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xcb_change_gc(3) XCB Requests xcb_change_gc(3) NAME xcb_change_gc - change graphics context components SYNOPSIS #include <xcb/xproto.h> Request function xcb_void_cookie_t xcb_change_gc(xcb_connection_t *conn, xcb_gcontext_t gc, uint32_t value_mask, const void *value_list); REQUEST ARGUMENTS conn The XCB connection to X11. gc The graphics context to change. value_maskOne of the following values: XCB_GC_FUNCTION TODO: Refer to GX XCB_GC_PLANE_MASK In graphics operations, given a source and destination pixel, the result is computed bitwise on corresponding bits of the pixels; that is, a Boolean operation is performed in each bit plane. The plane-mask restricts the operation to a subset of planes, so the result is: ((src FUNC dst) AND plane-mask) OR (dst AND (NOT plane-mask)) XCB_GC_FOREGROUND Foreground colorpixel. XCB_GC_BACKGROUND Background colorpixel. XCB_GC_LINE_WIDTH The line-width is measured in pixels and can be greater than or equal to one, a wide line, or the special value zero, a thin line. XCB_GC_LINE_STYLE The line-style defines which sections of a line are drawn: Solid The full path of the line is drawn. DoubleDash The full path of the line is drawn, but the even dashes are filled differ- ently than the odd dashes (see fill- style), with Butt cap-style used where even and odd dashes meet. OnOffDash Only the even dashes are drawn, and cap-style applies to all internal ends of the individual dashes (except Not- Last is treated as Butt). XCB_GC_CAP_STYLE The cap-style defines how the endpoints of a path are drawn: NotLast The result is equivalent to Butt, ex- cept that for a line-width of zero the final endpoint is not drawn. Butt The re- sult is square at the endpoint (perpendicular to the slope of the line) with no projection beyond. Round The result is a circular arc with its diameter equal to the line-width, centered on the endpoint; it is equivalent to Butt for line-width zero. Projecting The result is square at the end, but the path continues beyond the endpoint for a distance equal to half the line-width; it is equivalent to Butt for line-width zero. XCB_GC_JOIN_STYLE The join-style defines how corners are drawn for wide lines: Miter The outer edges of the two lines extend to meet at an angle. However, if the angle is less than 11 degrees, a Bevel join-style is used instead. Round The result is a circular arc with a diameter equal to the line-width, centered on the joinpoint. Bevel The result is Butt endpoint styles, and then the trian- gular notch is filled. XCB_GC_FILL_STYLE The fill-style defines the contents of the source for line, text, and fill requests. For all text and fill requests (for example, PolyText8, PolyText16, PolyFill- Rectangle, FillPoly, and PolyFillArc) as well as for line requests with line-style Solid, (for example, PolyLine, PolySegment, PolyRectangle, PolyArc) and for the even dashes for line requests with line-style OnOffDash or DoubleDash: Solid Foreground Tiled Tile OpaqueStip- pled A tile with the same width and height as stipple but with background everywhere stipple has a zero and with foreground everywhere stipple has a one Stippled Foreground masked by stipple For the odd dashes for line requests with line-style DoubleDash: Solid Background Tiled Same as for even dashes OpaqueStippled Same as for even dashes Stippled Background masked by stipple XCB_GC_FILL_RULE XCB_GC_TILE The tile/stipple represents an infinite two-dimensional plane with the tile/stipple replicated in all dimen- sions. When that plane is superimposed on the drawable for use in a graphics operation, the upper-left corner of some instance of the tile/stipple is at the coordi- nates within the drawable specified by the tile/stipple origin. The tile/stipple and clip origins are inter- preted relative to the origin of whatever destination drawable is specified in a graphics request. The tile pixmap must have the same root and depth as the gcon- text (or a Match error results). The stipple pixmap must have depth one and must have the same root as the gcontext (or a Match error results). For fill-style Stippled (but not fill-style OpaqueStippled), the stip- ple pattern is tiled in a single plane and acts as an additional clip mask to be ANDed with the clip-mask. Any size pixmap can be used for tiling or