601 lines
17 KiB
Plaintext
601 lines
17 KiB
Plaintext
The Xrender Library
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Version 0.7
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2002-11-6
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Keith Packard
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keithp@xfree86.org
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1. Introduction
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The Xrender library is designed as a lightweight library interface to the
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Render extension. This document describes how the library maps to the
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protocol without duplicating the semantics described by that document.
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2. Data Types
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2.1 Primitive Types
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For resources represented as CARD32 or XID on the wire, Xrender exposes them
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using an 'unsigned long' type as is the norm for 32-bit data objects in an
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Xlib compatible API.
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typedef unsigned long Glyph;
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typedef unsigned long GlyphSet;
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typedef unsigned long Picture;
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typedef unsigned long PictFormat;
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Glyphs are just CARD32 objects, while GlyphSet, Picture and PictFormat
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values are XIDs.
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typedef int XFixed;
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Fixed point numbers buck the Xlib convention by being represented as ints.
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Machines for which 'int' is smaller than 32 bits cannot support the Xrender
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library.
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2.2 PictFormat descriptions.
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The definition of a PictFormat is exposed by two data structures:
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typedef struct {
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short red;
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short redMask;
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short green;
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short greenMask;
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short blue;
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short blueMask;
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short alpha;
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short alphaMask;
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} XRenderDirectFormat;
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typedef struct {
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PictFormat id;
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int type;
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int depth;
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XRenderDirectFormat direct;
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Colormap colormap;
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} XRenderPictFormat;
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These serve both as a description of the available formats and as patterns
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against which available formats are matched.
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2.3 Picture Attributes
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When creating or changing Picture objects, attributes are passed much as
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they are for XCreateWindow/XChangeWindowAttributes. A structure capable of
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holding all of the attributes has the relevant ones set and a bitmask passed
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as a separate argument which marks the valid entries.
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typedef struct _XRenderPictureAttributes {
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Bool repeat;
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Picture alpha_map;
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int alpha_x_origin;
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int alpha_y_origin;
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int clip_x_origin;
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int clip_y_origin;
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Pixmap clip_mask;
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Bool graphics_exposures;
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int subwindow_mode;
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int poly_edge;
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int poly_mode;
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Atom dither;
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Bool component_alpha;
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} XRenderPictureAttributes;
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2.4 Colors
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The core protocol XColor type doesn't include an alpha component, so Xrender
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has a separate type.
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typedef struct {
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unsigned short red;
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unsigned short green;
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unsigned short blue;
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unsigned short alpha;
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} XRenderColor;
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2.5 Glyph Types
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Glyphs are stored in the server, so these definitions are passed from the
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client to the library and on to the server as glyphs are rasterized and
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transmitted over the wire.
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typedef struct _XGlyphInfo {
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unsigned short width;
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unsigned short height;
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short x;
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short y;
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short xOff;
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short yOff;
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} XGlyphInfo;
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2.6 Glyph Rendering types
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Glyph rendering can either take a single string of glyph indices or an array
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of one of the following structures.
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typedef struct _XGlyphElt8 {
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GlyphSet glyphset;
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_Xconst char *chars;
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int nchars;
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int xOff;
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int yOff;
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} XGlyphElt8;
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typedef struct _XGlyphElt16 {
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GlyphSet glyphset;
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_Xconst unsigned short *chars;
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int nchars;
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int xOff;
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int yOff;
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} XGlyphElt16;
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typedef struct _XGlyphElt32 {
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GlyphSet glyphset;
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_Xconst unsigned int *chars;
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int nchars;
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int xOff;
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int yOff;
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} XGlyphElt32;
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2.7 Geometric Types
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Geometric operations directly expose the available protocol datatypes
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typedef struct _XPointFixed {
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XFixed x, y;
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} XPointFixed;
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typedef struct _XLineFixed {
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XPointFixed p1, p2;
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} XLineFixed;
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typedef struct _XTriangle {
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XPointFixed p1, p2, p3;
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} XTriangle;
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typedef struct _XTrapezoid {
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XFixed top, bottom;
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XLineFixed left, right;
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} XTrapezoid;
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typedef struct _XTransform {
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XFixed matrix[3][3];
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} XTransform;
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2.8 Transformation Filters
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All of the filters are named simultaneously; Xrender provides no convenience
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functions for dealing with them.
