lazarus/lcl/interfaces/win32/win32object.inc
2007-07-02 07:00:51 +00:00

711 lines
23 KiB
PHP

{%MainUnit win32int.pp}
{
*****************************************************************************
* *
* This file is part of the Lazarus Component Library (LCL) *
* *
* See the file COPYING.modifiedLGPL, included in this distribution, *
* for details about the copyright. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. *
* *
*****************************************************************************
}
{$IFOPT C-}
// Uncomment for local trace
// {$C+}
// {$DEFINE ASSERT_IS_ON}
{$ENDIF}
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.Create
Params: None
Returns: Nothing
Constructor for the class.
------------------------------------------------------------------------------}
Constructor TWin32WidgetSet.Create;
Begin
Inherited Create;
FTimerData := TList.Create;
FMetrics.cbSize := SizeOf(FMetrics);
FMetricsFailed := not Windows.SystemParametersInfo(SPI_GETNONCLIENTMETRICS,
SizeOf(FMetrics), @FMetrics, 0);
if FMetricsFailed then
begin
FMetrics.iMenuHeight := GetSystemMetrics(SM_CYMENU);
end;
OnClipBoardRequest := nil;
Pointer(InitCommonControlsEx) := GetProcAddress(GetModuleHandle('comctl32.dll'), 'InitCommonControlsEx');
End;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.Destroy
Params: None
Returns: Nothing
Destructor for the class.
------------------------------------------------------------------------------}
Destructor TWin32WidgetSet.Destroy;
var
n: integer;
TimerInfo : PWin32TimerInfo;
Begin
Assert(False, 'Trace:TWin32WidgetSet is being destroyed');
n := FTimerData.Count;
if (n > 0) then
begin
DebugLn(Format('[TWin32WidgetSet.Destroy] WARNING: There are %d TimerInfo structures left, I''ll free them' ,[n]));
while (n > 0) do
begin
dec(n);
TimerInfo := PWin32Timerinfo(FTimerData[n]);
Dispose(TimerInfo);
FTimerData.Delete(n);
end;
end;
if FStockNullBrush <> 0 then
begin
DeleteObject(FStockNullBrush);
DeleteObject(FStockBlackBrush);
DeleteObject(FStockLtGrayBrush);
DeleteObject(FStockGrayBrush);
DeleteObject(FStockDkGrayBrush);
DeleteObject(FStockWhiteBrush);
end;
if FStatusFont <> 0 then
begin
Windows.DeleteObject(FStatusFont);
Windows.DeleteObject(FMessageFont);
end;
FTimerData.Free;
if FAppHandle <> 0 then
DestroyWindow(FAppHandle);
Windows.UnregisterClass(@ClsName, System.HInstance);
inherited Destroy;
End;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.AppInit
Params: None
Returns: Nothing
Initialize Windows
------------------------------------------------------------------------------}
procedure TWin32WidgetSet.AppInit(var ScreenInfo: TScreenInfo);
var
ICC: TINITCOMMONCONTROLSEX;
LogBrush: TLOGBRUSH;
SysMenu: HMENU;
Handle: HWND;
DC: HDC;
begin
Assert(False, 'Trace:Win32Object.Init - Start');
if not WinRegister then
begin
Assert(False, 'Trace:Win32Object.Init - Register Failed');
DebugLn('Trace:Win32Object.Init - Register Failed');
Exit;
end;
//Init stock objects;
LogBrush.lbStyle := BS_NULL;
FStockNullBrush := CreateBrushIndirect(LogBrush);
LogBrush.lbStyle := BS_SOLID;
LogBrush.lbColor := $000000;
FStockBlackBrush := CreateBrushIndirect(LogBrush);
LogBrush.lbColor := $C0C0C0;
FStockLtGrayBrush := CreateBrushIndirect(LogBrush);
LogBrush.lbColor := $808080;
FStockGrayBrush := CreateBrushIndirect(LogBrush);
LogBrush.lbColor := $404040;
FStockDkGrayBrush := CreateBrushIndirect(LogBrush);
LogBrush.lbColor := $FFFFFF;
FStockWhiteBrush := CreateBrushIndirect(LogBrush);
