tdf#159565 prerequisite: make hidden sections have zero-height frames

As mentioned in commit bb733957dd39e6f0b9d80bb59eb0177188794797 (tdf#114973
sw: enable SelectAll with hidden para at start/end, 2023-01-27), the hidden
sections didn't have frames. That prevented correct handling of the case
when such a frame was in the beginning of the document.

This change re-implements the hidden section to use 0-height frames, like
hidden paragraphs, as a pre-requisite for a follow-up change.

Some layout breakages noticed while working on this are unit-tested now.

This change needed to handle the case when the first section is hidden, and
then goes a page break with page style. In this case, the page style must
apply to the very first page of the document. Implementing this now, when
the frame that defines the page style is not the first in the document, I
accidentally fixed also the previously broken case when the first paragraph
was hidden. Now the page style defined in the second paragraph's page break
will apply correctly.

This change makes hidden sections break outer section's frames. This means
that when text borders are shown, there will be an artifact in the place of
the hidden sections (a horizontal line breaking outer frame). I suppose
it's not a problem, actually helping to see the layout better, so in line
with the "show text borders" helper functionality. If this proves to be
problematic, this can be handled specially in a follow-up.

Change-Id: I14ebf0559b463186aba28902cd10c5cc978ba456
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/163151
Tested-by: Mike Kaganski <mike.kaganski@collabora.com>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/sw/source/core/inc/frame.hxx b/sw/source/core/inc/frame.hxx
index ebfe4a0f2bb4..65f392b3eadc 100644
--- a/sw/source/core/inc/frame.hxx
+++ b/sw/source/core/inc/frame.hxx
@@ -894,6 +894,8 @@ public:
     // Fly in ... and footnotes
     bool IsProtected() const;
 
+    virtual bool IsHiddenNow() const;
+
     bool IsColLocked()  const { return mbColLocked; }
     virtual bool IsDeleteForbidden() const { return mnForbidDelete > 0; }