05-property-bindings/main.cpp

An example of how to use makeBoundProperty() to create a KDBindings::Property that is automatically updated once any of its inputs change.

The output of this example is:

The initial size of the image = 1920000 bytes
The new size of the image = 4608000 bytes
The new size of the image = 8294400 bytes

/*
  This file is part of KDBindings.
 
  SPDX-FileCopyrightText: 2021 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
  Author: Sean Harmer <sean.harmer@kdab.com>
 
  SPDX-License-Identifier: MIT
 
  Contact KDAB at <info@kdab.com> for commercial licensing options.
*/
 
#include <kdbindings/binding.h>
#include <kdbindings/property.h>
#include <kdbindings/signal.h>
 
#include <iostream>
 
using namespace KDBindings;
 
class Image
{
public:
    const int bytesPerPixel = 4;
    Property<int> width{ 800 };
    Property<int> height{ 600 };
    const Property<int> byteSize = makeBoundProperty(bytesPerPixel * width * height);
};
 
int main()
{
    Image img;
    std::cout << "The initial size of the image = " << img.byteSize.get() << " bytes" << std::endl;
 
    (void)img.byteSize.valueChanged().connect([](const int &newValue) {
        std::cout << "The new size of the image = " << newValue << " bytes" << std::endl;
    });
 
    img.width = 1920;
    img.height = 1080;
 
    return 0;
}