Opacity Handling using Qt Creator

In this post, you will learn how to change window opacity using Qt creator.

Steps:

1. Open Qt Creator Click on File from the menu and click on New File or Project…(Ctrl +  N).
2. From the left column select Application, from the middle column select Qt Widget Application.
3. Click on Choose.
4. Give a name to the project and set the path where you want to save this project files.
5. Click Next,
6. Default kits will be selected.
7. Click next.
8. Give the class name of your choice. I gave opacity.
9. Select Baseclass as QMainWindow from the dropdown list.
10. (Generate form box can be unchecked as we are not going to use it, we will be creating UI with code only).
11. Click Next
12. Click on Finish.

main.cpp doesn`t need to be modified.

Open opacity.h

and modify it as

#ifndef OPACITY_H
#define OPACITY_H

#include <QMainWindow>
#include <QDebug>
#include <QLabel>
#include <QKeyEvent>
#include <QEvent>

namespace Ui {
class Opacity;
}

class Opacity : public QMainWindow
{
    Q_OBJECT
    QLabel *lbl_opacity_val;
    QMap <int,qreal> map;
    QMap<int, qreal>::iterator itr;

public:
    explicit Opacity(QWidget *parent = nullptr);
    ~Opacity();

private:
    Ui::Opacity *ui;
    bool eventFilter(QObject*,QEvent*);
    void setOpacity(qreal);
};

#endif // OPACITY_H

Open opacity.cpp

and copy-paste below mentioned code.

Download Project files

Video

Thank you for reading.