View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0028146 | Lazarus | LCL | public | 2015-05-20 22:13 | 2016-11-27 19:58 |
| Reporter | wp | Assigned To | Juha Manninen | ||
| Priority | normal | Severity | minor | Reproducibility | sometimes |
| Status | closed | Resolution | fixed | ||
| Platform | x386-win32 | OS | Win 7 | OS Version | |
| Product Version | 1.4 | Product Build | |||
| Target Version | 1.6 | Fixed in Version | 1.6 | ||
| Summary | 0028146: Flicker in TListbox | ||||
| Description | The first/last visible line of a listbox flickers when the scrollbar is moved up or down quickly. The flicker can be avoided if the WMErasebackground message is handled without performing the erase action. This is a regression in version 1.4 because the issue was not present in version 1.2.6. Possibly it is related to r47451 where some changes in the background erasing process were made. | ||||
| Steps To Reproduce | Run attached demo. It shows two listboxes. The left one is a standard owner-drawn listbox. Drag the scrollbar to the center, and then drag it up and down quickly. Occasional flickering of the top and bottom lines will be seen. The right listbox overrides the WMEraseBackground message such that no repaint of the background occurs. There is no flicker. Run the demo in an older Lazarus version (I tested down to 1.0): they do not show any flicker. Therefore, I consider this to be a regression introduced in version 1.4. | ||||
| Additional Information | The flicker may be difficult to see. Please see the forum thread (http://forum.lazarus.freepascal.org/index.php/topic,28464.msg178098.html#msg178098) for more details. I am attaching also the demo "Listbox_Test" of the OP which slows down painting of the listbox items to enhance the flicker effect. According to the OP, the flicker occurs only on Windows. | ||||
| Tags | No tags attached. | ||||
| Fixed in Revision | r49170, r49561, r50131 | ||||
| LazTarget | - | ||||
| Widgetset | Win32/Win64 | ||||
| Attached Files |
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| related to | 0027261 | closed | Juha Manninen | Patch - Adding WS_EX_LAYOUTRTL support to SendPaintMessage |
| related to | 0028275 | resolved | Juha Manninen | incorrect painting listbox |
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listbox_flicker1.zip (4,666 bytes) |
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ListBox_Test.zip (2,865 bytes) |
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r47451 is pure refactoring. Did you really test it causes the problem? My gut feeling says the problem is somewhere else. |
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No it just caught my eye when looking through the recent svn log messages after having seen that WMEraseBackground can fix the problem. |
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Could somebody please bisect and find which revision caused the problem. |
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r47325 is ok, r47326 fails |
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It was introduced with this issue: http://bugs.freepascal.org/view.php?id=27261 Still not as dramatic as other people say, but is definitely there(ListBox_Test.zip). I see no difference in listbox_flicker1.zip |
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Somebody must provide a patch to fix this one. I don't know enough WinAPI to fix it myself. I also committed the patch from the related issue to prevent it from being ignored. LCL-Win is not very actively maintained now. |
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Catching the WM_EraseBackground message fixes it. I could create a patch with it. I am not 100% sure however if the root cause is not somewhere else. I'll investigate further in the next days. |
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win32wsstdctrls.pp.patch (1,539 bytes)
Index: lcl/interfaces/win32/win32wsstdctrls.pp
===================================================================
--- lcl/interfaces/win32/win32wsstdctrls.pp (revision 49165)
+++ lcl/interfaces/win32/win32wsstdctrls.pp (working copy)
@@ -583,6 +583,9 @@
WindowInfo: PWin32WindowInfo;
