paweld/lazarus
1
0
Fork 0
mirror of https://gitlab.com/freepascal.org/lazarus/lazarus.git synced 2025-04-19 01:29:31 +02:00
Code Issues Packages Projects Releases Wiki Activity

Merged revision(s) 53045 #028ed81448 from trunk:

Browse Source 
Win32: SetComboMinDropDownSize
- Support for the CB_SETMINVISIBLE message depends on ComCtlVersion, not on the value of ThemeServices.ThemesEnabled
- Send then CB_SETDROPPEDWIDTH message even if first message failed.
- Add a comment to explain why the function result cannot always be determined accurately
Resolves Issue #0030526.
........

git-svn-id: branches/fixes_1_6@53048 -
This commit is contained in:
maxim 2016-09-28 22:07:24 +00:00
parent 5f08b52cb3
commit f1db96cde7
1 changed files with 22 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
lcl/interfaces/win32/win32winapi.inc
View File

@ -3053,10 +3053,29 @@ end;
function TWin32WidgetSet.SetComboMinDropDownSize(Handle: HWND; MinItemsWidth,
MinItemsHeight, MinItemCount: integer): boolean;
var
LR: LRESULT;
begin
Result:= ThemeServices.ThemesEnabled and
boolean(Windows.SendMessage(Handle, CB_SETMINVISIBLE, MinItemCount, 0));
Result := Result and boolean(Windows.SendMessage(Handle, CB_SETDROPPEDWIDTH, MinItemsWidth, 0));
//CB_SETMINVISIBLE is only supported with the correct ComCtlVersion, it does not depend
//on the value of ThemeServices.ThemesEnabled
// https://msdn.microsoft.com/en-us/library/windows/desktop/bb775915(v=vs.85).aspx
Result:= (ComCtlVersion > ComCtlVersionIE6) and
(Windows.SendMessage(Handle, CB_SETMINVISIBLE, MinItemCount, 0) <> 0);
//Even if the above fails, then still we need to send the next message, (Issue #0030526)
//but we return True only if everything succeeds
LR := Windows.SendMessage(Handle, CB_SETDROPPEDWIDTH, MinItemsWidth, 0);
//debugln(['TWin32WidgetSet.SetComboMinDropDownSize: LR = ',LR]);
{
It seems there is no certain way to determine if the last SendMessage was actually successful:
According to https://msdn.microsoft.com/en-us/library/windows/desktop/bb775901(v=vs.85).aspx upon failure
LR should be CB_ERR (-1), but if the Handle is wrong, the result will be 0.
To complicate matters, if Handle is correct and MinItemsWidth = 0, then upon success
the result will also be 0.
This means that inside this function, a result value of 0 can be valid or invalid, and when
MinItemsWidht = 0, there is no way of telling (only end-user will see the result on screen).
For now we assume that a zero result is valid if MinItemsWidth = 0.
}
Result := Result and ((LR <> CB_ERR) and ((LR <> 0)) xor (MinItemsWidth = 0));
end;
{------------------------------------------------------------------------------