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diff --git a/src/egl/docs/EGL_MESA_screen_surface b/src/egl/docs/EGL_MESA_screen_surface new file mode 100644 index 0000000000..3a11da7ac9 --- /dev/null +++ b/src/egl/docs/EGL_MESA_screen_surface @@ -0,0 +1,578 @@ +Name + + MESA_screen_surface + +Name Strings + + EGL_MESA_screen_surface + +Contact + + Brian Paul + + To discuss, join the dri-egl@lists.freedesktop.org list. + +Status + + Preliminary - totally subject to change. + +Version + + 10 (10 August 2005) + +Number + + TBD + +Dependencies + + EGL 1.0 or later. + +Overview + + EGL 1.1 supports three types of drawing surfaces: + * Window surfaces + * Pixmap surfaces + * Pbuffer surfaces + This extension defines a fourth type of drawing surface: + * Screen surface + + A screen surface is a surface for which the (front) color buffer can + be directly displayed (i.e. scanned out) on a monitor (such as a flat + panel or CRT). In particular the color buffer memory will be allocated + at a location in VRAM (and in a suitable format) which can be displayed + by the graphics hardware. + + Note that the width and height of the screen surface need not exactly + match the monitor's current resolution. For example, while the monitor + may be configured to to show 1024x768 pixels, the associated screen + surface may be larger, such as 1200x1000. The "screen origin" attribute + will specify which region of the screen surface which is visible on the + monitor. The screen surface can be scrolled by changing this origin. + + This extension also defines functions for controlling the monitor's + display mode (width, height, refresh rate, etc), and specifing which + screen surface is to be displayed on a monitor. + + The new EGLModeMESA type and related functions are very similar to the + EGLConfig type and related functions. The user may get a list of + supported modes for a screen and specify the mode to be used when + displaying a screen surface. + + +Issues + + 1. Should EGL_INTERLACE be a supported mode attribute? + + Arguments against: + + No, this should be provided by another extension which would + also provide the mechanisms needed to play back interlaced video + material correctly on hardware that supports it. + This extension should prefer non-interlaced modes. [M. Danzer] + + Arguments for: + + An interlaced display can be of use without considering video + material. Being able to query whether a screen is operating in + interlaced mode can be used by applications to control their + drawing. For example: avoid drawing 1-pixel-wide horizontal lines + if screen is interlaced. [B. Paul] + + Resolution: Defer for future extension? + + + 2. Should EGL_REFRESH_RATE be a supported mode attribute? + + Arguments for: + + Yes, it's been shown that applications and/or users need to select + modes by this. [M. Danzer] + + Many examples have been given in which it's desirable to let the + user choose from a variety of refresh rates without having to + restart/reconfigure. [B. Paul] + + Arguments against: + + TBD. + + Resolution: Yes. + + + 3. Exactly how should the list of modes returned by eglChooseConfigMESA + be sorted? + + Current method is described in the text below. Subject to change. + + Alternately, leave the sorting order undefined so that each + implementation can return the modes in order of "most desirable" + to "least desirable" which may depend on the display technology + (CRT vs LCD, etc) or other factors. + + + 4. How should screen blanking be supported? Note that a screen can be + disabled or turned off by calling eglShowSurface(dpy, scrn, + EGL_NO_SURFACE, EGL_NO_MODE_MESA). But what about power-save mode? + + I would defer this to other extensions that depend on this one. + I can imagine people wanting different semantics not just in + relation to the power management API being exposed (DPMS or whatever) + but also relating to what events can trigger EGL_CONTEXT_LOST. Also + I'm not sure whether power management commands are properly operations + on the Display or on a screen surface. [A. Jackson] + + + 5. Should the EGL_PHYSICAL_SIZE_EGL query be kept? The size information + isn't always reliable (consider video projectors) but can still be + used to determine the pixel aspect ratio. + + Arguments for: + + X supports a similar query with DisplayWidthMM(), DisplayHeightMM(). + If this