if FMetricsFailed then
begin
FStatusFont := Windows.GetStockObject(DEFAULT_GUI_FONT);
FMessageFont := Windows.GetStockObject(DEFAULT_GUI_FONT);
end else begin
FStatusFont := Windows.CreateFontIndirect(@FMetrics.lfStatusFont);
FMessageFont := Windows.CreateFontIndirect(@FMetrics.lfMessageFont);
end;
//TODO: Remove when the WS interface is implemented
// Common controls only need to be initialized when used
// So they are initialized in the CreateHandle for common controls
InitCommonControls;
ICC.dwSize := SizeOf(TINITCOMMONCONTROLSEX);
ICC.dwICC := ICC_DATE_CLASSES;
if InitCommonControlsEx <> nil then
InitCommonControlsEx(@ICC);
// Create parent of all windows, `button on taskbar'
FAppHandle := CreateWindow(@ClsName, PChar(Application.Title), WS_POPUP or
WS_CLIPSIBLINGS or WS_SYSMENU or WS_MINIMIZEBOX,
0, {Windows.GetSystemMetrics(SM_CXSCREEN) div 2,}
0, {Windows.GetSystemMetrics(SM_CYSCREEN) div 2,}
0, 0, HWND(nil), HMENU(nil), HInstance, nil);
AllocWindowInfo(FAppHandle);
// set nice main icon
Windows.SendMessage(FAppHandle, WM_SETICON, ICON_BIG,
LParam(Windows.LoadIcon(MainInstance, 'MAINICON')));
// remove useless menuitems from sysmenu
SysMenu := Windows.GetSystemMenu(FAppHandle, False);
Windows.DeleteMenu(SysMenu, SC_MAXIMIZE, MF_BYCOMMAND);
Windows.DeleteMenu(SysMenu, SC_SIZE, MF_BYCOMMAND);
Windows.DeleteMenu(SysMenu, SC_MOVE, MF_BYCOMMAND);
// initialize ScreenInfo
Handle := GetDesktopWindow;
DC := Windows.GetDC(Handle);
ScreenInfo.PixelsPerInchX := GetDeviceCaps(DC, LOGPIXELSX);
ScreenInfo.PixelsPerInchY := GetDeviceCaps(DC, LOGPIXELSY);
ScreenInfo.ColorDepth := GetDeviceCaps(DC, BITSPIXEL);
ReleaseDC(Handle, DC);
// Thread.Synchronize support
WakeMainThread := @HandleWakeMainThread;
Assert(False, 'Trace:Win32Object.Init - Exit');
end;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.AppMinimize
Params: None
Returns: Nothing
Minimizes the whole application to the taskbar
------------------------------------------------------------------------------}
procedure TWin32WidgetSet.AppMinimize;
begin
Windows.SendMessage(FAppHandle, WM_SYSCOMMAND, SC_MINIMIZE, 0);
end;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.AppRestore
Params: None
Returns: Nothing
Restore minimized whole application from taskbar
------------------------------------------------------------------------------}
procedure TWin32WidgetSet.AppRestore;
begin
Windows.SendMessage(FAppHandle, WM_SYSCOMMAND, SC_RESTORE, 0);
end;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.AppBringToFront
Params: None
Returns: Nothing
Brings the entire application on top of all other non-topmost programs
------------------------------------------------------------------------------}
procedure TWin32WidgetSet.AppBringToFront;
begin
Windows.SetForegroundWindow(FAppHandle);
end;
procedure TWin32WidgetSet.SetDesigning(AComponent: TComponent);
begin
//if Data<>nil then EnableWindow((AComponent As TWinControl).Handle, boolean(Data^));
end;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.SetCallback
Params: Msg - message for which to set a callback
Sender - object to which callback will be sent
Returns: nothing
Applies a Message to the sender
------------------------------------------------------------------------------}
Procedure TWin32WidgetSet.SetCallback(Msg: LongInt; Sender: TObject);
Var
Window: HWnd;
Begin
Assert(False, 'Trace:TWin32WidgetSet.SetCallback - Start');
