bug#5721: Feature request: Function that returns absolute coordinates

[martin rudalics]

> I'd like the request to be reopened, because the current function
> `window-inside-absolute-pixel-edges' does not provide the requested
> behaviour.

I think your analysis is correct but will leave it to Jan to decide how
to proceed.

> Suppose no fringes, and header-line.  All considerations for a GTK build.
>
> 0--------------------------------------*
> |           display                    |
> | A----------------------------+       |
> | |      emacs@foo.bar         +       |
> | |-B------------------------+ +       |
> | | |       toolbar          | |       |
> | | +------------------------+ |       |
> | | |       menubar          | |       |
> | | C------------------------+ |       |
> | | |                        | |       |
> | | |       window           | |       |
> | | |   D---------+          | |       |
> | | |   | tooltip |          | |       |
> | | |   +---------+          | |       |
> | | +------------------------+ |       |
> | *----------------------------*       |
> |                                      |
> *--------------------------------------*

Where did/do we put the internal borders of the frame?

> We have a buffer position D =
> (D.x, D.y) in some window and want to display a tool-tip there. At the
> moment,
>
>        (posn-x-y (posn-at-point))
>
> gives us a position relative to C, so we would need it's absolute
> position.
>
> But `window-absolute-pixel-edges' gives the absolute position of
>
>     (C.x - (B.x - A.x), C.y - (B.y - A.y))
>   = (A.x , C.y - (B.y - A.y)) ,
>
> that is, it does not account for the width and height (B - A) of the
> window managers decorations.  Furthermore these sizes are unknown to the
> lisp side, making it impossible to complete the desired task.

I'm not sure whether we can correctly retrieve the decorations always
and everywhere.  But note that for maximized and full-screen frames
there usually are no outer borders and with full-screen frames there's
no titlebar either.  How does your patch handle these?

> So it seems to me that `window-absolute-pixel-edges' should return the
> absolute position of C, such that the tool-tip (or other frame) may be
> positioned at C + D.
>
> I noticed, that the frame struct already has members x_pixels_diff and
> y_pixels_diff, such that
>
>     (x_pixels_diff, y_pixels_diff) = (B.x - A.x, B.y - A.y) ,
>
> such that we may compute C with this values.  So I propose extending
> `calc_absolute_offset' by adding these pixel_diff values.  For GTK this
> appears to be especially easy, since these diff values already account
> for the tool-bar and menu-bar sizes.

martin