information can be easily queried with EDID, why not + make it available to the user? + + Arguments against: + + Historically, these values aren't always accurate. Also, they're + not always applicable to the display device. + + Other options: + + Perhaps just a pixel aspect ratio should be supported. [M. Danzer] + + Postpone for a future extension, if needed. [A. Jackson] + + + 6. Should detailed mode timing information be exposed by this API? + + Probably not. Instead, offer that information in a layered extension. + + + 7. How should the notion of a screen's "native" mode be expressed? + For example, LCD panels have a native resolution and refresh rate + that looks best but other sub-optimal resolutions may be supported. + + The mode attribute EGL_OPTIMAL_MESA will be set for modes which + best match the screen. [M. Danzer] + + + 8. Should eglQueryModeStringMESA() be included? This function returns + a human-readable string which corresponds to an EGLMode. + + Arguments for: + + A mode name such as "HDTV-720P" might mean more to users than + "1280x720@60Hz" if the later were generated via code. + + Arguments against: + + There's no standard syntax for the strings. May cause more + trouble than it's worth. + + Postpone for future extension. [A. Jackson] + + Latest discussion leaning toward omitting this function. + + + 9. Should we use "Get" or "Query" for functions which return state? + The EGL 1.x specification doesn't seem to be totally consistent + in this regard, but "Query" is used more often. + + Use "Get" for mode-related queries (as for EGLConfigs) but "Query" + for everything else. + + + 10. What should be the default size for screen surfaces? + + For Pbuffer surfaces the default width and height are zero. + We'll do the same for screen surfaces. Since there's no function + to resize surfaces it's useless to have a 0x0 screen, but this isn't + a situation that'll normally be encountered. + + + 11. Should there be a function for resizing a screen surface? + + Suppose one wants to change the screen's size in the EGL application. + Also suppose there's a hardware restriction such that only one screen + surface can exist at a time (either for lack of memory or because of + memory layout restrictions). + + The basic idea is that the currently displayed screen surface must + be deallocated before a new one can be created. Perhaps a resize + function would work better? + + + 12. How should sub-pixel LCD color information be made available? + What about the display's gamma value? + + Perhaps expose as additional read-only mode attributes. + + Perhaps postpone for a layered extension. + + + 13. What happens if the user attempts to delete a screen surface that + is currently being shown? + + Spec currently says that's illegal and that an error (TBD) will be + generated. + + + 14. What if the physical screen size can't be determined? Should + a query of EGL_PHYSICAL_SIZE_MESA return [0,0]? + + TBD. + + + 15. Suppose the device's number of RAMDACs is different from the + number of output ports. For example, a graphics card with + two RAMDACs but three ports (VGA, DVI, TV). + + Address this in a follow-on extension. [Matthias Hopf] + + + 16. How should we deal with on-the-fly device changes? For example, + the monitor being unplugged and replaced by another with different + characteristics? + + A HAL event could be received via DBUS in the application [J. Smirl, + A. Jackson]. + + Should there be an EGL mechanism for detecting this? Maybe an + EGL_SCREEN_LOST error (similar to EGL_CONTEXT_LOST) can be recorded + when there's a screen change. At least then the application can + poll to detect this situation. + + Maybe leave that to a future extension. + + See also the EGL_SCREEN_COUNT_MESA query. + + + 17. What if pixel-accurate panning is not supported (see + eglScreenPositionMESA)? [M. Danzer] + + Is this a common problem? Can we ignore it for now? + + + 18. Should eglShowSurfaceMESA be renamed to eglShowScreenSurfaceMESA? + + Probably. + + + +New Procedures and Functions + + EGLBoolean eglChooseModeMESA(EGLDisplay dpy, EGLScreenMESA screen, + const EGLint *attrib_list, + EGLModeMESA *modes, EGLint modes_size, + EGLint *num_modes) + + EGLBoolean eglGetModesMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLModeMESA *modes, EGLint modes_size, + EGLint *num_modes) + + EGLBoolean eglGetModeAttribMESA(EGLDisplay