destinations in PDF

destinations in PDF

[Peter Rolf]

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I missed the support in context, to define exact destination (page 553 
[533],
PDF Reference 1.5 PD) in interactive documents.
The defined types lack the support for destinations, that don't lie on 
the top
of a page.

An example to make it clear...
You have made a PDF document with bookmarks, the focus is set to width
for good readability. Now you press a bookmark for a section and Acroreader
opens the correct page. But hey, where is the section? If it starts at the
lower quarter of the page, it isn't visible at all.

So I tried to change this behaviour, playing around with bookmarks
(as one fuction using destinations). As I'm no TeX wizzard, the result is
very limited. But I hope it's enough to show that there are more or less 
good
reasons for an extension of destinations in context.

Regards,

   Peter


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Re: destinations in PDF

[Giuseppe Bilotta]

Thursday, June 12, 2003 Peter Rolf wrote:

PR> An example to make it clear...
PR> You have made a PDF document with bookmarks, the focus is set to width
PR> for good readability. Now you press a bookmark for a section and Acroreader
PR> opens the correct page. But hey, where is the section? If it starts at the
PR> lower quarter of the page, it isn't visible at all.

Welcome to the world of PDF vs TeX :)

The reason of the problem: TeX puts the reference mark for the
current line on the baseline; when a PDF reference is set that
refers to a particular point of the page (e.g. a Rectangle
reference, or an XYZ one), this means that the current
*baseline* will end up on the top of the screen, therefore
hiding the actual line.

One would therefore have to put the reference mark not where
TeX wants to put it, but at <TeX placement> + <appropriate
height> (where the height added would be "enough to show the
text we *really* want to refer to.)

The problem is: how to determine the appropriate height?

For normal text, this would be the current lineheight, for
example (plus a baseline skip so that the line does not
coincide *precisely* with the monitor border, and there's some
extra margin). For section heads, it would be the whole
sectionhead height. For floats, it would be the float height.

In general, for all ConTeXt objects we would need a "put
reference mark here" command; if the object is then made into a
reference, it should be put there. (When no such mark is
defined, it should default to <TeX placement> + <lineheight>)

Hans, this is a core thing, isn't it?

Oh, and yes we need to add "rectangle" references :)

-- 
Giuseppe "Oblomov" Bilotta

Re: destinations in PDF

[Hans Hagen]

At 12:34 12/06/2003 +0200, you wrote:

>In general, for all ConTeXt objects we would need a "put
>reference mark here" command; if the object is then made into a
>reference, it should be put there. (When no such mark is
>defined, it should default to <TeX placement> + <lineheight>)

even then you would run into problems with 'virtual content'

>Hans, this is a core thing, isn't it?

a proper bodyfontsize offset would be enough;

>Oh, and yes we need to add "rectangle" references :)

well, anything is possible, but as a starter:

-  the pdftex xyz should work ok
-  acrobat viewers should behave consistently (or in a controlled way)

we did play with the xyz thing didn't we? if there are problems, its time 
to repair pdftex (we can discuss this with thanh during tug 2003 in hawaii)

if there was an efficient extra hash mechanism (i don't want to to run out 
of tex mem/hash) we could do a lot more interesting things ... (like this)

Hans
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