cairo-pattern.c

来自「按照官方的说法：Cairo is a vector graphics libra」· C语言 代码 · 共 1,467 行 · 第 1/3 页

    if (image->base.status) {
	pixman_image_destroy (pixman_image);
	return CAIRO_STATUS_NO_MEMORY;
    }

    pixman_image_set_filter (pixman_image, PIXMAN_FILTER_BILINEAR);

    _cairo_matrix_to_pixman_matrix (&pattern->base.matrix, &pixman_transform);
    pixman_image_set_transform (pixman_image, &pixman_transform);

    switch (pattern->base.extend) {
    case CAIRO_EXTEND_NONE:
	pixman_image_set_repeat (pixman_image, PIXMAN_REPEAT_NONE);
	break;
    case CAIRO_EXTEND_REPEAT:
	pixman_image_set_repeat (pixman_image, PIXMAN_REPEAT_NORMAL);
	break;
    case CAIRO_EXTEND_REFLECT:
	pixman_image_set_repeat (pixman_image, PIXMAN_REPEAT_REFLECT);
	break;
    case CAIRO_EXTEND_PAD:
	pixman_image_set_repeat (pixman_image, PIXMAN_REPEAT_PAD);
	break;
    }

    pixman_composite (PIXMAN_OPERATOR_SRC,
		      pixman_image,
		      NULL,
		      image->pixman_image,
		      x, y,
		      0, 0,
		      0, 0,
		      width, height);

    pixman_image_destroy (pixman_image);

    status = _cairo_surface_clone_similar (dst, &image->base, out);

    cairo_surface_destroy (&image->base);

    attr->x_offset = -x;
    attr->y_offset = -y;
    cairo_matrix_init_identity (&attr->matrix);
    attr->extend = repeat ? CAIRO_EXTEND_REPEAT : CAIRO_EXTEND_NONE;
    attr->filter = CAIRO_FILTER_NEAREST;
    attr->acquired = FALSE;

    return status;
}

static cairo_int_status_t
_cairo_pattern_acquire_surface_for_solid (cairo_solid_pattern_t	     *pattern,
					  cairo_surface_t	     *dst,
					  int			     x,
					  int			     y,
					  unsigned int		     width,
					  unsigned int		     height,
					  cairo_surface_t	     **out,
					  cairo_surface_attributes_t *attribs)
{
    *out = _cairo_surface_create_similar_solid (dst,
						CAIRO_CONTENT_COLOR_ALPHA,
						1, 1,
						&pattern->color);
    if ((*out)->status)
	return CAIRO_STATUS_NO_MEMORY;

    attribs->x_offset = attribs->y_offset = 0;
    cairo_matrix_init_identity (&attribs->matrix);
    attribs->extend = CAIRO_EXTEND_REPEAT;
    attribs->filter = CAIRO_FILTER_NEAREST;
    attribs->acquired = FALSE;

    return CAIRO_STATUS_SUCCESS;
}

/**
 * _cairo_pattern_is_opaque_solid
 *
 * Convenience function to determine whether a pattern is an opaque
 * (alpha==1.0) solid color pattern. This is done by testing whether
 * the pattern's alpha value when converted to a byte is 255, so if a
 * backend actually supported deep alpha channels this function might
 * not do the right thing.
 *
 * Return value: %TRUE if the pattern is an opaque, solid color.
 **/
cairo_bool_t
_cairo_pattern_is_opaque_solid (const cairo_pattern_t *pattern)
{
    cairo_solid_pattern_t *solid;

    if (pattern->type != CAIRO_PATTERN_TYPE_SOLID)
	return FALSE;

    solid = (cairo_solid_pattern_t *) pattern;

    return CAIRO_ALPHA_IS_OPAQUE (solid->color.alpha);
}

static cairo_bool_t
_gradient_is_opaque (const cairo_gradient_pattern_t *gradient)
{
    int i;

    for (i = 0; i < gradient->n_stops; i++)
	if (! CAIRO_ALPHA_IS_OPAQUE (gradient->stops[i].color.alpha))
	    return FALSE;

