The previous fix worked OK, but it was conceptually wrong. Puzzles
save files are better regarded as binary, not text: the length fields
are measured in bytes, so translating the file into a different
multibyte character encoding would invalidate them.
So it was wrong to fetch a C byte string containing the exactly right
binary data, then translate it into a Javascript string as if decoding
from UTF-8, then retranslate to a representation of a bytewise
encoding via encodeURIComponent, and then label the result as
application/octet-stream.
This probably wouldn't have caused any problems in practice, because I
don't remember any situation in which my save files use characters
outside printable ASCII (plus newline). But it's not actually
forbidden, so a save file might choose to do that some day, so that
UTF-8 decode/reencode hidden in the JS was a latent bug.
Now the URI-encoding is done on the C side, while we still know
exactly what the binary data ought to look like and can be sure we're
translating it byte for byte into the output encoding for the data:
URI. By the time the JS receives a string pointer from get_save_file,
it's already URI-encoded, which _guarantees_ that it's in ASCII and
won't be messed about with by Emscripten's UTF8ToString.
In commit f6434e84964d840 I said I had replaced all uses of
old-Emscripten's Pointer_stringify() function with new-Emscripten's
UTF8ToString(). In fact, I only replaced the ones in emcclib.js, but I
missed one in emccpre.js used in preparing downloadable save files.
Those were therefore broken, with a Javascript undefined-name error.
Using a stunt webserver which artificially introduces a 3s delay just
before the last line of the HTML output, I have reproduced a
uwer-reported loading/startup race bug:
Previously the wasm loading was started by the <script> element,
synchronously. If the wasm loading is fast, and finishes before the
HTML loading, the onRuntimeInitialized event may occur before
initPuzzles. But initPuzzles sets up the event handler.
Fix this bug, and introduce a new comment containing an argument for
the correctness of the new approach.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
I presume this will improve performance. Also, if I've understood
correctly, WASM-based compiled web code is capable of automatically
growing its memory, which the previous asm.js build of the puzzles
could not do, and occasionally caused people to complain that if they
tried to play a _really big_ game in their browser, the JS would
eventually freeze because the emulated memory ran out.
I've been putting off doing this for ages because my previous
Emscripten build setup was so finicky that I didn't like to meddle
with it. But now that the new cmake system in this source tree makes
things generally easier, and particularly since I've just found out
that the up-to-date Emscripten is available as a Docker image (namely
"emscripten/emsdk"), this seemed like a good moment to give it a try.
The source and build changes required for this update weren't too
onerous. I was half expecting a huge API upheaval, and indeed there
was _some_ change, but very little:
- in the JS initPuzzle function, move the call to Module.callMain()
into Module.onRuntimeInitialized instead of doing it at the top
level, because New Emscripten's .js output likes to load the
accompanying .wasm file asynchronously, so you can't call the WASM
main() until it actually exists.
- in the JS-side library code, replace all uses of Emscripten's
Pointer_stringify() function with the new name UTF8ToString(). (The
new version also has an ASCIIToString(), so I guess the reason for
the name change is that now you get to choose which character set
you meant. I need to use UTF-8, so that the × and ÷ signs in Keen
will work.)
- set EXTRA_EXPORTED_RUNTIME_METHODS=[cwrap,callMain] on the emcc
link command line, otherwise they aren't available for my JS setup
code to call.
- (removed -s ASM_JS=1 from the link options, though I'm not actually
sure it made any difference one way or the other in the new WASM
world)
- be prepared for a set of .wasm files to show up as build products
alongside the .js ones.
- stop building with -DCMAKE_BUILD_TYPE=Release! I'm not sure why
that was needed, but if I leave that flag on my cmake command line,
the output .js file fails to embed my emccpre.js, so the initial
call to initPuzzle() fails from the HTML wrapper page, meaning
nothing at all happens.
In other front ends, Shift-click is an alternative to the middle
button, and Ctrl-click the right button. Apparently I completely
forgot to implement this in the JS front end. Better late than never.
This is done by showing a dialog containing an <input type="file">
through which the user can 'upload' a save file - though, of course,
the 'upload' doesn't go to any HTTP server, but only into the mind of
the Javascript running in the same browser.
It would be even nicer to support drag-and-drop as an alternative UI
for getting the save file into the browser, but that isn't critical to
getting the first version of this feature out of the door.
This is done by getting midend_serialise to produce the complete
saved-game file as an in-memory string buffer, and then encoding that
into a data: URI which we provide to the user as a hyperlink in a
dialog box. The hyperlink has the 'download' attribute, which means
clicking on it should automatically offer to save the file, and also
lets me specify a not-too-silly default file name.
I'm about to want to call these from Javascript as well as from
Emscripten-compiled C, so I need versions of them that aren't wrapped
up in the Emscripten library object and also don't expect half their
parameters to be Emscripten-verse char pointers requiring calls to
Pointer_stringify.
The easiest way to achieve all of that is to turn the Emscripten-
ready versions of those functions in emcclib.js into tiny wrappers
around the JS versions, which do the pointer stringification and a
couple of other details like directing callbacks to the right C
functions.
