cairo-xlib-surface.c

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

    if (mask)
	_cairo_pattern_release_surface (mask_pattern, &mask->base, &mask_attr);

    _cairo_pattern_release_surface (src_pattern, &src->base, &src_attr);

    return status;
}

static cairo_int_status_t
_cairo_xlib_surface_fill_rectangles (void		     *abstract_surface,
				     cairo_operator_t	      op,
				     const cairo_color_t     *color,
				     cairo_rectangle_int16_t *rects,
				     int			      num_rects)
{
    cairo_xlib_surface_t *surface = abstract_surface;
    XRenderColor render_color;

    if (!CAIRO_SURFACE_RENDER_HAS_FILL_RECTANGLE (surface))
	return CAIRO_INT_STATUS_UNSUPPORTED;

    render_color.red   = color->red_short;
    render_color.green = color->green_short;
    render_color.blue  = color->blue_short;
    render_color.alpha = color->alpha_short;

    /* XXX: This XRectangle cast is evil... it needs to go away somehow. */
    _cairo_xlib_surface_ensure_dst_picture (surface);
    XRenderFillRectangles (surface->dpy,
			   _render_operator (op),
			   surface->dst_picture,
			   &render_color, (XRectangle *) rects, num_rects);

    return CAIRO_STATUS_SUCCESS;
}

/* Creates an A8 picture of size @width x @height, initialized with @color
 */
static Picture
_create_a8_picture (cairo_xlib_surface_t *surface,
		    XRenderColor         *color,
		    int                   width,
		    int                   height,
		    cairo_bool_t          repeat)
{
    XRenderPictureAttributes pa;
    unsigned long mask = 0;

    Pixmap pixmap = XCreatePixmap (surface->dpy, surface->drawable,
				   width <= 0 ? 1 : width,
				   height <= 0 ? 1 : height,
				   8);
    Picture picture;

    if (repeat) {
	pa.repeat = TRUE;
	mask = CPRepeat;
    }

    picture = XRenderCreatePicture (surface->dpy, pixmap,
				    XRenderFindStandardFormat (surface->dpy, PictStandardA8),
				    mask, &pa);
    XRenderFillRectangle (surface->dpy, PictOpSrc, picture, color,
			  0, 0, width, height);
    XFreePixmap (surface->dpy, pixmap);

    return picture;
}

/* Creates a temporary mask for the trapezoids covering the area
 * [@dst_x, @dst_y, @width, @height] of the destination surface.
 */
static Picture
_create_trapezoid_mask (cairo_xlib_surface_t *dst,
			cairo_trapezoid_t    *traps,
			int                   num_traps,
			int                   dst_x,
			int                   dst_y,
			int                   width,
			int                   height,
			XRenderPictFormat     *pict_format)
{
    XRenderColor transparent = { 0, 0, 0, 0 };
    XRenderColor solid = { 0xffff, 0xffff, 0xffff, 0xffff };
    Picture mask_picture, solid_picture;
    XTrapezoid *offset_traps;
    int i;

    /* This would be considerably simpler using XRenderAddTraps(), but since
     * we are only using this in the unbounded-operator case, we stick with
     * XRenderCompositeTrapezoids, which is available on older versions
     * of RENDER rather than conditionalizing. We should still hit an
     * optimization that avoids creating another intermediate surface on
     * the servers that have XRenderAddTraps().
     */
    mask_picture = _create_a8_picture (dst, &transparent, width, height, FALSE);
    solid_picture = _create_a8_picture (dst, &solid, width, height, TRUE);

    offset_traps = malloc (sizeof (XTrapezoid) * num_traps);
    if (!offset_traps)
	return None;

    for (i = 0; i < num_traps; i++) {
	offset_traps[i].top = traps[i].top - 0x10000 * dst_y;
	offset_traps[i].bottom = traps[i].bottom - 0x10000 * dst_y;
	offset_traps[i].left.p1.x = traps[i].left.p1.x - 0x10000 * dst_x;
	offset_traps[i].left.p1.y = traps[i].left.p1.y - 0x10000 * dst_y;
	offset_traps[i].left.p2.x = traps[i].left.p2.x - 0x10000 * dst_x;
	offset_traps[i].left.p2.y = traps[i].left.p2.y - 0x10000 * dst_y;
	offset_traps[i].right.p1.x = traps[i].right.p1.x - 0x10000 * dst_x;
	offset_traps[i].right.p1.y = traps[i].right.p1.y - 0x10000 * dst_y;
	offset_traps[i].right.p2.x = traps[i].right.p2.x - 0x10000 * dst_x;
	offset_traps[i].right.p2.y = traps[i].right.p2.y - 0x10000 * dst_y;
    }

