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Implement a better way of handling exceptions in PaperScript on Firefox and Chrome.

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Use dynamically inserted script tag rather than compiled function since Firefox reports correct line numbers there.
This commit is contained in:
Jürg Lehni 2014-01-04 21:57:29 +01:00
parent 9dea3f3b74
commit 4302682c1c
2 changed files with 32 additions and 60 deletions
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30
src/core/Callback.js
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@ -77,32 +77,16 @@ var Callback = {
if (!handlers)
return false;
var args = [].slice.call(arguments, 1),
PaperScript = paper.PaperScript,
handleException = PaperScript && PaperScript.handleException,
that = this;
function callHandlers() {
for (var i in handlers) {
// When the handler function returns false, prevent the default
// behaviour and stop propagation of the event by calling stop()
if (handlers[i].apply(that, args) === false
&& event && event.stop) {
event.stop();
break;
}
for (var i in handlers) {
// When the handler function returns false, prevent the default
// behaviour and stop propagation of the event by calling stop()
if (handlers[i].apply(that, args) === false
&& event && event.stop) {
event.stop();
break;
}
}
// See PaperScript.handleException for an explanation of the following.
// Firefox is to blame for the necessity of this...
if (handleException) {
try {
callHandlers();
} catch (e) {
handleException(e);
}
} else {
callHandlers();
}
return true;
},

62
src/core/PaperScript.js
View file

@ -248,15 +248,15 @@ var PaperScript = Base.exports.PaperScript = (function() {
// undefined arguments, so that their name exists, rather than
// injecting a code line that defines them as variables.
// They are exported again at the end of the function.
handlers = ['onFrame', 'onResize'].concat(toolHandlers),
res;
handlers = ['onFrame', 'onResize'].concat(toolHandlers);
code = compile(code);
// compile a list of paramter names for all variables that need to
// appear as globals inside the script. At the same time, also collect
// their values, so we can pass them on as arguments in the function
// call.
var params = ['_$_', '$_', 'view', 'tool'],
args = [_$_, $_ , view, tool];
args = [_$_, $_ , view, tool],
func;
// Look through all enumerable properties on the scope and expose these
// too as pseudo-globals.
for (var key in scope) {
@ -276,44 +276,32 @@ var PaperScript = Base.exports.PaperScript = (function() {
// We need an additional line that returns the handlers in one object.
code += '\nreturn { ' + handlers + ' };';
/*#*/ if (__options.environment == 'browser') {
if (window.InstallTrigger) { // Firefox
// Add a semi-colon at the start so Firefox doesn't swallow empty
// lines and shift error messages.
code = ';' + code;
// On Firefox, all error numbers inside evaled code are relative to
// the line where the eval happened. Totally silly, but that's how
// it is. So we're calculating the base of lineNumbers, to remove it
// again from reported errors. Luckily, Firefox is the only browser
// where we can define the lineNumber for exceptions.
var handle = PaperScript.handleException;
if (!handle) {
handle = PaperScript.handleException = function(e) {
throw e.lineNumber >= lineNumber
? new Error(e.message, e.fileName,
e.lineNumber - lineNumber)
: e;
};
// We're using a crazy hack to detect wether the library is
// minified or not: By generating a second error on the 2nd line
// and using the difference in line numbers to calculate the
// offset to the eval, it works in both casees.
var lineNumber = new Error().lineNumber;
lineNumber += (new Error().lineNumber - lineNumber) * 3;
}
try {
res = Function(params, code).apply(scope, args);
// NOTE: in order for the calculation of the above lineNumber
// offset to work, we cannot add any statements before the above
// line of code, nor can we put it into a separate function.
} catch (e) {
handle(e);
}
if (window.InstallTrigger || window.chrome) { // Firefox and Chrome
// On Firefox, all error numbers inside dynamically compiled code
// are relative to the line where the eval / compilation happened.
// To fix this issue, we're temporarily inserting a new script
// tag. We also use this on Chrome to fix an issue with compiled
// functions:
// https://code.google.com/p/chromium/issues/detail?id=331655
var script = document.createElement('script'),
head = document.head;
// Do not add a new-line before the code on Chrome since the error
// messages are shifted by one line there...
if (!window.chrome)
code = '\n' + code;
script.appendChild(document.createTextNode(
'paper._execute = function(' + params + ') {' + code + '\n}'
));
head.appendChild(script);
func = paper._execute;
head.removeChild(script);
} else {
res = Function(params, code).apply(scope, args);
func = Function(params, code);
}
/*#*/ } else { // !__options.environment == 'browser'
res = Function(params, code).apply(scope, args);
func = Function(params, code);
/*#*/ } // !__options.environment == 'browser'
var res = func.apply(scope, args);
// Now install the 'global' tool and view handlers, and we're done!
Base.each(toolHandlers, function(key) {
var value = res[key];