Assert(False, Format('Trace:TWin32WidgetSet.SetCallback - Class Name --> %S', [Sender.ClassName]));
Assert(False, Format('Trace:TWin32WidgetSet.SetCallback - Message Name --> %S', [GetMessageName(Msg)]));
If Sender Is TControlCanvas Then
Window := TControlCanvas(Sender).Handle
Else If Sender Is TCustomForm Then
Window := TCustomForm(Sender).Handle
Else
Window := TWinControl(Sender).Handle;
if Window=0 then exit;
Assert(False, 'Trace:TWin32WidgetSet.SetCallback - Exit');
End;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.RemoveCallbacks
Params: Sender - object from which to remove callbacks
Returns: nothing
Removes Call Back Signals from the sender
------------------------------------------------------------------------------}
Procedure TWin32WidgetSet.RemoveCallbacks(Sender: TObject);
Var
Window: HWnd;
Begin
If Sender Is TControlCanvas Then
Window := TControlCanvas(Sender).Handle
Else If Sender Is TCustomForm Then
Window := TCustomForm(Sender).Handle
Else
Window := (Sender as TWinControl).Handle;
if Window=0 then exit;
End;
function TWin32WidgetSet.InitHintFont(HintFont: TObject): Boolean;
begin
TFont(HintFont).Name := FMetrics.lfStatusFont.lfFaceName;
TFont(HintFont).Style := [];
TFont(HintFont).Height := FMetrics.lfStatusFont.lfHeight;
TFont(HintFont).Color := clInfoText;
TFont(HintFont).Pitch := fpDefault;
Result := true;
end;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.AppProcessMessages
Params: None
Returns: Nothing
Handle all pending messages
------------------------------------------------------------------------------}
procedure TWin32WidgetSet.AppProcessMessages;
var
AMessage: TMsg;
AccelTable: HACCEL;
retVal, index: dword;
pHandles: Windows.LPHANDLE;
begin
repeat
{$ifdef DEBUG_ASYNCEVENTS}
if Length(FWaitHandles) > 0 then
DebugLn('[ProcessMessages] WaitHandleCount=', IntToStr(FWaitHandleCount),
', WaitHandle[0]=', IntToHex(FWaitHandles[0], 8));
{$endif}
pHandles := nil;
if FWaitHandleCount > 0 then
pHandles := @FWaitHandles[0];
retVal := Windows.MsgWaitForMultipleObjects(FWaitHandleCount,
pHandles, false, 0, QS_ALLINPUT);
if (WAIT_OBJECT_0 <= retVal) and (retVal < WAIT_OBJECT_0 + FWaitHandleCount) then
begin
index := retVal-WAIT_OBJECT_0;
FWaitHandlers[index].OnEvent(FWaitHandlers[index].UserData, 0);
end else
if retVal = WAIT_OBJECT_0 + FWaitHandleCount then
begin
while PeekMessage(AMessage, HWnd(Nil), 0, 0,PM_REMOVE) do
begin
AccelTable := GetWindowInfo(AMessage.HWnd)^.Accel;
if (AccelTable = HACCEL(nil))
or (TranslateAccelerator(AMessage.HWnd, AccelTable, @AMessage) = 0) then
begin
TranslateMessage(@AMessage);
DispatchMessage(@AMessage);
end;
end;
end else
if retVal = WAIT_TIMEOUT then
begin
// check for pending to-be synchronized methods
CheckSynchronize;
CheckPipeEvents;
break;
end else
if retVal = $FFFFFFFF then
begin
DebugLn('[TWin32WidgetSet.AppProcessMessages] MsgWaitForMultipleObjects returned: ', IntToStr(GetLastError));
break;
end;
until false;
End;
procedure TWin32WidgetSet.CheckPipeEvents;
var
lHandler: PPipeEventInfo;
lBytesAvail: dword;
SomethingChanged: Boolean;
ChangedCount:integer;
begin
lHandler := FWaitPipeHandlers;
ChangedCount:=0;
while (lHandler <> nil) and (ChangedCount<10) do
begin
SomethingChanged:=true;
if Windows.PeekNamedPipe(lHandler^.Handle, nil, 0, nil, @lBytesAvail, nil) then
begin
if lBytesAvail <> 0 then
lHandler^.OnEvent(lHandler^.UserData, [prDataAvailable])
else
SomethingChanged := false;
end else
lHandler^.OnEvent(lHandler^.UserData, [prBroken]);
