include -toyplot-anchor-shift in calculation of line.right extents fo…

[eaton-lab]

I was having problems with text being cut-off on the right side because the Marker extents layout.right attribute did not appear to take into account the -toyplot-anchor-shift value. This was a problem for Toytree because I would routinely plot text with style {'text-anchor': 'start', '-toyplot-anchor-shift': '20px'}.

This problem is also apparent in the example for -toyplot-anchor-shift from the Toyplot documentation:

canvas = toyplot.Canvas(width=500, height=300)
axes = canvas.cartesian(show=False, ymin=-2.5, ymax=1.5)
axes.vlines(0, color="lightgray")
axes.text(0, 1, "Shifted +0px", style={"-toyplot-anchor-shift":"0", "text-anchor":"start", "font-size":"24px"})
axes.scatterplot(0, 1, color="black", size=3)
m0 = axes.text(0, 0, "Shifted +20px", style={"-toyplot-anchor-shift":"20px", "text-anchor":"start", "font-size":"24px"})
axes.scatterplot(0, 0, color="black", size=3)
m1 = axes.text(0, -1, "Shifted +40px", style={"-toyplot-anchor-shift":"40px", "text-anchor":"start", "font-size":"24px"})
axes.scatterplot(0, -1, color="black", size=3);
axes.text(0, -2, "Shifted -20px", style={"-toyplot-anchor-shift":"-20px", "text-anchor":"start", "font-size":"24px"})
axes.scatterplot(0, -2, color="black", size=3);

The marker extents do not take into account the anchor shift. You can see the right value is unchanged for m0 and m1:

>>> m0.extents('x')[1], m1.extents('x')[1]

((array([ 0.]), array([ 147.432]), array([-14.4]), array([ 14.4])),
 (array([ 0.]), array([ 147.432]), array([-14.4]), array([ 14.4])))

After making the edit that is in the pull request the extents seem to appropriately valued:

>>> m0.extents('x')[1], m1.extents('x')[1]

((array([ 0.]), array([ 167.432]), array([-14.4]), array([ 14.4])),
 (array([ 0.]), array([ 187.432]), array([-14.4]), array([ 14.4])))

[coveralls]

Coverage remained the same at 93.787% when pulling 2a40499 on eaton-lab:local into e6fe2a7 on sandialabs:master.

[tshead2]

Boy do I hate text layout at this point. I'll merge this as soon as I have a chance to think through any other ramifications.

Cheers,
Tim

[tshead2]

OK, I made a slightly different change, so that line.left and line.right are both set properly. Let me know if it solves the underlying problems in Toytree.

Cheers,
Tim

[tshead2]

You may also be interested in https://github.com/sandialabs/toyplot/blob/master/sandbox/text-layout-shift.ipynb for some examples of troubleshooting tools for text layout.