    XRenderCompositeTrapezoids (dst->dpy, PictOpAdd,
				solid_picture, mask_picture,
				pict_format,
				0, 0,
				offset_traps, num_traps);

    XRenderFreePicture (dst->dpy, solid_picture);
    free (offset_traps);

    return mask_picture;
}

static cairo_int_status_t
_cairo_xlib_surface_composite_trapezoids (cairo_operator_t	op,
					  cairo_pattern_t	*pattern,
					  void			*abstract_dst,
					  cairo_antialias_t	antialias,
					  int			src_x,
					  int			src_y,
					  int			dst_x,
					  int			dst_y,
					  unsigned int		width,
					  unsigned int		height,
					  cairo_trapezoid_t	*traps,
					  int			num_traps)
{
    cairo_surface_attributes_t	attributes;
    cairo_xlib_surface_t	*dst = abstract_dst;
    cairo_xlib_surface_t	*src;
    cairo_int_status_t		status;
    composite_operation_t       operation;
    int				render_reference_x, render_reference_y;
    int				render_src_x, render_src_y;
    XRenderPictFormat		*pict_format;

    if (!CAIRO_SURFACE_RENDER_HAS_TRAPEZOIDS (dst))
	return CAIRO_INT_STATUS_UNSUPPORTED;

    operation = _categorize_composite_operation (dst, op, pattern, TRUE);
    if (operation == DO_UNSUPPORTED)
	return CAIRO_INT_STATUS_UNSUPPORTED;

    status = _cairo_pattern_acquire_surface (pattern, &dst->base,
					     src_x, src_y, width, height,
					     (cairo_surface_t **) &src,
					     &attributes);
    if (status)
	return status;

    operation = _recategorize_composite_operation (dst, op, src, &attributes, TRUE);
    if (operation == DO_UNSUPPORTED) {
	status = CAIRO_INT_STATUS_UNSUPPORTED;
	goto BAIL;
    }

    switch (antialias) {
    case CAIRO_ANTIALIAS_NONE:
	pict_format = XRenderFindStandardFormat (dst->dpy, PictStandardA1);
	break;
    default:
	pict_format = XRenderFindStandardFormat (dst->dpy, PictStandardA8);
	break;
    }

    if (traps[0].left.p1.y < traps[0].left.p2.y) {
	render_reference_x = _cairo_fixed_integer_floor (traps[0].left.p1.x);
	render_reference_y = _cairo_fixed_integer_floor (traps[0].left.p1.y);
    } else {
	render_reference_x = _cairo_fixed_integer_floor (traps[0].left.p2.x);
	render_reference_y = _cairo_fixed_integer_floor (traps[0].left.p2.y);
    }

    render_src_x = src_x + render_reference_x - dst_x;
    render_src_y = src_y + render_reference_y - dst_y;

    _cairo_xlib_surface_ensure_dst_picture (dst);
    status = _cairo_xlib_surface_set_attributes (src, &attributes);
    if (status)
	goto BAIL;

    if (!_cairo_operator_bounded_by_mask (op)) {
	/* XRenderCompositeTrapezoids() creates a mask only large enough for the
	 * trapezoids themselves, but if the operator is unbounded, then we need
	 * to actually composite all the way out to the bounds, so we create
	 * the mask and composite ourselves. There actually would
	 * be benefit to doing this in all cases, since RENDER implementations
	 * will frequently create a too temporary big mask, ignoring destination
	 * bounds and clip. (XRenderAddTraps() could be used to make creating
	 * the mask somewhat cheaper.)
	 */
	Picture mask_picture = _create_trapezoid_mask (dst, traps, num_traps,
						       dst_x, dst_y, width, height,
						       pict_format);
	if (!mask_picture) {
	    status = CAIRO_STATUS_NO_MEMORY;
	    goto BAIL;
	}

