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LCL/TTrackbar: Avoid flickering in Windows 7 and older. Issue #40836.

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wp_xyz 2024-03-11 16:36:44 +01:00
parent d4a103eaea
commit 0b7f1f3c0c
1 changed files with 24 additions and 1 deletions
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25
lcl/interfaces/win32/win32wscomctrls.pp
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@ -831,6 +831,8 @@ end;
{$endif}
{ TWin32WSTrackBar }
function TrackBarParentMsgHandler(const AWinControl: TWinControl; Window: HWnd;
Msg: UInt; WParam: Windows.WParam; LParam: Windows.LParam;
var MsgResult: Windows.LResult; var WinProcess: Boolean): Boolean;
@ -861,7 +863,27 @@ begin
end;
end;
{ TWin32WSTrackBar }
function TrackbarWndProc(Window: HWnd; Msg: UInt; WParam: Windows.WParam;
LParam: Windows.LParam): LResult; stdcall;
var
Control: TWinControl;
LMessage: TLMessage;
begin
case Msg of
// prevent flickering
WM_ERASEBKGND:
begin
Control := GetWin32WindowInfo(Window)^.WinControl;
LMessage.msg := Msg;
LMessage.wParam := WParam;
LMessage.lParam := LParam;
LMessage.Result := 1;
Result := DeliverMessage(Control, LMessage);
end;
else
Result := WindowProc(Window, Msg, WParam, LParam);
end;
end;
class function TWin32WSTrackBar.CreateHandle(const AWinControl: TWinControl;
const AParams: TCreateParams): HWND;
@ -875,6 +897,7 @@ begin
begin
pClassName := TRACKBAR_CLASS;
WindowTitle := StrCaption;
SubClassWndProc := @TrackbarWndProc;
end;
// create window
FinishCreateWindow(AWinControl, Params, false);