Function markBitmaps

docs/app/js/sanddance-app.js:138631–138650

($, avoidMarks, labelInside, isGroupArea)

    ];
}
function markBitmaps($, avoidMarks, labelInside, isGroupArea) {
    // create canvas
    const width = $.width, height = $.height, border = labelInside || isGroupArea, context = (0, _vegaCanvas.canvas)(width, height).getContext("2d"); // render all marks to be avoided into canvas
    avoidMarks.forEach((items)=>draw(context, items, border)); // get canvas buffer, create bitmaps
    const buffer = new Uint32Array(context.getImageData(0, 0, width, height).data.buffer), layer1 = $.bitmap(), layer2 = border && $.bitmap(); // populate bitmap layers
    let x, y, u, v, alpha;
    for(y = 0; y < height; ++y)for(x = 0; x < width; ++x){
        alpha = buffer[y * width + x] & ALPHA_MASK;
        if (alpha) {
            u = $(x);
            v = $(y);
            if (!isGroupArea) layer1.set(u, v); // update interior bitmap
            if (border && alpha ^ INSIDE_OPACITY_IN_ALPHA) layer2.set(u, v); // update border bitmap
        }
    }
    return [
        layer1,
        layer2
    ];
}
function draw(context, items, interior) {
    if (!items.length) return;
    const type = items[0].mark.marktype;