DustVoice's st (from suckless.org) fork
ae1923d275
I have another patch here for review that optimizes the performance of glyph drawing, primarily when using non-unit kerning values, and fixes a few other minor issues. It's dependent on the earlier patch from me that stores unicode codepoints in a Rune type, typedef'd to uint_least32_t. This patch is a pretty big change to xdraws so your scrutiny is appreciated. First, some performance numbers. I used Yu-Jie Lin termfps.sh shell script to benchmark before and after, and you can find it in the attachments. On my Kaveri A10 7850k machine, I get the following results: Before Patch ============ 1) Font: "Liberation Mono:pixelsize=12:antialias=false:autohint=false" cwscale: 1.0, chscale: 1.0 For 273x83 100 frames. Elapsed time : 1.553 Frames/second: 64.352 Chars /second: 1,458,159 2) Font: "Inconsolata:pixelsize=14:antialias=true:autohint=true" cwscale: 1.001, chscale: 1.001 For 239x73 100 frames. Elapsed time : 159.286 Frames/second: 0.627 Chars /second: 10,953 After Patch =========== 3) Font: "Liberation Mono:pixelsize=12:antialias=false:autohint=false" cwscale: 1.0, chscale: 1.0 For 273x83 100 frames. Elapsed time : 1.544 Frames/second: 64.728 Chars /second: 1,466,690 4) Font: "Inconsolata:pixelsize=14:antialias=true:autohint=true" cwscale: 1.001, chscale: 1.001 For 239x73 100 frames. Elapsed time : 1.955 Frames/second: 51.146 Chars /second: 892,361 As you can see, while the improvements for fonts with unit-kerning is marginal, there's a huge ~81x performance increase with the patch when using kerning values other than 1.0. So what does the patch do? The `xdraws' function would render each glyph one at a time if non-unit kerning values were configured, and this was the primary cause of the slow down. Xft provides a handful of functions which allow you to render multiple characters or glyphs at time, each with a unique <x,y> position, so it was simply a matter of massaging the data into a format that would allow us to use one of these functions. I've split `xdraws' up into two functions. In the first pass with `xmakeglyphfontspecs' it will iterate over all of the glyphs in a given row and it will build up an array of corresponding XftGlyphFontSpec records. Much of the old logic for resolving fonts for glyphs using Xft and fontconfig went into this function. The second pass is done with `xrenderglyphfontspecs' which contains the old logic for determining colors, clearing the background, and finally rendering the array of XftGlyphFontSpec records. There's a couple of other things that have been improved by this patch. For instance, the UTF-32 codepoints in the Line's were being re-encoded back into UTF-8 strings to be passed to `xdraws' which in turn would then decode back to UTF-32 to verify that the Font contained a matching glyph for the code point. Next, the UTF-8 string was being passed to `XftDrawStringUtf8' which internally mallocs a scratch buffer and decodes back to UTF-32 and does the lookup of the glyphs all over again. This patch gets rid of all of this redundant round-trip encoding and decoding of characters to be rendered and only looks up the glyph index once (per font) during the font resolution phase. So this is probably what's responsible for the marginal improvements seen when kerning values are kept to 1.0. I imagine there are other performance improvements here too, not seen in the above benchmarks, if the user has lots of non-ASCII code plane characters on the screen, or several different fonts are being utilized during screen redraw. Anyway, if you see any problems, please let me know and I can fix them. |
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| arg.h | ||
| config.def.h | ||
| config.mk | ||
| FAQ | ||
| LEGACY | ||
| LICENSE | ||
| Makefile | ||
| README | ||
| st.1 | ||
| st.c | ||
| st.info | ||
| TODO | ||
st - simple terminal
--------------------
st is a simple terminal emulator for X which sucks less.
Requirements
------------
In order to build st you need the Xlib header files.
Installation
------------
Edit config.mk to match your local setup (st is installed into
the /usr/local namespace by default).
Afterwards enter the following command to build and install st (if
necessary as root):
make clean install
Running st
----------
If you did not install st with make clean install, you must compile
the st terminfo entry with the following command:
tic -s st.info
See the man page for additional details.
Credits
-------
Based on Aurélien APTEL <aurelien dot aptel at gmail dot com> bt source code.