javascript - Kinetic js 5.1 globalCompositeOperation how to -


i'm new kinetic js. im trying .globalcompositeoperation work in 2 parts of project have, have tried several solutions can find here, using 'drawfunc', , 'scenefunc', etc... far no luck.

one part of project im trying 'destination-out' work on kinetic.sprite:

var strokessprite = new kinetic.sprite({                         image: e,                         animation: 'intro',                         animations: {                             'intro': config.spritestrokes.frames                         },                         framerate: 7,                         frameindex: 0,                         scenefunc: function (ctx) {                             ctx.save();                             ctx.globalcompositeoperation = 'destination-out';                             ctx.restore();                         }      var strokes = new kinetic.layer({                         width: 1280,                         height: 1280,                         x: stage.getwidth() / 2,                         y: stage.getheight() / 2,                         offset: {                             x: 1280 / 2,                             y: 1280 / 2                         }                     });                     strokes.add(backgroundpainted);                     strokes.add(strokessprite);                     strokes.draw();                     stage.add(strokes);

"backgroundpainted" kinetic.image

unfortunately here sprite layer being animated on top of 'backgroundpainted', no composite operation being applied :(.

for 2nd instance have, similar, have 2 layers, both shapes inside, added stage. im applying same 'scenefunc' layer on top, , drawing them then. layers both display, no composition being applied. :(

any pointers on should at? see example 'drawfunc' has been changed 'scenefunc' recently, , maybe else has changed, ive tried pretty examples can find here on stack.

thanks

kineticjs not support globalcompositeoperation.

kineticjs gives wrapper around html5 canvas context, wrapper subset of context not include context.globalcompositeoperation property.

a workaround

you can create canvas element (without appending page). compositing on offscreen canvas. present canvas inside kineticjs, create kinetic.image image property pointing offscreen canvas:

var myoffscreencanvas=document.createelement("canvas");  ... compositing ...  // kinetic.image display myoffscreencanvas  var mycompositedimage = new kinetic.image({      image:myoffscreencanvas,      ...  });

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