OSX users may have to install libX11 to use the GUI tools. If |
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you care about this then read the messages since they tell you |
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how to get these optional features installed. |
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</p><p> |
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Alternatively, if you want to add more python bindings to dlib's |
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python interface then you probably want to avoid the setup.py file |
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and work directly using CMake. In particular, dlib's python API is |
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built by the CMake project in the tools/python folder. You build |
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this project using the usual CMake commands and when compiled it |
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outputs the dlib shared library that defines the python API for dlib. |
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</p><br><br><center><a name="Using%20dlib%20from%20C++"></a><h1>Using dlib from C++</h1></center> |
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|
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The best way to compile a program that uses dlib is to use <a href="http://www.cmake.org">CMake</a>. For |
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example, the following commands will compile the example programs on any operating |
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system: |
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<pre class="code_box"> |
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cd examples |
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mkdir build |
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cd build |
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cmake .. |
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cmake --build . --config Release |
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</pre> |
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Note that you need to have a C++11 compiler installed on your system. There are free C++11 compilers |
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for most operating systems. For example, Visual Studio is free on Windows and GCC is free and |
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works well on Mac OS X and Linux systems. If you have multiple compilers/IDEs installed then you can |
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tell CMake which one you want it to use via the -G option. |
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<p> |
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The <a href="examples/CMakeLists.txt.html">examples/CMakeLists.txt</a> file tells CMake how to build |
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the examples. You can create your own projects by starting with this file and editing it however you like. |
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You can also perform additional configuration of a cmake project using the cmake-gui or ccmake tool. For example, |
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if you are using dlib's face detector then you should turn on either SSE4 or AVX instructions since this |
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makes it run much faster (also see <a href="faq.html#Whyisdlibslow">this FAQ</a>). |
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</p><p> |
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Finally, note that when using Visual Studio, CMake will by default generate a 32bit executable. |
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This means the programs you compile will only be able to use 2GB of RAM. To avoid this, you need |
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to tell CMake to generate a 64bit executable. You do this by using a command like |
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<pre class="code_box">cmake -G "Visual Studio 14 2015 Win64" -T host=x64 ..</pre> instead of <pre class="code_box">cmake ..</pre> |
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You can see the list of valid arguments to <tt>-G</tt> by running <tt>cmake</tt> with no options. Note also the <tt>-T host=x64</tt> |
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option, which tells Visual Studio to let the compiler use more than 2GB of RAM. That is important if you don't want the compiler to |
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crash from running out of RAM in some situations. |
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</p><br><a name="Compiling%20C++%20Examples%20Without%20CMake"></a><h2>Compiling C++ Examples Without CMake</h2><p> |
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In most cases, to use this library all you have to do is extract it somewhere, make |
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sure the folder <i>containing</i> the dlib folder is in your include path, and |
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finally add dlib/all/source.cpp to your |
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project. |
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</p><p> |
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Again, note that you should <b><i>not</i></b> add the dlib folder itself to your compiler's include path. |
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Doing so will cause the |
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build to fail because of name collisions (e.g. dlib/string.h with string.h from the standard library). |
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Instead you should add the folder that contains the dlib folder to your include search path and then use |
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include statements of the form <tt>#include <dlib/queue.h></tt>. This will ensure that everything |
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builds correctly. |
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</p><p> |
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Note also that if you want to work with jpeg/png/gif files using dlib then you will |
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need to link your program with libjpeg, libpng, and/or libgif. You also need to tell dlib |
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about this by defining the DLIB_JPEG_SUPPORT, DLIB_PNG_SUPPORT, and DLIB_GIF_SUPPORT preprocessor directives. |
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How you "link to libjpeg/libpng/libgif" varies from platform to platform. On UNIX machines you |
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usually just add a -ljpeg, -lpng, or -lgif switch to your compiler (after installing the libraries). |
