Is .drawToImage() very slow?

Hi, all.

First question. Long long drawing time 

I have an object in canvas which is blueprint A4 format. There are another object on canvas, but me interested only objects that contain blueprint(points and lines) for print it together as normal blueprint.

But this operation so long. All  layers is 2d.

I use external library for printing but i use performance now and make next structure of code:

printbutton.onClick = function() {
    var bp = wade.getSceneObject("blueprint");
    var area = {};
    area.minX = -bp.getSprite(0).getSize.x/2;
    area.minY = -bp.getSprite(0).getSize.y/2;
    area.maxX = bp.getSprite(0).getSize.x/2;
    area.maxY = bp.getSprite(0).getSize.y/2;

    var arrS = wade.getSpritesInArea(area,5);

    var temp = new SceneObject();                
    var a0 = new Sprite('procedural_square',5);
    console.log("start iteration");

    for(var i=0;i<arrS.length;i++){
    	if(!arrS[i].getSceneObject().isTemplate()&&arrS[i].getSceneObject().getName()!=='mr') {
    		var t0 =;
    		var temp0 = arrS[i].clone();
            var newzero = new Sprite('summ'+i,5);
            var t1 =;
            console.log("iteration "+i+" took " + (t1 - t0) + " milliseconds.")
            if((t1 - t0)>1000) {

	console.log("end iteration");

    var src = wade.getImageDataURL('chert');
    printJS({printable: src, type: 'image', header: 'NINJA CEILING'});

    console.log("end print");

    return true;

I see next output:

start iteration
VM11367:172 iteration 0 took 19.080000000001746 milliseconds.
VM11367:172 iteration 1 took 100.84000000001106 milliseconds.
VM11367:172 iteration 3 took 765.2149999999965 milliseconds.
VM11367:172 iteration 4 took 49.22499999999127 milliseconds.
VM11367:172 iteration 5 took 850.3350000000064 milliseconds.
VM11367:172 iteration 6 took 426.84500000000116 milliseconds.
VM11367:172 iteration 7 took 34.50500000000466 milliseconds.
VM11367:172 iteration 8 took 1019.820000000007 milliseconds.
VM11367:174 Sprite {_animations: Object, _currentAnimation: "default", _numAnimations: 1, _scaleFactor: Object, _imageArea: Object…}
VM11367:172 iteration 9 took 670.2200000000012 milliseconds.
VM11367:172 iteration 10 took 603.6200000000099 milliseconds.
VM11367:172 iteration 11 took 93.47500000000582 milliseconds.
VM11367:172 iteration 12 took 895.8999999999942 milliseconds.
VM11367:172 iteration 13 took 643.9499999999971 milliseconds.
VM11367:172 iteration 14 took 689.8950000000041 milliseconds.
VM11367:172 iteration 15 took 656.0949999999866 milliseconds.
VM11367:172 iteration 16 took 81.63499999999476 milliseconds.
VM11367:172 iteration 17 took 652.3699999999808 milliseconds.
VM11367:172 iteration 18 took 403.8299999999872 milliseconds.
VM11367:172 iteration 19 took 410.8050000000221 milliseconds.
VM11367:172 iteration 20 took 394.84500000000116 milliseconds.
VM11367:172 iteration 21 took 372.1649999999936 milliseconds.
VM11367:172 iteration 22 took 378.4899999999907 milliseconds.
VM11367:172 iteration 23 took 688.109999999986 milliseconds.
VM11367:172 iteration 24 took 653.0149999999994 milliseconds.
VM11367:172 iteration 25 took 664.6499999999942 milliseconds.
VM11367:172 iteration 26 took 647.6549999999988 milliseconds.
VM11367:172 iteration 27 took 641.1849999999977 milliseconds.
VM11367:172 iteration 28 took 637.1649999999936 milliseconds.
VM11367:172 iteration 30 took 660.1399999999994 milliseconds.
VM11367:172 iteration 31 took 655.1300000000047 milliseconds.
VM11367:172 iteration 32 took 654.7249999999913 milliseconds.
VM11367:172 iteration 33 took 647.3349999999919 milliseconds.
VM11367:172 iteration 34 took 618.0400000000081 milliseconds.
VM11367:179 end iteration
VM11367:185 end print

it is worth noting that the delay cause simple objects and the result is random.
if you print several times one and the same configuration that the delay will always jump on different elements

Why is so slow? Or  it normal?

