paweld/lazarus
1
0
Fork 0
mirror of https://gitlab.com/freepascal.org/lazarus/lazarus.git synced 2025-08-15 23:39:24 +02:00
Code Issues Packages Projects Releases Wiki Activity

* Fixed thumbtracking on scrollbars

Browse Source 
git-svn-id: trunk@9497 -
This commit is contained in:
marc 2006-06-24 10:51:49 +00:00
parent ea9419ecb7
commit 1d05474b23
2 changed files with 48 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

79
lcl/interfaces/win32/win32callback.inc
View File

@ -564,19 +564,45 @@ Var
Pos := 0;
end;
if not (Lo(WParam) in [SB_THUMBTRACK, SB_THUMBPOSITION]) then Exit;
if not (Lo(WParam) in [SB_THUMBTRACK, SB_THUMBPOSITION])
then begin
WindowInfo^.TrackValid := False;
Exit;
end;
// Note on thumb tracking
// When using the scrollwheel, windows sends SB_THUMBTRACK
// messages, but only when scroll.max < 32K. So in that case
// Hi(WParam) won't cycle.
// When ending scrollbar tracking we also get those
// messages. Now Hi(WParam) is cycling.
// To get the correct value you need to use GetScrollInfo.
//
// Now there is a problem. GetScrollInfo returns always the old
// position. So in case we get track messages, we'll keep the
// last trackposition.
// To get the correct position, we use the most significant
// part of the last known value (or the value returned by
// ScrollInfo). The missing least significant part is given
// by Hi(WParam), since it is cycling, the or of both will give
// the position
// This only works if the difference between the last pos and
// the new pos is < 64K, so it might fail if we don't get track
// messages
// MWE.
// For thumb messges, retrieve the real position,
ScrollInfo.cbSize := SizeOf(ScrollInfo);
if Lo(WParam) = SB_THUMBTRACK
then begin
ScrollInfo.fMask := SIF_TRACKPOS;
// older windows versions may not support trackpos, so fill it with some default
ScrollInfo.nTrackPos := Hi(WParam);
if WindowInfo^.TrackValid
then ScrollInfo.nTrackPos := (WindowInfo^.TrackPos and $FFFF0000) or Hi(WParam)
else ScrollInfo.nTrackPos := Hi(WParam);
end
else begin
ScrollInfo.fMask := SIF_POS;
// older windows versions may not support trackpos, so fill it with some default
ScrollInfo.nPos := Hi(WParam);
end;
@ -592,38 +618,21 @@ Var
else GetScrollInfo(Window, SB_VERT, ScrollInfo);
end;
with LMScroll do
begin
if Lo(WParam) = SB_THUMBTRACK
then Pos := ScrollInfo.nTrackPos
else Pos := (ScrollInfo.nPos and $FFFF0000) or Hi(WParam);
// Note on the above
// When using the scrollwheel, windows sends SB_THUMBTRACK
// messages, but only when scroll.max < 32K. So in that case
// Hi(WParam) won't cycle.
// When ending scrollbar tracking we also get those
// messages. Now Hi(WParam) is cycling.
// To get the correct value you need to use GetScrollInfo.
//
// Now there is a problem. GetScrollInfo returns the old position
// while using the wheelmouse, and during tracking it returns
// the new position.
// To get around this, I use the most significant part of the
// value returned by ScrollInfo, since that is always correct
// The missing least significant part is given by Hi(WParam)
// (since it is cycling) and is also always valid.
// So the combination of both also is.
// In the case of the wheelmouse this only works if the
// difference between the old pos and the new pos is < 64K.
// I think we safely can asuume that (you wont get messages
// anyhow if the range was > 32K :).
// MWE.
if Pos < High(SmallPos)
then SmallPos := Pos
else SmallPos := High(SmallPos);
if Lo(WParam) = SB_THUMBTRACK
then begin
LMScroll.Pos := ScrollInfo.nTrackPos;
WindowInfo^.TrackPos := ScrollInfo.nTrackPos;
WindowInfo^.TrackValid := True;
end
else begin
if WindowInfo^.TrackValid
then LMScroll.Pos := (WindowInfo^.TrackPos and $FFFF0000) or Hi(WParam)
else LMScroll.Pos := (ScrollInfo.nPos and $FFFF0000) or Hi(WParam);
end;
if LMScroll.Pos < High(LMScroll.SmallPos)
then LMScroll.SmallPos := LMScroll.Pos
else LMScroll.SmallPos := High(LMScroll.SmallPos);
end;
procedure HandleSetCursor;

4
lcl/interfaces/win32/win32proc.pp
View File

@ -56,6 +56,10 @@ Type
MouseX, MouseY: word; // noticing spurious WM_MOUSEMOVE messages
case integer of
0: (spinValue: single);
1: (
TrackValid: Boolean; // Set when we have a valid trackpos
TrackPos: Integer // keeps the thumb position while tracking
);
end;
function WM_To_String(WM_Message: Integer): string;