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On windows it's less well defined. So dlib comes with a copy of libjpeg and libpng in the dlib/external |
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folder so you can statically compile them into your application if no system wide version |
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is available on your machine. If all this talk about linking is confusing to you then |
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just use CMake. It will set this all up for you. |
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</p><p> |
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Dlib is also capable of using any optimized BLAS or LAPACK libraries that are |
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installed on your system. Linking to these libraries will make many things run |
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faster. To do this you define the DLIB_USE_BLAS and/or DLIB_USE_LAPACK preprocessor |
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directives and then link your program with whatever BLAS or LAPACK libraries you |
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have. If you use CMake it will set this up automatically. |
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</p><a name="Compiling%20on%20Linux%20From%20Command%20Line"></a><h3>Compiling on Linux From Command Line</h3> |
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From within the examples folder, you can compile nearly all of the examples with a single command like so: |
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<pre class="code_box"> |
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g++ -std=c++11 -O3 -I.. ../dlib/all/source.cpp -lpthread -lX11 example_program_name.cpp |
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</pre> |
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|
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On non-Linux systems like Solaris, you might have to link to other libraries. For example, I have seen systems |
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where it was also necessary to supply -lnsl or -lsocket options to g++. Additionally, the X11 development |
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library isn't installed on Ubuntu by default. So if you require it and are using Ubuntu you can install |
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it by typing: |
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<pre class="code_box"> |
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sudo apt-get install libx11-dev |
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</pre><a name="Compiling%20on%20Windows%20Using%20GCC"></a><h3>Compiling on Windows Using GCC</h3><p> |
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The commands for gcc on windows are the same as above but you may also have to link |
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(via the -l option) to the following libraries: gdi32, comctl32, user32, winmm, ws2_32, or imm32. |
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</p><a name="Compiling%20on%20Windows%20Using%20Visual%20Studio%202015%20or%20Newer"></a><h3>Compiling on Windows Using Visual Studio 2015 or Newer</h3><p> |
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All you need to do is create an empty console project. Then add dlib/all/source.cpp to it and add the |
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folder containing the dlib folder to the #include search path. Then you can compile any example program |
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by adding it to your project. |
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</p><p> |
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Again, note that dlib will only be able to work with jpeg and png files if you link |
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in libjpeg and libpng. In Visual Studio, the easiest way to do this is to add all the |
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libjpeg, libpng, and zlib source files in the dlib/external folder into your project and also define the |
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DLIB_PNG_SUPPORT and DLIB_JPEG_SUPPORT preprocessor directives. If you don't know |
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how to configure Visual Studio then you should use CMake as shown above since it will |
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take care of everything automatically. |
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</p><br><a name="Installing%20dlib%20as%20a%20precompiled%20library"></a><h2>Installing dlib as a precompiled library</h2><p> |
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Dlib's cmake scripts contain the standard install target. So you |
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can use CMake to install dlib system wide as a precompiled static or |
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shared library just like you would any other C++ library. |
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However, most users should use CMake as described at the top of this |
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page (specifically as shown in the <a href="examples/CMakeLists.txt.html">examples project</a>) since |
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that's the simplest method. In particular, it allows you to turn |
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dlib's debugging modes on and off whenever you want, which is |
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something you really should use since dlib's debugging modes are one |
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of its strongest features. |
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</p><p> |
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We should also make a special note of the problems associated with |
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using precompiled C++ libraries with Visual Studio. <b>The TLDR is |
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that you should not use precompiled libraries (i.e. .lib files) |
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with Visual Studio unless you really know what you are doing.</b> |
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This is not a dlib limitation. It has nothing to do with dlib. |
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It's just how Visual Studio works. Please do not ask me about it. |
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If you want to understand this you should read the Visual Studio |
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documentation and <a href="http://siomsystems.com/mixing-visual-studio-versions/">this excellent overview</a> in particular. |
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</p><p> |