    return TRUE;
}

/**
 * _cairo_pattern_is_opaque
 *
 * Convenience function to determine whether a pattern is an opaque
 * pattern (of any type). The same caveats that apply to
 * _cairo_pattern_is_opaque_solid apply here as well.
 *
 * Return value: %TRUE if the pattern is a opaque.
 **/
cairo_bool_t
_cairo_pattern_is_opaque (const cairo_pattern_t *abstract_pattern)
{
    const cairo_pattern_union_t *pattern;

    pattern = (cairo_pattern_union_t *) abstract_pattern;
    switch (pattern->base.type) {
    case CAIRO_PATTERN_TYPE_SOLID:
	return _cairo_pattern_is_opaque_solid (abstract_pattern);
    case CAIRO_PATTERN_TYPE_SURFACE:
	return cairo_surface_get_content (pattern->surface.surface) == CAIRO_CONTENT_COLOR;
    case CAIRO_PATTERN_TYPE_LINEAR:
    case CAIRO_PATTERN_TYPE_RADIAL:
	return _gradient_is_opaque (&pattern->gradient.base);
    }

    ASSERT_NOT_REACHED;
    return FALSE;
}

static cairo_int_status_t
_cairo_pattern_acquire_surface_for_surface (cairo_surface_pattern_t   *pattern,
					    cairo_surface_t	       *dst,
					    int			       x,
					    int			       y,
					    unsigned int	       width,
					    unsigned int	       height,
					    cairo_surface_t	       **out,
					    cairo_surface_attributes_t *attr)
{
    cairo_int_status_t status;
    int tx, ty;

    attr->acquired = FALSE;

    if (_cairo_surface_is_image (dst))
    {
	cairo_image_surface_t *image;

	status = _cairo_surface_acquire_source_image (pattern->surface,
						      &image,
						      &attr->extra);
	if (status)
	    return status;

	*out = &image->base;
	attr->acquired = TRUE;
    }
    else
    {
	status = _cairo_surface_clone_similar (dst, pattern->surface, out);
    }

    attr->extend = pattern->base.extend;
    attr->filter = pattern->base.filter;
    if (_cairo_matrix_is_integer_translation (&pattern->base.matrix,
					      &tx, &ty))
    {
	cairo_matrix_init_identity (&attr->matrix);
	attr->x_offset = tx;
	attr->y_offset = ty;
	attr->filter = CAIRO_FILTER_NEAREST;
    }
    else
    {
	attr->matrix = pattern->base.matrix;
	attr->x_offset = attr->y_offset = 0;
    }

    return status;
}

/**
 * _cairo_pattern_acquire_surface:
 * @pattern: a #cairo_pattern_t
 * @dst: destination surface
 * @x: X coordinate in source corresponding to left side of destination area
 * @y: Y coordinate in source corresponding to top side of destination area
 * @width: width of destination area
 * @height: height of destination area
 * @surface_out: location to store a pointer to a surface
 * @attributes: surface attributes that destination backend should apply to
 * the returned surface
 *
 * A convenience function to obtain a surface to use as the source for
 * drawing on @dst.
 *
 * Return value: %CAIRO_STATUS_SUCCESS if a surface was stored in @surface_out.
 **/
cairo_int_status_t
_cairo_pattern_acquire_surface (cairo_pattern_t		   *pattern,
				cairo_surface_t		   *dst,
				int			   x,
				int			   y,
				unsigned int		   width,
				unsigned int		   height,
				cairo_surface_t		   **surface_out,
				cairo_surface_attributes_t *attributes)
{
    cairo_status_t status;

    if (pattern->status) {
	*surface_out = NULL;
	attributes->acquired = FALSE;
	return pattern->status;
    }

    switch (pattern->type) {
    case CAIRO_PATTERN_TYPE_SOLID: {
	cairo_solid_pattern_t *src = (cairo_solid_pattern_t *) pattern;

	status = _cairo_pattern_acquire_surface_for_solid (src, dst,
							   x, y, width, height,
							   surface_out,
							   attributes);
	} break;
    case CAIRO_PATTERN_TYPE_LINEAR:
    case CAIRO_PATTERN_TYPE_RADIAL: {
	cairo_gradient_pattern_t *src = (cairo_gradient_pattern_t *) pattern;

