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

    surface->screen_info = screen_info;

    surface->gc = NULL;
    surface->drawable = drawable;
    surface->screen = screen;
    surface->owns_pixmap = FALSE;
    surface->use_pixmap = 0;
    surface->width = width;
    surface->height = height;

    surface->buggy_repeat = FALSE;
    if (strstr (ServerVendor (dpy), "X.Org") != NULL) {
	if (VendorRelease (dpy) <= 60802000)
	    surface->buggy_repeat = TRUE;
    } else if (strstr (ServerVendor (dpy), "XFree86") != NULL) {
	if (VendorRelease (dpy) <= 40500000)
	    surface->buggy_repeat = TRUE;
    } else if (strstr (ServerVendor (dpy), "Sun Microsystems, Inc.") != NULL) {
	if (VendorRelease (dpy) <= 60800000)
	    surface->buggy_repeat = TRUE;
    }

    surface->dst_picture = None;
    surface->src_picture = None;

    surface->visual = visual;
    surface->xrender_format = xrender_format;
    surface->depth = depth;

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

    return (cairo_surface_t *) surface;
}

static Screen *
_cairo_xlib_screen_from_visual (Display *dpy, Visual *visual)
{
    int	    s;
    int	    d;
    int	    v;
    Screen *screen;
    Depth  *depth;

    for (s = 0; s < ScreenCount (dpy); s++) {
	screen = ScreenOfDisplay (dpy, s);
	if (visual == DefaultVisualOfScreen (screen))
	    return screen;
	for (d = 0; d < screen->ndepths; d++) {
	    depth = &screen->depths[d];
	    for (v = 0; v < depth->nvisuals; v++)
		if (visual == &depth->visuals[v])
		    return screen;
	}
    }
    return NULL;
}

/**
 * cairo_xlib_surface_create:
 * @dpy: an X Display
 * @drawable: an X Drawable, (a Pixmap or a Window)
 * @visual: the visual to use for drawing to @drawable. The depth
 *          of the visual must match the depth of the drawable.
 *          Currently, only TrueColor visuals are fully supported.
 * @width: the current width of @drawable.
 * @height: the current height of @drawable.
 *
 * Creates an Xlib surface that draws to the given drawable.
 * The way that colors are represented in the drawable is specified
 * by the provided visual.
 *
 * NOTE: If @drawable is a Window, then the function
 * cairo_xlib_surface_set_size must be called whenever the size of the
 * window changes.
 *
 * Return value: the newly created surface
 **/
cairo_surface_t *
cairo_xlib_surface_create (Display     *dpy,
			   Drawable	drawable,
			   Visual      *visual,
			   int		width,
			   int		height)
{
    Screen *screen = _cairo_xlib_screen_from_visual (dpy, visual);

    if (screen == NULL) {
	_cairo_error (CAIRO_STATUS_INVALID_VISUAL);
	return (cairo_surface_t*) &_cairo_surface_nil;
    }

    return _cairo_xlib_surface_create_internal (dpy, drawable, screen,
						visual, NULL, width, height, 0);
}

/**
 * cairo_xlib_surface_create_for_bitmap:
 * @dpy: an X Display
 * @bitmap: an X Drawable, (a depth-1 Pixmap)
 * @screen: the X Screen associated with @bitmap
 * @width: the current width of @bitmap.
 * @height: the current height of @bitmap.
 *
 * Creates an Xlib surface that draws to the given bitmap.
 * This will be drawn to as a CAIRO_FORMAT_A1 object.
 *
 * Return value: the newly created surface
 **/
cairo_surface_t *
cairo_xlib_surface_create_for_bitmap (Display  *dpy,
				      Pixmap	bitmap,
				      Screen   *screen,
				      int	width,
				      int	height)
{
    return _cairo_xlib_surface_create_internal (dpy, bitmap, screen,
						NULL, NULL, width, height, 1);
}

/**
 * cairo_xlib_surface_create_with_xrender_format:
 * @dpy: an X Display
 * @drawable: an X Drawable, (a Pixmap or a Window)
 * @screen: the X Screen associated with @drawable
 * @format: the picture format to use for drawing to @drawable. The depth
 *          of @format must match the depth of the drawable.
 * @width: the current width of @drawable.
 * @height: the current height of @drawable.
 *
 * Creates an Xlib surface that draws to the given drawable.
 * The way that colors are represented in the drawable is specified
 * by the provided picture format.
 *
 * NOTE: If @drawable is a Window, then the function
 * cairo_xlib_surface_set_size must be called whenever the size of the
 * window changes.
 *
 * Return value: the newly created surface
 **/
cairo_surface_t *
cairo_xlib_surface_create_with_xrender_format (Display		    *dpy,
					       Drawable		    drawable,
					       Screen		    *screen,
					       XRenderPictFormat    *format,
					       int		    width,
					       int		    height)
{
    return _cairo_xlib_surface_create_internal (dpy, drawable, screen,
						NULL, format, width, height, 0);
}

