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BView: Fix ClipTo[Inverse]Picture() syncing.

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When BPictures are created on the stack and go out of scope, they send a
AS_DELETE_PICTURE command to the ServerApp thread, and that command may be
processed sooner than the AS_VIEW_CLIP_TO_PICTURE command in the ServerWindow
thread, causing that command to no longer find a ServerPicture for the given
token. Apparently, the Be API leaves you the choice not to sync, in case for
example when you cache your BPictures and they remain valid. The default
value for "sync" is true. The BeBook could explain the situation better when
sync is needed and when not.
This commit is contained in:
Stephan Aßmus
2014-02-01 10:39:12 +01:00
parent 138e4c77eb
commit b58b8cdd30
1 changed files with 16 additions and 6 deletions
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src/kits/interface/View.cpp
+16 -6
View File
@@ -5092,20 +5092,30 @@ BView::_ClipToPicture(BPicture* picture, BPoint where, bool invert, bool sync)
if (!_CheckOwnerLockAndSwitchCurrent())
return;
if (!picture) {
if (picture == NULL) {
fOwner->fLink->StartMessage(AS_VIEW_CLIP_TO_PICTURE);
fOwner->fLink->Attach<int32>(-1);
// NOTE: No need to sync here, since the -1 token cannot
// become invalid on the server.
} else {
fOwner->fLink->StartMessage(AS_VIEW_CLIP_TO_PICTURE);
fOwner->fLink->Attach<int32>(picture->Token());
fOwner->fLink->Attach<BPoint>(where);
fOwner->fLink->Attach<bool>(invert);
}
// TODO: I think that "sync" means another thing here:
// the bebook, at least, says so.
if (sync)
fOwner->fLink->Flush();
// NOTE: "sync" defaults to true in public methods. If you know what
// you are doing, i.e. if you know your BPicture stays valid, you
// can avoid the performance impact of syncing. In a use-case where
// the client creates BPictures on the stack, these BPictures may
// have issued a AS_DELETE_PICTURE command to the ServerApp when Draw()
// goes out of scope, and the command is processed earlier in the
// ServerApp thread than the AS_VIEW_CLIP_TO_PICTURE command in the
// ServerWindow thread, which will then have the result that no
// ServerPicture is found of the token.
if (sync)
Sync();
}
}