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typedef struct _XFilters {
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int nfilter;
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char **filter;
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int nalias;
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short *alias;
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} XFilters;
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2.9 Index type PictFormat colors
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PictFormats of Index type advertise which colors will be used for drawing
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through this type.
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typedef struct _XIndexValue {
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unsigned long pixel;
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unsigned short red, green, blue, alpha;
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} XIndexValue;
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3 Application Startup Functions
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3.1 Initialization functions
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Bool XRenderQueryExtension (Display *dpy,
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int *event_basep,
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int *error_basep)
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This function returns True if the Render extension is available on dpy.
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event_basep and error_basep will be filled in with the first event and error
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numbers used by the extension (note that Render currently uses no events).
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Status XRenderQueryVersion (Display *dpy,
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int *major_versionp,
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int *minor_versionp)
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XRenderQueryVersion returns zero if the Render extension is not present or
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some error occurred while attempting to discover the current Render version
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number. Otherwise, XRenderQueryVersion returns 1 and stores the version
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number returned by the server in *major_versionp and *minor_versionp, which
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will be less than or equal to the library version numbers RENDER_MAJOR and
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RENDER_MINOR.
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Status XRenderQueryFormats (Display *dpy)
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XRenderQueryFormats returns 1 if it successfully fetches the available
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PictFormat information from the X server, 0 otherwise. Applications needn't
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invoke this function directly (hmm, perhaps it should be removed from the
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external interfaces then).
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3.2 Subpixel Order
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int XRenderQuerySubpixelOrder (Display *dpy, int screen)
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Bool XRenderSetSubpixelOrder (Display *dpy, int screen, int subpixel)
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Applications interested in the geometry of the elements making up a single
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pixel on the screen should use XRenderQuerySubpixelOrder and not cache the
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return value. XRenderSetSubpixelOrder is used by the XRandR library to
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update the value stored by Xrender when the subpixel order changes as a
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result of screen reconfiguration.
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3.3 PictFormat matching
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Xrender provides these APIs to help locate appropriate PictFormats; they are
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intended to work much like the Visual matching APIs in Xlib. The
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application provides a specification including the necessary PictFormat
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characteristics and Xrender returns a matching XRenderPictFormat structure
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which describes the PictFormat.
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XRenderPictFormat *
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XRenderFindFormat (Display *dpy,
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unsigned long mask,
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_Xconst XRenderPictFormat *templ,
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int count)
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#define PictFormatID (1 << 0)
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#define PictFormatType (1 << 1)
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#define PictFormatDepth (1 << 2)
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#define PictFormatRed (1 << 3)
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#define PictFormatRedMask (1 << 4)
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#define PictFormatGreen (1 << 5)
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#define PictFormatGreenMask (1 << 6)
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#define PictFormatBlue (1 << 7)
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#define PictFormatBlueMask (1 << 8)
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#define PictFormatAlpha (1 << 9)
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#define PictFormatAlphaMask (1 << 10)
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#define PictFormatColormap (1 << 11)
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XRenderFindFormat locates a PictFormat matching the characteristics provided
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in the templ. Only elements whose associated bit in mask are compared.
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XRenderPictFormat *
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XRenderFindVisualFormat (Display *dpy, _Xconst Visual *visual)
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Finds the PictFormat suitable for use with the specified visual.
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XRenderPictFormat *
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XRenderFindStandardFormat (Display *dpy,
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int format)
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#define PictStandardARGB32 0
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#define PictStandardRGB24 1
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#define PictStandardA8 2
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#define PictStandardA4 3
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#define PictStandardA1 4
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#define PictStandardNUM 5
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As a convenience, this function locates PictFormats that coorespond to
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commonly used formats.
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ARGB32 depth 32, bits 31-24 A, 23-16 R, 15-8 G, 7-0 B
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RGB24 depth 24, bits 23-16 R, 15-8 G, 7-0 B
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A8 depth 8, bits 7-0 A
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A4 depth 4, bits 3-0 A
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A1 depth 1, bits 0 A
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Any server supporting Render must have a PictFormat cooresponding to each of
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these standard formats.
