Sorry if this is an old issue; it's certainly of very low priority. I was playing around w/ font colors for, e.g. the main title in a plot, and noticed that overwriting some text with the identical text, but in white, leaves a small but noticeable 'border' outlining each letter. I played around a bit with overwriting plotted lines in the chart and didn't seem to see this effect. Is this a known limitation on rendering fonts or some such? thanks Carl
font placement in Quartz
2 messages · Carl Witthoft, Simon Urbanek
On Nov 19, 2008, at 17:33 , Carl Witthoft wrote:
Sorry if this is an old issue; it's certainly of very low priority. I was playing around w/ font colors for, e.g. the main title in a plot, and noticed that overwriting some text with the identical text, but in white, leaves a small but noticeable 'border' outlining each letter. I played around a bit with overwriting plotted lines in the chart and didn't seem to see this effect. Is this a known limitation on rendering fonts or some such?
It is the expected consequence of anti-aliasing. Since the edges of the text are not fully opaque (more precisely the pixels that are not entirely filled by the text glyph), they won't entirely mask what's underneath and thus any previous content (including perviously drawn text) will shine through (c.f. plotting text with alpha < 1). This is an intended behavior for semi-opaque drawing although less intuitive when the opacity is implicitly adjusted by anti-aliasing. You can avoid this effect by disabling anti-aliasing (at the cost of inferior visual quality). Cheers, Simon