Controlling Column Visibility in Qt Table Views with QTableView::setColumnHidden()

Purpose

• Setting hide to false will make the hidden column visible again.
• By setting the hide parameter to true, you can hide a specific column identified by its column index.
• This function is used to control the visibility of columns in a QTableView widget within a Qt application.

Syntax

void QTableView::setColumnHidden(int column, bool hide);

Parameters

• hide: A boolean value that determines the visibility of the column:
  • true: Hides the specified column.
  • false: Shows the hidden column.
• column: An integer representing the index of the column you want to hide or show. Column indices start from 0 (the leftmost column) and go up to the total number of columns minus 1 (the rightmost column).

Usage

1. #include <QtWidgets>
   

2. Obtain a Reference to Your QTableView Object
   

   • You'll typically have a pointer or reference to your QTableView object in your code.

3. Call setColumnHidden()
   

   tableView->setColumnHidden(columnIndex, hide);
   

   • Replace columnIndex with the actual index of the column you want to hide/show.
   • Set hide to true to hide or false to show.

Example

#include <QtWidgets>

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    // Create a sample table view
    QTableView *tableView = new QTableView;
    QStringList headerLabels;
    headerLabels << "Column 1" << "Column 2" << "Column 3";
    QStandardItemModel *model = new QStandardItemModel(0, headerLabels.size());
    tableView->setModel(model);

    // Hide the second column (index 1)
    tableView->setColumnHidden(1, true);

    // ... (rest of your application code)

    tableView->show();
    return app.exec();
}

In this example:

• The second column ("Column 2") will be hidden when the application runs.

Additional Notes

• For more advanced control over column visibility, you might explore techniques like custom item delegates or overriding the visualRect() function.
• Consider using isColumnHidden() to check if a column is currently hidden.
• Hiding or showing columns will adjust the overall width of the table view to accommodate the changes.
• Remember that column indices start from 0.

---

Hiding and Showing Multiple Columns

#include <QtWidgets>

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    // Create a table view and model
    QTableView *tableView = new QTableView;
    QStringList headerLabels;
    for (int i = 0; i < 5; ++i) {
        headerLabels << QString("Column %1").arg(i + 1);
    }
    QStandardItemModel *model = new QStandardItemModel(0, headerLabels.size());
    tableView->setModel(model);

    // Hide columns 1 and 3
    int columnsToHide[] = {1, 3};
    for (int col : columnsToHide) {
        tableView->setColumnHidden(col, true);
    }

    // Optionally, show column 2 later
    // tableView->setColumnHidden(2, false);

    tableView->show();
    return app.exec();
}

This code hides the second and fourth columns (indices 1 and 3) initially. You could uncomment the setColumnHidden(2, false); line to show the third column dynamically.

Hiding Columns Based on User Input

#include <QtWidgets>

class MyTableWidget : public QWidget {
    Q_OBJECT

public:
    MyTableWidget(QWidget *parent = nullptr) : QWidget(parent) {
        // Create UI elements (table view, button, etc.)
        // ...
    }

private slots:
    void onHideSecondColumnButtonClicked() {
        tableView->setColumnHidden(1, true);
    }

private:
    QTableView *tableView;
    // Other UI elements and member variables
};

This example outlines a custom widget that includes a QTableView and a button. Clicking the button would trigger a slot function (onHideSecondColumnButtonClicked) that hides the second column (index 1). You'd need to fill in the details of creating the UI elements and connecting the button click signal to the slot.

Conditional Column Visibility (Using Model Data)

#include <QtWidgets>

class MyTableModel : public QStandardItemModel {
    Q_OBJECT

public:
    MyTableModel(int rows, int columns, QObject *parent = nullptr)
        : QStandardItemModel(rows, columns, parent) {}

    Qt::ItemFlags flags(const QModelIndex &index) const override {
        Qt::ItemFlags flags = QStandardItemModel::flags(index);
        // Check model data at specific index and conditionally set hidden flag
        if (/* condition based on model data at index */) {
            flags |= Qt::ItemIsHidden;
        }
        return flags;
    }
};

This approach demonstrates a custom model that overrides the flags() function to control column visibility based on the model data. Here, the flags() function checks a condition using model data at a particular index and sets the Qt::ItemIsHidden flag if the condition is met. This allows you to dynamically determine which columns to hide based on your data.

---

Using QHeaderView::setSectionHidden()

• While functionally similar, using setColumnHidden() on the QTableView might be more intuitive for direct column manipulation.
• It takes the section index (similar to column index) and a bool parameter for hiding/showing.
• This function operates on the QHeaderView associated with the QTableView.

Syntax

void QHeaderView::setSectionHidden(int section, bool hide);

Custom Item Delegate

• This approach offers more granular control over the visual representation of hidden columns. It's useful when you want to achieve effects like dimming or graying out hidden columns instead of completely removing them.
• Override the paint() function to conditionally draw or not draw items based on column index or model data.
• Create a subclass of QItemDelegate.

Model-Based Visibility

• This is suitable when visibility decisions are primarily driven by the model's data.
• The QTableView will automatically adjust its display based on the data returned by the model.
• Override the data() function to return nullptr or a placeholder value for hidden columns.
• Implement a custom model that inherits from QAbstractItemModel.

Hiding Entire Columns Before Setting the Model

• This approach avoids the need for dynamic hiding/showing later on.
• If you know the column structure beforehand, you can directly set the number of columns in your model (e.g., QStandardItemModel) before assigning it to the QTableView.

• Consider hiding entire columns before setting the model if the column structure is fixed.
• Model-based visibility is ideal when hiding decisions are tightly coupled with model data.
• If you need more control over the visual representation of hidden columns, a custom item delegate is the way to go.
• Use setSectionHidden() if you prefer working with the QHeaderView directly.
• For basic hiding/showing functionality, setColumnHidden() is the most straightforward option.