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

    XRenderSetPictureTransform (surface->dpy, surface->src_picture, &xtransform);

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_xlib_surface_set_filter (cairo_xlib_surface_t *surface,
				cairo_filter_t	     filter)
{
    char *render_filter;

    if (!surface->src_picture)
	return CAIRO_STATUS_SUCCESS;

    if (!CAIRO_SURFACE_RENDER_HAS_FILTERS (surface))
    {
	if (filter == CAIRO_FILTER_FAST || filter == CAIRO_FILTER_NEAREST)
	    return CAIRO_STATUS_SUCCESS;

	return CAIRO_INT_STATUS_UNSUPPORTED;
    }

    switch (filter) {
    case CAIRO_FILTER_FAST:
	render_filter = FilterFast;
	break;
    case CAIRO_FILTER_GOOD:
	render_filter = FilterGood;
	break;
    case CAIRO_FILTER_BEST:
	render_filter = FilterBest;
	break;
    case CAIRO_FILTER_NEAREST:
	render_filter = FilterNearest;
	break;
    case CAIRO_FILTER_BILINEAR:
	render_filter = FilterBilinear;
	break;
    default:
	render_filter = FilterBest;
	break;
    }

    XRenderSetPictureFilter (surface->dpy, surface->src_picture,
			     render_filter, NULL, 0);

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_xlib_surface_set_repeat (cairo_xlib_surface_t *surface, int repeat)
{
    XRenderPictureAttributes pa;
    unsigned long	     mask;

    if (!surface->src_picture)
	return CAIRO_STATUS_SUCCESS;

    mask = CPRepeat;
    pa.repeat = repeat;

    XRenderChangePicture (surface->dpy, surface->src_picture, mask, &pa);

    return CAIRO_STATUS_SUCCESS;
}

static cairo_int_status_t
_cairo_xlib_surface_set_attributes (cairo_xlib_surface_t	  *surface,
				       cairo_surface_attributes_t *attributes)
{
    cairo_int_status_t status;

    _cairo_xlib_surface_ensure_src_picture (surface);

    status = _cairo_xlib_surface_set_matrix (surface, &attributes->matrix);
    if (status)
	return status;

    switch (attributes->extend) {
    case CAIRO_EXTEND_NONE:
	_cairo_xlib_surface_set_repeat (surface, 0);
	break;
    case CAIRO_EXTEND_REPEAT:
	_cairo_xlib_surface_set_repeat (surface, 1);
	break;
    case CAIRO_EXTEND_REFLECT:
    case CAIRO_EXTEND_PAD:
	return CAIRO_INT_STATUS_UNSUPPORTED;
    }

    status = _cairo_xlib_surface_set_filter (surface, attributes->filter);
    if (status)
	return status;

    return CAIRO_STATUS_SUCCESS;
}

/* Checks whether we can can directly draw from src to dst with
 * the core protocol: either with CopyArea or using src as a
 * a tile in a GC.
 */
static cairo_bool_t
_surfaces_compatible (cairo_xlib_surface_t *dst,
		      cairo_xlib_surface_t *src)
{
    /* same screen */
    if (!_cairo_xlib_surface_same_screen (dst, src))
	return FALSE;

    /* same depth (for core) */
    if (src->depth != dst->depth)
	return FALSE;

    /* if Render is supported, match picture formats */
    if (src->xrender_format != NULL && src->xrender_format == dst->xrender_format)
	return TRUE;

    /* Without Render, match visuals instead */
    if (src->visual == dst->visual)
	return TRUE;

    return FALSE;
}

static cairo_bool_t
_surface_has_alpha (cairo_xlib_surface_t *surface)
{
    if (surface->xrender_format) {
	if (surface->xrender_format->type == PictTypeDirect &&
	    surface->xrender_format->direct.alphaMask != 0)
	    return TRUE;
	else
	    return FALSE;
    } else {

	/* In the no-render case, we never have alpha */
	return FALSE;
    }
}

/* Returns true if the given operator and source-alpha combination
 * requires alpha compositing to complete.
 */
static cairo_bool_t
_operator_needs_alpha_composite (cairo_operator_t op,
				 cairo_bool_t     surface_has_alpha)
{
    if (op == CAIRO_OPERATOR_SOURCE ||
	(!surface_has_alpha &&
	 (op == CAIRO_OPERATOR_OVER ||
	  op == CAIRO_OPERATOR_ATOP ||
	  op == CAIRO_OPERATOR_IN)))
	return FALSE;

    return TRUE;
}

/* There is a bug in most older X servers with compositing using a
 * untransformed repeating source pattern when the source is in off-screen
 * video memory, and another with repeated transformed images using a
 * general tranform matrix. When these bugs could be triggered, we need a
 * fallback: in the common case where we have no transformation and the
 * source and destination have the same format/visual, we can do the
 * operation using the core protocol for the first bug, otherwise, we need
 * a software fallback.
 *
 * We can also often optimize a compositing operation by calling XCopyArea
 * for some common cases where there is no alpha compositing to be done.
 * We figure that out here as well.
 */
typedef enum {
    DO_RENDER,		/* use render */
    DO_XCOPYAREA,	/* core protocol XCopyArea optimization/fallback */
    DO_XTILE,		/* core protocol XSetTile optimization/fallback */
    DO_UNSUPPORTED	/* software fallback */
} composite_operation_t;

