// Round here is **CRUCIAL** otherwise the images are filtered
// and the performance sucks (more than expected).
var xoff = Math.round((x * size - xMin) / gZoomFactor);
var yoff = Math.round((y * size - yMin) / gZoomFactor);
// Draw placeholder tile unless we overdraw.
// Round here is **CRUCIAL** otherwise the images are filtered
// and the performance sucks (more than expected).
var xoff = Math.round((x * size - xMin) / gZoomFactor);
var yoff = Math.round((y * size - yMin) / gZoomFactor);
// Draw placeholder tile unless we overdraw.