/**
 * cairo_xlib_surface_set_size:
 * @surface: a #cairo_surface_t for the XLib backend
 * @width: the new width of the surface
 * @height: the new height of the surface
 *
 * Informs cairo of the new size of the X Drawable underlying the
 * surface. For a surface created for a Window (rather than a Pixmap),
 * this function must be called each time the size of the window
 * changes. (For a subwindow, you are normally resizing the window
 * yourself, but for a toplevel window, it is necessary to listen for
 * ConfigureNotify events.)
 *
 * A Pixmap can never change size, so it is never necessary to call
 * this function on a surface created for a Pixmap.
 **/
void
cairo_xlib_surface_set_size (cairo_surface_t *abstract_surface,
			     int              width,
			     int              height)
{
    cairo_xlib_surface_t *surface = (cairo_xlib_surface_t *) abstract_surface;

    if (! _cairo_surface_is_xlib (abstract_surface)) {
	_cairo_surface_set_error (abstract_surface,
				  CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return;
    }

    surface->width = width;
    surface->height = height;
}
/**
 * cairo_xlib_surface_set_drawable:
 * @surface: a #cairo_surface_t for the XLib backend
 * @drawable: the new drawable for the surface
 * @width: the width of the new drawable
 * @height: the height of the new drawable
 *
 * Informs cairo of a new X Drawable underlying the
 * surface. The drawable must match the display, screen
 * and format of the existing drawable or the application
 * will get X protocol errors and will probably terminate.
 * No checks are done by this function to ensure this
 * compatibility.
 **/
void
cairo_xlib_surface_set_drawable (cairo_surface_t   *abstract_surface,
				 Drawable	    drawable,
				 int		    width,
				 int		    height)
{
    cairo_xlib_surface_t *surface = (cairo_xlib_surface_t *)abstract_surface;

    if (! _cairo_surface_is_xlib (abstract_surface)) {
	_cairo_surface_set_error (abstract_surface, CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return;
    }

    /* XXX: and what about this case? */
    if (surface->owns_pixmap)
	return;

    if (surface->drawable != drawable) {
	if (surface->dst_picture)
	    XRenderFreePicture (surface->dpy, surface->dst_picture);

	if (surface->src_picture)
	    XRenderFreePicture (surface->dpy, surface->src_picture);

	surface->dst_picture = None;
	surface->src_picture = None;

	surface->drawable = drawable;
    }
    surface->width = width;
    surface->height = height;
}

/**
 * cairo_xlib_surface_get_display:
 * @surface: a #cairo_xlib_surface_t
 *
 * Get the X Display for the underlying X Drawable.
 *
 * Return value: the display.
 *
 * Since: 1.2
 **/
Display *
cairo_xlib_surface_get_display (cairo_surface_t *abstract_surface)
{
    cairo_xlib_surface_t *surface = (cairo_xlib_surface_t *) abstract_surface;

    if (! _cairo_surface_is_xlib (abstract_surface)) {
	_cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return NULL;
    }

    return surface->dpy;
}

/**
 * cairo_xlib_surface_get_drawable:
 * @surface: a #cairo_xlib_surface_t
 *
 * Get the underlying X Drawable used for the surface.
 *
 * Return value: the drawable.
 *
 * Since: 1.2
 **/
Drawable
cairo_xlib_surface_get_drawable (cairo_surface_t *abstract_surface)
{
    cairo_xlib_surface_t *surface = (cairo_xlib_surface_t *) abstract_surface;

    if (! _cairo_surface_is_xlib (abstract_surface)) {
	_cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return 0;
    }

    return surface->drawable;
}

/**
 * cairo_xlib_surface_get_screen:
 * @surface: a #cairo_xlib_surface_t
 *
 * Get the X Screen for the underlying X Drawable.
 *
 * Return value: the screen.
 *
 * Since: 1.2
 **/
Screen *
cairo_xlib_surface_get_screen (cairo_surface_t *abstract_surface)
{
    cairo_xlib_surface_t *surface = (cairo_xlib_surface_t *) abstract_surface;

    if (! _cairo_surface_is_xlib (abstract_surface)) {
	_cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return NULL;
    }

