Investigate SVG text quality settings

[jonathanolson]

Related issues:

• Original investigation: SVG text settings #170
• Notes: Test text rendering cross-browser #164
• text looks crappy on IE9 (svg) #94
• The first time mousing over a control panel text, it slightly changes shape on IE11 #297
• [0.2] Weird font property toggle on unrelated change #264
• Letters jump around in firefox #195

We'll want to look at SVG text settings, notably the SVG attributes 'textLength', 'lengthAdjust' and 'text-rendering'. To start, see how http://phetsims.github.io/scenery/tests/text-quality-test.html looks across browsers (it starts on medium unanimated). There are specific qualities that we want on each browser:

• SVG text length should precisely match DOM/Canvas text length (see where the black square is in relation to the letters)
• SVG text should not flicker while moving (kerning changes)
• SVG text should be crisp
• SVG text should look properly kerned (letter spacing is consistent and good looking)
• SVG text should look consistent between low/high scales
• SVG text should show smooth changes while scaling (use low 6, low 6.5 and low 6 close to see slight differences)

For each supported browser we should have information about what settings have the highest quality. I believe we are using geometricPrecision with a length override using spacingAndGlyphs (so we can match Canvas/DOM size on all browsers), but we may need different settings on different browsers.

Feel free to add/remove settings from text-quality-test.html to investigate, and let me know about any questions.

Thanks!

[jonathanolson]

Additionally please see phetsims/joist#143 (comment) and see if text bounds vertically are changed by textLength/lengthAdjust with Safari or other browsers.

[samreid]

Here's where it cropped up in Bending Light and Neuron:
phetsims/bending-light#335

[samreid]

Please see the bending light issue for screenshots and more detail.

[jessegreenberg]

1/7/2016 - Bumping up priority of this, it is an issue for sims that we are trying to deploy/redeploy.