xref: /xsrc/external/mit/xf86-video-intel-old/dist/uxa/uxa-glyphs.c

/*
 * Copyright © 2008 Red Hat, Inc.
 * Partly based on code Copyright © 2000 SuSE, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of Red Hat not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  Red Hat makes no representations about the
 * suitability of this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 *
 * Red Hat DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL Red Hat
 * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of SuSE not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  SuSE makes no representations about the
 * suitability of this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 *
 * SuSE DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL SuSE
 * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Author: Owen Taylor <otaylor@fishsoup.net>
 * Based on code by: Keith Packard
 */

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include <stdlib.h>

#include "uxa-priv.h"

#include "mipict.h"

#if DEBUG_GLYPH_CACHE
#define DBG_GLYPH_CACHE(a) ErrorF a
#else
#define DBG_GLYPH_CACHE(a)
#endif

/* Width of the pixmaps we use for the caches; this should be less than
 * max texture size of the driver; this may need to actually come from
 * the driver.
 */
#define CACHE_PICTURE_WIDTH 1024

/* Maximum number of glyphs we buffer on the stack before flushing
 * rendering to the mask or destination surface.
 */
#define GLYPH_BUFFER_SIZE 256

typedef struct {
    PicturePtr source;
    uxa_composite_rect_t rects[GLYPH_BUFFER_SIZE];
    int count;
} uxa_glyph_buffer_t;

typedef enum {
    UXA_GLYPH_SUCCESS,    /* Glyph added to render buffer */
    UXA_GLYPH_FAIL,       /* out of memory, etc */
    UXA_GLYPH_NEED_FLUSH, /* would evict a glyph already in the buffer */
} uxa_glyph_cache_result_t;

void
uxa_glyphs_init(ScreenPtr pScreen)
{
    uxa_screen_t    *uxa_screen = uxa_get_screen(pScreen);
    int		    i = 0;

    memset(uxa_screen->glyphCaches, 0, sizeof(uxa_screen->glyphCaches));

    uxa_screen->glyphCaches[i].format = PICT_a8;
    uxa_screen->glyphCaches[i].glyphWidth = uxa_screen->glyphCaches[i].glyphHeight = 16;
    i++;
    uxa_screen->glyphCaches[i].format = PICT_a8;
    uxa_screen->glyphCaches[i].glyphWidth = uxa_screen->glyphCaches[i].glyphHeight = 32;
    i++;
    uxa_screen->glyphCaches[i].format = PICT_a8r8g8b8;
    uxa_screen->glyphCaches[i].glyphWidth = uxa_screen->glyphCaches[i].glyphHeight = 16;
    i++;
    uxa_screen->glyphCaches[i].format = PICT_a8r8g8b8;
    uxa_screen->glyphCaches[i].glyphWidth = uxa_screen->glyphCaches[i].glyphHeight = 32;
    i++;

    assert(i == UXA_NUM_GLYPH_CACHES);

    for (i = 0; i < UXA_NUM_GLYPH_CACHES; i++) {
	uxa_screen->glyphCaches[i].columns = CACHE_PICTURE_WIDTH / uxa_screen->glyphCaches[i].glyphWidth;
	uxa_screen->glyphCaches[i].size = 256;
	uxa_screen->glyphCaches[i].hashSize = 557;
    }
}

static void
uxa_unrealize_glyph_caches(ScreenPtr    pScreen,
			   unsigned int format)
{
    uxa_screen_t    *uxa_screen = uxa_get_screen(pScreen);
    int		    i;

    for (i = 0; i < UXA_NUM_GLYPH_CACHES; i++) {
	uxa_glyph_cache_t *cache = &uxa_screen->glyphCaches[i];

	if (cache->format != format)
	    continue;

	if (cache->picture) {
	    FreePicture ((pointer) cache->picture, (XID) 0);
	    cache->picture = NULL;
	}

	if (cache->hashEntries) {
	    xfree(cache->hashEntries);
	    cache->hashEntries = NULL;
	}

	if (cache->glyphs) {
	    xfree(cache->glyphs);
	    cache->glyphs = NULL;
	}
	cache->glyphCount = 0;
    }
}

