<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body text="#000000" bgcolor="#FFFFFF"> <div class="moz-cite-prefix"> <blockquote type="cite">The easiest would be to add a new API analogous to hb_ot_font_set_funcs(), that does NOT have the symbol shift in it</blockquote> That works.<br> <br> Thanks,<br> Eric.<br> <br> <br> On 1/19/18 4:43 PM, Behdad Esfahbod wrote:<br> </div> <blockquote type="cite" cite="mid:CAF63+7VVv94xsOXf2zcuHAPgiwz0REinTMmtvRCsCD_ykPy+aQ@mail.gmail.com"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <div dir="ltr"> <div> <div>Ok, let's see how we can address this...<br> <br> </div> I don't like a setting on the buffer as currently the get_glyph() callback has no way of accessing that information. The easiest would be to add a new API analogous to hb_ot_font_set_funcs(), that does NOT have the symbol shift in it. It's not the most elegant solution but easiest. Would that work for you?<br> <br> </div> That said, this issue is also related, as it pertains another non-Unicode encoding, though, in the font not the buffer:<br> <br> <a href="https://github.com/harfbuzz/harfbuzz/issues/681" moz-do-not-send="true">https://github.com/harfbuzz/harfbuzz/issues/681</a><br> </div> <div class="gmail_extra"><br> <div class="gmail_quote">On Thu, Jan 18, 2018 at 11:27 PM, Eric Muller <span dir="ltr"><<a href="mailto:emuller@amazon.com" target="_blank" moz-do-not-send="true">emuller@amazon.com</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <div text="#000000" bgcolor="#FFFFFF"> <div class="m_4762254172372698478moz-cite-prefix">I want to build a rendering system where U+0041 renders as an "A", regardless of the selected font.<span class="HOEnZb"><font color="#888888"><br> <br> Eric.</font></span> <div> <div class="h5"><br> <br> <br> On 1/17/18 3:48 PM, Behdad Esfahbod wrote:<br> </div> </div> </div> <div> <div class="h5"> <blockquote type="cite"> <div dir="ltr">What's the actual problem you are facing?<br> </div> <div class="gmail_extra"><br> <div class="gmail_quote">On Mon, Jan 15, 2018 at 9:58 AM, Eric Muller <span dir="ltr"><<a href="mailto:emuller@amazon.com" target="_blank" moz-do-not-send="true">emuller@amazon.com</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <div text="#000000" bgcolor="#FFFFFF"> <div class="m_4762254172372698478m_-4940559382455268948moz-cite-prefix"><span><br> <blockquote type="cite">It's clear that if the symbol font is asked by name, we should do the shift.</blockquote> </span> I think I disagree, in the sense that HB should not impose that behavior on it's clients. HB is clearly the right place to implement the behavior, but the choice of having that behavior or not should be with the client.<br> <br> For any document format, rendering the moral equivalent of <p font-family='symbol'>A<<wbr>/p> with something else that an "A" implies that all ASCII is PUA. That's a choice Word, InDesign, Notepad may make if they want, but it should not be imposed on all users of HB. <br> <br> Personally, I think it is a very bad choice for HTML, and Firefox seems to agree. It seems nice and user friendly at first, but this makes the document ambiguous. What about <p font-family='minion, symbol'>A</p>? It's an A or not an A depending on the presence of "minion" in the client. What does the document mean?<br> <br> Of course, <p font-family='symbol'><<wbr>/p> should render with the glyph symbol.cmap(F041). So even if the shift is never done, the glyph is usable. It's just that you don't have the convenience of an IME-like mechanism provided by the shaping engine, but you gain a reliable semantic for the text.<br> <br> <blockquote type="cite">That's good behavior [in Word], but beyond what HarfBuzz can do.</blockquote> Yes, which is why the shift may be acceptable or even desirable for some clients, and so hopefully the client could choose.<span><br> <br> <blockquote type="cite">What would clients do with that control then? How would they set it?</blockquote> </span> If I build an app that is meant to work like other GDI apps, I allow the shift (and may be add mitigating measures like Word). If I build an app such as Firefox, I don't allow it. The choice is entirely driven by the type application I want to build, and how I want to define my document format.<br> <br> <br> If you were to implement this choice, I can see it either in the construction of the HB unicode functions, or in the hb_buffer (either globally, or one a character by character basis). I have a preference for the latter: this choice could be passed down to the cmap lookup functions, HB or not; it could also be different on different parts of a document, may be reacting to markup.