Method resizeColumns

plugins/problemreporter/problemtreeview.cpp:159–217

}

void ProblemTreeView::resizeColumns()
{
    // Don't simply call QTreeView::resizeColumnToContents() for each column here,
    // because it is not useful enough to justify significant performance cost.
    // Instead, set column widths to heuristic values independent on the contents (the problem list).

    const int averageCharWidth = fontMetrics().averageCharWidth();
    const int headerWidth = header()->width();
    if (averageCharWidth == m_averageCharWidth && headerWidth == m_headerWidth) {
        // No reason to change column widths. This early return is not just an optimization: KDevelop should not
        // gratuitously reapply unchanged heuristic column widths, because the user may have fine-tuned them manually.
        return;
    }
    m_averageCharWidth = averageCharWidth;
    m_headerWidth = headerWidth;

    struct ColumnSizePolicy
    {
        int minWidthInCharacters;
        int stretchFactor;
    };
    static constexpr std::array<ColumnSizePolicy, 5> sizePolicy{
        ColumnSizePolicy{40, 20}, // Error
        ColumnSizePolicy{25, 1}, //  Source
        ColumnSizePolicy{30, 10}, // File
        ColumnSizePolicy{10, 1}, //  Line
        ColumnSizePolicy{10, 1}, //  Column
    };
    static_assert(sizePolicy.size() == ProblemModel::LastColumn);

    // Cannot use std::accumulate() here, because it is not constexpr in C++17.
    static constexpr ColumnSizePolicy totalAllColumns = [] {
        ColumnSizePolicy sum{};
        for (auto p : sizePolicy) {
            sum.minWidthInCharacters += p.minWidthInCharacters;
            sum.stretchFactor += p.stretchFactor;
        }
        return sum;
    }();

    ColumnSizePolicy total = totalAllColumns;
    if (!model()->features().testFlag(ProblemModel::ShowSource)) {
        // Disregard the size policy of the hidden Source column.
        static constexpr auto hiddenColumn = sizePolicy[ProblemModel::Source];
        total.minWidthInCharacters -= hiddenColumn.minWidthInCharacters;
        total.stretchFactor -= hiddenColumn.stretchFactor;
    }
    Q_ASSERT(total.stretchFactor > 0);

    const int remainingPixels = std::max(0, headerWidth - total.minWidthInCharacters * averageCharWidth);

    // Give each column its minimum needed width. If there is any horizontal space left,
    // distribute it among columns in proportion to their stretch factors.
    for (std::size_t i = 0; i < sizePolicy.size(); ++i) {
        int width = sizePolicy[i].minWidthInCharacters * averageCharWidth;
        width += remainingPixels * sizePolicy[i].stretchFactor / total.stretchFactor;
        setColumnWidth(i, width);
    }