#define NeedsComponent(f) (PICT_FORMAT_A(f) != 0 && PICT_FORMAT_RGB(f) != 0)

/* All caches for a single format share a single pixmap for glyph storage,
 * allowing mixing glyphs of different sizes without paying a penalty
 * for switching between source pixmaps. (Note that for a size of font
 * right at the border between two sizes, we might be switching for almost
 * every glyph.)
 *
 * This function allocates the storage pixmap, and then fills in the
 * rest of the allocated structures for all caches with the given format.
 */
static Bool
uxa_realize_glyph_caches(ScreenPtr    pScreen,
			 unsigned int format)
{
    uxa_screen_t    *uxa_screen = uxa_get_screen(pScreen);
    int		    depth = PIXMAN_FORMAT_DEPTH(format);
    PictFormatPtr   pPictFormat;
    PixmapPtr	    pPixmap;
    PicturePtr	    pPicture;
    CARD32          component_alpha;
    int		    height;
    int		    i;
    int		    error;

    pPictFormat = PictureMatchFormat(pScreen, depth, format);
    if (!pPictFormat)
	return FALSE;

    /* Compute the total vertical size needed for the format */

    height = 0;
    for (i = 0; i < UXA_NUM_GLYPH_CACHES; i++) {
	uxa_glyph_cache_t *cache = &uxa_screen->glyphCaches[i];
	int rows;

	if (cache->format != format)
	    continue;

	cache->yOffset = height;

	rows = (cache->size + cache->columns - 1) / cache->columns;
	height += rows * cache->glyphHeight;
    }

    /* Now allocate the pixmap and picture */

    pPixmap = (*pScreen->CreatePixmap) (pScreen,
					CACHE_PICTURE_WIDTH,
					height, depth, 0);
    if (!pPixmap)
	return FALSE;

    component_alpha = NeedsComponent(pPictFormat->format);
    pPicture = CreatePicture(0, &pPixmap->drawable, pPictFormat,
			     CPComponentAlpha, &component_alpha, serverClient,
			     &error);

    (*pScreen->DestroyPixmap) (pPixmap); /* picture holds a refcount */

    if (!pPicture)
	return FALSE;

    /* And store the picture in all the caches for the format */

    for (i = 0; i < UXA_NUM_GLYPH_CACHES; i++) {
	uxa_glyph_cache_t *cache = &uxa_screen->glyphCaches[i];
	int j;

	if (cache->format != format)
	    continue;

	cache->picture = pPicture;
	cache->picture->refcnt++;
	cache->hashEntries = xalloc(sizeof(int) * cache->hashSize);
	cache->glyphs = xalloc(sizeof(uxa_cached_glyph_t) * cache->size);
	cache->glyphCount = 0;

	if (!cache->hashEntries || !cache->glyphs)
	    goto bail;

	for (j = 0; j < cache->hashSize; j++)
	    cache->hashEntries[j] = -1;

	cache->evictionPosition = rand() % cache->size;
    }

    /* Each cache references the picture individually */
    FreePicture ((pointer) pPicture, (XID) 0);
    return TRUE;

bail:
    uxa_unrealize_glyph_caches(pScreen, format);
    return FALSE;
}

void
uxa_glyphs_fini (ScreenPtr pScreen)
{
    uxa_screen_t    *uxa_screen = uxa_get_screen(pScreen);
    int		    i;

    for (i = 0; i < UXA_NUM_GLYPH_CACHES; i++) {
	uxa_glyph_cache_t *cache = &uxa_screen->glyphCaches[i];

	if (cache->picture)
	    uxa_unrealize_glyph_caches(pScreen, cache->format);
    }
}

static int
uxa_glyph_cache_hash_lookup(uxa_glyph_cache_t *cache, GlyphPtr pGlyph)
{
    int slot;

