mailing-list for TeXmacs Users

["David Allouche" <address@hidden>]

On Sun, Oct 26, 2008 at 20:48, Henri Lesourd <address@hidden> wrote:

Andrea Gamba wrote:

It would be also nice that the window is always centered when zooming in/out.
Now it is aligned to the left, do you think it is possible to change this
setting?

 

No, there are no Scheme commands to change the alignment
of the displayed text inside the window (nor to move or
resize the TeXmacs window, btw).

Henri, I think you misunderstood Andrea.

What Andrea seems to have in mind is that when changing the shrinking factor, the position at the center of the window should not change.

In more technical terms: texmacs has a several coordinate systems: one in which boxes are positioned on a page, and another in which the page is positioned in the editor's viewport. When the shrinking factor is changed, only one page point can have a invariant viewport position. Let's call this point the "pinned point". According to Andrea, currently the viewport's top-left corner is pinned. And he would like to pin the center of the viewport.

From the perspective of the viewport's implementor, the current behaviour is the simplest fundamental one. It would be reasonable to require that pinning be implemented in scheme.

I expect that texmacs does not provide the necessary glue. Here's what would be needed:

 * getting and setting the relative position of the viewport and page coordinate systems
 * getting the size of the viewport in page coordinates

Not presuming of what the actual glue should look like. This kind of API is tricky to get right.