euhat

C++ memo

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Terms,

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RTTI: Runtime Type Identification		// typeid
RAII: Resource Acquisition Is Initialization	// std::mutex

VS Code memo

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launch.json

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{
	"version": "0.2.0",
	"configurations": [
		{
			"name": "dbg a.out",
			"type": "cppdbg",
			"request": "launch",
			"program": "${workspaceRoot}/path/to/a.out",
			"args": [
				"-b",
				"sim"
			],
			"stopAtEntry": false,
			"cwd": "${workspaceRoot}/path/to/",
			"environment": [
				{
					"name": "LD_LIBRARY_PATH",
					"value": "./:${workspaceRoot}/path/to/:/usr/local/cuda-11.1/lib64"
				},
				{
					"name": "GST_DEBUG_DUMP_DOT_DIR",
					"value": "/home/work/tmp"
				}
			],
			"externalConsole": false,
			"MIMode": "gdb",
			"setupCommands": [
				{
					"description": "Enable pretty-printing for gdb",
					"text": "-enable-pretty-printing",
					"ignoreFailures": true
				}
			]
		},
		{
			"name": "C++ Attach (GDB)",
			"type": "cppdbg",
			"request": "attach",
			"targetArchitecture": "x64",
			"program": "${workspaceRoot}/path/to/a.out",
			"processId": "${command:pickProcess}"
		}
	]
}

Don't translate tab to spaces,

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File -> Preferences -> Settings -> Text Editor -> Insert Spaces / Detect Indentation

Display std::string or std::vector content

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-exec -enable-pretty-printing

Blender source memo

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#blender\source\blender\editors
ED_region_do_draw editors\screen\area.c
	outliner_main_region_draw editors\space_outliner\space_outliner.cc
		draw_outliner editors\space_outliner\outliner_draw.cc
			outliner_buttons
				UI_but_active_only editors\interface\interface.cc
					UI_but_active_only_ex
						ui_but_activate_event editors\interface\interface_handlers.c
							ui_do_button
								ui_do_but_TEX

Python Operator Precedence

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The upper operators have higher precedence than the lower.

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Grouping			()
Function call			f()
Slicing				[index:index]
Array subscription		[]
Bitwise NOT			~x
Unary plus/minus		+, -
Mul/Div/Mod			*, /, %
Add/Sub				+, -
Bitwise shift			<<, >>
Bitwise AND			&
Bitwise XOR			^
Bitwise OR			|
Relation			==, !=, >, >=, <, <=, is, is not, in, not in
				not
				and
				or
				lambda

refer to:
https://discuss.codechef.com/t/operator-precedence-table/14545

Stunning forbidden keyword about QSettings

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    QSettings cfg(CONFIG_INI_PATH, QSettings::IniFormat);
    cfg.beginGroup("general"); // <-- other keywords are all ok.
    std::string val = cfg.value("itemCount").toString().toStdString();
    int video_count = cfg.value("itemCount").toInt();
    cfg.endGroup();

'general' keyword will lead 'val' to output empty in Qt5.15.2.

Notify us socket is ready after WSAEWOULDBLOCK

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Two ways to achieve this goal:

  • Use select api.
  • Use WSAEventSelect and WSAWaitForMultipleEvents. This method is recommended, for we can add a cancellable event along with the socket for polling like GCancellable structure in glib. Cancellable architecture responds smarter than tangible waiting for the ending of sub-modules.

refer to:
gstreamer/subprojects/glib/gio/gsocket.c:g_socket_condition_timed_wait
https://blog.csdn.net/qq_30145355/article/details/78379969

Build FFMpeg in Windows

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In MSYS2 x64 bash,

pacman -S mingw-w64-x86_64-toolchain
pacman -S base-devel
pacman -S yasm nasm gcc

basedir=/d/work/open

cd ${basedir}/x264
./configure --prefix=${basedir}/x264_install --enable-static --extra-cflags="-O0 -g3" --enable-debug
make
make install

cd ${basedir}/ffmpeg
./configure --prefix=${basedir}/ffmpeg_install --enable-static --disable-shared --extra-cflags=-I${basedir}/x264_install/include --extra-ldflags=-L${basedir}/x264_install/lib
make
make install

refer to:
http://events.jianshu.io/p/53ecc4dbe7d0
https://www.videolan.org/developers/x264.html
http://ffmpeg.org/download.html
https://www.msys2.org/
https://git-scm.com/download/win

Perspectively transform points

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After we get the transformation matrix 'trans_mat' from the 'getPerspectiveTransform', we can transform a point in this way

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        cv::Point2f src = cv::Point2f(123, 456);
        std::vector<cv::Point2f> in_pts, out_pts;
        in_pts.push_back(src);
        cv::perspectiveTransform(in_pts, out_pts, trans_mat);
        cv::Point2f dst = out_pts.front();

refer to:
https://blog.csdn.net/xiaowei_cqu/article/details/26478135