    slot = (*(CARD32 *) pGlyph->sha1) % cache->hashSize;

    while (TRUE) { /* hash table can never be full */
	int entryPos = cache->hashEntries[slot];
	if (entryPos == -1)
	    return -1;

	if (memcmp(pGlyph->sha1, cache->glyphs[entryPos].sha1, sizeof(pGlyph->sha1)) == 0){
	    return entryPos;
	}

	slot--;
	if (slot < 0)
	    slot = cache->hashSize - 1;
    }
}

static void
uxa_glyph_cache_hash_insert(uxa_glyph_cache_t *cache,
			GlyphPtr         pGlyph,
			int              pos)
{
    int slot;

    memcpy(cache->glyphs[pos].sha1, pGlyph->sha1, sizeof(pGlyph->sha1));

    slot = (*(CARD32 *) pGlyph->sha1) % cache->hashSize;

    while (TRUE) { /* hash table can never be full */
	if (cache->hashEntries[slot] == -1) {
	    cache->hashEntries[slot] = pos;
	    return;
	}

	slot--;
	if (slot < 0)
	    slot = cache->hashSize - 1;
    }
}

static void
uxa_glyph_cache_hash_remove(uxa_glyph_cache_t *cache,
			int              pos)
{
    int slot;
    int emptiedSlot = -1;

    slot = (*(CARD32 *) cache->glyphs[pos].sha1) % cache->hashSize;

    while (TRUE) { /* hash table can never be full */
	int entryPos = cache->hashEntries[slot];

	if (entryPos == -1)
	    return;

	if (entryPos == pos) {
	    cache->hashEntries[slot] = -1;
	    emptiedSlot = slot;
	} else if (emptiedSlot != -1) {
	    /* See if we can move this entry into the emptied slot, we can't
	     * do that if if entry would have hashed between the current position
	     * and the emptied slot. (taking wrapping into account). Bad positions
	     * are:
	     *
	     * |   XXXXXXXXXX             |
	     *     i         j
	     *
	     * |XXX                   XXXX|
	     *     j                  i
	     *
	     * i - slot, j - emptiedSlot
	     *
	     * (Knuth 6.4R)
	     */

	    int entrySlot = (*(CARD32 *) cache->glyphs[entryPos].sha1) % cache->hashSize;

	    if (!((entrySlot >= slot && entrySlot < emptiedSlot) ||
		  (emptiedSlot < slot && (entrySlot < emptiedSlot || entrySlot >= slot))))
	    {
		cache->hashEntries[emptiedSlot] = entryPos;
		cache->hashEntries[slot] = -1;
		emptiedSlot = slot;
	    }
	}

	slot--;
	if (slot < 0)
	    slot = cache->hashSize - 1;
    }
}

#define CACHE_X(pos) (((pos) % cache->columns) * cache->glyphWidth)
#define CACHE_Y(pos) (cache->yOffset + ((pos) / cache->columns) * cache->glyphHeight)

/* The most efficient thing to way to upload the glyph to the screen
 * is to use CopyArea; uxa pixmaps are always offscreen.
 */
static Bool
uxa_glyph_cache_upload_glyph(ScreenPtr		    pScreen,
			     uxa_glyph_cache_t	    *cache,
			     int		    pos,
			     GlyphPtr		    pGlyph)
{
    PicturePtr	    pGlyphPicture = GlyphPicture(pGlyph)[pScreen->myNum];
    PixmapPtr	    pGlyphPixmap = (PixmapPtr)pGlyphPicture->pDrawable;
    PixmapPtr	    pCachePixmap = (PixmapPtr)cache->picture->pDrawable;
    GCPtr	    pGC;