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3.4 Index type PictFormat color values
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XIndexValue *
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XRenderQueryPictIndexValues(Display *dpy,
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_Xconst XRenderPictFormat *format,
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int *num)
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If format refers to an Index type PictFormat, XRenderQueryPictIndexValues
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returns the set of pixel values and their associated colors used when
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drawing to Pictures created with that format. Otherwise,
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XRenderQueryPictIndexValues generates a BadMatch error.
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3.5 Querying available filters
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XFilters *
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XRenderQueryFilters (Display *dpy, Drawable drawable);
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Filters are used with non-identity transformation matrices, this function
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returns a datastructure identifying the available filters on display that
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can be associated with pictures for the screen associated with drawable.
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Free this structure with XFree.
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4 Picture Functions
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Picture
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XRenderCreatePicture (Display *dpy,
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Drawable drawable,
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_Xconst XRenderPictFormat *format,
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unsigned long valuemask,
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_Xconst XRenderPictureAttributes *attributes)
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#define CPRepeat (1 << 0)
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#define CPAlphaMap (1 << 1)
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#define CPAlphaXOrigin (1 << 2)
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#define CPAlphaYOrigin (1 << 3)
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#define CPClipXOrigin (1 << 4)
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#define CPClipYOrigin (1 << 5)
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#define CPClipMask (1 << 6)
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#define CPGraphicsExposure (1 << 7)
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#define CPSubwindowMode (1 << 8)
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#define CPPolyEdge (1 << 9)
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#define CPPolyMode (1 << 10)
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#define CPDither (1 << 11)
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#define CPComponentAlpha (1 << 12)
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#define CPLastBit 11
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Creates a picture for drawable in the specified format. Any values
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specified in 'attributes' and 'valuemask' are used in place of the default
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values.
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void
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XRenderChangePicture (Display *dpy,
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Picture picture,
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unsigned long valuemask,
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_Xconst XRenderPictureAttributes *attributes)
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Change values in picture to those specified by valuemask and attributes.
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void
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XRenderSetPictureClipRectangles (Display *dpy,
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Picture picture,
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int xOrigin,
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int yOrigin,
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_Xconst XRectangle *rects,
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int n)
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Sets the clip mask in picture to the union of rects offset by
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xOrigin/yOrigin.
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void
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XRenderSetPictureClipRegion (Display *dpy,
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Picture picture,
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Region r)
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Sets the clip mask in picture to r.
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void
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XRenderSetPictureTransform (Display *dpy,
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Picture picture,
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XTransform *transform)
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Sets the projective transformation matrix of picture to transform.
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void
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XRenderFreePicture (Display *dpy,
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Picture picture)
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Instructs the server to free picture.
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5 GlyphSet functions
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GlyphSet
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XRenderCreateGlyphSet (Display *dpy, _Xconst XRenderPictFormat *format)
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Creates a glyphset, every glyph in the set will use PictFormat format.
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GlyphSet
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XRenderReferenceGlyphSet (Display *dpy, GlyphSet existing)
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Creates a new GlyphSet ID which references an existing GlyphSet. The
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two IDs refer to the same object so that changes using one ID will be
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visible through the other ID. This is designed to allow multiple clients to
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share the same GlyphSet so that it doesn't get destroyed when the first
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client exits.
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void
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XRenderFreeGlyphSet (Display *dpy, GlyphSet glyphset)
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Frees the glyphset ID. If no other GlyphSet IDs refer to the underlying
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GlyphSet, it will be destroyed.
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void
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XRenderAddGlyphs (Display *dpy,
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GlyphSet glyphset,
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_Xconst Glyph *gids,
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_Xconst XGlyphInfo *glyphs,
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int nglyphs,
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_Xconst char *images,
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int nbyte_images)
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Add glyphs to glyphset. The images are packed together in Z-pixmap format
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according to the depth of the PictFormat used in creating glyphset.
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void
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XRenderFreeGlyphs (Display *dpy,
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GlyphSet glyphset,
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_Xconst Glyph *gids,
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int nglyphs)
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Free some glyphs from glyphset.
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6 Glyph Drawing Routines
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Xrender provides two parallel APIs for glyph rendering, a simple API which
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accepts a single string similar to XDrawString and a more complex API which
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accepts an array of XGlyphElt{8,16,32} structures, each of which includes a
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glyphset, string and x/y offsets which parallel the XDrawText API. Xrender
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also provides glyphs in three sizes, 8 16 and 32 bits. The simple API is
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just a convenience for the user as both forms generate the same underlying
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Render protocol.