if SomethingChanged then
lHandler := FWaitPipeHandlers
else begin
lHandler := lHandler^.Next;
ChangedCount := 0;
end;
inc(ChangedCount);
end;
end;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.AppWaitMessage
Params: None
Returns: Nothing
Passes execution control to Windows
------------------------------------------------------------------------------}
procedure TWin32WidgetSet.AppWaitMessage;
var
timeout: dword;
pHandles: Windows.LPHANDLE;
begin
RedrawMenus;
Assert(False, 'Trace:TWin32WidgetSet.WaitMessage - Start');
if FWaitPipeHandlers <> nil then
timeout := 100
else
timeout := INFINITE;
pHandles := nil;
if FWaitHandleCount > 0 then
pHandles := @FWaitHandles[0];
Windows.MsgWaitForMultipleObjects(FWaitHandleCount, pHandles,
false, timeout, QS_ALLINPUT);
Assert(False,'Trace:Leave wait message');
End;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.AppTerminate
Params: None
Returns: Nothing
Tells Windows to halt and destroy
------------------------------------------------------------------------------}
Procedure TWin32WidgetSet.AppTerminate;
Begin
Assert(False, 'Trace:TWin32WidgetSet.AppTerminate - Start');
End;
procedure TWin32WidgetSet.AppSetTitle(const ATitle: string);
begin
{$ifdef WindowsUnicodeSupport}
if UnicodeEnabledOS
then Windows.SetWindowTextW(FAppHandle, PWideChar(Utf8Decode(ATitle)))
else Windows.SetWindowText(FAppHandle, PChar(Utf8ToAnsi(ATitle)));
{$else}
Windows.SetWindowText(FAppHandle, PChar(ATitle));
{$endif}
end;
function TWin32WidgetSet.LCLPlatform: TLCLPlatform;
begin
Result:= lpWin32;
end;
{------------------------------------------------------------------------------
Function: CreateTimer
Params: Interval:
TimerFunc: Callback
Returns: a Timer id (use this ID to destroy timer)
Design: A timer which calls TimerCallBackProc, is created.
The TimerCallBackProc calls the TimerFunc.
------------------------------------------------------------------------------}
function TWin32WidgetSet.CreateTimer(Interval: integer; TimerFunc: TFNTimerProc) : THandle;
var
TimerInfo: PWin32TimerInfo;
begin
Assert(False,'Trace:Create Timer: ' + IntToStr(Interval));
Result := 0;
if (Interval > 0) and (TimerFunc <> nil) then begin
New(TimerInfo);
TimerInfo^.TimerFunc := TimerFunc;
TimerInfo^.TimerID := Windows.SetTimer(0, 0, Interval, @TimerCallBackProc);
if TimerInfo^.TimerID=0 then
dispose(TimerInfo)
else begin
FTimerData.Add(TimerInfo);
Result := TimerInfo^.TimerID;
end;
end;
Assert(False,'Trace:Result: ' + IntToStr(result));
end;
{------------------------------------------------------------------------------
Function: DestroyTimer
Params: TimerHandle
Returns:
------------------------------------------------------------------------------}
function TWin32WidgetSet.DestroyTimer(TimerHandle: THandle) : boolean;
var
n : integer;
TimerInfo : PWin32Timerinfo;
begin
Result:= false;
Assert(False,'Trace:removing timer: '+ IntToStr(TimerHandle));
n := FTimerData.Count;
while (n>0) do begin
dec(n);
TimerInfo := FTimerData[n];
if (TimerInfo^.TimerID=UINT(TimerHandle)) then
begin
Result := Boolean(Windows.KillTimer(0, UINT(TimerHandle)));
FTimerData.Delete(n);
Dispose(TimerInfo);
end;
end;
Assert(False,'Trace:Destroy timer Result: '+ BOOL_RESULT[result]);
end;
procedure TWin32WidgetSet.HandleWakeMainThread(Sender: TObject);
begin
// wake up GUI thread by sending a message to it
Windows.PostMessage(AppHandle, WM_NULL, 0, 0);
end;