    /* UploadToScreen only works if bpp match */
    if (pGlyphPixmap->drawable.bitsPerPixel != pCachePixmap->drawable.bitsPerPixel)
	return FALSE;

    pGC = GetScratchGC(pCachePixmap->drawable.depth, pScreen);
    ValidateGC(&pCachePixmap->drawable, pGC);
    (void) uxa_copy_area (&pGlyphPixmap->drawable,
			  &pCachePixmap->drawable,
			  pGC,
			  0, 0, pGlyph->info.width, pGlyph->info.height,
			  CACHE_X(pos), CACHE_Y(pos));
    FreeScratchGC (pGC);
    return TRUE;
}

static uxa_glyph_cache_result_t
uxa_glyph_cache_buffer_glyph(ScreenPtr		pScreen,
			     uxa_glyph_cache_t	*cache,
			     uxa_glyph_buffer_t *buffer,
			     GlyphPtr		pGlyph,
			     int		xGlyph,
			     int		yGlyph)
{
    uxa_composite_rect_t    *rect;
    int			    pos;

    if (buffer->source && buffer->source != cache->picture)
	return UXA_GLYPH_NEED_FLUSH;

    if (!cache->picture) {
	if (!uxa_realize_glyph_caches(pScreen, cache->format))
	    return UXA_GLYPH_FAIL;
    }

    DBG_GLYPH_CACHE(("(%d,%d,%s): buffering glyph %lx\n",
		     cache->glyphWidth, cache->glyphHeight, cache->format == PICT_a8 ? "A" : "ARGB",
		     (long)*(CARD32 *) pGlyph->sha1));

    pos = uxa_glyph_cache_hash_lookup(cache, pGlyph);
    if (pos != -1) {
	DBG_GLYPH_CACHE(("  found existing glyph at %d\n", pos));
    } else {
	if (cache->glyphCount < cache->size) {
	    /* Space remaining; we fill from the start */
	    pos = cache->glyphCount;
	    cache->glyphCount++;
	    DBG_GLYPH_CACHE(("  storing glyph in free space at %d\n", pos));

	    uxa_glyph_cache_hash_insert(cache, pGlyph, pos);

	} else {
	    /* Need to evict an entry. We have to see if any glyphs
	     * already in the output buffer were at this position in
	     * the cache
	     */

	    pos = cache->evictionPosition;
	    DBG_GLYPH_CACHE(("  evicting glyph at %d\n", pos));
	    if (buffer->count) {
		int x, y;
		int i;

		x = CACHE_X(pos);
		y = CACHE_Y(pos);

		for (i = 0; i < buffer->count; i++) {
		    if (buffer->rects[i].xSrc == x && buffer->rects[i].ySrc == y) {
			DBG_GLYPH_CACHE(("  must flush buffer\n"));
			return UXA_GLYPH_NEED_FLUSH;
		    }
		}
	    }

	    /* OK, we're all set, swap in the new glyph */
	    uxa_glyph_cache_hash_remove(cache, pos);
	    uxa_glyph_cache_hash_insert(cache, pGlyph, pos);

	    /* And pick a new eviction position */
	    cache->evictionPosition = rand() % cache->size;
	}

	/* Now actually upload the glyph into the cache picture; if
	 * we can't do it with UploadToScreen (because the glyph is
	 * offscreen, etc), we fall back to CompositePicture.
	 */
	if (!uxa_glyph_cache_upload_glyph(pScreen, cache, pos, pGlyph)) {
	    CompositePicture (PictOpSrc,
			      GlyphPicture(pGlyph)[pScreen->myNum],
			      None,
			      cache->picture,
			      0, 0,
			      0, 0,
			      CACHE_X(pos),
			      CACHE_Y(pos),
			      pGlyph->info.width,
			      pGlyph->info.height);
	}

