CODEWITHSUNDEEP
javascriptarraysfunctionobject
fxck
fxck

Reputation: 4908

javascript functions arguments in an array

what I'm trying to do is this

    $.each($(".canvas"), function(n) {
        var canvas = $(this)[0].getContext("2d");     
        canvas.drawImage(options[n]);
    });

where options would be an array of arguments, but can't figure out how should the array be formatted for it to work

obviously not

['img, 0,  0, 70, 17, 21, 16, 70, 17', 'img, 0,  0, 80, 12, 21, 16, 70, 17']

this neither

[''+img+', 0,  0, 70, 17, 21, 16, 70, 17', ''+img+', 0,  0, 80, 12, 21, 16, 70, 17']

nor this 

{0: [img, 0,  0, 70, 17, 21, 16, 70, 17]}

this would not work either

var options = [[img, 0,  0, 70, 17, 21, 16, 70, 17],
               [img, 0, 16, 70, 17, 21, 16, 70, 17],
               [img, 0, 32, 70, 17, 21, 16, 70, 17],
               [img, 0, 48, 70, 17, 21, 16, 70, 17]];

img.onload = function() {
    $.each($(".canvas"), function(n) {
        var canvas = $(this)[0].getContext("2d");     
        canvas.drawImage(options[n].join(', '));
    });
};

the error is alway Uncaught TypeError: Type error or Uncaught TypeError: Illegal invocation

Upvotes: 2

Views: 422

Answers (1)

Matt Ball
Matt Ball

Reputation: 360056

Use Function.apply.

canvas.drawImage.apply(canvas, options[n]);

Where options[n] looks something like

[img, 0, 0, 70, 17, 21, 16, 70, 17]

Full example:

var options = [[img, 0,  0, 70, 17, 21, 16, 70, 17],
               [img, 0, 16, 70, 17, 21, 16, 70, 17],
               [img, 0, 32, 70, 17, 21, 16, 70, 17],
               [img, 0, 48, 70, 17, 21, 16, 70, 17]];

$(img).load(function()
{
    $(".canvas").each(function(n)
    {
        var canvas = this.getContext('2d');     
        canvas.drawImage.apply(canvas, options[n]);
    });
});

Demo: http://jsfiddle.net/mattball/5EQbC/

Upvotes: 4

Related Questions