NCCreateParams: PNCCreateParams;
LMessage: TLMessage;
+ Count: LResult;
+ Top: Integer;
+ ARect: TRect;
begin
case Msg of
WM_NCCREATE:
@@ -609,6 +612,26 @@
LMessage.Result := 0;
Exit(DeliverMessage(WindowInfo^.WinControl, LMessage));
end;
+ WM_ERASEBKGND:
+ // Avoid unnecessary background paints to avoid flickering of the listbox
+ begin
+ WindowInfo := GetWin32WindowInfo(Window);
+ Count := SendMessage(Window, LB_GETCOUNT, 0, 0);
+ if Assigned(WindowInfo^.WinControl) and
+ (TCustomListBox(WindowInfo^.WinControl).Columns < 2) and
+ (Count <> LB_ERR) and (SendMessage(Window, LB_GETITEMRECT, Count - 1, Windows.LParam(@ARect)) <> LB_ERR) then
+ begin
+ Top := ARect.Bottom;
+ Windows.GetClientRect(Window, ARect);
+ ARect.Top := Top;
+ if not IsRectEmpty(ARect) then
+ Windows.FillRect(HDC(WParam), ARect, WindowInfo^.WinControl.Brush.Reference.Handle);
+ Result := 1;
+ end
+ else
+ Result := CallDefaultWindowProc(Window, Msg, WParam, LParam);
+ Exit;
+ end;
end;
// normal processing
Result := WindowProc(Window, Msg, WParam, LParam);
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The attached patch applies the WM_ERASEBACKGROUND handling of TCheckListbox also to TCustomListbox. This fixes the issue for single-column listboxes. Multi-column listboxes still show some flickering (BTW: the same with TCheckListbox), but i did not find a way to avoid this without introducing other painting artefacts. Since listboxes are only rarely used in the multi-column mode I think this is a viable workaround. |
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Applied, thanks. |
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Thanks. Will it make it into 1.4.2? |
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No, this patch is bad, it breaks background painting of listboxes with the standard style. See http://forum.lazarus.freepascal.org/index.php/topic,29060.msg183135.html#msg183135: Run "examples/fontenum/fontenumerator.lpi" and scroll the center font listbox down for at least one page. |
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win32wsstdctrls.pp-new.patch (581 bytes)
Index: win32wsstdctrls.pp
===================================================================
--- win32wsstdctrls.pp (revision 49559)
+++ win32wsstdctrls.pp (working copy)
@@ -613,7 +613,8 @@
Exit(DeliverMessage(WindowInfo^.WinControl, LMessage));
end;
WM_ERASEBKGND:
- if WindowsVersion <= wvXP then // Standardbehavior for XP
+ if (WindowsVersion <= wvXP) or not ThemeServices.ThemesEnabled then
+ // Standardbehavior for XP, or no themes
Result := CallDefaultWindowProc(Window, Msg, WParam, LParam)
else
begin
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Uploaded a new patch which takes care of the standard style painting issue. |
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Applied the patch, please test. |
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According to a discussion in the forum (http://forum.lazarus.freepascal.org/index.php/topic,28464.msg190710.html#msg190710) user ncs-sniper reports that flicker comes back in Laz 1.4.4 on Windows XP. The attached patch is based on an idea of ncs-sniper and fixes the flickering issue without touching the other cases. |
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win32wsstdctrls.laz144.patch (1,425 bytes)
Index: lcl/interfaces/win32/win32wsstdctrls.pp
===================================================================
--- lcl/interfaces/win32/win32wsstdctrls.pp (revision 50095)
+++ lcl/interfaces/win32/win32wsstdctrls.pp (working copy)
@@ -613,13 +613,19 @@
Exit(DeliverMessage(WindowInfo^.WinControl, LMessage));
end;
WM_ERASEBKGND:
- if (WindowsVersion <= wvXP) or not ThemeServices.ThemesEnabled then
- // Standardbehavior for XP, or no themes
- Result := CallDefaultWindowProc(Window, Msg, WParam, LParam)
- else
begin
+ WindowInfo := GetWin32WindowInfo(Window);
+ if ((WindowsVersion <= wvServer2003) or not ThemeServices.ThemesEnabled) then
+ begin
+ if Assigned(WindowInfo^.WinControl) and not
+ (TCustomListbox(WindowInfo^.WinControl).Style in [lbOwnerDrawFixed, lbOwnerDrawVariable])
+ then begin
+ // Standard behavior for XP/WinServer2003, no themes, no OwnerDraw