    return surface->screen;
}

/**
 * cairo_xlib_surface_get_visual:
 * @surface: a #cairo_xlib_surface_t
 *
 * Get the X Visual used for underlying X Drawable.
 *
 * Return value: the visual.
 *
 * Since: 1.2
 **/
Visual *
cairo_xlib_surface_get_visual (cairo_surface_t *abstract_surface)
{
    cairo_xlib_surface_t *surface = (cairo_xlib_surface_t *) abstract_surface;

    if (! _cairo_surface_is_xlib (abstract_surface)) {
	_cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return NULL;
    }

    return surface->visual;
}

/**
 * cairo_xlib_surface_get_depth:
 * @surface: a #cairo_xlib_surface_t
 *
 * Get the number of bits used to represent each pixel value.
 *
 * Return value: the depth of the surface in bits.
 *
 * Since: 1.2
 **/
int
cairo_xlib_surface_get_depth (cairo_surface_t *abstract_surface)
{
    cairo_xlib_surface_t *surface = (cairo_xlib_surface_t *) abstract_surface;

    if (! _cairo_surface_is_xlib (abstract_surface)) {
	_cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return 0;
    }

    return surface->depth;
}

/**
 * cairo_xlib_surface_get_width:
 * @surface: a #cairo_xlib_surface_t
 *
 * Get the width of the X Drawable underlying the surface in pixels.
 *
 * Return value: the width of the surface in pixels.
 *
 * Since: 1.2
 **/
int
cairo_xlib_surface_get_width (cairo_surface_t *abstract_surface)
{
    cairo_xlib_surface_t *surface = (cairo_xlib_surface_t *) abstract_surface;

    if (! _cairo_surface_is_xlib (abstract_surface)) {
	_cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return -1;
    }

    return surface->width;
}

/**
 * cairo_xlib_surface_get_height:
 * @surface: a #cairo_xlib_surface_t
 *
 * Get the height of the X Drawable underlying the surface in pixels.
 *
 * Return value: the height of the surface in pixels.
 *
 * Since: 1.2
 **/
int
cairo_xlib_surface_get_height (cairo_surface_t *abstract_surface)
{
    cairo_xlib_surface_t *surface = (cairo_xlib_surface_t *) abstract_surface;

    if (! _cairo_surface_is_xlib (abstract_surface)) {
	_cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return -1;
    }

    return surface->height;
}

typedef struct _cairo_xlib_surface_font_private {
    Display		*dpy;
    GlyphSet		glyphset;
    cairo_format_t	format;
    XRenderPictFormat	*xrender_format;
} cairo_xlib_surface_font_private_t;

static cairo_status_t
_cairo_xlib_surface_font_init (Display		    *dpy,
			       cairo_scaled_font_t  *scaled_font,
			       cairo_format_t	     format)
{
    cairo_xlib_surface_font_private_t	*font_private;

    font_private = malloc (sizeof (cairo_xlib_surface_font_private_t));
    if (!font_private)
	return CAIRO_STATUS_NO_MEMORY;

    font_private->dpy = dpy;
    font_private->format = format;
    font_private->xrender_format = _CAIRO_FORMAT_TO_XRENDER_FORMAT(dpy, format);
    font_private->glyphset = XRenderCreateGlyphSet (dpy, font_private->xrender_format);
    scaled_font->surface_private = font_private;
    scaled_font->surface_backend = &cairo_xlib_surface_backend;
    return CAIRO_STATUS_SUCCESS;
}

static void
_cairo_xlib_surface_scaled_font_fini (cairo_scaled_font_t *scaled_font)
{
    cairo_xlib_surface_font_private_t	*font_private = scaled_font->surface_private;

    if (font_private) {
	XRenderFreeGlyphSet (font_private->dpy, font_private->glyphset);
	free (font_private);
    }
}

static void
_cairo_xlib_surface_scaled_glyph_fini (cairo_scaled_glyph_t *scaled_glyph,
				       cairo_scaled_font_t  *scaled_font)
{
    cairo_xlib_surface_font_private_t	*font_private = scaled_font->surface_private;

    if (font_private != NULL && scaled_glyph->surface_private != NULL) {
	unsigned long	glyph_index = _cairo_scaled_glyph_index(scaled_glyph);
	XRenderFreeGlyphs (font_private->dpy,
			   font_private->glyphset,
			   &glyph_index, 1);
    }
}

static cairo_bool_t
_native_byte_order_lsb (void)
{
    int	x = 1;

    return *((char *) &x) == 1;
}

static cairo_status_t
_cairo_xlib_surface_add_glyph (Display *dpy,
			       cairo_scaled_font_t  *scaled_font,
			       cairo_scaled_glyph_t *scaled_glyph)
{
    XGlyphInfo glyph_inf