To do this, I've completely replaced the API between mid-end and front
end, so any downstream front end maintainers will have to do some
rewriting of their own (sorry). I've done the necessary work in all
five of the front ends I keep in-tree here - Windows, GTK, OS X,
Javascript/Emscripten, and Java/NestedVM - and I've done it in various
different styles (as each front end found most convenient), so that
should provide a variety of sample code to show downstreams how, if
they should need it.
I've left in the old puzzle back-end API function to return a flat
list of presets, so for the moment, all the puzzle backends are
unchanged apart from an extra null pointer appearing in their
top-level game structure. In a future commit I'll actually use the new
feature in a puzzle; perhaps in the further future it might make sense
to migrate all the puzzles to the new API and stop providing back ends
with two alternative ways of doing things, but this seemed like enough
upheaval for one day.
The previous control buttons and dropdowns based on form elements were
always a bit ugly: partly in a purely visual sense, and partly because
of the nasty bodge I had to do with splitting the usual 'Custom' game
type menu item into two (to get round the fact that if an element of a
<select> is already selected, browsers won't send an event when it's
re-selected). Also, I'm about to want to introduce hierarchical
submenus in the Type menu, and <select> doesn't support that at all.
So here's a replacement system which does everything by CSS
properties, including the popping-up of menus when the mouse moves
over their parent menu item. (Thanks to the Internet in general for
showing me how that trick is done.)
The mouseup listener was calling event.preventDefault(), as part of
the mechanism for making mouse clicks and drags on the puzzle's resize
handle have resizing effects _instead_ of the normal browser
behaviour. However, calling event.preventDefault() on _every_ mouseup,
rather than just the ones associated with the resize handle, was
overkill, and I've recently noticed that it's breaking attempts to
select from the game type dropdown by clicking the mouse. So now I'm
only calling preventDefault() on the mouseups that I have reason to
think are actually relevant to what I'm trying to do.
(I don't know why I've only just noticed this. I suppose a change of
behaviour between Firefox versions is the most likely cause.)
I've just upgraded to emcc 1.16.0, in which something fiddly has
happened to the semantics of Module.run() vs noInitialRun - now
setting the latter seems to cause the former to do everything except
calling main(), and then refuse to ever do anything again. So now I
have to use Module.callMain() in place of Module.run() when I finally
do get round to wanting to call main().
[originally from svn r10180]
Rather than design an ersatz 'window frame' surrounding the puzzle
canvas, I've simply overlaid the resize handle on the corner of the
puzzle itself (canvas or status bar, depending on whether the latter
exists), trusting that all games in my collection provide a reasonable
border within their drawing area. (OS X already does this with its
resize handle, so it's not as if there's no precedent.)
Unlike the desktop versions, I control the resize behaviour completely
in this environment, so I can constrain the canvas to only ever be
sensible sizes with no dead space round the edges (and, in particular,
preserve the aspect ratio).
Right-clicking the resize handle will restore the puzzle's default
tile size. I had intended to implement a maximise-to-browser-window
button too, but was annoyingly foiled by scrollbars - if you maximise
to the current window width, and as a result the text below the puzzle
scrolls off the bottom, then a vertical scrollbar appears and eats
into the width you just maximised to. Gah.
[originally from svn r9822]
the game-type <select>, since IE turns out to ignore display:none on
options. Oh well.
Instead I now do a more transparent thing: when custom game params are
in use, there's a "Custom" option selected in the dropdown, and a
separate 'Re-customise' option which brings the config box back up.
When an ordinary preset is selected, the Custom option is missing, and
there's just a 'Customise'.
In the process I've tinkered a bit to arrange that the custom 'preset'
is always represented by a negative number rather than one past the
last real preset; that seems more consistent overall.
[originally from svn r9811]
Unlike Firefox, IE and Chrome don't generate keypress events at all if
you suppress the default handling of keydowns. Therefore, we have to
figure out everything from the keydown event, because if we unsuppress
the default handling of any keydowns then we'll get annoyances like ^R
going back to meaning reload-page rather than redo-move.
[originally from svn r9810]
the return value of relative_mouse_coords! I only got away with that
error because the canvas was at offset zero compared to its immediate
parent element.
[originally from svn r9808]
didn't like them, which doesn't matter as such since they won't run
these JS puzzles anyway (no TypedArray support) but it hints that
other JS implementations might be picky about this too.
[originally from svn r9804]
mention that the HTML pages generated by html/jspage.pl are also an
integral part of this front end. (The NestedVM frontend is more
self-contained, needing only an appropriate <applet> tag, but this one
expects quite a few components to exist on the page and have the right
ids.)
[originally from svn r9803]
puzzle startup. The puzzle web pages now enclose the whole puzzle
(buttons, canvas, permalinks) in a div set to display:none, and
instead display an apologetic message saying 'sorry, it didn't work';
then, if we get through the whole init function without crashing, we
show the puzzle and hide the apology.
[originally from svn r9802]
type dropdown, we still get an 'onchange' event if they select it a
second time. Normally this wouldn't happen, because onchange means
what it says and we only get it if a _different_ element is selected.
My solution is to create two list items called Custom, set one of them
as display:none to stop it showing up when the list is dropped down,
and to select it after the configuration box closes.
[originally from svn r9788]
applets, here's an alternative webification in Javascript, using
Emscripten in asm.js mode (so that as browsers incorporate asm.js
optimisation, the game generation should run really fast).
[originally from svn r9781]