/* Initial check for the render bugs; we need to recheck for the
 * offscreen-memory bug after we turn patterns into surfaces, since that
 * may introduce a repeating pattern for gradient patterns.  We don't need
 * to check for the repeat+transform bug because gradient surfaces aren't
 * transformed.
 *
 * All we do here is reject cases where we *know* are going to
 * hit the bug and won't be able to use a core protocol fallback.
 */
static composite_operation_t
_categorize_composite_operation (cairo_xlib_surface_t *dst,
				 cairo_operator_t      op,
				 cairo_pattern_t      *src_pattern,
				 cairo_bool_t	       have_mask)

{
    if (!dst->buggy_repeat)
	return DO_RENDER;

    if (src_pattern->type == CAIRO_PATTERN_TYPE_SURFACE)
    {
	cairo_surface_pattern_t *surface_pattern = (cairo_surface_pattern_t *)src_pattern;

	if (_cairo_matrix_is_integer_translation (&src_pattern->matrix, NULL, NULL) &&
	    src_pattern->extend == CAIRO_EXTEND_REPEAT)
	{
	    /* This is the case where we have the bug involving
	     * untransformed repeating source patterns with off-screen
	     * video memory; reject some cases where a core protocol
	     * fallback is impossible.
	     */
	    if (have_mask ||
		!(op == CAIRO_OPERATOR_SOURCE || op == CAIRO_OPERATOR_OVER))
		return DO_UNSUPPORTED;

	    if (_cairo_surface_is_xlib (surface_pattern->surface)) {
		cairo_xlib_surface_t *src = (cairo_xlib_surface_t *)surface_pattern->surface;

		if (op == CAIRO_OPERATOR_OVER && _surface_has_alpha (src))
		    return DO_UNSUPPORTED;

		/* If these are on the same screen but otherwise incompatible,
		 * make a copy as core drawing can't cross depths and doesn't
		 * work rightacross visuals of the same depth
		 */
		if (_cairo_xlib_surface_same_screen (dst, src) &&
		    !_surfaces_compatible (dst, src))
		    return DO_UNSUPPORTED;
	    }
	}

	/* Check for the other bug involving repeat patterns with general
	 * transforms. */
	if (!_cairo_matrix_is_integer_translation (&src_pattern->matrix, NULL, NULL) &&
	    src_pattern->extend == CAIRO_EXTEND_REPEAT)
	    return DO_UNSUPPORTED;
    }

    return DO_RENDER;
}

/* Recheck for composite-repeat once we've turned patterns into Xlib surfaces
 * If we end up returning DO_UNSUPPORTED here, we're throwing away work we
 * did to turn gradients into a pattern, but most of the time we can handle
 * that case with core protocol fallback.
 *
 * Also check here if we can just use XCopyArea, instead of going through
 * Render.
 */
static composite_operation_t
_recategorize_composite_operation (cairo_xlib_surface_t	      *dst,
				   cairo_operator_t	       op,
				   cairo_xlib_surface_t	      *src,
				   cairo_surface_attributes_t *src_attr,
				   cairo_bool_t		       have_mask)
{
    cairo_bool_t is_integer_translation =
	_cairo_matrix_is_integer_translation (&src_attr->matrix, NULL, NULL);
    cairo_bool_t needs_alpha_composite =
	_operator_needs_alpha_composite (op, _surface_has_alpha (src));

    if (!have_mask &&
	is_integer_translation &&
	src_attr->extend == CAIRO_EXTEND_NONE &&
	!needs_alpha_composite &&
	_surfaces_compatible(src, dst))
    {
	return DO_XCOPYAREA;
    }

    if (!dst->buggy_repeat)
	return DO_RENDER;

    if (is_integer_translation &&
	src_attr->extend == CAIRO_EXTEND_REPEAT &&
	(src->width != 1 || src->height != 1))
    {
	if (!have_mask &&
	    !needs_alpha_composite &&
	    _surfaces_compatible (dst, src))
	{
	    return DO_XTILE;
	}

	return DO_UNSUPPORTED;
    }

    return DO_RENDER;
}

static int
_render_operator (cairo_operator_t op)
{
    switch (op) {
    case CAIRO_OPERATOR_CLEAR:
	return PictOpClear;

    case CAIRO_OPERATOR_SOURCE:
	return PictOpSrc;
    case CAIRO_OPERATOR_OVER:
	return PictOpOver;
    case CAIRO_OPERATOR_IN:
	return PictOpIn;
    case CAIRO_OPERATOR_OUT:
	return PictOpOut;
    case CAIRO_OPERATOR_ATOP:
	return PictOpAtop;