    }


    buffer->source = cache->picture;

    rect = &buffer->rects[buffer->count];
    rect->xSrc = CACHE_X(pos);
    rect->ySrc = CACHE_Y(pos);
    rect->xDst = xGlyph - pGlyph->info.x;
    rect->yDst = yGlyph - pGlyph->info.y;
    rect->width = pGlyph->info.width;
    rect->height = pGlyph->info.height;

    buffer->count++;

    return UXA_GLYPH_SUCCESS;
}

#undef CACHE_X
#undef CACHE_Y

static uxa_glyph_cache_result_t
uxa_buffer_glyph(ScreenPtr	    pScreen,
		 uxa_glyph_buffer_t *buffer,
		 GlyphPtr	    pGlyph,
		 int		    xGlyph,
		 int		    yGlyph)
{
    uxa_screen_t    *uxa_screen = uxa_get_screen(pScreen);
    unsigned int    format = (GlyphPicture(pGlyph)[pScreen->myNum])->format;
    int		    width = pGlyph->info.width;
    int		    height = pGlyph->info.height;
    uxa_composite_rect_t    *rect;
    PicturePtr	    source;
    int		     i;

    if (buffer->count == GLYPH_BUFFER_SIZE)
	return UXA_GLYPH_NEED_FLUSH;

    if (PICT_FORMAT_BPP(format) == 1)
	format = PICT_a8;

    for (i = 0; i < UXA_NUM_GLYPH_CACHES; i++) {
	uxa_glyph_cache_t *cache = &uxa_screen->glyphCaches[i];

	if (format == cache->format &&
	    width <= cache->glyphWidth &&
	    height <= cache->glyphHeight) {
	    uxa_glyph_cache_result_t result = uxa_glyph_cache_buffer_glyph(pScreen, &uxa_screen->glyphCaches[i],
									   buffer,
									   pGlyph, xGlyph, yGlyph);
	    switch (result) {
	    case UXA_GLYPH_FAIL:
		break;
	    case UXA_GLYPH_SUCCESS:
	    case UXA_GLYPH_NEED_FLUSH:
		return result;
	    }
	}
    }

    /* Couldn't find the glyph in the cache, use the glyph picture directly */

    source = GlyphPicture(pGlyph)[pScreen->myNum];
    if (buffer->source && buffer->source != source)
	return UXA_GLYPH_NEED_FLUSH;

    buffer->source = source;

    rect = &buffer->rects[buffer->count];
    rect->xSrc = 0;
    rect->ySrc = 0;
    rect->xDst = xGlyph - pGlyph->info.x;
    rect->yDst = yGlyph - pGlyph->info.y;
    rect->width = pGlyph->info.width;
    rect->height = pGlyph->info.height;

    buffer->count++;

    return UXA_GLYPH_SUCCESS;
}

static void
uxa_glyphs_to_mask(PicturePtr		pMask,
		   uxa_glyph_buffer_t	*buffer)
{
    uxa_composite_rects(PictOpAdd, buffer->source, pMask,
		      buffer->count, buffer->rects);

    buffer->count = 0;
    buffer->source = NULL;
}

static void
uxa_glyphs_to_dst(CARD8			op,
		  PicturePtr		pSrc,
		  PicturePtr		pDst,
		  uxa_glyph_buffer_t	*buffer,
		  INT16			xSrc,
		  INT16			ySrc,
		  INT16			xDst,
		  INT16			yDst)
{
    int i;

    for (i = 0; i < buffer->count; i++) {
	uxa_composite_rect_t	*rect = &buffer->rects[i];

	CompositePicture (op,
			  pSrc,
			  buffer->source,
			  pDst,
			  xSrc + rect->xDst - xDst,
			  ySrc + rect->yDst - yDst,
			  rect->xSrc,
			  rect->ySrc,
			  rect->xDst,
			  rect->yDst,
			  rect->width,
			  rect->height);
    }

    buffer->count = 0;
    buffer->source = NULL;
}

/* Cut and paste from render/glyph.c - probably should export it instead */
static void
uxa_glyph_extents (int		nlist,
	      GlyphListPtr	list,
	      GlyphPtr	       *glyphs,
	      BoxPtr		extents)
{
    int		x1, x2, y1, y2;
    int		n;
    GlyphPtr	glyph;
    int		x, y;

