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more commenting, if only to clean up my own mind

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git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@15235 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Stephan Aßmus 2005-11-30 00:29:19 +00:00
parent 1ba9992d13
commit 7e68917fe7
1 changed files with 27 additions and 5 deletions
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32
src/tests/servers/app/newerClipping/WindowLayer.cpp
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@ -311,12 +311,24 @@ WindowLayer::Show()
void
WindowLayer::ProcessDirtyRegion(BRegion* region)
{
// this is exectuted in the desktop thread,
// and it means that the window thread currently
// blocks on the global region lock
// if this is exectuted in the desktop thread,
// it means that the window thread currently
// blocks to get the read lock, if it is
// executed from the window thread, it should
// have the read lock and the desktop thread
// is blocking to get the write lock. IAW, this
// is only executed in one thread.
if (fDirtyRegion.CountRects() == 0) {
// the window needs to be informed
// when the dirty region was empty
// when the dirty region was empty.
// NOTE: when the window thread has processed
// the dirty region in MessageReceived(),
// it will make the region empty again,
// when it is empty here, we need to send
// the message to initiate the next update round.
// Until the message is processed in the window
// thread, the desktop thread can add parts to
// the region as it likes.
PostMessage(MSG_REDRAW, this);
}
// this is executed from the desktop thread
@ -327,7 +339,10 @@ WindowLayer::ProcessDirtyRegion(BRegion* region)
void
WindowLayer::MarkDirty(BRegion* regionOnScreen)
{
// for triggering MSG_REDRAW
// for marking any part of the desktop dirty
// this will get write access to the global
// region lock, and result in ProcessDirtyRegion()
// to be called for any windows affected
if (fDesktop)
fDesktop->MarkDirty(regionOnScreen);
}
@ -337,6 +352,9 @@ void
WindowLayer::MarkContentDirty(BRegion* regionOnScreen)
{
// for triggering MSG_REDRAW
// since this won't affect other windows, read locking
// is sufficient. If there was no dirty region before,
// an update message is triggered
if (fDesktop && fDesktop->ReadLockClipping()) {
regionOnScreen->IntersectWith(&fVisibleContentRegion);
@ -389,6 +407,10 @@ WindowLayer::CopyContents(BRegion* region, int32 xOffset, int32 yOffset)
// what is left visible from the original region
// at the destination after the region which could be
// copied has been excluded, is considered dirty
// NOTE: it may look like dirty regions are not moved
// if no region could be copied, but that's alright,
// since these parts will now be in newDirty anyways
// (with the right offset)
newDirty.OffsetBy(xOffset, yOffset);
newDirty.IntersectWith(&fVisibleContentRegion);
if (newDirty.CountRects() > 0)