	XRenderComposite (dst->dpy,
			  _render_operator (op),
			  src->src_picture,
			  mask_picture,
			  dst->dst_picture,
			  src_x + attributes.x_offset,
			  src_y + attributes.y_offset,
			  0, 0,
			  dst_x, dst_y,
			  width, height);

	XRenderFreePicture (dst->dpy, mask_picture);

	status = _cairo_surface_composite_shape_fixup_unbounded (&dst->base,
								 &attributes, src->width, src->height,
								 width, height,
								 src_x, src_y,
								 0, 0,
								 dst_x, dst_y, width, height);

    } else {
	/* XXX: The XTrapezoid cast is evil and needs to go away somehow. */
	XRenderCompositeTrapezoids (dst->dpy,
				    _render_operator (op),
				    src->src_picture, dst->dst_picture,
				    pict_format,
				    render_src_x + attributes.x_offset,
				    render_src_y + attributes.y_offset,
				    (XTrapezoid *) traps, num_traps);
    }

 BAIL:
    _cairo_pattern_release_surface (pattern, &src->base, &attributes);

    return status;
}

static cairo_int_status_t
_cairo_xlib_surface_set_clip_region (void              *abstract_surface,
				     pixman_region16_t *region)
{
    cairo_xlib_surface_t *surface = (cairo_xlib_surface_t *) abstract_surface;

    if (surface->clip_rects) {
	free (surface->clip_rects);
	surface->clip_rects = NULL;
    }

    surface->have_clip_rects = FALSE;
    surface->num_clip_rects = 0;

    if (region == NULL) {
	if (surface->gc)
	    XSetClipMask (surface->dpy, surface->gc, None);

	if (surface->xrender_format && surface->dst_picture) {
	    XRenderPictureAttributes pa;
	    pa.clip_mask = None;
	    XRenderChangePicture (surface->dpy, surface->dst_picture,
				  CPClipMask, &pa);
	}
    } else {
	pixman_box16_t *boxes;
	XRectangle *rects = NULL;
	int n_boxes, i;

	n_boxes = pixman_region_num_rects (region);
	if (n_boxes > 0) {
	    rects = malloc (sizeof(XRectangle) * n_boxes);
	    if (rects == NULL)
		return CAIRO_STATUS_NO_MEMORY;
	} else {
	    rects = NULL;
	}

	boxes = pixman_region_rects (region);

	for (i = 0; i < n_boxes; i++) {
	    rects[i].x = boxes[i].x1;
	    rects[i].y = boxes[i].y1;
	    rects[i].width = boxes[i].x2 - boxes[i].x1;
	    rects[i].height = boxes[i].y2 - boxes[i].y1;
	}

	surface->have_clip_rects = TRUE;
	surface->clip_rects = rects;
	surface->num_clip_rects = n_boxes;

	if (surface->gc)
	    _cairo_xlib_surface_set_gc_clip_rects (surface);

	if (surface->dst_picture)
	    _cairo_xlib_surface_set_picture_clip_rects (surface);
    }

    return CAIRO_STATUS_SUCCESS;
}

static cairo_int_status_t
_cairo_xlib_surface_get_extents (void		         *abstract_surface,
				 cairo_rectangle_int16_t *rectangle)
{
    cairo_xlib_surface_t *surface = abstract_surface;

    rectangle->x = 0;
    rectangle->y = 0;

    rectangle->width  = surface->width;
    rectangle->height = surface->height;

    return CAIRO_STATUS_SUCCESS;
}

static void
_cairo_xlib_surface_get_font_options (void                  *abstract_surface,
				      cairo_font_options_t  *options)
{
    cairo_xlib_surface_t *surface = abstract_surface;

