[QT] Fixes feel when resizing the last column on tables (issue #2862)

Re-submitting this pull request with a single commit.

This patch introduces a GUIUtil class that is used when setting up the 2 tables we have so far on the Qt-GUI.
In the past you could only resize the last column, which has BTC amounts from the right border of the column header, something that was rather unnatural.

If a new table were ever to be added to the interface, fixing the last columns resizing behavior is rather simple. Just look at how we initialize here a TableViewLastColumnResizingFixer object when setting up the table header's behavior, and then how we override the resize event of the component (can be the table, or the dialog) and we invoke columnResizingFixer->stretchColumnWidth(columnIndex);

1 files changed, 115 insertions, 0 deletions

diff --git a/src/qt/guiutil.cpp b/src/qt/guiutil.cpp
index 7e1831f037..4a4fece3e1 100644
--- a/src/qt/guiutil.cpp
+++ b/src/qt/guiutil.cpp
@@ -379,6 +379,121 @@ bool ToolTipToRichTextFilter::eventFilter(QObject *obj, QEvent *evt)
     return QObject::eventFilter(obj, evt);
 }
 
+void TableViewLastColumnResizingFixer::connectViewHeadersSignals()
+{
+    connect(tableView->horizontalHeader(), SIGNAL(sectionResized(int,int,int)), this, SLOT(on_sectionResized(int,int,int)));
+    connect(tableView->horizontalHeader(), SIGNAL(geometriesChanged()), this, SLOT(on_geometriesChanged()));
+}
+
+//we need to disconnect these while handling the resize events, otherwise we can enter infinite loops
+void TableViewLastColumnResizingFixer::disconnectViewHeadersSignals()
+{
+    disconnect(tableView->horizontalHeader(), SIGNAL(sectionResized(int,int,int)), this, SLOT(on_sectionResized(int,int,int)));
+    disconnect(tableView->horizontalHeader(), SIGNAL(geometriesChanged()), this, SLOT(on_geometriesChanged()));
+}
+
+//setup the resize mode, handles compatibility for QT5 and below as the method signatures changed. (refactored here for readability)
+void TableViewLastColumnResizingFixer::setViewHeaderResizeMode(int logicalIndex, QHeaderView::ResizeMode resizeMode)
+{
+#if QT_VERSION < 0x050000
+    tableView->horizontalHeader()->setResizeMode(logicalIndex, resizeMode);
+#else
+    tableView->horizontalHeader()->setSectionResizeMode(logicalIndex, resizeMode);
+#endif
+}
+
+void TableViewLastColumnResizingFixer::resizeColumn(int nColumnIndex, int width) {
+    tableView->setColumnWidth(nColumnIndex, width);
+    tableView->horizontalHeader()->resizeSection(nColumnIndex, width);
+}
+
+int TableViewLastColumnResizingFixer::getColumnsWidth()
+{
+    int nColumnsWidthSum = 0;
+    for (int i = 0; i < columnCount; i++)
+    {
+        nColumnsWidthSum += tableView->horizontalHeader()->sectionSize(i);
+    }
+    return nColumnsWidthSum;
+}
+
+int TableViewLastColumnResizingFixer::getAvailableWidthForColumn(int column)
+{
+    int nResult = lastColumnMinimumWidth;
+    int nTableWidth = tableView->horizontalHeader()->width();
+
+    if (nTableWidth > 0)
+    {
+        int nOtherColsWidth = getColumnsWidth() - tableView->horizontalHeader()->sectionSize(column);
+        nResult = std::max(nResult, nTableWidth - nOtherColsWidth);
+    }
+
+    return nResult;
+}
+
+//make sure we don't make the columns wider than the table's viewport's width.
+void TableViewLastColumnResizingFixer::adjustTableColumnsWidth()
+{
+    disconnectViewHeadersSignals();
+    resizeColumn(lastColumnIndex, getAvailableWidthForColumn(lastColumnIndex));
+    connectViewHeadersSignals();
+
+    int nTableWidth = tableView->horizontalHeader()->width();
+    int nColsWidth = getColumnsWidth();
+    if (nColsWidth > nTableWidth)
+    {
+        resizeColumn(secondToLastColumnIndex,getAvailableWidthForColumn(secondToLastColumnIndex));
+    }
+}
+
+//make column use all the space available, useful during window resizing.
+void TableViewLastColumnResizingFixer::stretchColumnWidth(int column) {
+    disconnectViewHeadersSignals();
+    resizeColumn(column, getAvailableWidthForColumn(column));
+    connectViewHeadersSignals();
+}
+
+//when a section is resized this is a slot-proxy for ajustAmountColumnWidth()
+void TableViewLastColumnResizingFixer::on_sectionResized(int logicalIndex, int oldSize, int newSize)
+{
+    adjustTableColumnsWidth();
+    int remainingWidth = getAvailableWidthForColumn(logicalIndex);
+    if (newSize > remainingWidth)
+    {
+       resizeColumn(logicalIndex, remainingWidth);
+    }
+}
+
+//when the table's geometry is ready, we manually perform the Stretch of the "Message" column
+//as the "Stretch" resize mode does not allow for interactive resizing.
+void TableViewLastColumnResizingFixer::on_geometriesChanged()
+{
+    if ((getColumnsWidth() - this->tableView->horizontalHeader()->width()) != 0)
+    {
+        disconnectViewHeadersSignals();
+        resizeColumn(secondToLastColumnIndex, getAvailableWidthForColumn(secondToLastColumnIndex));
+        connectViewHeadersSignals();
+    }
+}
+
+/**
+ * Initializes all internal variables and prepares the
+ * the resize modes of the last 2 columns of the table and
+ */
+TableViewLastColumnResizingFixer::TableViewLastColumnResizingFixer(QTableView* table, int lastColMinimumWidth, int allColsMinimumWidth) :
+        tableView(table),
+        lastColumnMinimumWidth(lastColMinimumWidth),
+        allColumnsMinimumWidth(allColsMinimumWidth)
+{
+    columnCount = tableView->horizontalHeader()->count();
+    lastColumnIndex = columnCount - 1;
+    secondToLastColumnIndex = columnCount - 2;
+    tableView->horizontalHeader()->setMinimumSectionSize(allColumnsMinimumWidth);
+    setViewHeaderResizeMode(secondToLastColumnIndex, QHeaderView::Interactive);
+    setViewHeaderResizeMode(lastColumnIndex, QHeaderView::Interactive);
+}
+
+
 #ifdef WIN32
 boost::filesystem::path static StartupShortcutPath()
 {