    case CAIRO_OPERATOR_DEST:
	return PictOpDst;
    case CAIRO_OPERATOR_DEST_OVER:
	return PictOpOverReverse;
    case CAIRO_OPERATOR_DEST_IN:
	return PictOpInReverse;
    case CAIRO_OPERATOR_DEST_OUT:
	return PictOpOutReverse;
    case CAIRO_OPERATOR_DEST_ATOP:
	return PictOpAtopReverse;

    case CAIRO_OPERATOR_XOR:
	return PictOpXor;
    case CAIRO_OPERATOR_ADD:
	return PictOpAdd;
    case CAIRO_OPERATOR_SATURATE:
	return PictOpSaturate;
    default:
	return PictOpOver;
    }
}

static cairo_int_status_t
_cairo_xlib_surface_composite (cairo_operator_t		op,
			       cairo_pattern_t		*src_pattern,
			       cairo_pattern_t		*mask_pattern,
			       void			*abstract_dst,
			       int			src_x,
			       int			src_y,
			       int			mask_x,
			       int			mask_y,
			       int			dst_x,
			       int			dst_y,
			       unsigned int		width,
			       unsigned int		height)
{
    cairo_surface_attributes_t	src_attr, mask_attr;
    cairo_xlib_surface_t	*dst = abstract_dst;
    cairo_xlib_surface_t	*src;
    cairo_xlib_surface_t	*mask;
    cairo_int_status_t		status;
    composite_operation_t       operation;
    int				itx, ity;

    if (!CAIRO_SURFACE_RENDER_HAS_COMPOSITE (dst))
	return CAIRO_INT_STATUS_UNSUPPORTED;

    operation = _categorize_composite_operation (dst, op, src_pattern,
						 mask_pattern != NULL);
    if (operation == DO_UNSUPPORTED)
	return CAIRO_INT_STATUS_UNSUPPORTED;

    status = _cairo_pattern_acquire_surfaces (src_pattern, mask_pattern,
					      &dst->base,
					      src_x, src_y,
					      mask_x, mask_y,
					      width, height,
					      (cairo_surface_t **) &src,
					      (cairo_surface_t **) &mask,
					      &src_attr, &mask_attr);
    if (status)
	return status;

    operation = _recategorize_composite_operation (dst, op, src, &src_attr,
						   mask_pattern != NULL);
    if (operation == DO_UNSUPPORTED) {
	status = CAIRO_INT_STATUS_UNSUPPORTED;
	goto BAIL;
    }

    status = _cairo_xlib_surface_set_attributes (src, &src_attr);
    if (status)
	goto BAIL;

    switch (operation)
    {
    case DO_RENDER:
	_cairo_xlib_surface_ensure_dst_picture (dst);
	if (mask) {
	    status = _cairo_xlib_surface_set_attributes (mask, &mask_attr);
	    if (status)
		goto BAIL;

	    XRenderComposite (dst->dpy,
			      _render_operator (op),
			      src->src_picture,
			      mask->src_picture,
			      dst->dst_picture,
			      src_x + src_attr.x_offset,
			      src_y + src_attr.y_offset,
			      mask_x + mask_attr.x_offset,
			      mask_y + mask_attr.y_offset,
			      dst_x, dst_y,
			      width, height);
	} else {
	    XRenderComposite (dst->dpy,
			      _render_operator (op),
			      src->src_picture,
			      0,
			      dst->dst_picture,
			      src_x + src_attr.x_offset,
			      src_y + src_attr.y_offset,
			      0, 0,
			      dst_x, dst_y,
			      width, height);
	}

	break;

    case DO_XCOPYAREA:
	_cairo_xlib_surface_ensure_gc (dst);
	XCopyArea (dst->dpy,
		   src->drawable,
		   dst->drawable,
		   dst->gc,
		   src_x + src_attr.x_offset,
		   src_y + src_attr.y_offset,
		   width, height,
		   dst_x, dst_y);
	break;

    case DO_XTILE:
	/* This case is only used for bug fallbacks, though it is theoretically
	 * applicable to the case where we don't have the RENDER extension as
	 * well.
	 *
	 * We've checked that we have a repeating unscaled source in
	 * _recategorize_composite_operation.
	 */

	_cairo_xlib_surface_ensure_gc (dst);
	_cairo_matrix_is_integer_translation (&src_attr.matrix, &itx, &ity);

	XSetTSOrigin (dst->dpy, dst->gc,
		      - (itx + src_attr.x_offset), - (ity + src_attr.y_offset));
	XSetTile (dst->dpy, dst->gc, src->drawable);
	XSetFillStyle (dst->dpy, dst->gc, FillTiled);

	XFillRectangle (dst->dpy, dst->drawable, dst->gc,
			dst_x, dst_y, width, height);
	break;

    default:
	ASSERT_NOT_REACHED;
    }

    if (!_cairo_operator_bounded_by_source (op))
      status = _cairo_surface_composite_fixup_unbounded (&dst->base,
							 &src_attr, src->width, src->height,
							 mask ? &mask_attr : NULL,
							 mask ? mask->width : 0,
							 mask ? mask->height : 0,
							 src_x, src_y,
							 mask_x, mask_y,
							 dst_x, dst_y, width, height);

 BAIL: