From ebef7baa265f097b3372ed6239495255c6b64e49 Mon Sep 17 00:00:00 2001
From: John Levon <levon@movementarian.org>
Date: Mon, 21 Oct 2002 00:15:48 +0000
Subject: [PATCH] Darren's patch, reworked

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@5451 a592a061-630c-0410-9148-cb99ea01b6c8
---
 src/BufferView.C       |  4 ++--
 src/BufferView.h       |  4 ++--
 src/BufferView_pimpl.C | 20 +++++++++++++-------
 src/BufferView_pimpl.h |  6 ++++--
 src/ChangeLog          |  8 ++++++++
 5 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/src/BufferView.C b/src/BufferView.C
index 514026d7f5..edc9f36393 100644
--- a/src/BufferView.C
+++ b/src/BufferView.C
@@ -258,9 +258,9 @@ bool BufferView::dispatch(FuncRequest const & ev)
 }
 
 
-int BufferView::scroll(long time)
+void BufferView::scroll(int lines)
 {
-	return pimpl_->scroll(time);
+	pimpl_->scroll(lines);
 }
 
 
diff --git a/src/BufferView.h b/src/BufferView.h
index 1bec27f90a..afe153561e 100644
--- a/src/BufferView.h
+++ b/src/BufferView.h
@@ -165,8 +165,8 @@ public:
 	void toggleToggle();
 	///
 	void center();
-	///
-	int scroll(long time);
+	/// scroll document by the given number of lines of default height
+	void scroll(int lines);
 
 	/// Scroll the view by a number of pixels
 	void scrollDocView(int);
diff --git a/src/BufferView_pimpl.C b/src/BufferView_pimpl.C
index 36b457694f..eeb0c4383a 100644
--- a/src/BufferView_pimpl.C
+++ b/src/BufferView_pimpl.C
@@ -384,19 +384,25 @@ void BufferView::Pimpl::scrollDocView(int value)
 }
 
 
-int BufferView::Pimpl::scroll(long time)
+void BufferView::Pimpl::scroll(int lines)
 {
-	if (!buffer_)
-		return 0;
+	if (!buffer_) {
+		return;
+	}
 
 	LyXText const * t = bv_->text;
+	int const line_height = t->defaultHeight();
 
-	double const diff = t->defaultHeight()
-		+ double(time) * double(time) * 0.125;
+	int const disp = lines * line_height;
 
-	scrollDocView(int(diff));
+	// Restrict to a valid value
+	int new_first_y = std::min(t->height - 4 * line_height, disp);
+	new_first_y = std::max(0, disp);
+
+	scrollDocView(new_first_y);
+
+	// Update the scrollbar.
 	workarea().setScrollbarParams(t->height, t->first_y, t->defaultHeight());
-	return 0;
 }
 
 
diff --git a/src/BufferView_pimpl.h b/src/BufferView_pimpl.h
index 369df9fc5f..9a77eba226 100644
--- a/src/BufferView_pimpl.h
+++ b/src/BufferView_pimpl.h
@@ -60,8 +60,10 @@ struct BufferView::Pimpl : public boost::signals::trackable {
 	void updateScrollbar();
 	///
 	void scrollDocView(int value);
-	/// wheel mouse scroll
-	int scroll(long time);
+	/**
+	 * Wheel mouse scroll, move by multiples of text->defaultHeight().
+	 */
+	void scroll(int lines);
 	///
 	void workAreaKeyPress(LyXKeySymPtr key, key_modifier::state state);
 	///
diff --git a/src/ChangeLog b/src/ChangeLog
index 6d7d0c5f74..1f6575f03b 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2002-10-21  John Levon  <levon@movementarian.org>
+
+	* BufferView.h:
+	* BufferView.C:
+	* BufferView_pimpl.h:
+	* BufferView_pimpl.C: fix mouse wheel handling based on
+	  patch from Darren Freeman
+ 
 2002-10-09  Dekel Tsur  <dekelts@tau.ac.il>
 
 	* lyx_main.C (queryUserLyXDir): Fix automatic reconfiguration.
-- 
2.39.2