All 4 Comments


Sprite.drawToImage() in itself isn't particularly slow... however calling Sprite.drawToImage(imageName, true) not only draws to an off-screen canvas, it creates a new canvas before drawing to it. If the canvas is large (in your case it seems to be about 3000x2000), then creating it may take some time depending on your browser and your CPU.

It seems to me that you don't want to create so many canvases though, seeing as you only need one for your final result. Could you not create one single canvas, then draw into it multiple times? Setting the second parameter of Sprite.drawToImage to false (or not setting it at all) will just draw on top of what you already have in your canvas, speeding the whole thing up considerably.


Thank ,Gio

i reduce my code:

for(var i=0;i<arrS.length;i++){
              	if(!arrS[i].getSceneObject().isTemplate()&&arrS[i].getSceneObject().getName()!=='mr') {
    var temp0 = arrS[i].clone();
var src = wade.getImageDataURL('summ');
printJS({printable: src, type: 'image', header: 'NINJA CEILING'});

But this return not expected result^

what am I doing wrong?


That looks almost right, but you first need to create a blank (transparent) image of the right size:

wade.createTransparentImage('summ', 2970, 2100);

Then you don't need to set the position of your scene object - that is irrelevant when it's drawn into an off-screen image. Instead, pass that position offset into Sprite.drawToImage - it's the 3rd parameter: Sprite.drawToImage('summ', false, offset);


Thank you.

however, why there are outbursts:

start iteration
VM16555:166 iteration 0 took 9.139999999984866 milliseconds.
VM16555:166 iteration 1 took 11.395000000004075 milliseconds.
VM16555:166 iteration 3 took 6.4799999999959255 milliseconds.
VM16555:166 iteration 4 took 4.2000000000116415 milliseconds.
VM16555:166 iteration 5 took 0.7349999999860302 milliseconds.
VM16555:166 iteration 6 took 2.26500000001397 milliseconds.
VM16555:166 iteration 7 took 0.9850000000005821 milliseconds.
VM16555:166 iteration 8 took 2.9400000000023283 milliseconds.
VM16555:166 iteration 9 took 1000.5849999999919 milliseconds.
VM16555:166 iteration 10 took 20.375000000014552 milliseconds.
VM16555:166 iteration 11 took 386.9400000000023 milliseconds.
VM16555:166 iteration 12 took 19.544999999998254 milliseconds.
VM16555:166 iteration 13 took 8.005000000019209 milliseconds.
VM16555:166 iteration 14 took 0.5600000000122236 milliseconds.
VM16555:166 iteration 15 took 0.3600000000005821 milliseconds.
VM16555:166 iteration 16 took 0.39999999999417923 milliseconds.
VM16555:166 iteration 17 took 0.4250000000029104 milliseconds.
VM16555:166 iteration 19 took 0.3800000000046566 milliseconds.
VM16555:166 iteration 20 took 878.945000000007 milliseconds.
VM16555:166 iteration 21 took 17.664999999993597 milliseconds.
VM16555:166 iteration 22 took 369.24000000000524 milliseconds.
VM16555:166 iteration 23 took 22.754999999990105 milliseconds.
VM16555:166 iteration 24 took 361.5650000000169 milliseconds.
VM16555:166 iteration 25 took 30.205000000001746 milliseconds.
VM16555:166 iteration 26 took 33.33499999999185 milliseconds.
VM16555:166 iteration 27 took 0.6600000000180444 milliseconds.
VM16555:166 iteration 28 took 0.47499999999126885 milliseconds.
VM16555:166 iteration 29 took 0.3049999999930151 milliseconds.
VM16555:166 iteration 30 took 0.29499999999825377 milliseconds.
VM16555:166 iteration 31 took 0.3000000000029104 milliseconds.
VM16555:166 iteration 32 took 0.3000000000029104 milliseconds.
VM16555:166 iteration 33 took 822.9699999999866 milliseconds.

random point or lines everytime, but I think it's the lesser evil

The second question is how to make callback for this. It is possible that when they click print and not waiting for treatment will go to smoke or to drink tea/

I can define variable as length of array, and send delta=1/lenght every iteration to custom function with loader picture.

but maybe there's something in WADE that I don't know, because it seems that the more i dig in WADE the less I understand :)

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