How to use a shape without using its tools?

[Thorsten Zachmann]

On Thursday, July 07, 2011 09:34:55 Inge Wallin wrote:
> I have just added a patch to the reviewboard:
> http://git.reviewboard.kde.org/r/101871/  This mail is about an issue with
> this patch.
> 
> Here is the description of (one of) the issues that it solves:
> > 1. It fixes a serious issue with loading frame shapes with unknown
> > contents. Previously, when a frame with unrecognized contents, such as
> > an embedded spreadsheet, was loaded, it went through all the objects in
> > the frame. If even one of the objects were recognized, such as a preview
> > image, then a shape was created for that object. This means that the
> > real contents of the frame got lost and only the preview image could be
> > saved back.  This is not how it's supposed to be.  The new logic is to
> > create an Unavail shape as soon as the payload of the frame, i.e. the
> > first object in it, is unrecognized. It is then up to the unavail shape
> > to load and store any preview images. It is also up to the unavail shape
> > to save everything back. This patch does this.
> > 
> > 2. It gives the Unavail shape the ability to show preview images.
> > Actually it gives the shape the ability to show both vector images using
> > SVG and bitmap images using any format that QImage supports. We have not
> > integrated this with the picture shape since we couldn't find a way to
> > disable the picture tool for this shape alone.
> 
> I chatted with Zagge about this, and he said that he didn't like the fact
> that with this patch, showing a preview image is only possible with svg
> and bitmap formats.  All preview of other vector formats like WMF, EMF and
> SVM is lost. This is true, and indeed serious.
> 
> When preparing this patch, Dan and I tried to integrate the picture shape
> and if that had gone well also the vector shape. However, that failed
> because we couldn't find a way to disable the picture tool. We do not want
> the user to be able to replace the preview image with something else.

I think we should not limit this functionality. I feel it would be much better 
to display a warning when the user edits the shape that it contains e.g. 
additional information that will be lost when the operation is done.

> So, as it is now the patch is important (it fixes a dataloss problem) but
> it also removes some nice preview features.  We would be able to solve
> this problem if we could find a way to use the image or vector shapes but
> with their tools disabled.  Any ideas on how to do that?

I see at least 2 ways to do that.

1. Use a ProxyShape that displays the content of the shape that can represent 
the data. A mechanism like that is used in the KWCopyShape that displays the 
content of another shape at a different position.

2. Use a flag that disables modification of the shape by its tool.

Both methods can also be used to implement the warning I talked about above.

Throsten