Resizing Columns in Qt TreeView with QTreeView::resizeColumnToContents()

• Functionality
  

  1. QTreeView::resizeColumnToContents() calculates the minimum width required to display all the items in the specified column comfortably. This includes factors like the text content, font size, and any indentation for child nodes.
  2. It then resizes the column to this calculated width.

• Function
  resizeColumnToContents(int column)

  • column (int)
    This argument specifies the index of the column you want to resize. The first column has an index of 0, the second has an index of 1, and so on.

Points to Consider

• You can use this function for multiple columns by calling it with the desired column indices.
• It's recommended to call resizeColumnToContents() after populating the QTreeView with data for an accurate size calculation.
• This function only affects the width of a single column.

Additional Notes

• While resizeColumnToContents() is convenient, it might not always be ideal. For example, if you have a fixed layout or want to control column sizes precisely, you can use the setColumnWidth() function instead.

---

#include <QApplication>
#include <QTreeView>
#include <QStringListModel>

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

  // Create a QTreeView
  QTreeView treeView;

  // Create a model with some data
  QStringListModel model;
  QStringList list;
  list << "This is a long item" << "Shorter item" << "Another long item here";
  model.setStringList(list);

  // Set the model for the tree view
  treeView.setModel(&model);

  // Resize the first column to fit its contents after data is set
  treeView.resizeColumnToContents(0);

  // Display the tree view
  treeView.show();

  return app.exec();
}

This code:

1. Creates a QTreeView object.
2. Creates a QStringListModel and populates it with some sample data (text strings).
3. Sets the model for the QTreeView.
4. Calls resizeColumnToContents(0) on the QTreeView after setting the model. This resizes the first column (index 0) to fit the content of the data strings.
5. Finally, shows the QTreeView on the screen.

1. Save the code as a .cpp file (e.g., resize_column.cpp).
2. Compile the code using a Qt compiler (e.g., qmake and make for a basic setup).
3. Run the compiled executable to see the QTreeView with the first column automatically resized to fit the content.

---

1. • This function allows you to set a specific width (in pixels) for a column.

   • It provides more precise control over column sizes compared to resizeColumnToContents().

   • Example
     

   treeView.setColumnWidth(0, 150); // Set width of first column to 150 pixels
   

2. Using a custom delegate
   

   • Qt allows creating custom delegate classes to customize how items are displayed in a QTreeView.

   • You can implement logic within the delegate to determine the width required for each item and set the column width accordingly.

   • This approach offers fine-grained control but requires more advanced Qt development knowledge.