	/* fast path for gradients with less than 2 color stops */
	if (src->n_stops < 2)
	{
	    cairo_solid_pattern_t solid;

	    if (src->n_stops)
	    {
		cairo_color_t color;

		_cairo_color_init_rgba (&color,
					src->stops->color.red / 65536.0,
					src->stops->color.green / 65536.0,
					src->stops->color.blue / 65536.0,
					src->stops->color.alpha / 65536.0);

		_cairo_pattern_init_solid (&solid, &color);
	    }
	    else
	    {
		const cairo_color_t *color;

		color =	_cairo_stock_color (CAIRO_STOCK_TRANSPARENT);
		_cairo_pattern_init_solid (&solid, color);
	    }

	    status = _cairo_pattern_acquire_surface_for_solid (&solid, dst,
							       x, y,
							       width, height,
							       surface_out,
							       attributes);
	}
	else
	{
	    status = _cairo_pattern_acquire_surface_for_gradient (src, dst,
								  x, y,
								  width, height,
								  surface_out,
								  attributes);
	}
    } break;
    case CAIRO_PATTERN_TYPE_SURFACE: {
	cairo_surface_pattern_t *src = (cairo_surface_pattern_t *) pattern;

	status = _cairo_pattern_acquire_surface_for_surface (src, dst,
							     x, y, width, height,
							     surface_out,
							     attributes);
    } break;
    default:
	status = CAIRO_INT_STATUS_UNSUPPORTED;
    }

    return status;
}

/**
 * _cairo_pattern_release_surface:
 * @pattern: a #cairo_pattern_t
 * @surface: a surface obtained by _cairo_pattern_acquire_surface
 * @attributes: attributes obtained by _cairo_pattern_acquire_surface
 *
 * Releases resources obtained by _cairo_pattern_acquire_surface.
 **/
void
_cairo_pattern_release_surface (cairo_pattern_t		   *pattern,
				cairo_surface_t		   *surface,
				cairo_surface_attributes_t *attributes)
{
    if (attributes->acquired)
    {
	cairo_surface_pattern_t *surface_pattern;

	assert (pattern->type == CAIRO_PATTERN_TYPE_SURFACE);
	surface_pattern = (cairo_surface_pattern_t *) pattern;

	_cairo_surface_release_source_image (surface_pattern->surface,
					     (cairo_image_surface_t *) surface,
					     attributes->extra);
    }
    else
    {
	cairo_surface_destroy (surface);
    }
}

cairo_int_status_t
_cairo_pattern_acquire_surfaces (cairo_pattern_t	    *src,
				 cairo_pattern_t	    *mask,
				 cairo_surface_t	    *dst,
				 int			    src_x,
				 int			    src_y,
				 int			    mask_x,
				 int			    mask_y,
				 unsigned int		    width,
				 unsigned int		    height,
				 cairo_surface_t	    **src_out,
				 cairo_surface_t	    **mask_out,
				 cairo_surface_attributes_t *src_attributes,
				 cairo_surface_attributes_t *mask_attributes)
{
    cairo_int_status_t	  status;
    cairo_pattern_union_t src_tmp, mask_tmp;

    if (src->status)
	return src->status;
    if (mask && mask->status)
	return mask->status;

    /* If src and mask are both solid, then the mask alpha can be
     * combined into src and mask can be ignored. */

    /* XXX: This optimization assumes that there is no color
     * information in mask, so this will need to change when we
     * support RENDER-style 4-channel masks. */
    if (src->type == CAIRO_PATTERN_TYPE_SOLID &&
	mask && mask->type == CAIRO_PATTERN_TYPE_SOLID)
    {
	cairo_color_t combined;
	cairo_solid_pattern_t *src_solid = (cairo_solid_pattern_t *) src;
	cairo_solid_pattern_t *mask_solid = (cairo_solid_pattern_t *) mask;

	combined = src_solid->color;
	_cairo_color_multiply_alpha (&combined, mask_solid->color.alpha);

