不能更改KineticJS 5.0.1 PixelRatio

Question

Building a canvas with KineticJS 5.0.1 and it looks awful on my Retina screen. I couldn't figure out what was going on because KineticJS jsfiddle's look just fine. Then I realized that jsfiddle uses version 4.3.1. Switched and now everything is beautiful and retina.

Why doesn't v5 handle this automatically anymore? And how can I fix it? I tried to set Kinetic.pixelRatio=2 but that didn't do anything.

Answer 1

It turns out that pixelRatio is hard-coded into kineticJS v5+. This is due to some sort of zooming/scaling issue and also, in part, performance issues. I am going to experiment but in the meantime, this can be easily fixed in the source code for kineticJS. Find this function:

;(function() {
    // calculate pixel ratio
    var canvas = Kinetic.Util.createCanvasElement(),
        context = canvas.getContext('2d'),
        // if using a mobile device, calculate the pixel ratio.  Otherwise, just use
        // 1.  For desktop browsers, if the user has zoom enabled, it affects the pixel ratio
        // and causes artifacts on the canvas.  As of 02/26/2014, there doesn't seem to be a way
        // to reliably calculate the browser zoom for modern browsers, which is why we just set
        // the pixel ratio to 1 for desktops
        _pixelRatio = Kinetic.UA.mobile ? (function() {
            var devicePixelRatio = window.devicePixelRatio || 1,
            backingStoreRatio = context.webkitBackingStorePixelRatio
                || context.mozBackingStorePixelRatio
                || context.msBackingStorePixelRatio
                || context.oBackingStorePixelRatio
                || context.backingStorePixelRatio
                || 1;
            return devicePixelRatio / backingStoreRatio;
        })() : 1;

And change the 1 on the very last line to window.devicePixelRatio. The performance really isn't so bad but I think what I'm going to try doing, since my use just needs a short animation for many objects when a button is pressed, is to have it animate in KineticJS at pixelRatio 1 and then clear it and redraw the finished product at pixelRatio=whatever is appropriate for the device.