Handle axis padding in SVG

[sirrice]

Notice the left and bottom padding in the outer container that makes the nested marks not take up the full space. It is because Observable Plot automatically allocates padding to draw axes, which is something we may not always want. We can manually hide them by using

let cityRects = canvas.rect(cityavgprice, 
   { ...sq("avgprice")(), stroke: "black", fill: "none" },
   {x: {axis:null}, y:{axis:null}});

But we should have a shorthand.

[xytuang]

Added shorthand for setting no axis:

axis: null

This hides both xaxis and yaxis.

Usage:

let cityRects = canvas.rect(cityavgprice, { ...sq("avgprice")(), stroke: "black", fill: "none" }, {axis: null});

If the user wants to hide only one of the axes, they can do

xaxis: null to hide the xaxis and yaxis: null to hide the yaxis. This seems reasonable depending on what kind of chart the user wants to plot. A bar chart for example might require only one of the axes.

database-vis/src/viz/core/mark.ts

Line 136 in 62bd695

unwrapOptions(options) {