Mouse wheel behaviour in the IDE source editor
lazarus / 9-Editor

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Valentin · 2011-05-01 00:15

Hi all,

Does someone know how mouse wheel scrolling can be reduced in the IDE?
The scrolling amount is percentage of the page height and for me the
default value is quite big (~20 lines). Most programs scroll 3 to 5
rows.

I've followed http://bugs.freepascal.org/view.php?id=7498 and changed
the corresponding file in gtk2 directory, but after Lazarus compiling
nothing has changed...

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typo · 2011-05-01 01:19

Here it scrolls 3 lines.

Lazarus 0.9.30 r29749 FPC 2.4.2 i386-win32-win32/win64

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Martin_fr · 2011-05-01 10:11

Under windows there is a system configuration to set the amount of
lines per wheel click (usually  between 1 and 3)

I do not know about GTK2, but I would expect that Gtk2 has a similar
setting. So maybe the constant you changed is no longer?

Anyway, maybe someone else knows more.
But you should specify which distribution of Linux you are using (or
if you have gtk on windows, or...).
If you know also add the version of your gtk2 installation.

Also Sine you do not specify otherwise: You do use 0.9.30?

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Blaazen · 2011-05-01 13:08

Look at this:
Code: [Select]function TMouse.GetWheelScrollLines: Integer;
begin
  if FWheelScrollLines = 0 then
  begin
    if not WidgetSet.SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0,
@FWheelScrollLines, 0) then
      FWheelScrollLines := 3;
  end;
  Result := FWheelScrollLines;
end;     
I have Kubuntu + Qt 4.7.1 and I can change number of scroll-lines in
my System Settings (Input Devices -> Mouse -> Advanced ) but it seems
Lazarus cannot read this value and  "mouse.WheelScrollLines" is always
3 (even if i restart IDE).

BTW I have mouse with very crappy scroll wheel so I avoid using it at
all.

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zeljko · 2011-05-01 13:22

That's because KDE doesn't set it for qt, but for KDE env. There must
be qt4config (or similar name) where you can set such values for pure
qt apps. Remember that Lazarus is not KDE but qt app.

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Valentin · 2011-05-01 15:00

using Ubuntu 10.10 with Gnome 2.32 desktop, Lazarus 0.9.30 (gtk2 IDE).
This scrolling disadvantage is only int IDE source editor. Any other
Lazarus scroll controls (Object Inspector, Environment Options, Code
explorer, etc) are ~3 lines.

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Martin_fr · 2011-05-01 16:21

You are right, i can reproduce this in fedora. Scrolling depends on
window height and it shouldn't.

Looks like a bug to me.

indeed in
function Gtk2ScrolledWindowScrollCB(AScrollWindow: PGtkScrolledWindow;
AEvent: PGdkEventScroll; AWidgetInfo: PWidgetInfo): gboolean; cdecl;

lcl/interfaces/gtk2/gtk2wscontrols.pp line 175
  AValue :=  power(Range^.adjustment^.page_size, 2 / 3);

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Blaazen · 2011-05-03 14:47

Quote from: zeljko on May 01, 2011, 03:22:16 pmThat's because KDE
doesn't set it for qt, but for KDE env. There must be qt4config (or
similar name) where you can set such values for pure qt apps. Remember
that Lazarus is not KDE but qt app.
I am still not sure if it is implemented. I installed qtconfog-qt4
(from kubuntu repositories) and I also looked to config file:
.config/Trolltech.conf (section: qt)
Code: [Select][qt]
  ...
  wheelScrollLines=5
  ...and WheelScrolllLines is always 3. (Even if I restart IDE).

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zeljko · 2011-05-03 15:30

http://doc.trolltech.com/4.7/qapplication.html#wheelScrollLines-prop
just check with some writeln() QApplication_wheelScrollLines() when
app is created in qtobjects.inc. It should respect it's conf file. We
do not touch wheelScrollLines property in any case inside qtlcl.

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Blaazen · 2011-05-03 15:50

Code: [Select]writeln(QApplication_wheelScrollLines))also gives 3 .
Maybe I look to bad configuration file? Qt4 is from Nokia now,
Trolltech is past.

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zeljko · 2011-05-03 17:46

There should be Trolltech.conf somewhere ni /etc too ....I've found
that I don't have qtconfig installed on Fedora 14 but
$HOME/.config/Trolltech.conf exists, but also there's nothing about
mouse wheel inside that conf file (so I assume it's 3 by default).