Developer CD Series 1997 January: Mac OS SDK/Dev.CD Jan 97 SDK2.toast/Development Kits (Disc 2)/OpenDoc Development Framework/ODF-Interest Archive/May 96/Re Forcing a draw.5

Internet Message Format | 1996-12-03 | 5.2 KB | [TEXT/ttxt]

Subject:     Re: Forcing a draw
Sent:        5/18/96 7:31 AM
Received:    5/22/96 8:31 AM
From:        Arni McKinley, [e-mail]
Reply-To:    [e-mail]
To:          OpenDoc Development Framework Discussion List, ODF-Interest@CILabs.

>Bill Finzer
>Key Curriculum Press

>In a DoMouseDown of a subView, the user is dragging a point in a graph, thus
>changing the data in the model layer. The model has dependents, including
>some views, which are notified of the change. The views need to redraw
>themselves immediately; i.e., without waiting for an update, so that the user
>gets feedback about the effects of the drag during the drag.
>
>I have been unable to discover any way to force an immediate redraw of an
>individual view. Can anyone help me?


Bill,

The solution to your particular problem has to do with the following insight:
A given part content may appear in several frames. It should happen that
when you change that content it should change everywhere. On the other
hand, each frame is a unique presentation of the content; you should be
able to change the drawing of that presentation of the content
independently of what is being shown in other frames. One frame may show a
larger scaled drawing of the content than another for example, or it may
show the content scrolled, or may show a different presentation entirely
(say a 3D presentation).

Finally any given frame may be showing its particular presentation through
various facets and every facet whould be showing exactly the same drawing
of that presentation as every other facet.

A simple example of multiple frames is this: Suppose your part is embedded
in a container. It is being seen by the user through one frame; now the
user opens the part and sees it through a window ("View In Window"). There
are now two frames open showing the same content.

How to achieve this in ODF?
(1) Make sure that the content is carried by your part code. DR1 now has a
"FW_CContent" which takes care of carrying content. You can use that for
the part; ODFDraw has several very good example of its use.
(2) Make sure that all variables which describe the view of the content are
carried by the frame and its subviews. The frame is now a FW_CSuperView. A
scaling factor for example is a good variable to keep in the frame or its
main subview.
(3) Make sure that you use the Draw() method of the frame to draw larger
frame related things, like outlines around the frame etc, and the subviews
to draw their own things (the main view would draw the content). Just what
draws what is somewhat arbitrary, but there are some considerations
depending upon the content.
(4) Generally all drawing is done automatically on the update. Generate
updates by calling "view->Invalidate(ev)". Including a rectangle or ODShape
will isolate the update region effectively; leaving them out invalidates
the entire view shape. There is a third parameter in DR1 (I forget if it
was in d11, but I don't think so) which allows you to specify whether to
invalidate the same view in all frames. This is useful if you change the
content of the part and want the frames to change their views accordingly.
(5) Since frames all have a different FW_CPresentation, invalidations are
actually shipped through the frame's presentation. You can do the same if
you want to invalidate directly, though this isn't usually necessary.
Invalidate does it better. For example:
frame->GetPresentation()->Invalidate()
(6) Suppose you have an object you want to redraw wihtin a single facet at
an odd time, like a shape during a mouseDown. You can get hold of the facet
within which a mouseDown has occurred by asking the mouseEvent:
        ODFacet* theFacet = theMouseEvent.GetFacet(ev);
        FW_CViewContext vc(ev, this, theFacet );
        theShape->RenderShape(ev, theFacet, vc);
(7) Suppose you want to set the time in a display area while a simulation
is one frame is underway and you don't want to wait for the update. You
might do this:

void ContrlrFrame::SetCurrentTime( Environment *ev, FW_Double time )
{
        fContrlrView->SetCurrentTime( ev, time );

        // Now draw thie current time to all of the frame's facets
        //              Acquire it since we get rid of it locally
        FW_CAcquiredODShape invalidShape = fContrlrView->GetPresTextShape(ev);
        DrawAllFacets( ev, invalidShape );
}
void ContrlrFrame::DrawAllFacets( Environment *ev, ODShape *invalidShape )
{
        FW_CFrameFacetIterator facetIte(ev, this);
        for (ODFacet* facet = facetIte.First(ev);
facetIte.IsNotComplete(ev); facet = facetIte.Next(ev))
        {
                Draw( ev, facet, invalidShape );

                FW_CAcquiredODShape aqClipShape =
facet->AcquireAggregateClipShape(ev, NULL);
                fContrlrView->Draw(ev, facet, aqClipShape );
        }
}

Notice that setting the time in this context is something that happens in a
given frame. All of the other frames could be running their simulations
simultaneously. The part content is the shapes; the content is being viewed
through different frames, so, if you don't want to save the paths of the
shapes with the shape, but with the frame, you could have the shapes doing
very different things in all the different frames.

Hope this is of help to you.

Arni