qt tutorial c

as follows: click the "Open" button to Open a dialog box. Select an Image and load it with a hidden Image object. After loading, the Canvas object is triggered to draw an Image; when you drag with your fingers (or press the left mouse button), the center of the selected box is moved with your fingers, and the image in the box is normal brightness. When you raise your finger, the Operation menu is displayed, if "Save" is selected, an image of the selected area is saved to the file through a hidd

internally calls ColorDialog to select the color.ColorDialog is created dynamically using Qt.createqmlobject (), please refer to the "Qt Quick component and Object dynamic creation specific explanation" for specific usage methods.After the user has selected a color. The fill color of the rectangle on the top half of the button changes, and the colorpicked () signal is emitted at the same time. Assuming the user cancels the selection, the default colo

Starting from a memory leak?Very simple entry procedure, you should be familiar with it ^_^#include In the context of the delete from Qt, we mentioned that the program has a memory leak (the representation is that the destructor is not called), and there are three workarounds: Assigning a Label object to a stack instead of a heap Set tag bit qt::wa_deleteonclose for label Call Delete yourse

When using QT designer to design the form interface, we can use the form control in the widget box to easily draw the interface, such as dragging a button and a text editor. Although the controls in QT designer can meet most of our needs, sometimes some special requirements are also generated. For example, in an input box, we need to enter the longitude and latitude, in this case, there are two input method

QT Portal access: Any QT user can view this feature when you are a group master or group Administrator of one or more groups, you can turn on/off the QT portal for the corresponding group Introduction to the function of the QT Portal: It is a quick access to the QT room. In

Many C/C ++ beginners often make the mistake of using malloc and new to allocate a piece of memory but forget to release it, resulting in Memory leakage. The QT object model provides a parent-child relationship between QT objects. When many objects establish this parent-child relationship in a certain order, they are organized into a tree. When deleting a parent object, QT's object model ensures that all it

The year may almost passed, and the students started school. I think the campus will be a lot more lively, and the CSDN will also be a bit lively. The Mid-Autumn Festival has passed, and there are still many unfinished moon cakes around you. Therefore, you can eat them as breakfast every morning, hoping they will not be wasted. This month has many things and is very busy, so it is so late that I can take the time to write an article. This time I introduced Qt's support for OpenGL. I attended the

Transferred from: http://www.stardrad.com/blog/qt-5%E7%A8%8B%E5%BA%8F%E5%9C%A8windows%E4%B8%8A%E7%9A%84%E5%8F%91%E5%B8%83/http://blog.163.com/[email protected]/blog/static/1582209320132291718389/Recently made a QT program, but the release process is difficult, because QT5 has a lot of DLLs, the following two details the QT DLL dependency library, and how to query

All rights reserved Foruok. Please specify the source (Http://blog.csdn.net/foruok) If you wish to reprint. Assuming that you performed the Qt on Android app on the target Android device, you might want to see the log information for the program output. There are ADB tools in the Android SDK, and when you are connected to a target device, you can use ADB logcat to view the log of the app output on your Android device.Let's introduce the use of ADB too

QT Development (46)--the basis ofQT database programmingFirst,Introduction to the Qt SQL module 1. QtSQLModuleIntroductionQT provides support for SQL database through QT SQL Module , andthe API in QT SQL module is divided into three layers: drive layer,SQL interface layer, user interface layer.If you want to use Classe

I hope that the contents of the event loop in the previous chapter have not knocked you around. This chapter will go back to the relevant content on the thread. In the previous chapters we learned about QThread the simple use of classes. However, QT provides a thread-specific class that is not so simple, otherwise we do not need to repeatedly emphasize the use of threads must be extremely careful, a careless will fall into the trap.In fact,

QT Development (15)--qt coordinate system Introduction ofQT coordinate system Every window in QT has a coordinate system, the upper left corner of the default window is the origin of the coordinates, then the horizontal to the right, then the horizontal to the left, and then the vertical downward, and then vertically up and down in turn. The origin point is the (

"QT is not correctly installed, Run make install" Solution for "invalid QT version" Well, if you encounter this situation, I believe your QT version is copied. This is also the case. I tried to copy the QT version to another path, but I found that qtcreator could not recognize it. However, the following methods can hel

QT is a cross-platform, C + + graphical user interface application framework. It gives application developers the functionality they need to build an art-level graphical user interface. QT is completely object-oriented, easy to scale, and allows for true component programming.QT Creator cross-platform Qt IDE, Qt Creato

I. INTRODUCTION of QTQt is a cross-platform C + + graphical user Interface application Development framework developed by caused by parity technology in 1991. It can either develop GUI programs or be used to develop non-GUI programs, such as console tools and servers. QT is an object-oriented framework that uses special code generation extensions (called Meta Object Compiler, MOC) and some macros that are easy to extend and allow for component program

In Qt, the pure C ++ project is released as a dll method (detailed steps). qt detailed steps Directory General Creation Method Export methods and call methods of common functions Methods and call methods for exporting classes and their member functions As we all know, we canClass and FunctionExport to form a. dll file for use by other programs. The following describes how to use it in the

Qt entry routine (1), qt entry routine The following uses "Hello Qt" as an example to briefly introduce how to build a Qt project. 1 QLabel routine 1.1 Hello Qt #1 and #2 indicate the contained header file; #6. Create an Instance Object of the QApplication class, and enable

Play with Qt (1) and play with Qt ( Recently I have been reading some things about the game engine. I have several small game ideas. In fact, the implementation is quite troublesome. I want to find a game engine to see if it can be coded. A lot of 2D engines were found after the revolution, among which the domestic cocos2dx seems to be widely used, but many people disagree with this. As a result, I decided

Obj-c in the eyes of qt/c++ developersFor the first time we defined iOS apps, I had to learn objective-c related grammar and knowledge for developers from Qt/c++.To make it easier for readers to understand the content of this blog, I'll describe a lot of what I've learned. This will be many other brain dumps rather than a single tutorialSo I still hope it will be very helpful for you, I will first write the

BrieflyIn debugging the program, sometimes need to debug into Qt source code, which not only helps us understand the internal implementation mechanism, but also to solve some hidden problems are very helpful.All know F11 is "single Step into", but in the process of debugging, press F11 but can not enter. Some people say that the need to statically compile Qt can, in fact, just need a few simple configuratio