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win32: improve double buffering protection (#0011145)

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git-svn-id: trunk@15455 -
This commit is contained in:
paul 2008-06-18 00:49:25 +00:00
parent f678aaf278
commit cba644ed21
1 changed files with 12 additions and 30 deletions
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42
lcl/interfaces/win32/win32callback.inc
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@ -174,36 +174,9 @@ type
BitmapWidth: integer;
BitmapHeight: integer;
end;
PDoubleBuffer = ^TDoubleBuffer;
var
CurDoubleBuffer: TDoubleBuffer = (DC: 0; Bitmap: 0; BitmapWidth: 0; BitmapHeight: 0);
SavedBuffers: TList = nil;
function SaveDoubleBuffer: Boolean;
var
Item: PDoubleBuffer;
begin
if SavedBuffers = nil then
SavedBuffers := TList.Create;
New(Item);
Item^ := CurDoubleBuffer;
SavedBuffers.Add(Item);
FillChar(CurDoubleBuffer, SizeOf(CurDoubleBuffer), 0);
Result := True;
end;
procedure RestoreDoubleBuffer;
var
Item: PDoubleBuffer;
begin
Item := SavedBuffers[SavedBuffers.Count - 1];
SavedBuffers.Delete(SavedBuffers.Count - 1);
CurDoubleBuffer := Item^;
Dispose(Item);
if SavedBuffers.Count = 0 then
FreeAndNil(SavedBuffers);
end;
function CheckMouseMovement: boolean;
// returns true if mouse did not move between lmousebutton down
@ -387,6 +360,7 @@ var
needParentPaint: boolean;
lNotebookFound: boolean;
BufferWasSaved: Boolean;
BackupBuffer: TDoubleBuffer;
begin
// note: ignores the received DC
// do not use default deliver message
@ -436,9 +410,13 @@ var
if useDoubleBuffer then
begin
if CurDoubleBuffer.DC <> 0 then
begin
// we've been called from another paint handler. To prevent killing of
// not own DC and HBITMAP lets save then and restore on exit
BufferWasSaved := SaveDoubleBuffer
BackupBuffer := CurDoubleBuffer;
FillChar(CurDoubleBuffer, SizeOf(CurDoubleBuffer), 0);
BufferWasSaved := True;
end
else
BufferWasSaved := False;
CurDoubleBuffer.DC := Windows.CreateCompatibleDC(0);
@ -565,7 +543,11 @@ var
DeleteDC(CurDoubleBuffer.DC);
CurDoubleBuffer.DC := 0;
if BufferWasSaved then
RestoreDoubleBuffer;
begin
if CurDoubleBuffer.Bitmap <> 0 then
DeleteObject(CurDoubleBuffer.Bitmap);
CurDoubleBuffer := BackupBuffer;
end;
{$ifdef DEBUG_DOUBLEBUFFER}
if CopyBitmapToClipboard then
begin