stippling, although some sizes may be faster to use than others. XCB_GC_STIPPLE The tile/stipple represents an infinite two-dimensional plane with the tile/stipple replicated in all dimen- sions. When that plane is superimposed on the drawable for use in a graphics operation, the upper-left corner of some instance of the tile/stipple is at the coordi- nates within the drawable specified by the tile/stipple origin. The tile/stipple and clip origins are inter- preted relative to the origin of whatever destination drawable is specified in a graphics request. The tile pixmap must have the same root and depth as the gcon- text (or a Match error results). The stipple pixmap must have depth one and must have the same root as the gcontext (or a Match error results). For fill-style Stippled (but not fill-style OpaqueStippled), the stip- ple pattern is tiled in a single plane and acts as an additional clip mask to be ANDed with the clip-mask. Any size pixmap can be used for tiling or stippling, although some sizes may be faster to use than others. XCB_GC_TILE_STIPPLE_ORIGIN_X TODO XCB_GC_TILE_STIPPLE_ORIGIN_Y TODO XCB_GC_FONT Which font to use for the ImageText8 and ImageText16 requests. XCB_GC_SUBWINDOW_MODE For ClipByChildren, both source and destination windows are additionally clipped by all viewable InputOutput children. For IncludeInferiors, neither source nor des- tination window is clipped by inferiors. This will re- sult in including subwindow contents in the source and drawing through subwindow boundaries of the destina- tion. The use of IncludeInferiors with a source or des- tination window of one depth with mapped inferiors of differing depth is not illegal, but the semantics is undefined by the core protocol. XCB_GC_GRAPHICS_EXPOSURES Whether ExposureEvents should be generated (1) or not (0). The default is 1. XCB_GC_CLIP_ORIGIN_X TODO XCB_GC_CLIP_ORIGIN_Y TODO XCB_GC_CLIP_MASK The clip-mask restricts writes to the destination draw- able. Only pixels where the clip-mask has bits set to 1 are drawn. Pixels are not drawn outside the area cov- ered by the clip-mask or where the clip-mask has bits set to 0. The clip-mask affects all graphics requests, but it does not clip sources. The clip-mask origin is interpreted relative to the origin of whatever destina- tion drawable is specified in a graphics request. If a pixmap is specified as the clip-mask, it must have depth 1 and have the same root as the gcontext (or a Match error results). If clip-mask is None, then pixels are always drawn, regardless of the clip origin. The clip-mask can also be set with the SetClipRectangles request. XCB_GC_DASH_OFFSET TODO XCB_GC_DASH_LIST TODO XCB_GC_ARC_MODE TODO value_listValues for each of the components specified in the bitmask value_mask. The order has to correspond to the order of possible value_mask bits. See the example. DESCRIPTION Changes the components specified by value_mask for the specified graphics context. RETURN VALUE Returns an xcb_void_cookie_t. Errors (if any) have to be handled in the event loop. If you want to handle errors directly with xcb_request_check instead, use xcb_change_gc_checked. See xcb-requests(3) for details. ERRORS xcb_alloc_error_t The X server could not allocate the requested resources (no mem- ory?). xcb_font_error_t TODO: reasons? xcb_g_context_error_t TODO: reasons? xcb_match_error_t TODO: reasons? xcb_pixmap_error_t TODO: reasons? xcb_value_error_t TODO: reasons? EXAMPLE /* * Changes the foreground color component of the specified graphics context. * */ void my_example(xcb_connection_t *conn, xcb_gcontext_t gc, uint32_t fg, uint32_t bg) { /* C99 allows us to use a compact way of changing a single component: */ xcb_change_gc(conn, gc, XCB_GC_FOREGROUND, (uint32_t[]){ fg }); /* The more explicit way. Beware that the order of values is important! */ uint32_t mask = 0; mask |= XCB_GC_FOREGROUND; mask |= XCB_GC_BACKGROUND; uint32_t values[] = { fg, bg }; xcb_change_gc(conn, gc, mask, values); xcb_flush(conn); } SEE ALSO xcb-requests(3), xcb-examples(3) AUTHOR Generated from xproto.xml. Contact xcb@lists.freedesktop.org for correc- tions and improvements. X Version 11 libxcb 1.17.0 xcb_change_gc(3)
NAME | SYNOPSIS | REQUEST ARGUMENTS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLE | SEE ALSO | AUTHOR
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