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However, for the lazy, I'll summarize the issue with Visual Studio here. |
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The problem is that Visual Studio has multiple incompatible |
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runtimes and it is illegal to mix object code compiled with |
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different runtimes in a single application. For example, if you |
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compile a C++ library in Visual Studio's "Release" mode then it is |
|
illegal to use in an application compiled in Visual Studio's |
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"Debug" mode. |
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<p></p> |
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This is made especially bad since each version of |
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Visual Studio contains its own set of runtimes, at least |
|
8 different runtimes per each version of Visual Studio, and all of |
|
them are incompatible with each other. Most Visual Studio users |
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seem to be completely unaware of this, many who contact me demonstrably |
|
do not even understand what the words "runtime" or "object code" even |
|
refer to. So the issue of ensuring that all object code (and |
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precompiled libraries) in an application use the same runtimes |
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is made extremely difficult when using precompiled libraries. |
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However, if you just use CMake as described at the top of this |
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page then it will never be an issue, which is one of the reasons I recommend it. |
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</p><p> |
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To summarize, if you don't understand what the above paragraphs are talking |
|
about then you absolutely should not be installing dlib as a precompiled library |
|
in Visual Studio. Instead, go to the top of this page and read the instructions |
|
there. Follow those instructions, it's super easy and will Just Work. |
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</p><br><center><a name="Miscellaneous%20Preprocessor%20Directives"></a><h1>Miscellaneous Preprocessor Directives</h1></center><p> |
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In addition to the preprocessor directives mentioned above, there |
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are a few more you can supply during the build process to cause the |
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library to build in various optional ways. By default, the library |
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will always do something reasonable, but they are listed here in |
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the event that you need to use them. |
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</p><a name="ENABLE_ASSERTS"></a><a name="#define%20ENABLE_ASSERTS"></a><h3>#define ENABLE_ASSERTS</h3><p> |
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Defining this directive causes all the <a href="metaprogramming.html#DLIB_ASSERT">DLIB_ASSERT</a> macros to |
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be active. If you are using Visual Studio or CMake then ENABLE_ASSERTS will be automatically enabled |
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for you when you compile in debug mode. However, if you are using a different build system then you |
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might have to manually enable it if you want to turn the asserts on. |
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</p><a name="DLIB_ISO_CPP_ONLY"></a><a name="#define%20DLIB_ISO_CPP_ONLY"></a><h3>#define DLIB_ISO_CPP_ONLY</h3><p> |
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This is a #define directive that you can set to cause the library to exclude all non ISO C++ code (The things in the <a href="api.html">API wrappers</a> section and any objects that depend on those wrappers). |
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This is useful if you are trying to build on a system that isn't fully supported by the library or if you |
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just decide you don't want any of that stuff compiled into your program for your own reasons. |
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</p><a name="DLIB_NO_GUI_SUPPORT"></a><a name="#define%20DLIB_NO_GUI_SUPPORT"></a><h3>#define DLIB_NO_GUI_SUPPORT</h3><p> |
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This is just like the DLIB_ISO_CPP_ONLY option except that it excludes only the GUI part of the library. |
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An example of when you might want to use this would be if you don't need GUI support and you are building |
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on a UNIX platform that doesn't have the X11 headers installed. |
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</p><a name="DLIB_THREAD_POOL_TIMEOUT"></a><a name="#define%20DLIB_THREAD_POOL_TIMEOUT%20<time-in-milliseconds>"></a><h3>#define DLIB_THREAD_POOL_TIMEOUT <time-in-milliseconds></h3><p> |
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If you use dlib to create your threads then you receive the benefit of the dlib dynamic thread pool (Note that the |
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dlib::<a href="api.html#thread_pool">thread_pool</a> object is something else unrelated to this so don't confuse |
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the two). This pool |
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enables dlib to spawn new threads very rapidly since it draws threads back out of its thread pool when |
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the pool isn't empty. |
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</p><p> |
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Thus, when a thread that was created by dlib ends it actually goes back into the dlib thread pool |
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and waits DLIB_THREAD_POOL_TIMEOUT milliseconds before totally terminating and releasing its resources back |
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to the operating system. The default timeout used by this library is 30,000 milliseconds (30 seconds). You |
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may however change this to whatever you like by defining DLIB_THREAD_POOL_TIMEOUT to some new value. |
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</p></div></div></div><div id="bottom_content"></div></body></html> |
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