procedure TWin32WidgetSet.AttachMenuToWindow(AMenuObject: TComponent);
var
AMenu: TMenu;
AWinControl: TWinControl;
begin
AMenu := AMenuObject as TMenu;
if AMenu is TMainMenu then
begin
AWinControl := TWinControl(AMenu.Owner);
Windows.SetMenu(AWinControl.Handle, AMenu.Handle);
//Set the right order menu after attach the menu
SetMenuFlag(AMenu.Handle, MFT_RIGHTORDER or MFT_RIGHTJUSTIFY, AMenu.IsRightToLeft);
AddToChangedMenus(AWinControl.Handle);
end;
end;
{ Private methods (in no significant order) }
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.WinRegister
Params: None
Returns: If the window was successfully regitered
Registers the main window class
------------------------------------------------------------------------------}
Function TWin32WidgetSet.WinRegister: Boolean;
Var
WindowClass: WndClass;
WindowClassW: WndClassW;
Begin
Assert(False, 'Trace:WinRegister - Start');
if UnicodeEnabledOS
then begin
with WindowClassW do
begin
Style := CS_DBLCLKS{CS_HRedraw or CS_VRedraw};
LPFnWndProc := @WindowProc;
CbClsExtra := 0;
CbWndExtra := 0;
hInstance := System.HInstance;
hIcon := Windows.LoadIcon(MainInstance, 'MAINICON');
if hIcon = 0 then
hIcon := Windows.LoadIcon(0, IDI_APPLICATION);
hCursor := Windows.LoadCursor(0, IDC_ARROW);
hbrBackground := 0; {GetSysColorBrush(Color_BtnFace);}
LPSzMenuName := Nil;
LPSzClassName := PWideChar(WideString(ClsName));
end;
Result := Windows.RegisterClassW(@WindowClassW) <> 0;
end
else begin
with WindowClass do
begin
Style := CS_DBLCLKS{CS_HRedraw or CS_VRedraw};
LPFnWndProc := @WindowProc;
CbClsExtra := 0;
CbWndExtra := 0;
hInstance := System.HInstance;
hIcon := Windows.LoadIcon(MainInstance, 'MAINICON');
if hIcon = 0 then
hIcon := Windows.LoadIcon(0, IDI_APPLICATION);
hCursor := Windows.LoadCursor(0, IDC_ARROW);
hbrBackground := 0; {GetSysColorBrush(Color_BtnFace);}
LPSzMenuName := Nil;
LPSzClassName := @ClsName;
end;
Result := Windows.RegisterClass(@WindowClass) <> 0;
end;
Assert(False, 'Trace:WinRegister - Exit');
End;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.NormalizeIconName
Params: IconName - The name of the icon to normalize
Returns: Nothing
Adjusts an icon name to the proper format
------------------------------------------------------------------------------}
Procedure TWin32WidgetSet.NormalizeIconName(Var IconName: String);
Var
IcoLen: Integer;
Begin
DoDirSeparators(IconName);
IcoLen := Pos('.xmp', LowerCase(IconName));
If IcoLen <> 0 Then
Begin
Delete(IconName, IcoLen, Length('.xpm'));
Insert('.ico', IconName, Length(IconName));
End
End;
Procedure TWin32WidgetSet.NormalizeIconName(Var IconName: PChar);
Var
Str: String;
Begin
Str := String(IconName);
NormalizeIconName(Str);
IconName := StrToPChar(Str);
End;
function TWin32WidgetSet.CreateThemeServices: TThemeServices;
begin
Result := TWin32ThemeServices.Create;
end;
{------------------------------------------------------------------------------
Function: TWin32WidgetSet.CreateComponent
Params: Sender - object for which to create visual representation
Returns: nothing
Tells Windows to create a control
------------------------------------------------------------------------------}
function TWin32WidgetSet.CreateComponent(Sender: TObject): THandle;
begin
DebugLn('WARNING: TWin32WidgetSet.CreateComponent is deprecated, should not be reachable!!');
Result := 0;
end;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.AssignSelf
Params: Window - The window to assign
Data - The data to assign to the window
