1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
% language=us
\environment interaction-style
\startcomponent interaction-javascript
\startchapter[title={JavaScript}]
Annotations can be controlled with \JAVASCRIPT\ but it really depends on the
viewer if it works out well. Using these scripts is a multi||step process where
common functions and data structures can be shared and collected in preambles:
\starttyping
\startJSpreamble {name}
MyCounter = 0 ;
\stopJSpreamble
\stoptyping
The more action oriented scripts are defined as:
\starttyping
\startJScode {increment}
MyCounter = MyCounter + 1 ; // or: ++MyCounter ;
\stopJScode
\stoptyping
This script is executed with:
\starttyping
\goto {advance by one} [JS(increment)]
\stoptyping
Nicer is to define a function:
\starttyping
\startJSpreamble {helpers} used now
function Increment(n) {
MyCounter = MyCounter + n ;
}
\stopJSpreamble
\stoptyping
and then say:
\starttyping
\goto {advance by one} [JS(Increment{5})]
\stoptyping
The distribution contains a collection of scripts that can be preloaded and used
when needed. You can recognize the files by the \type {java-imp-} prefix. To
prevent all preambles ending up in the \PDF\ file, we can say:
\starttyping
\startJSpreamble {something} used later
\stopJSpreamble
\stoptyping
We already saw that one can also say \type {used now} and there's also a way
to filter specific preambles on usage:
\starttyping
\startJScode {mything} uses {something}
\stopJScode
\stoptyping
One should be aware of the fact that there is no decent way to check if every
script is all right! Even worse, the \JAVASCRIPT\ interpreter currently used in
the \ACROBAT\ tools is not reentrant, and breaks down on typos
The full repertoire of commands is:
\showsetup{startJScode}
\showsetup{startJSpreamble}
\showsetup{addtoJSpreamble}
\showsetup{setJSpreamble}
As we're into \LUA\ and because \LUA\ is so lightweight I've wondered several
times now if it would make sense to embed \LUA\ in \PDF\ viewers. After all,
annotations are an extension mechanism. In the early days of \PDF\ this was
actually quite doable because \ACROBAT\ reader (and exchange) had a plugin model.
However, the more functionality ended up in the program, the least interesting
(and popular) the plugins mechanism became. Some open source viewers have an
\API\ so in principle adding the lightweight \LUA\ interpreter (of course with
\LPEG, and quite probably without file \IO) is possible. It has been discussed at
a recent \CONTEXT\ meeting, so who knows \unknown For now we're stuck with
\JAVASCRIPT.
An example of \JAVASCRIPT\ usage is the following, where we load a video and add
some controls. Beware that this kind of functionality is very viewer dependent
and therefore also very unstable over time. Even worse, if you look at the loaded
\JAVASCRIPT\ file you will notice a dependency on soon obsolete (in \ACROBAT\ at
least) shockwave support. First we load a library that will predefine a video
graphic: and then create an instance:
\starttyping
\useJSscripts[vplayer]
\setupinteraction
[state=start]
\externalfigure
[shockwave]
[frame=on,
width=480pt,
height=270pt,
file=test.mp4,
label=foo]
\stoptyping
The controls are defined with:
\starttyping
\goto{START} [JS(StartShockwave{foo})]
\goto{REWIND}[JS(RewindShockwave{foo})]
\goto{PAUSE} [JS(PauseShockwave{foo})]
\goto{STOP} [JS(StopShockwave{foo})]
\stoptyping
or, as we have some defined reference shortcuts:
\starttyping
\goto{START} [StartShockwave{foo}]
\goto{REWIND}[RewindShockwave{foo}]
\goto{PAUSE} [PauseShockwave{foo}]
\goto{STOP} [StopShockwave{foo}]
\stoptyping
It's actually not that hard to add all kind of functionality if only we could be
sure of stable support and continuity.
\stopchapter
\stopcomponent
|
