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{%MainUnit ../graphics.pp}
{******************************************************************************
TBitmapCanvas
******************************************************************************
*****************************************************************************
This file is part of the Lazarus Component Library (LCL)
See the file COPYING.modifiedLGPL.txt, included in this distribution,
for details about the license.
*****************************************************************************
}
{------------------------------------------------------------------------------
Method: TBitmapCanvas.Create
Params: ABitMap: the owner of the class
Returns: Nothing
Constructor for the class.
------------------------------------------------------------------------------}
constructor TBitmapCanvas.Create(AImage: TRasterImage);
begin
inherited Create;
// set FImage after inherited create to make sure that the inherited Create
// won't trigger a call to FImage
FImage := AImage;
end;
{------------------------------------------------------------------------------
Method: TBitmapCanvas.CreateHandle
Params: None
Returns: Nothing
Creates the handle.
------------------------------------------------------------------------------}
procedure TBitmapCanvas.CreateHandle;
var
DC: HDC;
begin
if HandleAllocated then exit;
if FImage = nil then exit;
FImage.BitmapHandleNeeded;
FImage.PaletteNeeded;
if FImage.FSharedImage.BitmapCanvas <> nil then
(FImage.FSharedImage.BitmapCanvas as TBitmapCanvas).FreeDC;
FImage.FSharedImage.BitmapCanvas := Self;
DC := CreateCompatibleDC(0);
if FImage.BitmapHandleAllocated
then FOldBitmap := SelectObject(DC, FImage.BitmapHandle)
else FOldBitmap := 0;
if FImage.PaletteAllocated
then begin
FOldPalette := SelectPalette(DC, FImage.Palette, True);
RealizePalette(DC);
end
else begin
FOldPalette := 0;
end;
// since moveto doesn't force a unshare, it is possible that a moveto was
// done in the old DC.
with PenPos do
LCLIntf.MoveToEx(DC, X, Y, nil);
Handle := DC;
//DebugLn('TBitmapCanvas.CreateHandle END Self=',DbgS(Self),' DC=',DbgS(DC),
// ' Handle=',DbgS(GetUpdatedHandle([csHandleValid])));
end;
{------------------------------------------------------------------------------
Method: TBitmapCanvas.Destroy
Params: None
Returns: Nothing
Destructor for the class.
------------------------------------------------------------------------------}
destructor TBitmapCanvas.Destroy;
begin
FreeDC;
inherited Destroy;
end;
{------------------------------------------------------------------------------
Method: TControlCanvas.FreeDC
Params: None
Returns: Nothing
Frees the device context
------------------------------------------------------------------------------}
procedure TBitmapCanvas.FreeDC;
var
OldHandle: HBITMAP;
begin
if not HandleAllocated then exit;
//DebugLn('TBitmapCanvas.FreeDC START Self=',DbgS(Self),' FBitmap=',DbgS(FBitmap));
if FImage = nil
then begin
Handle := 0;
Exit;
end;
OldHandle := FHandle;
Handle := 0;
FImage.FSharedImage.BitmapCanvas := nil;
if FOldBitmap <> 0
then begin
SelectObject(OldHandle, FOldBitmap);
FOldBitmap := 0;
end;
if FOldPalette <> 0
then begin
SelectPalette(OldHandle, FOldPalette, True);
FOldPalette := 0;
end;
DeleteDC(OldHandle);
end;
// included by graphics.pp
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