Subject: patch: eliminating a new/delete penalty in drawChars()
From: WJCarpenter (bill-abisource@carpenter.ORG)
Date: Sat Jul 15 2000 - 01:03:34 CDT
[[RESEND: I don't think anyone committed this patch, and I didn't
want it to fall between the cracks. Tx -- wjc]]
This patch, against 071200 nightly sources, provides a minor
performance improvement for the Unix version of drawChars(). It
eliminates the overhead of new/delete for most invocations of the
function.
For every Unix drawChars(), a copy of the string has to be made to
convert from 16bit to 32bit character elements. Before this patch,
that was always done via new/delete of enough storage to hold the
copy. This patch uses a blob of automatic storage for the copy if the
size of the string is less than 150 characters (which should cover all
the normal cases and a fair percentage of the abnormal ones), else it
reverts to the old new/delete stuff.
The BeOS drawChars() has the same characteristics as the Unix version,
but I had high confidence I would break the BeOS build if I tried to
code that up without being able to compile it.
-- bill@carpenter.ORG (WJCarpenter) PGP 0x91865119 38 95 1B 69 C9 C6 3D 25 73 46 32 04 69 D6 ED F3
diff -ru abi-071200-ORIG/src/af/gr/unix/gr_UnixGraphics.cpp abi-071200/src/af/gr/unix/gr_UnixGraphics.cpp --- abi-071200-ORIG/src/af/gr/unix/gr_UnixGraphics.cpp Sun Jul 9 13:54:11 2000 +++ abi-071200/src/af/gr/unix/gr_UnixGraphics.cpp Wed Jul 12 22:50:11 2000 @@ -112,42 +112,26 @@ UT_ASSERT(m_pFont); GdkFont *font = m_pFont->getGdkFont(); - - if (iLength > 1) { - /* - * TODO - We need to seriously look for a way to avoid this. - * Doing a memory allocation on every draw is painful. - */ - // Blargh... GDK wants strings in 32 bits, we use 16 internally - GdkWChar *pNChars = new GdkWChar[iLength]; - - for (int i = 0; i < iLength; i++) - { - pNChars[i] = remapGlyph(pChars[i + iCharOffset], UT_FALSE); - } - - - // Use "wide-char" function - gdk_draw_text_wc (m_pWin, font, m_pGC, - xoff, yoff + font->ascent, pNChars, iLength); - //XDrawString16 (drawable_private->xdisplay, drawable_private->xwindow, - // gc_private->xgc, xoff, yoff + xfont->ascent, pNChars, - // iLength); - - delete pNChars; - } else { - - // the vast majority of calls to this function are - // to draw a single character, so we'll optimize this case - - GdkWChar pChar = remapGlyph(pChars[iCharOffset], UT_FALSE); - gdk_draw_text_wc (m_pWin, font, m_pGC, - xoff, yoff + font->ascent, &pChar, 1); + // Blargh... GDK wants strings in 32 bits, we use 16 internally + GdkWChar *pNChars, utb[150]; // arbitrary biggish size for utb + if ((unsigned)iLength < (sizeof(utb) / sizeof(utb[0]))) + { + // avoid new/delete overhead for most cases via ubiquitous temp buf + pNChars = utb; + } + else + { + pNChars = new GdkWChar[iLength]; + } + for (int i = 0; i < iLength; i++) + { + pNChars[i] = remapGlyph(pChars[i + iCharOffset], UT_FALSE); } + // Use "wide-char" function + gdk_draw_text_wc(m_pWin, font, m_pGC, xoff, yoff + font->ascent, pNChars, iLength); + if (pNChars != utb) delete pNChars; -#if 1 flush(); -#endif } void GR_UnixGraphics::setFont(GR_Font * pFont)
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