Sept. 14, 2015, 12:36 p.m.


QGraphicsItem, QGraphicsItem example, QGraphicsItem Qt, QGraphicsItem слот, Qt, множественное наследование

Let's talk a little about the inheritance from QGraphicsItem and application of signals and slots system in interaction with graphical objects on the graphic scene QGraphicsScene . The objective of this lesson is to create an application that on the graphic scene to be displayed object class QGraphicsItem , by clicking on which will appear QMessageBox dialog box signaling the event clicking on the graphic.

The project structure to work with QGraphicsItem

The structure of the project include:

  • - profile;
  • mainwindow.h - header file of the main application window;
  • mainwindow.cpp - file source code of the main application window;
  • mypoint.h - header code of the class inherited from QGraphicsItem;
  • mypoint.cpp - respectively, the source code;
  • main.cpp - master file from which you start the application, in the classroom is not considered as created by default;
  • mainwindow.ui - design file of the main window.
Sept. 12, 2015, 10:05 p.m.


vlc, mkv, avi, конвертирование

"Как конвертировать mkv в avi?" - казалось бы заезженная тема, но и тут можно кое-что добавить. Вы не устали от того, что когда делаешь подобный запрос, то поисковики вываливают целые пачки неизвестно какого программного обеспечения, которое ещё ко всему предлагает установить дополнительный софт, сходит на какой-нибудь сайт, или установить что-нибудь вроде яндекс-бара. Лично я от этого уже устал. Поэтому хотелось бы предложить простой вариант, как конвертировать видео из формата .mkv в .avi, .webm, .mp4 и т.д. А также наоборот.

Этим вариантом является VLC-плеер , который справляется с этой задачей на отлично и при этом не имеет выше перечисленных минусов. А также обладает широким функционалом и замечательной поддержкой различный видео и аудио кодеков.

А теперь приступим к пошаговому руководству по конвертированию видео.

Как конвертировать mkv в avi

Шаг Первый

Для начала необходимо скачать и установить VLC-плеер. Скачивание производим с официального сайта, представленного на ссылке выше. Устанавливаем и запускаем.

Sept. 12, 2015, 12:12 p.m.


QGraphicsScene, QGraphicsScene пример, Qt, QGraphicsScene Qt5, QGraphicsScene example

From this article we begin to explore the Qt graphic libraries, to be exact, QGraphicsScene. This class provides the functionality to manage a large number of 2D objects. QGraphicsScene set to QGraphicsView.

We describe the features that need to be implemented in our application:

  • Adding a graphic scene in QGraphicsView.
  • Rendering the graphics objects on the two stage via lines, namely a rectangle and a square.
  • Dynamic resizing of graphic scenes, depending on changes QGraphicsView sizes.
  • Dynamically changing objects on the graphic scene, depending on the size of the graphic scene.

Project Structure for QGraphicsScene

Project Structure for QGraphicsScene

By the project structure "Default" added another class MyGraphicView .

The fact is that for the convenience of working with QGraphicsScene it was decided to create a class that inherits from QGraphicsView already inside to operate graphical scene and its objects.

Sept. 11, 2015, 6 a.m.

Fiber Optic Transmission Lines

fiber, волс, OTDR, рефлектометр

Pulse reflectometers OTDR (Optical Time Domain Reflectometer) operate on a similar principle, which is used in reflectometers for testing electrical cables. Reflectometer submits a powerful light pulse into the optical fiber, as well as an electrical reflectometer submits powerful probe pulse in the electrical cable. At the same time it carried out the measurement of power and pulse delay time that is returned back to the OTDR. The difference between the electric OTDR is that the metallic conductor returns only pulses that are reflected by strong inhomogeneities in the cable, that is, from the location of cable deformation, while the optical fiber return pulses are not only places of large irregularities, but also due to the Rayleigh effect scattering. Rayleigh scattering occurs due to changes in the refractive index of the optical fiber when it is stretched during manufacture. Such inhomogeneities arising in the manufacture of the optical fiber is extremely small, but have some effect on the scattering of the light beam that is scattered by these irregularities in all directions, including back to the OTDR.

Passage of the light beam from the optical fiber OTDR
Sept. 9, 2015, 5:07 a.m.

Data Transmission Technologies

FDDI, Token Ring, токен

Token Ring and FDDI technologies have significantly more complex implementation than the same Ethernet technology on a shared data environment. Much of this complexity was due to the fact that the developers have tried to improve the effectiveness of the technology: to increase fault tolerance, make the environment predictable design priority service specific data packets, such as voice traffic, which is sensitive to delays. In this they succeeded, for example, a more advanced version of Token Ring, FDDI namely for a long time been used as a campus backbone networks of enterprises.

Sept. 8, 2015, 4:59 a.m.

Data Transmission Technologies

SDH, STM-RR, радиорелейная система, РРЛ

SDH technology is not limited to use as a transmission medium, only the fiber-optic cable (FOC). Also, widespread use of radio for the organization of radio relay line SDH networks. Relay channels have great promise for replacing relay RDN systems, the possibility of more effective interaction with the existing SDH systems, optimization of networks SDH circuits in the complex for laying FOC areas of organization of alternative SDH signal transduction pathways and backup of the existing fiber-optic SDH lines.

Manufacturers MRR


  1. Microwave radio relay system SDH «96xx», which includes the following modifications:
    1. LH - system level STM-1 with long inter-station sections;
    2. UH - system level STM-1 for use in an urban environment;
    3. LM - system level OC-1 for use with the access networks;
    4. UM - system level OC-1 for use in urban environments.
  2. The transport relay system "9667 TH» STM-1 level;

ECI: radio-relay systems SDH «SDH-Radio» level STM-1 and STM-4;

NEC: SDH radio relay signaling system level STM-1 signals or PDH E4.

