SEARCH KEYWORD -- Weak reference


  Save QWidget as image

Qt library is an excellent GUI library for C++ programmers developed by Nokia and now is an open source project. Often, we may use QPainter to draw strings, lines or images on a QWidget. We can override the QWidget's paintEvent() method when we want to use QPianter object to draw something on a QWidget. If we want to save the items drawn on QWidget as image for later reference, what can we do? We can save a QWidget as an image. Here is the code for achieving this: QPixmap pixmap(this->size())...

   Qt,C++,QWidget,Image     2012-08-19 12:01:18

  The Strange Behavior of the void Type in TypeScript

Preface In TypeScript (TS), there is a type called void. It represents "nothing" but it's important to note that it's not the same as "nothing" in JavaScript(JS). Typically, void is used to declare the return type of functions. Although you can declare a variable as void, we generally don't do this because it serves no meaningful purpose. Let's explore why in the examples below. The void Type Declaring a Variable as void let name: void; // Declare a variable `name` with type `void`. name = 'nan...

   TYPESCRIPT,JAVASCRIPT,VOID,TYPE     2024-09-13 23:44:26

  Facebook : App Center is more suitable for developers

Facebook recently announced that they will release their own app store named App Center. It will be released in a few weeks. At the same time, Facebook also released the introduction page of the App Center, it introduces to developers the process of app submission and the standards of app approval.Facebook allows developer to provide charged apps via App Center. Since it has over 900 million active users globally, so many developers are willing to develop apps on this platform. Facebook will dec...

   Facebook,App Center,Introduction     2012-05-13 01:03:56

  A simple example on implementing progress bar in GoLang

Sometimes when handling a long running process, there would be need to track the progress so that people know something is still running instead of doubting something goes wrong. In this case, a progress bar which indicates the current status and progress would be desired. This post will show an example on how to implement progress bar using GoLang. Let's take a look at the final outcome first before jumping into the implementation detail. The key in the implementation is actually just the \r ...

   TUTORIAL,EXAMPLE,GOLANG,PROGRESS BAR     2020-08-08 23:53:15

  Those famous Emacs users

I don't think using Emacs can improve one's programming skills, I don't think some famous people used Emacs before can provide something, either. But these famous people encouraged me to learn Emacs when I wanted to give it up. Here I created a list of famous Emacs users. Most of people in this list are not famous because they developed or used Emacs, but they are famous and also use Emacs. Joe Armstrong -- Erlang's author In The Setup, Joe mentioned that "I write books using XML markup in emacs...

   Emacs,History     2013-07-28 21:36:09

  Recursive class initialization in Java

When a Java class is referenced and initialized, it has to go through the loading and linking first. Once the loading and linking complete successfully. The class will be initialized. The static variables and constant variables will be initialized during this process. Once the class is initialized, it is ready for use. If when class A is initialized and it is referencing a class B, the class B will also get initialized. But what will happen if class B is referencing class A as well? This is call...

   Java,JVM,class initialization,static final     2015-04-15 21:04:29

  How to upload file to FTP server using C# Asp.Net

This post is about uploading files to FTP server in asp.net development. You will learn step-by-step to upload files programmatically to FTP web server. All the examples shared in this post are intended by professionals to make you learn about the subject Here, I will explain you an example of Uploading Files to FTP Server programmatically in C#.Net. Using this approach, the Files will be programmatically uploaded to FTP Web Server. For example, I will create a function in which we will simply p...

   ASP.NET,DEVELOPMENT     2016-06-24 08:45:37

  Understanding GoLang interface

If goroutine and channel are considered as the foundation for GoLang concurrency, interface would be the key for data types in GoLang. In practical Go programming, almost all data types are built/used around interfaces, interface is the core of GoLang data structures. Go is not a typical OOP language, it has no class and inheritance concept syntactically. But it doesn't mean that there cannot be polymorphism in GoLang. Because of interface, it achieves the same polymorphism effect as in C++, tho...

   INTERFACE,GOLANG     2021-05-15 04:16:42

  The hidden risk of passing slice as function parameter

In Go's source code or other open source libraries, there are lots of cases where a slice pointer is passed to function instead of slice itself. This brings up a doubt why not passing slice directly as its internal is backed by an array pointer to point to underlying data? For example, in log package, the formatHeader function takes a parameter buf as type *[]byte instead of []byte. func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {} Let's understand the r...

   GOLANG,SLICE,SLICE POINTER     2020-12-13 06:11:14

  Create temp file in Bash using mktemp and trap

When working on Linux Bash, sometimes there is need to create temporary file. A common way of creating temp file on Linux is creating some file in /tmp directory. However there is security risk when creating temp file in /tmp directory. This post will show how to securely create temp file in Linux Bash. When creating file in /tmp directory, there are some security risks. This directory can be accessed by any user on the system, any user can write data into this directory as well. The files creat...

   LINUX,MKTEMP,TRAP,TEMP FILE     2019-12-30 23:28:23

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