    x = 0;
    y = 0;
    extents->x1 = MAXSHORT;
    extents->x2 = MINSHORT;
    extents->y1 = MAXSHORT;
    extents->y2 = MINSHORT;
    while (nlist--)
    {
	x += list->xOff;
	y += list->yOff;
	n = list->len;
	list++;
	while (n--)
	{
	    glyph = *glyphs++;
	    x1 = x - glyph->info.x;
	    if (x1 < MINSHORT)
		x1 = MINSHORT;
	    y1 = y - glyph->info.y;
	    if (y1 < MINSHORT)
		y1 = MINSHORT;
	    x2 = x1 + glyph->info.width;
	    if (x2 > MAXSHORT)
		x2 = MAXSHORT;
	    y2 = y1 + glyph->info.height;
	    if (y2 > MAXSHORT)
		y2 = MAXSHORT;
	    if (x1 < extents->x1)
		extents->x1 = x1;
	    if (x2 > extents->x2)
		extents->x2 = x2;
	    if (y1 < extents->y1)
		extents->y1 = y1;
	    if (y2 > extents->y2)
		extents->y2 = y2;
	    x += glyph->info.xOff;
	    y += glyph->info.yOff;
	}
    }
}

/**
 * Returns TRUE if the glyphs in the lists intersect.  Only checks based on
 * bounding box, which appears to be good enough to catch most cases at least.
 */
static Bool
uxa_glyphs_intersect(int nlist, GlyphListPtr list, GlyphPtr *glyphs)
{
    int x1, x2, y1, y2;
    int n;
    GlyphPtr glyph;
    int x, y;
    BoxRec extents;
    Bool first = TRUE;

    x = 0;
    y = 0;
    extents.x1 = 0;
    extents.y1 = 0;
    extents.x2 = 0;
    extents.y2 = 0;
    while (nlist--) {
       x += list->xOff;
       y += list->yOff;
       n = list->len;
       list++;
       while (n--) {
           glyph = *glyphs++;

           if (glyph->info.width == 0 || glyph->info.height == 0) {
               x += glyph->info.xOff;
               y += glyph->info.yOff;
               continue;
           }

           x1 = x - glyph->info.x;
           if (x1 < MINSHORT)
               x1 = MINSHORT;
           y1 = y - glyph->info.y;
           if (y1 < MINSHORT)
               y1 = MINSHORT;
           x2 = x1 + glyph->info.width;
           if (x2 > MAXSHORT)
               x2 = MAXSHORT;
           y2 = y1 + glyph->info.height;
           if (y2 > MAXSHORT)
               y2 = MAXSHORT;

           if (first) {
               extents.x1 = x1;
               extents.y1 = y1;
               extents.x2 = x2;
               extents.y2 = y2;
               first = FALSE;
           } else {
               if (x1 < extents.x2 && x2 > extents.x1 &&
                   y1 < extents.y2 && y2 > extents.y1)
               {
                   return TRUE;
               }

               if (x1 < extents.x1)
                  extents.x1 = x1;
               if (x2 > extents.x2)
                   extents.x2 = x2;
               if (y1 < extents.y1)
                   extents.y1 = y1;
               if (y2 > extents.y2)
                   extents.y2 = y2;
           }
           x += glyph->info.xOff;
           y += glyph->info.yOff;
       }
    }

    return FALSE;
}

void
uxa_glyphs (CARD8 	 op,
	   PicturePtr	 pSrc,
	   PicturePtr	 pDst,
	   PictFormatPtr maskFormat,
	   INT16	 xSrc,
	   INT16	 ySrc,
	   int		 nlist,
	   GlyphListPtr	 list,
	   GlyphPtr	*glyphs)
{
    PicturePtr	pPicture;
    PixmapPtr   pMaskPixmap = 0;
    PicturePtr  pMask;
    ScreenPtr   pScreen = pDst->pDrawable->pScreen;
    int		width = 0, height = 0;
    int		x, y;
    int		xDst = list->xOff, yDst = list->yOff;
    int		n;
    GlyphPtr	glyph;
    int		error;
    BoxRec	extents = {0, 0, 0, 0};
    CARD32	component_alpha;
    uxa_glyph_buffer_t buffer;