Returns: Nothing
Assigns data to a window
------------------------------------------------------------------------------}
procedure TWin32WidgetSet.AssignSelf(Window: HWnd; Data: Pointer);
begin
Assert(False, 'Trace:[TWin32WidgetSet.AssignSelf] Trying to code it. It''s probably wrong.');
end;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.ShowHide
Params: Sender - The sending object
Returns: Nothing
Shows or hides a control
------------------------------------------------------------------------------}
Procedure TWin32WidgetSet.ShowHide(Sender: TObject);
Var
Handle: HWND;
ParentPanel: HWND;
Flags: dword;
Begin
If (TControl(Sender).FCompStyle = csPage) or (TControl(Sender).FCompStyle = csToolButton) then exit;
Handle := ObjectToHWND(Sender);
ParentPanel := GetWindowInfo(Handle)^.ParentPanel;
if ParentPanel <> 0 then
Handle := ParentPanel;
If TControl(Sender).HandleObjectShouldBeVisible Then
Begin
Assert(False, 'Trace: [TWin32WidgetSet.ShowHide] Showing the window');
if TControl(Sender).FCompStyle = csHintWindow then
begin
Windows.SetWindowPos(Handle, HWND_TOPMOST, 0, 0, 0, 0, SWP_SHOWWINDOW or SWP_NOMOVE or SWP_NOSIZE or SWP_NOACTIVATE or SWP_NOOWNERZORDER);
end else begin
Flags := SW_SHOW;
if TControl(Sender) is TCustomForm then
case TCustomForm(Sender).WindowState of
wsMaximized: Flags := SW_SHOWMAXIMIZED;
wsMinimized: Flags := SW_SHOWMINIMIZED;
end;
Windows.ShowWindow(Handle, Flags);
{ ShowWindow does not send WM_SHOWWINDOW when creating overlapped maximized window }
{ TODO: multiple WM_SHOWWINDOW when maximizing after initial show? }
if Flags = SW_SHOWMAXIMIZED then
Windows.SendMessage(Handle, WM_SHOWWINDOW, 1, 0);
end;
If (Sender Is TCustomForm) Then
SetClassLong(Handle, GCL_HICON, LONG(TCustomForm(Sender).GetIconHandle));
End
Else
Begin
Assert(False, 'TRACE: [TWin32WidgetSet.ShowHide] Hiding the window');
ShowWindow(Handle, SW_HIDE);
End;
End;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.DCReDraw
Params: CanvasHandle - HDC to redraw
Returns: Nothing
Redraws (the window of) a canvas
------------------------------------------------------------------------------}
procedure TWin32WidgetSet.DCRedraw(CanvasHandle: HDC);
begin
// TODO: implement me!
Assert(False, 'TRACE:[TWin32WidgetSet.ReDraw] Redrawing...');
Assert(False, 'TRACE:Invalidating the window');
Assert(False, 'TRACE:Updating the window');
Assert(False, 'TRACE:[TWin32WidgetSet.ReDraw] Finished redrawing');
end;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.SetPixel
Params: Canvas - canvas to set color on
X, Y - position
AColor - new color for specified position
Returns: nothing
Set the color of the specified pixel on the canvas
------------------------------------------------------------------------------}
procedure TWin32WidgetSet.DCSetPixel(CanvasHandle: HDC; X, Y: integer; AColor: TGraphicsColor);
begin
Windows.SetPixel(CanvasHandle, X, Y, AColor);
end;
{------------------------------------------------------------------------------
Method: TWin32WidgetSet.GetPixel
Params: Canvas - canvas to get color from
X, Y - position
Returns: Color at specified point
Get the color of the specified pixel on the canvas
-----------------------------------------------------------------------------}
function TWin32WidgetSet.DCGetPixel(CanvasHandle: HDC; X, Y: integer): TGraphicsColor;
begin
Result := Windows.GetPixel(CanvasHandle, X, Y);
end;
{$IFDEF ASSERT_IS_ON}
{$UNDEF ASSERT_IS_ON}
{$C-}
{$ENDIF}