Sept. 7, 2015, 5:26 a.m.

Data Transmission Technologies

dwdm, OTN, стек протоколов

DWDM networks are not initially digital networks because they provide users with only a few spectral channels, which are only data transmission medium. Also originally DWDM multiplexers perform SDH multiplexer functionality, in consequence of which inherited a number of shortcomings that became apparent with increasing data rates.

Optical Transport Network (OTN)

Disadvantages DWDM systems inherited from SDH systems:

  • Insufficient effectiveness of FEC codes, taken as SDH standard. This prevents further increase the spectral density of channels in DWDM multiplexers.
  • Too "small" switching units for backbone networks operating at speeds of 10 and 40 Gb / s. Even the maximum size of the containers VC-4 (140 Mbit / s) are large enough for the unit of STM-multiplexer 256, which must commute up to 256 containers for each of its ports.
  • Not taken into account peculiarities of different types of traffic. SDH technology developers took into account only the voice traffic.

To overcome these drawbacks, a new technology aimed optical transport networks (Optical Transport Network, OTN)

Sept. 6, 2015, 5:54 a.m.

Fiber Optic Transmission Lines

fiber, волс, измерения, оптический тестер

There are two methods of measuring the loss in the optical fibers which, in accordance with G. 651 and G. 652, is considered the reference - fiber breakup method and the method of insertion loss. The loss measurements are made by means of optical testers. In the method of fiber breakup P1 measured power (in dBm), passed through the fiber. The fiber breaks off at a distance of about two meters away from the injection point and measured radiation power P2 (dBm), passed through a short section of the remaining fiber. The value of loss in the fiber is determined as the difference between A (dB) = P1 (dBm) - P2 (dBm)

Measurement of losses by the breakup of fiber
Sept. 5, 2015, 12:43 p.m.

Data Transmission Technologies

DELL, Route-Map

VLAN Traffic Redirection

Passing traffic without PBR

Example. Comparison of packets from one VLAN, then routing the output of another VLAN to their destination.

Remote server X, Y, Z hourly cached on the local server A, B, C. Members VLAN 10 use locally cached server 99% of the time, but occasionally need access to current data from the server X, Y, Z, which are located in another city . Traffic on the road between the local and remote servers are often higher than 100% of the bandwidth. To minimize delays in traffic between VLAN 10 user stations and remote servers are configured PBR to avoid bottlenecks.

Sept. 4, 2015, 11:54 a.m.


qcheckbox, qcheckbox center, Qt, QTableWidget

One of the first problems in working with The QTableWidget , which are trying to solve, start to work with this widget - setting QCheckBox in the middle of the cell. The fact that the standard check box in QTableWidget checkbox attached to the left edge of the cell, while the right side is given for explanatory text. But the text may not be, but the area still remains. But at the same time it allows you to set QTableWidget in his cell widgets, which we use to solve this problem.

This article is an extension of a previous article on working with QTableWidget , therefore, to see the full code of the project I encourage you also to the article. This article provides only the code necessary to solve the problem.

Project Structure for QCheckBox center

Project structure remains the same as in the previous article .


The form for the application window QCheckBox

In the main application will be placed:

  • QTableWidget
  • QLable

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Thank you, Evgenii Legotckoi

Feb. 26, 2020, 9:48 p.m.

C++ - Test 001. The first program and data types

  • Result:60points,
  • Rating points-1
Feb. 25, 2020, 5:40 a.m.

C++ - Test 005. Structures and Classes

  • Result:83points,
  • Rating points4
Feb. 24, 2020, 2:47 p.m.
Dmitrij Zlobin

C ++ - Test 004. Pointers, Arrays and Loops

  • Result:40points,
  • Rating points-8
Last comments
Feb. 24, 2020, 3:54 a.m.
Evgenij Legotskoj

Добрый день. Там будет url, на который указывает ссылка тега a в пагинаторе, если правильно помню )) Написал этот код и забыл.
Feb. 24, 2020, 12:37 a.m.

Евгений Здравствуйте! Не могу понять вот эту часть кода: url: jQuery(this).attr('action') наверное здесь должен быть путь к url, тогда 'action' на какой url указывает?
Feb. 17, 2020, 3:22 a.m.
Evgenij Legotskoj

Добрый день. Это кастомный тег, помещается в файл, который находится в каталоге templatetags myapp/ templatetags/
Feb. 16, 2020, 1:36 p.m.

Добрый вечер! Монжно по подробней о теге get_companion? ссылка не работает.
Now discuss on the forum
Feb. 26, 2020, 6:13 p.m.

Добавил в папку проекта следующие либы, ничего не изменилось. Надо что-то где-то дополнительно прописывать или нет? Я просто не очень понимаю...
Feb. 25, 2020, 8:06 a.m.

Feb. 24, 2020, 12:04 p.m.
Evgenij Legotskoj

Добрый день. Вот пример с дружественного ресурса с движением камеры
Feb. 24, 2020, 6:29 a.m.
Evgenij Legotskoj

Qt не предоставляет функционала по запросу root прав во время выполнения программы. Поэтому нужно использовать платформозависимый функционал, для Linux это будет выглядеть так: #include…
Feb. 24, 2020, 3:47 a.m.
Evgenij Legotskoj

Добрый день. Что означает клиентская область? Это изображение? Вам нужно распознавать символы текста или всё-таки пользователь будет вводить текст с клавиатуры, просто в любом месте "абстр…
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