dpy, EGLModeMESA mode, + EGLint attrib, EGLint *value) + + + EGLBoolean eglGetScreensMESA(EGLDisplay dpy, EGLScreenMESA *screens, + EGLint screens_size, EGLint *num_screens) + + EGLSurface eglCreateScreenSurfaceMESA(EGLDisplay dpy, EGLConfig config, + const EGLint *attrib_list) + + EGLBoolean eglShowSurfaceMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLSurface surface, EGLModeMESA mode) + + EGLBoolean eglScreenPositionMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLint x, EGLint y) + + + EGLBoolean eglQueryScreenMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLint attrib, EGLint *value); + + EGLBoolean eglQueryScreenSurfaceMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLSurface *surface) + + EGLBoolean eglQueryScreenModeMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLModeMESA *mode) + + const char *eglQueryModeStringMESA(EGLDisplay dpy, EGLMode mode); + + +New Types + + EGLModeMESA + EGLScreenMESA + +New Tokens + + New error codes: + + EGL_BAD_SCREEN_MESA + EGL_BAD_MODE_MESA + + Screen-related tokens: + + EGL_SCREEN_COUNT_MESA + EGL_SCREEN_POSITION_MESA + EGL_PHYSICAL_SIZE_MESA + EGL_SCREEN_BIT_MESA + EGL_SCREEN_POSITION_GRANULARITY_MESA + + Mode-related tokens: + + EGL_MODE_ID_MESA + EGL_REFRESH_RATE_MESA + EGL_INTERLACED_MESA + EGL_OPTIMAL_MESA + EGL_NO_MODE_MESA + + +Additions to Chapter X of the EGL 1.1 Specification + + [XXX this all has to be rewritten to fit into the EGL specification + and match the conventions of an EGL extension. For now, just list + all the functions with brief descriptions.] + + + EGLBoolean eglChooseModeMESA(EGLDisplay dpy, const EGLScreenMESA screen, + EGLint *attrib_list, EGLModeMESA *modes, + EGLint modes_size, EGLint *num_modes) + + Like eglChooseConfig, returns a list of EGLModes which match the given + attribute list. This does not set the screen's current display mode. + The attribute list is a list of token/value pairs terminated with + EGL_NONE. Supported attributes include: + + Name Description + --------------------- --------------------------------------------- + EGL_WIDTH Mode width (resolution) + EGL_HEIGHT Mode height (resolution) + EGL_REFRESH_RATE_MESA The mode's refresh rate, multiplied by 1000 + EGL_INTERLACED_MESA 1 indicates an interlaced mode, 0 otherwise + EGL_OPTIMAL_MESA Set if the most is especially optimal for the + screen (ex. for particular LCD resolutions) + + Any other token will generate the error EGL_BAD_ATTRIBUTE. + + The list of modes returned by eglChooseModeMESA will be sorted + according to the following criteria. See the discussion of table 3.3 + in the EGL specification for more information. + + Selection Sort Sort + Attribute Default Criteria Order Priority + -------------------- -------------- ----------- ------ -------- + EGL_OPTIMAL_MESA EGL_DONT_CARE Exact 1,0 1 + EGL_INTERLACED_MESA EGL_DONT_CARE Exact 0,1 2 + EGL_REFRESH_RATE EGL_DONT_CARE AtLeast Larger 3 + EGL_WIDTH EGL_DONT_CARE AtLeast Larger 4 + EGL_HEIGHT EGL_DONT_CARE AtLeast Larger 5 + EGL_MODE_ID_MESA EGL_DONT_CARE Exact Smaller 6 + + + EGLBoolean eglGetModesMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLModeMESA *modes, EGLint modes_size, + EGLint *num_modes) + + Like eglGetConfigs, returns a list of all modes supported by the + given screen. The returned modes will be sorted in the same manner + as for eglChooseModeMESA(). + + + + EGLBoolean eglGetModeAttribMESA(EGLDisplay dpy, EGLModeMESA mode, + EGLint attrib, EGLint *value) + + Used to query mode attributes. The following attributes are supported: + + Name Return value description + --------------------- ---------------------------------------------- + EGL_OPTIMAL_MESA 1 indicates an optimal mode, 0 otherwise + EGL_INTERLACED_MESA 1 indicates an interlaced mode, 0 otherwise + EGL_REFRESH_RATE_MESA The mode's refresh rate, multiplied by 1000 + EGL_WIDTH Mode width (resolution) + EGL_HEIGHT Mode height (resolution) + EGL_MODE_ID_MESA A unique small integer identifier for the mode + + Any other token will generate the error EGL_BAD_ATTRIBUTE. + + + + EGLBoolean eglGetScreensMESA(EGLDisplay dpy, EGLScreenMESA *screens, + EGLint screens_size, EGLint *num_screens) + + This function returns an array of all available screen handles. + <screens_size> is the maximum number of screens to return in the + <screens> array. <num_screens> will return the number of