Inspiring

Answered

Animate CC HTML5 Canvas: Fire function on frame access?

Forum|Forum|9 years ago
March 15, 2017
4 replies
3722 views

I have a function that resets the position of a MC, that does not do what I expect:

function reset_mark() {
this.mark.x = 1200;
this.mark.y = -15;
}

Which I call from various frames via:

reset_mark();

I have also tried:

this.reset_mark();

MovieClip(root).reset_mark();

this.MovieClip(root).reset_mark();

But none seem to work... am I missing something painfully obvious? I wouldn't be surprised.

Thanks.

This topic has been closed for replies.

Correct answer ClayUUID

Or you could skip the redirection and do this instead...

this.reset_mark = function() {

this.mark.x = 1200;

this.mark.y = -15;

}

this.reset_mark();

Scope refresher:

Global

bla = "foo";

window.bla = "foo"; // better, because it makes intended global scope explicit

Current TImeline

this.bla = "foo";

Current Frame

var bla;

var bla = "foo";

Declaring a function using the function statement applies the same scope as using var, so it's confined to the scope of the current frame. Using a function expression instead and assigning it as a property of this allows it to be accessible to an entire timeline.

javascript scope of function declarations - Stack Overflow

jeffery wrightAuthor

Inspiring

Thanks everyone... I am used to declaring a function this way:

function someFunction(){

};

So yes:

this.someFunction=function(){

}

and calling it:

this.someFunction();

did the trick... it seems backwards to code it that way, I wonder why variables are not coded similarly?

this.myVariable=var; for example.

Thanks again for all your help!

C

ClayUUID

Legend

https://forums.adobe.com/people/jeffery+wright wrote
did the trick... it seems backwards to code it that way, I wonder why variables are not coded similarly?

Variables are coded similarly. Almost identically, in fact.

These declare a variable and a function as private to the local scope:

var myVar = "foo";

function myFunction() {

alert("bar");

};

These assign a variable and a function as a public property and method, respectively, of an object:

myObj.myVar = "foo";

myObj.myFunction = function() {

alert("bar");

};

The former uses a function declaration, while the latter uses a function expression.

markr17328370

Participant

If you are trying to reach a global scope, which I think you are, meaning you want to place this function on one key frame and fire it from a different key frame or layer. Re write your code like this:

--- write these things this way for local ---

var foo = bar;

var count = 0;

function foobar(){

// do stuff;

}

foobar();

count++;

--- write these things this way for global ---

foo = bar;

count = 0;

foobar = function(){

// do stuff;

}

foobar();

count++;

C

ClayUUID

Legend

None of that code has anything to do with what the original poster was trying to accomplish a year ago.

markr17328370

Participant

ClayUUID wrote
None of that code has anything to do with what the original poster was trying to accomplish a year ago.

I have also tried:
this.reset_mark();
MovieClip(root).reset_mark();
this.MovieClip(root).reset_mark();

To me it appears that they were not able to access the function by not utilizing the proper scope given the posters attempts of change. Now if they were modifying the x or y values to achieve proper placement then I would agree with you. But that was not what the poster was attempting to change.

Colin Holgate

Inspiring

You can solve the problem like this:

this.reset_mark = reset_mark;

this.reset_mark();

function reset_mark() {

this.mark.x = 1200;

this.mark.y = -15;

}

C

ClayUUIDCorrect answer

Legend

Or you could skip the redirection and do this instead...

this.reset_mark = function() {

this.mark.x = 1200;

this.mark.y = -15;

}

this.reset_mark();

Scope refresher:

Global

bla = "foo";

window.bla = "foo"; // better, because it makes intended global scope explicit

Current TImeline

this.bla = "foo";

Current Frame

var bla;

var bla = "foo";

Declaring a function using the function statement applies the same scope as using var, so it's confined to the scope of the current frame. Using a function expression instead and assigning it as a property of this allows it to be accessible to an entire timeline.

javascript scope of function declarations - Stack Overflow