Wt

A WTreeView widget grows horizontally inside a WHBoxLayout when its data is updated and if it has a border. This was raised as part of a forum dicussion [[[http://redmine.emweb.be/boards/2/topics/4815]]]. The code below demonstrates the problem. If the setBorder call is removed, then everything works as expected and the tree view stays at a constant width. Please also note that even without a border the same effect occurs if the data updates alternate between needing a scrollbar and not needing one. I can provide a second example code for this if required. The problems occur with Wt code taken from the git on 20 Aug 2012.

#include <Wt/WApplication>
#include <Wt/WHBoxLayout>
#include <Wt/WStandardItem>
#include <Wt/WStandardItemModel>
#include <Wt/WTreeView>
#include <Wt/WGroupBox>
#include <Wt/WPushButton>

using namespace std;
using namespace Wt;

class WtTestApp : public WApplication
{
    public:
        WStandardItemModel* m_model;
        bool m_dataset;

        WtTestApp(const WEnvironment& env) :
            WApplication(env),
            m_dataset(false)
        {
            m_model= new WStandardItemModel(0, 1);

            WTreeView* tv;
            tv= new WTreeView();
            tv->decorationStyle().setBorder(WBorder(WBorder::Solid, 1));
            tv->setModel(m_model);

            WGroupBox* groupBox= new WGroupBox("Group");

            WPushButton* button= new WPushButton("Refresh", groupBox);
            button->clicked().connect(this, &WtTestApp::refresh);

            WHBoxLayout* l= new WHBoxLayout(root());
            l->setContentsMargins(0, 0, 0, 0);
            l->addWidget(tv, 1);
            l->addWidget(groupBox, 1);

            refresh();
        }

        void refresh(void)
        {
            m_model->clear();

            if (m_dataset)
            {
                m_model->appendRow(new WStandardItem("Row 4"));
                m_model->appendRow(new WStandardItem("Row 5"));
                m_model->appendRow(new WStandardItem("Row 6"));
                m_model->setHeaderData(0, Horizontal, boost::any(string("Data 2")));
            }
            else
            {
                m_model->appendRow(new WStandardItem("Row 1"));
                m_model->appendRow(new WStandardItem("Row 2"));
                m_model->appendRow(new WStandardItem("Row 3"));
                m_model->setHeaderData(0, Horizontal, boost::any(string("Data 1")));
            }

            m_dataset= !m_dataset;
        }
};

WApplication* createApp(const WEnvironment& env)
{
    return new WtTestApp(env);
}

int main(int argc, char *argv[])
{
    return WRun(argc, argv, &createApp);
}