如何限制QHeaderView大小（调整部分大小时）？

Question

QHeaderView sections can go out of view (to the right) when resizing. That is I can resize a section to be too big and other sections will disappear to the right.

Is it possible to limit this? Such as set max width of header.

I tried setMaximumWidth on table and header (actually in the real app I have just header without standard table) but it didn't help.

UPD:

Actually I want other columns to shrink instead of going out of visible area, something like in MS Word:

So if there is no built-in option for behavior like this, then I guess I need to find a suitable signal to adjust sizes after resizing, such as decreasing/increasing size of the next or previous column...

Answer 1

In Qt 5.12 set

QHeaderView()->setCascadingSectionResizes(true);

and

QHeaderView()->setSectionResizeMode(c, QHeaderView::Stretch);
c = lastColumn;

Answer 2

Well, as some comments have said, you can use signals from the QHeaderView to listen for changes and subsequently change them using resizeSection() . Below I have written a AutoResizer which performs your wanted resizing.

AutoResizer.hpp

#ifndef AUTORESIZER_HPP
#define AUTORESIZER_HPP

#include <QObject>

class QHeaderView;

class AutoResizer : public QObject
{
    Q_OBJECT

    QHeaderView *m_header;
public:
    AutoResizer(QHeaderView *parent = 0);

private slots:
    // Listen to resized sections
    void sectionResized(int logicalIndex, int oldSize, int newSize);
};

#endif // AUTORESIZER_HPP

AutoResizer.cpp

#include "AutoResizer.hpp"

#include <QHeaderView>

AutoResizer::AutoResizer(QHeaderView *parent) : QObject(parent), m_header(parent)
{
    // Connect ourselves to the section resize signal
    connect(m_header,SIGNAL(sectionResized(int,int,int)),SLOT(sectionResized(int,int,int)));

    // Enable last column to stretch as we don't do that ourselves
    m_header->setStretchLastSection(true);
}

void AutoResizer::sectionResized(int logicalIndex, int oldSize, int newSize)
{
    // Do some bookkeeping
    int count = m_header->model()->columnCount(QModelIndex());
    int length = m_header->width(); // The width of the headerview widget
    int sum = m_header->length(); // The total length of all sections combined

    // Check whether there is a discrepancy
    if(sum != length) {
        // Check if it's not the last header
        if(logicalIndex < count) {
            // Take the next header size (the one right to the resize handle)
            int next_header_size = m_header->sectionSize(logicalIndex+1);
            // If it can shrink
            if(next_header_size > (sum - length)) {
                // shrink it
                m_header->resizeSection(logicalIndex+1, next_header_size - (sum - length));
            } else {
                // The next header can't shrink, block the resize by setting the old size again
                m_header->resizeSection(logicalIndex, oldSize);
            }
        }
    }
}

There are some caveats. I haven't tested this on reorder-able headers, it talks about "logicalIndices" which might mean you need some translation using sectionPosition . It also doesn't do much when the view is made smaller though it will fix itself once a column is being resized. And you should look whether setting the ResizeMode to Stretch doesn't already sufficiently solve your issue.