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6.1 Simple single-string glyph drawing functions
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These are identical except for the format of the glyph ids.
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void
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XRenderCompositeString8 (Display *dpy,
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int op,
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Picture src,
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Picture dst,
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_Xconst XRenderPictFormat *maskFormat,
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GlyphSet glyphset,
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int xSrc,
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int ySrc,
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int xDst,
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int yDst,
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_Xconst char *string,
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int nchar)
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void
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XRenderCompositeString16 (Display *dpy,
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int op,
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Picture src,
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Picture dst,
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_Xconst XRenderPictFormat *maskFormat,
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GlyphSet glyphset,
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int xSrc,
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int ySrc,
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int xDst,
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int yDst,
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_Xconst unsigned short *string,
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int nchar)
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void
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XRenderCompositeString32 (Display *dpy,
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int op,
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Picture src,
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Picture dst,
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_Xconst XRenderPictFormat *maskFormat,
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GlyphSet glyphset,
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int xSrc,
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int ySrc,
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int xDst,
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int yDst,
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_Xconst unsigned int *string,
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int nchar)
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6.2 Complete glyph drawing functions
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As with the simple functions above, these differ only in the type of the
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underlying glyph id storage type.
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void
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XRenderCompositeText8 (Display *dpy,
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int op,
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Picture src,
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Picture dst,
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_Xconst XRenderPictFormat *maskFormat,
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int xSrc,
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int ySrc,
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int xDst,
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int yDst,
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_Xconst XGlyphElt8 *elts,
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int nelt)
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void
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XRenderCompositeText16 (Display *dpy,
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int op,
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Picture src,
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Picture dst,
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_Xconst XRenderPictFormat *maskFormat,
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int xSrc,
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int ySrc,
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int xDst,
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int yDst,
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_Xconst XGlyphElt16 *elts,
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int nelt)
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void
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XRenderCompositeText32 (Display *dpy,
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int op,
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Picture src,
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Picture dst,
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_Xconst XRenderPictFormat *maskFormat,
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int xSrc,
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int ySrc,
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int xDst,
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int yDst,
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_Xconst XGlyphElt32 *elts,
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int nelt)
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7 Basic Graphics Functions
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These are the simplest graphics functions upon which the other functions are
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conceptually built.
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7.1 Composite
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XRenderComposite exposes the RenderComposite protocol request directly.
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void
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XRenderComposite (Display *dpy,
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int op,
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Picture src,
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Picture mask,
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Picture dst,
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int src_x,
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int src_y,
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int mask_x,
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int mask_y,
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int dst_x,
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int dst_y,
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unsigned int width,
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unsigned int height)
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7.2 Rectangles
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These functions composite rectangles of the specified color, they differ
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only in that XRenderFillRectangles draws more than one at a time.
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void
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XRenderFillRectangle (Display *dpy,
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int op,
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Picture dst,
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_Xconst XRenderColor *color,
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int x,
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int y,
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unsigned int width,
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unsigned int height)
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void
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XRenderFillRectangles (Display *dpy,
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int op,
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Picture dst,
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_Xconst XRenderColor *color,
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_Xconst XRectangle *rectangles,
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int n_rects)
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8 Geometric Objects
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All geometric drawing with Render is performed with sequences of trapezoids
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or triangles; the client is responsible for breaking more complex figures
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into these simple shapes.
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8.1 Trapezoids
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void
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XRenderCompositeTrapezoids (Display *dpy,
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int op,
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Picture src,
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Picture dst,
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_Xconst XRenderPictFormat *maskFormat,
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int xSrc,
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int ySrc,
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_Xconst XTrapezoid *traps,
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int ntrap)
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XRenderCompositeTrapezoids builds RenderTrapezoids requests to composite the
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specified list of trapezoids to dst. XRenderCompositeTrapezoids will split
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the list of trapezoids to build requests no larger than the maximum request
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size supported by the server. This can create rendering artifacts as the
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precompositing done by RenderTrapezoids when a maskFormat is specified
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cannot span multiple requests.
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8.2 Triangles
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Render provides three different ways of encoding triangles on the wire,
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Xrender exposes those with three separate triangle drawing routines. As
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with trapezoids above, Xrender will split the arguments to fit requests into
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the servers limits, but this may cause rendering artifacts.
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