Qt开发笔记
该文档是关于Qt开发的笔记，包含C/C++和QT开发的技术分享，已于2024年1月20日发布。
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Qt开发笔记
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Language Translation
Qt Framework
User Interface
To translate language for all interfaces in a Qt application, create a QAction in MainWindow to change the language, implement a slot to load the translator, and ensure the
changeEvent method in both MainWindow and SettingDialog is set up to handle QEvent::LanguageChange. This allows automatic updates of the UI when the language changes, simplifying the code and ensuring consistent handling across the application.Jan 20, 2024 01:42 AM
FileTransfer
QtNetworking
HttpPost
To transfer a file using HTTP POST in Qt, utilize
QNetworkAccessManager and QNetworkRequest. The provided code demonstrates creating a multipart/form-data request, reading a local file, and sending it to a specified upload URL. Ensure to replace the local file path and upload URL as needed. The response is handled by connecting to the finished signal of QNetworkReply, allowing for error checking and response processing.Jan 20, 2024 01:42 AM
Software Update
Release Notes
User Experience
MegaApp 2.0 has been released with new features including a Collaboration Suite and Dark Mode, improvements such as 50% faster performance and a revamped UI/UX, and several bug fixes. Updated documentation is available, and users are encouraged to upgrade and provide feedback.
Jan 20, 2024 01:42 AM
Cryptography
C++ Programming
OpenSSL Library
The document provides an example of RSA encryption and decryption in C++ using the OpenSSL library. It demonstrates generating an RSA key pair, encrypting a QString, and then decrypting it back to QString. The code includes necessary functions and compilation instructions, emphasizing secure practices in cryptography.
Jan 20, 2024 01:42 AM
Encryption
Python
GUI Development
The document outlines a Python application that manages Wi-Fi connections and file synchronization using SSH. It includes methods for initializing Wi-Fi, scanning available networks, connecting to a selected network, and transferring files between a local machine and a remote device. The application utilizes PyQt for the GUI and paramiko for SSH operations, handling exceptions and updating the user interface accordingly.
Jan 20, 2024 01:42 AM
RemoteTerminalOutput
QtApplication
SSHConnection
To redirect continuous terminal output from a remote machine to a local Qt UI application, establish an SSH connection using
QProcess. Set up SSH with keys for password-less authentication, create a UI with a QTextEdit for output display, and a button to start the SSH session. The application reads and appends the remote output to the text edit area. Additional considerations include error handling and using dedicated libraries for more robust implementations.Jan 20, 2024 01:42 AM
Qt Framework
Data Validation
Error Handling
The document includes a code snippet that checks if a line contains any characters other than digits and commas using a regular expression. If invalid characters are found, it displays an error message and updates the status bar to indicate the file failed to load.
Jan 20, 2024 01:42 AM
Qt Development
Programming Concepts
Software Development
The document provides basic knowledge on Qt development, including online installation using domestic mirrors, data transfer between QDialog and the main window, differences between Debug and Release versions of Qt dynamic libraries, and using QEventLoop with QTimer for timed signal handling.