	_cairo_pattern_init_solid (&src_tmp.solid, &combined);

	mask = NULL;
    }
    else
    {
	_cairo_pattern_init_copy (&src_tmp.base, src);
    }

    status = _cairo_pattern_acquire_surface (&src_tmp.base, dst,
					     src_x, src_y,
					     width, height,
					     src_out, src_attributes);
    if (status) {
	_cairo_pattern_fini (&src_tmp.base);
	return status;
    }

    if (mask == NULL)
    {
	_cairo_pattern_fini (&src_tmp.base);
	*mask_out = NULL;
	return CAIRO_STATUS_SUCCESS;
    }

    _cairo_pattern_init_copy (&mask_tmp.base, mask);

    status = _cairo_pattern_acquire_surface (&mask_tmp.base, dst,
					     mask_x, mask_y,
					     width, height,
					     mask_out, mask_attributes);

    if (status)
	_cairo_pattern_release_surface (&src_tmp.base,
					*src_out, src_attributes);

    _cairo_pattern_fini (&src_tmp.base);
    _cairo_pattern_fini (&mask_tmp.base);

    return status;
}

/**
 * _cairo_pattern_get_extents:
 *
 * Return the "target-space" extents of @pattern in @extents.
 *
 * For unbounded patterns, the @extents will be initialized with
 * "infinite" extents, (minimum and maximum fixed-point values).
 *
 * XXX: Currently, bounded gradient patterns will also return
 * "infinite" extents, though it would be possible to optimize these
 * with a little more work.
 **/
cairo_status_t
_cairo_pattern_get_extents (cairo_pattern_t         *pattern,
			    cairo_rectangle_int16_t *extents)
{
    if (pattern->extend == CAIRO_EXTEND_NONE &&
	pattern->type == CAIRO_PATTERN_TYPE_SURFACE)
    {
	cairo_status_t status;
	cairo_rectangle_int16_t surface_extents;
	cairo_surface_pattern_t *surface_pattern =
	    (cairo_surface_pattern_t *) pattern;
	cairo_surface_t *surface = surface_pattern->surface;
	cairo_matrix_t imatrix;
	double x, y;
	/* Initialize to keep the compiler quiet. */
	int left=0, right=0, top=0, bottom=0;
	int lx, rx, ty, by;
	int sx, sy;
	cairo_bool_t set = FALSE;

	status = _cairo_surface_get_extents (surface, &surface_extents);
	if (status)
	    return status;

	imatrix = pattern->matrix;
	cairo_matrix_invert (&imatrix);

	for (sy = 0; sy <= 1; sy++) {
	    for (sx = 0; sx <= 1; sx++) {
		x = surface_extents.x + sx * surface_extents.width;
		y = surface_extents.y + sy * surface_extents.height;
		cairo_matrix_transform_point (&imatrix, &x, &y);
		if (x < 0) x = 0;
		if (x > INT16_MAX) x = INT16_MAX;
		if (y < 0) y = 0;
		if (y > INT16_MAX) y = INT16_MAX;
		lx = floor (x); rx = ceil (x);
		ty = floor (y); by = ceil (y);
		if (!set) {
		    left = lx;
		    right = rx;
		    top = ty;
		    bottom = by;
		    set = TRUE;
		} else {
		    if (lx < left) left = lx;
		    if (rx > right) right = rx;
		    if (ty < top) top = ty;
		    if (by > bottom) bottom = by;
		}
	    }
	}
	extents->x = left; extents->width = right - left;
	extents->y = top; extents->height = bottom - top;
	return CAIRO_STATUS_SUCCESS;
    }

    /* XXX: We could optimize gradients with pattern->extend of NONE
     * here in some cases, (eg. radial gradients and 1 axis of
     * horizontal/vertical linear gradients).
     */

    extents->x = 0;
    extents->y = 0;
    extents->width = INT16_MAX;
    extents->height = INT16_MAX;

    return CAIRO_STATUS_SUCCESS;
}