+ Result := CallDefaultWindowProc(Window, Msg, WParam, LParam);
+ exit;
+ end
+ end;
// Avoid unnecessary background paints to avoid flickering of the listbox
- WindowInfo := GetWin32WindowInfo(Window);
Count := SendMessage(Window, LB_GETCOUNT, 0, 0);
if Assigned(WindowInfo^.WinControl) and
(TCustomListBox(WindowInfo^.WinControl).Columns < 2) and
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I applied the new patch, thanks. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2015-05-20 22:13 | wp | New Issue | |
| 2015-05-20 22:13 | wp | Status | new => assigned |
| 2015-05-20 22:13 | wp | Assigned To | => Juha Manninen |
| 2015-05-20 22:13 | wp | File Added: listbox_flicker1.zip | |
| 2015-05-20 22:14 | wp | File Added: ListBox_Test.zip | |
| 2015-05-20 22:15 | wp | Additional Information Updated | View Revisions |
| 2015-05-20 23:41 | Juha Manninen | Note Added: 0083862 | |
| 2015-05-20 23:41 | Juha Manninen | Status | assigned => feedback |
| 2015-05-21 00:02 | wp | Note Added: 0083864 | |
| 2015-05-21 00:02 | wp | Status | feedback => assigned |
| 2015-05-21 00:24 | wp | OS | => Win 7 |
| 2015-05-21 00:24 | wp | Platform | => x386-win32 |
| 2015-05-21 00:25 | Juha Manninen | Note Added: 0083865 | |
| 2015-05-21 01:28 | wp | Note Added: 0083866 | |
| 2015-05-21 07:18 | Balázs Székely | Note Added: 0083871 | |
| 2015-05-21 07:19 | Balázs Székely | Note Edited: 0083871 | View Revisions |
| 2015-05-21 07:23 | Balázs Székely | Note Edited: 0083871 | View Revisions |
| 2015-05-21 07:55 | Balázs Székely | Note Edited: 0083871 | View Revisions |
| 2015-05-21 08:55 | Juha Manninen | Relationship added | related to 0027261 |
| 2015-05-22 22:52 | Juha Manninen | Note Added: 0083920 | |
| 2015-05-22 22:58 | wp | Note Added: 0083921 | |
| 2015-05-25 17:24 | wp | File Added: win32wsstdctrls.pp.patch | |
| 2015-05-25 17:29 | wp | Note Added: 0083995 | |
| 2015-05-26 00:31 | Juha Manninen | Fixed in Revision | => r49170 |
| 2015-05-26 00:31 | Juha Manninen | Note Added: 0083998 | |
| 2015-05-26 00:31 | Juha Manninen | Status | assigned => resolved |
| 2015-05-26 00:31 | Juha Manninen | Resolution | open => fixed |
| 2015-05-26 20:25 | wp | Note Added: 0084023 | |
| 2015-05-26 20:25 | wp | Status | resolved => closed |
| 2015-06-12 15:49 | wp | Relationship added | related to 0028275 |
| 2015-07-18 22:59 | wp | Note Added: 0084985 | |
| 2015-07-18 22:59 | wp | Status | closed => assigned |
| 2015-07-18 22:59 | wp | Resolution | fixed => reopened |
| 2015-07-20 12:49 | wp | File Added: win32wsstdctrls.pp-new.patch | |
| 2015-07-20 12:50 | wp | Note Added: 0084999 | |
| 2015-07-22 10:42 | Juha Manninen | Fixed in Revision | r49170 => r49170, r49561 |
| 2015-07-22 10:42 | Juha Manninen | Note Added: 0085013 | |
| 2015-07-22 10:42 | Juha Manninen | Status | assigned => resolved |
| 2015-07-22 10:42 | Juha Manninen | Resolution | reopened => fixed |
| 2015-07-22 11:41 | wp | Status | resolved => closed |
| 2015-07-22 11:41 | wp | Target Version | => 1.4.4 |
| 2015-10-19 19:40 | wp | Note Added: 0086718 | |
| 2015-10-19 19:40 | wp | Status | closed => assigned |
| 2015-10-19 19:40 | wp | Resolution | fixed => reopened |
| 2015-10-19 19:40 | wp | Target Version | 1.4.4 => 1.4.6 |
| 2015-10-19 19:41 | wp | File Added: win32wsstdctrls.laz144.patch | |
| 2015-10-19 19:43 | wp | Note Edited: 0086718 | View Revisions |
| 2015-10-20 23:00 | Juha Manninen | Fixed in Revision | r49170, r49561 => r49170, r49561, r50131 |
| 2015-10-20 23:00 | Juha Manninen | Note Added: 0086759 | |
| 2015-10-20 23:00 | Juha Manninen | Status | assigned => resolved |
| 2015-10-20 23:00 | Juha Manninen | Resolution | reopened => fixed |
| 2015-10-22 11:23 | wp | Status | resolved => closed |
| 2016-11-27 19:57 | Bart Broersma | Status | closed => assigned |
| 2016-11-27 19:57 | Bart Broersma | Resolution | fixed => reopened |
| 2016-11-27 19:57 | Bart Broersma | Target Version | 1.4.6 => 1.6 |
| 2016-11-27 19:57 | Bart Broersma | Status | assigned => resolved |
| 2016-11-27 19:57 | Bart Broersma | Resolution | reopened => fixed |
| 2016-11-27 19:58 | Bart Broersma | Status | resolved => closed |
| 2016-11-27 19:58 | Bart Broersma | Fixed in Version | => 1.6 |