    /* If we don't have a mask format but all the glyphs have the same format
     * and don't intersect, use the glyph format as mask format for the full
     * benefits of the glyph cache.
     */
    if (!maskFormat) {
       Bool sameFormat = TRUE;
       int i;

       maskFormat = list[0].format;

       for (i = 0; i < nlist; i++) {
           if (maskFormat->format != list[i].format->format) {
               sameFormat = FALSE;
               break;
           }
       }

       if (!sameFormat || (maskFormat->depth != 1 &&
			   uxa_glyphs_intersect(nlist, list, glyphs))) {
	   maskFormat = NULL;
       }
    }

    if (maskFormat)
    {
	GCPtr	    pGC;
	xRectangle  rect;

	uxa_glyph_extents (nlist, list, glyphs, &extents);

	if (extents.x2 <= extents.x1 || extents.y2 <= extents.y1)
	    return;
	width = extents.x2 - extents.x1;
	height = extents.y2 - extents.y1;

	if (maskFormat->depth == 1) {
	    PictFormatPtr a8Format = PictureMatchFormat (pScreen, 8, PICT_a8);

	    if (a8Format)
		maskFormat = a8Format;
	}

	pMaskPixmap = (*pScreen->CreatePixmap) (pScreen, width, height,
						maskFormat->depth,
						CREATE_PIXMAP_USAGE_SCRATCH);
	if (!pMaskPixmap)
	    return;
	component_alpha = NeedsComponent(maskFormat->format);
	pMask = CreatePicture (0, &pMaskPixmap->drawable,
			       maskFormat, CPComponentAlpha, &component_alpha,
			       serverClient, &error);
	if (!pMask)
	{
	    (*pScreen->DestroyPixmap) (pMaskPixmap);
	    return;
	}
	pGC = GetScratchGC (pMaskPixmap->drawable.depth, pScreen);
	ValidateGC (&pMaskPixmap->drawable, pGC);
	rect.x = 0;
	rect.y = 0;
	rect.width = width;
	rect.height = height;
	(*pGC->ops->PolyFillRect) (&pMaskPixmap->drawable, pGC, 1, &rect);
	FreeScratchGC (pGC);
	x = -extents.x1;
	y = -extents.y1;
    }
    else
    {
	pMask = pDst;
	x = 0;
	y = 0;
    }
    buffer.count = 0;
    buffer.source = NULL;
    while (nlist--)
    {
	x += list->xOff;
	y += list->yOff;
	n = list->len;
	while (n--)
	{
	    glyph = *glyphs++;
	    pPicture = GlyphPicture (glyph)[pScreen->myNum];

	    if (glyph->info.width > 0 && glyph->info.height > 0 &&
		uxa_buffer_glyph(pScreen, &buffer, glyph, x, y) == UXA_GLYPH_NEED_FLUSH)
	    {
		if (maskFormat)
		    uxa_glyphs_to_mask(pMask, &buffer);
		else
		    uxa_glyphs_to_dst(op, pSrc, pDst, &buffer,
				   xSrc, ySrc, xDst, yDst);

		uxa_buffer_glyph(pScreen, &buffer, glyph, x, y);
	    }

	    x += glyph->info.xOff;
	    y += glyph->info.yOff;
	}
	list++;
    }

    if (buffer.count) {
	if (maskFormat)
	    uxa_glyphs_to_mask(pMask, &buffer);
	else
	    uxa_glyphs_to_dst(op, pSrc, pDst, &buffer,
			      xSrc, ySrc, xDst, yDst);
    }

    if (maskFormat)
    {
	x = extents.x1;
	y = extents.y1;
	CompositePicture (op,
			  pSrc,
			  pMask,
			  pDst,
			  xSrc + x - xDst,
			  ySrc + y - yDst,
			  0, 0,
			  x, y,
			  width, height);
	FreePicture ((pointer) pMask, (XID) 0);
	(*pScreen->DestroyPixmap) (pMaskPixmap);
    }
}