<span class="m_4762254172372698478HOEnZb"><font color="#888888"><br> <br> Eric.</font></span> <div> <div class="m_4762254172372698478h5"><br> <br> <br> On 1/15/18 6:46 AM, Behdad Esfahbod wrote:<br> </div> </div> </div> <div> <div class="m_4762254172372698478h5"> <blockquote type="cite"> <div dir="ltr"> <div class="gmail_extra">Hi Eric,<br> <br> </div> <div class="gmail_extra"> <div class="gmail_quote">On Mon, Jan 15, 2018 at 2:25 AM, Eric Muller <span dir="ltr"><<a href="mailto:emuller@amazon.com" target="_blank" moz-do-not-send="true">emuller@amazon.com</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">It seems that with a font that has only a 3, 0 cmap subtable (and may be some macintosh subtables), then HB will automatically do the shift by F000 (in the function get_glyph_from_symbol) for code points below U+00FF that are not mapped by the subtable.<br> </blockquote> <div><br> </div> <div>Right. Only in hb-ot-func though. Client font funcs can do otherwise.<br> <br> </div> <div> </div> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> It is clear that when U+0041 A is set with a symbol font, then that U+0041 has actually the semantics of a PUA code point, and certainly should not be treated as an "A". That's the whole point of a 3,0 cmap subtable.<br> </blockquote> <div><br> </div> <div>Correct.<br> <br> </div> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Consider an HTML page. The font-family is only a request and there is no guarantee that the actual font will or will not be a symbol font. Thus the semantic of the HTML page can change depending on the browser environment. Outside a browser, it seems that the safe treatment is therefore to consider all code points below U+00FF as PUA, which is clearly not tenable. So in that environment, I think that the shift should not be done. Of course, U+F041 should work.<br> </blockquote> <div><br> </div> <div>My take on this is that it's a bug of the font fallback logic if it falls back to a symbol font. I changed fontconfig to never do that.<br> </div> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Note that behavior of Word 2016 on Windows is actually more elaborate: enter U+0041, and set it with a non-symbol font; copy/paste or save to a text file, and the result is U+0041; but set this A in a symbol font, and copy/paste or save to a text file, and the result is U+F041.<br> </blockquote> <div><br> </div> <div>That's good behavior, but beyond what HarfBuzz can do.<br> <br> </div> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> I think that the shift should be controllable by the client, rather than systematically applied. I don't have a strong opinion about the default behavior (i.e. when HB's client does not specify whether the shift should be done or not).<br> </blockquote> <div><br> </div> <div>What would clients do with that control then? How would they set it?<br> <br> </div> <div>I implemented this shift in fontconfig and then harfbuzz because in LibreOffice and other software, there were existing documents that referred to windings or other symbol fonts and encoding characters in the ASCII range. It's clear that if the symbol font is asked by name, we should do the shift. If it's NOT, then it should not be chosen to render text to begin with, which means the shift can be applied unconditionally.<br> <br> </div> <div>How does that sound?<br> </div> <div>behdad<br> </div> <div> </div> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Thoughts?<br> <br> Thanks,<br> Eric.<br> </blockquote> <div> </div> </div> -- <br> <div class="m_4762254172372698478m_-4940559382455268948gmail_signature" data-smartmail="gmail_signature">behdad<br> <a href="http://behdad.org/" target="_blank" moz-do-not-send="true">http://behdad.org/</a></div> </div> </div> </blockquote> <br> </div> </div> </div> </blockquote> </div> <br> <br clear="all"> <br> -- <br> <div class="m_4762254172372698478gmail_signature" data-smartmail="gmail_signature">behdad<br> <a href="http://behdad.org/" target="_blank" moz-do-not-send="true">http://behdad.org/</a></div> </div> </blockquote> <br> </div> </div> </div> </blockquote> </div> <br> <br clear="all"> <br> -- <br> <div class="gmail_signature" data-smartmail="gmail_signature">behdad<br> <a href="http://behdad.org/" target="_blank" moz-do-not-send="true">http://behdad.org/</a></div> </div> </blockquote> <br> </body> </html>