Scaling pixmap images in qscrollarea

rjmoses

After many trials and tribulations and a lot of reading, I find myself in need of assistance from gurus who have dealt with images

I am working on an application where I want to have an area that will display a variable number of images. The user will then select an image and drag it to a location on a simulated display page. The idea is to be able to position a variety of images at specific spots on multiple screen pages.

I am looking to have two or more columns of images, appropriately scaled, in a scroll area. The entire application area is resizable, therefore, as space changes in the scroll area, the columns of images may grow or shrink as applicable.

I have tried many, many different test runs working with QLabel and QPixmaps but have not found a way get them to work together nicely. Part of the issue is that I do not understand sizePolicy, QViewports, QSrollarea, sizeHint, etc., relationships.

Any help in understanding how to have scalable images displayed in a scroll area will be greatly appreciated.

Screen layout: Left size is scrollarea for images, right side is composing area.

Current Test Code:

void MainWindow::loadImages()
{

#define NCOLS 2
#define MAX_WIDTH 100

QDir dir = QDir(imageLibrary);
QStringList allImageFiles = dir.entryList(QStringList("*.jpg"));

ui->currentLibrary->setText(imageLibrary);
ui->currentLibrary->setMaximumWidth(MAX_WIDTH);

ui->scrollArea->setGeometry(0,0,200,200);
QRect geo_availImagesGeometry = ui->scrollArea->geometry();

int width = geo_availImagesGeometry.width();   
int height = geo_availImagesGeometry.height();

QWidget * viewport = new QWidget;
ui->scrollArea->setWidget(viewport);
ui->scrollArea->setWidgetResizable(true);

QGridLayout * gl = new QGridLayout(viewport);

QSizePolicy policy(QSizePolicy::Preferred, QSizePolicy::Preferred);

for (int i = 0; i < allImageFiles.size(); i++) {
    QString thisfile = imageLibrary + "/" + allImageFiles[i];

    QPixmap pixmap(thisfile);
    QLabel * thisImage = new QLabel();

    //thisImage->setScaledContents(true); 	// Tried with and without this statement
    //pixmap.scaledToWidth(width);		// Tried with and without this statement

    thisImage->setSizePolicy(policy);
    thisImage->setPixmap(pixmap.scaled(width , width, Qt::KeepAspectRatio));

    thisImage->setToolTip(allImageFiles[i]);
    
//thisImage->setText(allImageFiles[i]);  // ????? Using this causes a segmentation violation

    gl->addWidget(thisImage, i/NCOLS, i % NCOLS);	// Add at row/column in scrollarea

}

QRect scrollGeom = viewport->childrenRect();		// Check what
ui->currentLibrary->setMaximumWidth(scrollGeom.width());	// Set width of library name to width of scroll area

QList<QLabel *> vplist = viewport->findChildren<QLabel *>();	// Debug -- See what the viewport has to say about sizes

ui->scrollArea->show();

}

SGaist

Hi,

What about using a QListView in icon mode with two columns ?

rjmoses

@sgaist

Interesting idea. Will it scale pixmaps?

mrjj

@rjmoses
Yes it will scale all images to match IconSize.