Provide horizontal auto scrolling for the tree view (implemented by Harald Hvaal). As soon as KTreeView is matured enough, it can be discussed whether it should be moved to kdelibs for KDE 4.2.

CCMAIL: [email protected]

svn path=/trunk/KDE/kdebase/apps/; revision=799723

1 files changed, 178 insertions, 0 deletions

diff --git a/src/ktreeview.cpp b/src/ktreeview.cpp
new file mode 100644
index 000000000..7448614f9
--- /dev/null
+++ b/src/ktreeview.cpp
@@ -0,0 +1,178 @@
+/***************************************************************************
+ *   Copyright (C) 2008 by <haraldhv (at) stud.ntnu.no>                    *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
+ ***************************************************************************/
+
+#include <KGlobalSettings>
+
+#include <QDebug>
+#include <QScrollBar>
+
+#include "ktreeview.h"
+#include "ktreeview_p.h"
+
+KTreeView::KTreeViewPrivate::KTreeViewPrivate(KTreeView *parent)
+	: parent(parent),
+	autoHorizontalScroll(true),
+	scrollTowards(0),
+	scrollPixels(5),
+	scrollDelay(50),
+	leftSideMargin(30),
+	considerDelay(500),
+	topLeftPoint(QPoint(10,10))
+{
+	Q_ASSERT(parent->verticalScrollBar());
+
+	considerDelayTimer.setInterval(considerDelay);
+
+	connect( &considerDelayTimer,
+			SIGNAL(timeout()),
+			this,
+			SLOT(considerAutoScroll())
+		   );
+
+	connect( parent->verticalScrollBar(),
+			SIGNAL(rangeChanged(int, int)),
+			&considerDelayTimer,
+			SLOT(start())
+		   );
+
+	connect( parent->verticalScrollBar(),
+			SIGNAL(valueChanged(int)),
+			&considerDelayTimer,
+			SLOT(start())
+		   );
+
+	connect( parent,
+			SIGNAL( collapsed ( const QModelIndex &)),
+			&considerDelayTimer,
+			SLOT(start())
+		   );
+
+	connect( parent,
+			SIGNAL( expanded ( const QModelIndex &)),
+			&considerDelayTimer,
+			SLOT(start())
+		   );
+
+}
+
+void KTreeView::KTreeViewPrivate::considerAutoScroll()
+{
+	qDebug() << "Considering auto scroll";
+
+	QModelIndex i = parent->indexAt(topLeftPoint);
+	int smallest = parent->width();
+
+	while (i.isValid())
+	{
+		QRect r = parent->visualRect(i);
+		if (r.top() > parent->height())
+			break;
+
+		int leftSide = r.left();
+
+		smallest = qMin(smallest, leftSide);
+		i = parent->indexBelow(i);
+	}
+
+	int currentScroll = parent->horizontalScrollBar()->value();
+
+	setScrollTowards(smallest + currentScroll - leftSideMargin);
+
+	considerDelayTimer.stop();
+
+}
+
+void KTreeView::KTreeViewPrivate::autoScrollTimeout()
+{
+
+	Q_ASSERT(parent);
+
+	QScrollBar *scrollBar = parent->horizontalScrollBar();
+	if (scrollBar == NULL)
+	{
+		qDebug() << "Warning: no scrollbar present, but told to scroll.";
+		scrollTimer.stop();
+		return;
+	}
+
+	int currentScroll = scrollBar->value();
+
+	int difference = currentScroll - scrollTowards;
+
+	if (qAbs(difference) < scrollPixels)
+	{
+		scrollBar->setValue(scrollTowards);
+		scrollTimer.stop();
+		return;
+	}
+
+	if (difference < 0)
+	{
+		scrollBar->setValue(currentScroll + scrollPixels);
+	}
+	else
+	{
+		scrollBar->setValue(currentScroll - scrollPixels);
+	}
+}
+
+void KTreeView::KTreeViewPrivate::setScrollTowards( int scrollTowards )
+{
+	if (scrollTowards < 0)
+		scrollTowards = 0;
+	this->scrollTowards = scrollTowards;
+	scrollTimer.start(scrollDelay);
+}
+
+//************************************************
+
+KTreeView::KTreeView(QWidget *parent)
+	: QTreeView(parent)
+	, d(new KTreeViewPrivate(this))
+{
+	/* The graphicEffectsLevel was not available in the 4.0.3 version of
+	 * the libs I was compiling with, so this is left out for now and
+	 * enabled by default...
+	 */
+	//if (KGlobalSettings::graphicEffectsLevel() >=
+			//KGlobalSettings::SimpleAnimationEffects)
+	//{
+		setAutoHorizontalScroll(true);
+	//}
+		connect(
+				&d->scrollTimer,
+				SIGNAL(timeout()),
+				d,
+				SLOT(autoScrollTimeout())
+			   );
+
+}
+
+void KTreeView::setAutoHorizontalScroll(bool value)
+{
+	d->autoHorizontalScroll = value;
+}
+
+bool KTreeView::autoHorizontalScroll( void )
+{
+	return d->autoHorizontalScroll;
+}
+
+#include "ktreeview.moc"
+#include "ktreeview_p.moc"