Re: canvas terminal

[Ethan M. <merritt@u.washington.edu>]

On Tuesday 14 April 2009 05:22:53 Petr Mikulik wrote:
> I have tried the "canvas demo" web page
> 	http://gnuplot.sourceforge.net/demo_canvas/
> 
> by Firefox and Seamonkey. However, only that one "Example of mouse tracking, 
> zoom/unzoom" on this main page is mouseable while others e.g.
> 	http://gnuplot.sourceforge.net/demo_canvas/simple.html
> 
> are static -- they look like a png bitmap. Shouldn't they be mouseable or 
> dynamic as well?

The terminal currently runs in 2 different modes.
It can produce an HTML document containing a single, mouseable, plot.
Or it can produce only a *.js file suitable for embedding in an
externally produced HTML document.   But in that case you have to set up
the mousing yourself at the time of generating the HTML document.
I did that by hand for the top level page of the demo set, but
the webify script is not smart enough to do that automatically for all
the individual demos.

There is a further complication that I haven't had time to sort out.
Help would be welcome.   If there are multiple plots on the same web
page,  how can the mousing code correctly identify which one is
"active" and generate the corresponding coordinate space.
It should be possible to do this based on the id tag of the individual
canvas elements, but for whatever reason I had trouble getting that to
work.

> Further, it there is "reset" written on the bottom of every page, including 
> demos for png and svg. Could webify.pl not print this line?

Yeah, probably.
There's a bigger annoyance, though.  The script always generates one extra
reference to a non-existent plot at the end of each demo.  This is true
for the png and svg versions as well.   The script would need to be 
rewritten to avoid this.  Again, help would be welcome.

 
> Looking for the canvas docs, I have found that "help canvas" shows 
> "Subtopics available for canvas: size" but it gives the same text as "help 
> canvas".

Right.  We already had help for "canvas", meaning the terminal-independent
plot area. 

> Moreover, there is a clash in "help canvas" (drawing area) vs "help term 
> canvas" (terminal). As it works "help png", "help postscript", etc., I think 
> "help canvas" should be equal to "help term canvas". Then "help canvas" 
> should be merged to "help size" or be renamed "help drawing canvas"...(?)

So you propose to change the terminology everywhere so that the plot area
is called something other than "the canvas"?


-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742