Jan 20, 2024 01:42 AM
File Transfer
Qt Programming
SSH Protocol
To transfer a file to a remote computer using SSH in Qt, utilize the
QProcess class to execute the scp command. The provided code demonstrates how to set the local and remote file paths, start the process, and check the exit code to confirm successful file transfer. Ensure SSH tools are installed and access is properly configured.Jan 20, 2024 01:42 AM
QtNetworking
JSONHandling
NetworkRequests
To post JSON data using the Qt library, utilize
QNetworkAccessManager and QNetworkRequest. Create a JSON object, convert it to a JSON document, and serialize it. Set the request URL and content type to application/json, then perform the POST request. Handle the response by checking for errors and processing the data. Ensure to include necessary Qt modules and manage additional requirements like error handling and authentication in real applications.Jan 20, 2024 01:42 AM
File Handling
Qt Programming
User Interface
The document provides a sample C++ code using Qt to open a file save dialog when a button is clicked. It demonstrates creating a
QPushButton that triggers QFileDialog::getSaveFileName() to allow users to select a file path. The selected path is displayed using qDebug(), and instructions are given for integrating the code into a Qt Widgets Application project.Jan 20, 2024 01:42 AM
WiFi Network Management
Qt Application Development
Network Configuration
The document provides a sample Qt application code for selecting a Wi-Fi network card and its associated hotspots using
QNetworkInterface and QNetworkConfigurationManager. It creates a UI with two combo boxes: one for network cards and another for hotspots, populating them based on available interfaces and configurations. The application updates the hotspot options dynamically based on the selected network card and handles configuration changes.Jan 20, 2024 01:42 AM
Qt Checkbox Functionality
User Interface Interaction
C++ Code Example
The document provides a C++ code snippet to create a GUI application using Qt, featuring a checkbox that is initially selected, enabling a text input field and a button. The checkbox's state controls the enabled status of the text input and button, allowing for dynamic interaction.
Jan 20, 2024 01:42 AM
Print SSH Output
Qt UI Integration
Signal Slot Mechanism
To print SSH output in a Qt UI interface, capture command output using libssh2 and utilize Qt's signal and slot mechanism. Create a signal in the FileTransfer class,
sshOutputReceived(QString output), and emit it after reading data from the remote file. Connect this signal to a slot in the MainWindow class to append the output to a QTextEdit widget, effectively displaying the SSH output in the UI.Jan 20, 2024 01:42 AM
Mutex Management
C++ Programming
Resource Management
To manage a mutex in C++, use std::lock_guard for automatic locking and unlocking when it goes out of scope. If manual control over the lock's lifetime is needed, use std::unique_lock, which allows for manual locking, unlocking, and even early destruction of the lock object. However, manually calling the destructor is unusual and should be done with caution to avoid undefined behavior.
Jan 20, 2024 01:42 AM
Multilingual Support
Qt Development
Translation Process
To generate different languages for a Qt UI interface, mark strings for translation using the
tr() function, create translation files with lupdate, translate the strings in Qt Linguist, mark translations as finished, compile .ts files into .qm files using lrelease, load the translation files in your application, and test the translations in each supported language.Jan 20, 2024 01:42 AM
Undefined Behavior
Memory Representation
Binary Compatibility
Passing an
int to a function expecting a double that was previously compiled for a float can lead to unexpected results, such as interpreting 850 as 620. This occurs due to implicit conversion and memory misinterpretation, highlighting the importance of binary compatibility and recompiling applications when changing function signatures in a DLL.Jan 20, 2024 01:42 AM
C++ Programming
Data Structures
Code Examples
In C++, you can iterate through a vector using several methods: a simple for loop, a range-based for loop (C++11 and later), iterators, iterators with the auto keyword, and a range-based for loop with auto. The choice of method depends on personal preference and C++ version, with the range-based for loop using auto being favored for its simplicity and readability.
Jan 20, 2024 01:42 AM
Cryptography
OpenSSL
Qt Framework
The document provides a C++ example of using the OpenSSL library to encrypt and decrypt a QString using AES in CBC mode. It details the conversion of QString to a standard string for encryption, the initialization of the AES key and IV, and the process of encrypting and decrypting data. It emphasizes the importance of secure key management and notes that the example does not handle padding for input strings that are not multiples of the AES block size.
Jan 20, 2024 01:42 AM
ProgressBarImplementation
QtProgramming
FileTransfer
To implement a progress bar in Qt for file transfers, add a
QProgressBar to the UI, update its value as files are transferred, and use a signal/slot mechanism to handle updates from a worker thread. Ensure to reset the progress bar upon completion and handle errors appropriately during transfers to provide users with visual feedback on the transfer status.Jan 20, 2024 01:42 AM
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