Make a palette image from palette data

[Kris Revi]

am i doing something wrong here?

QImage MainWindow::createPaletteImage(QJsonArray jsonArr)
{
    int width = 500;
    int height = 26;
    QImage image(width, height, QImage::Format_RGB32);
    image.fill(Qt::white);

    QPainter painter(&image);

    int amountPoint;
    amountPoint = jsonArr.count()/4;
    float p=0,s=1.0/(amountPoint-1);
    QLinearGradient gradient = QLinearGradient(0,0, rect().width(), 0);

    for (int i = 0; i < amountPoint; i++)
    {
        int pos = jsonArr.at(i).toInt();
        int r = jsonArr.at(i+1).toInt();
        int g = jsonArr.at(i+2).toInt();
        int b = jsonArr.at(i+3).toInt();

        gradient.setColorAt(p, QColor(r,g,b));
    }
    return image;
}

[Christian Ehrlicher]

@Kris-Revi said in Make a palette image from palette data:

int pos = jsonArr.at(i).toInt();
gradient.setColorAt(p, QColor(r,g,b));

Apart from the really strange idea to store a image in such an extensive way you want 'pos' in the second call.

[Kris Revi]

@Christian-Ehrlicher said in Make a palette image from palette data:

you want 'pos' in the second call.

        int pos = jsonArr.at(i).toInt();
        int r = jsonArr.at(i+1).toInt();
        int g = jsonArr.at(i+2).toInt();
        int b = jsonArr.at(i+3).toInt();

        gradient.setColorAt(pos, QColor(r,g,b));

huh like so? :S

[mpergand]

for(int p=0; p<amountPoint; p++)
        {
            int pos=jsonArr[p*4];
            int r=jsonArr[p*4+1];
            int g=jsonArr[p*4+2];
            int b=jsonArr[p*4+3];
            
            gradient.setColorAt(pos/255.0, QColor(r,g,b));
        }
       

[Kris Revi]

@mpergand

QImage MainWindow::createPaletteImage(QJsonArray jsonArr)
{
    int width = 500;
    int height = 26;
    QImage image(width, height, QImage::Format_RGB32);
    image.fill(Qt::white);

    QPainter painter(&image);

    int amountPoint;
    amountPoint = jsonArr.count()/4;
    float p=0,s=1.0/(amountPoint-1);
    QLinearGradient gradient = QLinearGradient(0,0, rect().width(), 0);

    for (int p = 0; p < amountPoint; p++)
    {
        int pos=jsonArr[p*4].toInt();
        int r=jsonArr[p*4+1].toInt();
        int g=jsonArr[p*4+2].toInt();
        int b=jsonArr[p*4+3].toInt();

        gradient.setColorAt(pos/255.0, QColor(r,g,b));
    }
    painter.fillRect(rect(),QBrush(gradient));
    return image;
}

produces

[mpergand]

Check the values in the debugger.

[Kris Revi]

@mpergand all i got is

POS :  0
RGB :  255 0 0
GRAD :  QBrush(QColor(Invalid),LinearGradientPattern)
POS :  0.12549
RGB :  171 85 0
GRAD :  QBrush(QColor(Invalid),LinearGradientPattern)
POS :  0.25098
RGB :  171 171 0
GRAD :  QBrush(QColor(Invalid),LinearGradientPattern)
POS :  0.376471
RGB :  0 255 0
GRAD :  QBrush(QColor(Invalid),LinearGradientPattern)
POS :  0.501961
RGB :  0 171 85
GRAD :  QBrush(QColor(Invalid),LinearGradientPattern)
POS :  0.627451
RGB :  0 0 255
GRAD :  QBrush(QColor(Invalid),LinearGradientPattern)
POS :  0.752941
RGB :  85 0 171
GRAD :  QBrush(QColor(Invalid),LinearGradientPattern)
POS :  0.878431
RGB :  171 0 85
GRAD :  QBrush(QColor(Invalid),LinearGradientPattern)
POS :  1
RGB :  255 0 0
GRAD :  QBrush(QColor(Invalid),LinearGradientPattern)

[mpergand]

Don't paste my code as this !
QLinearGradient gradient = QLinearGradient(0,0, rect().width(), 0);

should be the image width no ?

[Kris Revi]

@mpergand oh yea! now it worked :) thank you all

here is the working code and the solution

QImage MainWindow::createPaletteImage(QJsonArray jsonArr)
{
    int width = 500;
    int height = 26;
    QImage image(width, height, QImage::Format_RGB32);
    image.fill(Qt::white);

    QPainter painter(&image);

    int amountPoint;
    amountPoint = jsonArr.count()/4;
    float p=0,s=1.0/(amountPoint-1);
    QLinearGradient gradient = QLinearGradient(0,0, width, 0);

    for (int p = 0; p < amountPoint; p++)
    {
        int pos=jsonArr[p*4].toInt();
        int r=jsonArr[p*4+1].toInt();
        int g=jsonArr[p*4+2].toInt();
        int b=jsonArr[p*4+3].toInt();

        gradient.setColorAt(pos/255.0, QColor(r,g,b));
    }
    painter.fillRect(rect(),QBrush(gradient));
    return image;
}

[mpergand]

@Kris-Revi said in Make a palette image from palette data:
painter.fillRect(rect(),QBrush(gradient));

should be I think: QRect(0,0,width,height)