    *options = surface->screen_info->font_options;
}

static cairo_status_t
_cairo_xlib_surface_flush (void *abstract_surface)
{
    cairo_xlib_surface_t *surface = abstract_surface;
    XSync (surface->dpy, False);
    return CAIRO_STATUS_SUCCESS;
}

static void
_cairo_xlib_surface_scaled_font_fini (cairo_scaled_font_t *scaled_font);

static void
_cairo_xlib_surface_scaled_glyph_fini (cairo_scaled_glyph_t *scaled_glyph,
				       cairo_scaled_font_t  *scaled_font);

static const cairo_surface_backend_t cairo_xlib_surface_backend = {
    CAIRO_SURFACE_TYPE_XLIB,
    _cairo_xlib_surface_create_similar,
    _cairo_xlib_surface_finish,
    _cairo_xlib_surface_acquire_source_image,
    _cairo_xlib_surface_release_source_image,
    _cairo_xlib_surface_acquire_dest_image,
    _cairo_xlib_surface_release_dest_image,
    _cairo_xlib_surface_clone_similar,
    _cairo_xlib_surface_composite,
    _cairo_xlib_surface_fill_rectangles,
    _cairo_xlib_surface_composite_trapezoids,
    NULL, /* copy_page */
    NULL, /* show_page */
    _cairo_xlib_surface_set_clip_region,
    NULL, /* intersect_clip_path */
    _cairo_xlib_surface_get_extents,
    NULL, /* old_show_glyphs */
    _cairo_xlib_surface_get_font_options,
    _cairo_xlib_surface_flush,
    NULL, /* mark_dirty_rectangle */
    _cairo_xlib_surface_scaled_font_fini,
    _cairo_xlib_surface_scaled_glyph_fini,

    NULL, /* paint */
    NULL, /* mask */
    NULL, /* stroke */
    NULL, /* fill */
    _cairo_xlib_surface_show_glyphs,
    NULL  /* snapshot */
};

/**
 * _cairo_surface_is_xlib:
 * @surface: a #cairo_surface_t
 *
 * Checks if a surface is a #cairo_xlib_surface_t
 *
 * Return value: True if the surface is an xlib surface
 **/
static cairo_bool_t
_cairo_surface_is_xlib (cairo_surface_t *surface)
{
    return surface->backend == &cairo_xlib_surface_backend;
}

static cairo_surface_t *
_cairo_xlib_surface_create_internal (Display		       *dpy,
				     Drawable		        drawable,
				     Screen		       *screen,
				     Visual		       *visual,
				     XRenderPictFormat	       *xrender_format,
				     int			width,
				     int			height,
				     int			depth)
{
    cairo_xlib_surface_t *surface;
    cairo_xlib_screen_info_t *screen_info;

    screen_info = _cairo_xlib_screen_info_get (dpy, screen);
    if (screen_info == NULL) {
	_cairo_error (CAIRO_STATUS_NO_MEMORY);
	return (cairo_surface_t*) &_cairo_surface_nil;
    }

    surface = malloc (sizeof (cairo_xlib_surface_t));
    if (surface == NULL) {
	_cairo_error (CAIRO_STATUS_NO_MEMORY);
	return (cairo_surface_t*) &_cairo_surface_nil;
    }

    if (xrender_format) {
	depth = xrender_format->depth;
    } else if (visual) {
	int j, k;

	/* This is ugly, but we have to walk over all visuals
	 * for the display to find the depth.
	 */
	for (j = 0; j < screen->ndepths; j++) {
	    Depth *d = &screen->depths[j];
	    for (k = 0; k < d->nvisuals; k++) {
		if (&d->visuals[k] == visual) {
		    depth = d->depth;
		    goto found;
		}
	    }
	}
    found:
	;
    }

    if (cairo_xlib_render_disabled ||
	! XRenderQueryVersion (dpy, &surface->render_major, &surface->render_minor)) {
	surface->render_major = -1;
	surface->render_minor = -1;
    }

    if (CAIRO_SURFACE_RENDER_HAS_CREATE_PICTURE (surface)) {
	if (!xrender_format) {
	    if (visual)
		xrender_format = XRenderFindVisualFormat (dpy, visual);
	    else if (depth == 1)
		xrender_format = XRenderFindStandardFormat (dpy, PictStandardA1);
	}
    } else {
	xrender_format = NULL;
    }

    _cairo_surface_init (&surface->base, &cairo_xlib_surface_backend,
			 _xrender_format_to_content (xrender_format));

    surface->dpy = dpy;