Creating and saving a picture from data stored in std::vector

Question

Is there a method in Qt with which one can easily create a picture based on data stored in a std::vector? I mean that in the vector there are colors for each QPointF points of a QWidget on which I'm painting with QPainter, but I don't only need to draw this picture on the QWidget using the colors in the vector, but to save it as a picture too.

Answer 1

If you know the initial dimensions of your image and have a vector with the color information, you can do the following:

// Image dimensions.
const int width = 2;
const int height = 2;
// Color information: red, green, blue, black pixels
unsigned int colorArray[width * height] =
                    {qRgb(255, 0, 0), qRgb(0, 255, 0), qRgb(0, 0, 255), qRgb(0, 0, 0)};
// Initialize the vector
std::vector<unsigned int> colors(colorArray, colorArray + width * height);

// Create new image with the same dimensions.
QImage img(width, height, QImage::Format_ARGB32);
// Set the pixel colors from the vector.
for (int row = 0; row < height; row++) {
    for (int col = 0; col < width; col++) {
        img.setPixel(row, col, colors[row * width + col]);
    }
}
// Save the resulting image.
img.save("test.png");