Function comparePixels

test/helpers.js:237–307

(actual, expected, message, options)

};

var comparePixels = function(actual, expected, message, options) {
    function rasterize(item, group, resolution) {
        var raster = null;
        if (group) {
            var parent = item.parent,
                index = item.index;
            group.addChild(item);
            raster = group.rasterize(resolution, false);
            if (parent) {
                parent.insertChild(index, item);
            } else {
                item.remove();
            }
        }
        return raster;
    }

    if (!expected) {
        return QUnit.strictEqual(actual, expected, message, options);
    } else if (!actual) {
        // In order to compare pixels, just create an empty item that can be
        // rasterized to an empty raster.
        actual = new Group();
    }

    options = options || {};
    // In order to properly compare pixel by pixel, we need to put each item
    // into a group with a white background of the united dimensions of the
    // bounds of both items before rasterizing.
    var resolution = options.resolution || 72,
        actualBounds = actual.strokeBounds,
        expectedBounds = expected.strokeBounds,
        bounds = actualBounds.isEmpty()
            ? expectedBounds
            : expectedBounds.isEmpty()
                ? actualBounds
                : actualBounds.unite(expectedBounds);
    if (bounds.isEmpty()) {
        QUnit.equal('empty', 'empty', message);
        return;
    }
    var group = actual && expected && new Group({
            insert: false,
            children: [
                new Shape.Rectangle({
                    rectangle: bounds,
                    fillColor: 'white'
                })
            ]
        }),
        actualRaster = rasterize(actual, group, resolution),
        expectedRaster = rasterize(expected, group, resolution);
    if (!actualRaster || !expectedRaster) {
        QUnit.push(false, null, null, 'Unable to compare rasterized items: ' +
            (!actualRaster ? 'actual' : 'expected') + ' item is null',
            QUnit.stack(2));
    } else {
        // Compare the two rasterized items.