screen handles + placed in the array, even if <screens> is NULL. + + The number of screens and the availability of each may change over + time (hot-plugging). Screen handles will not be reused. When a + screen handle becomes invalid, function calls which reference an + invalid handle will generate EGL_BAD_SCREEN_MESA. + + The first screen handle returned will be considered to be the primary + one. + + + + EGLSurface eglCreateScreenSurfaceMESA(EGLDisplay dpy, EGLConfig config, + const EGLint *attrib_list) + + Create a surface that can be displayed on a screen. <attrib_list> is + an array of token/value pairs terminated with EGL_NONE. Valid tokens + include: + + Name Description + ---------------- -------------------------------- + EGL_WIDTH desired surface width in pixels + EGL_HEIGHT desired surface height in pixels + + Any other token will generate the error EGL_BAD_ATTRIBUTE. + The default width and height are zero. + + + + EGLBoolean eglShowSurfaceMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLSurface surface, EGLModeMESA mode) + + This function causes a screen to show the given surface (or more + precisely, the surface's front color buffer) with the given mode. + + If the surface is in any way incompatible with the mode, the error + EGL_BAD_MATCH will be generated, EGL_FALSE will be returned, and the + previous screen state will remain in effect. This might occur when + the bandwidth of the video-out subsystem is exceeded, or if the mode + specifies a width or height that's greater than the width or height + of the surface. + + To disable a screen, the values EGL_NO_SURFACE and EGL_NO_MODE_MESA + be passed as the <surface> and <mode> parameters. + + The values of EGL_SCREEN_POSITION_MESA are clamped to the new valid + range computed from the screen size and surface size. If the new + surface is EGL_NO_SURFACE, EGL_SCREEN_POSITION_MESA is set to [0, 0]. + + + Attempting to delete a screen surface which is currently being + displayed will result in the error EGL_BAD_ACCESS being generated. + + + + EGLBoolean eglScreenPositionMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLint x, EGLint y) + + Specifies the origin of the screen's view into the surface, if the + surface is larger than the screen. Valid values for x and y are + [0, surfaceWidth - screenWidth] and [0, surfaceHeight - screenHeight], + respectively. + + The x and y values are also constrained to be integer multiples of the + EGL_SCREEN_POSITION_GRANULARITY_MESA values. + + + + + EGLBoolean eglQueryScreenMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLint attrib, EGLint *value); + + Used to query screen attributes. <attrib> may be one of the following: + + Name Return value description + ------------------------ --------------------------------------------- + EGL_SCREEN_POSITION_MESA x, y position of the screen's origin with + respect to the surface. If no surface is + attached to the screen, [0, 0] is returned. + EGL_SCREEN_POSITION_GRANULARITY_MESA + Returns the granularity, in pixels, for + which the screen position is constrained. + EGL_PHYSICAL_SIZE_MESA Physical width and height of the screen + in millimeters + + Any other token will generate the error EGL_BAD_ATTRIBUTE. + + + + + EGLBoolean eglQueryScreenSurfaceMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLSurface *surface) + + Returns the surface currently displayed on the given screen. <surface> + may be EGL_NO_SURFACE if the screen isn't currently showing any surface. + + + + + EGLBoolean eglQueryScreenModeMESA(EGLDisplay dpy, EGLScreenMESA screen, + EGLModeMESA *mode) + + Returns the given screen's current display mode. The mode may be + EGL_NO_MODE_MESA if the screen is currently disabled. + + + + const char *eglQueryModeStringMESA(EGLDisplay dpy, EGLModeMESA mode); + + Returns a human-readable string for the given mode. The string is a + zero-terminated C string which the user should not attempt to free. + There is no standard syntax for mode strings. Applications should + not directly rely on mode strings. + + + +Version History + + 1. 15 March 2005 - BrianP + Initial version + + 2. 16 March 2005 - BrianP + Removed EGL_DEPTH_MESA + Added EGL_PHYSICAL_WIDTH_MESA, EGL_PHYSICAL_HEIGHT_MESA queries + Added EGL_OPTIMAL_MESA for width/height/refresh rate selection + Added possible eglQueryModeStringMESA() function + More details of the new functions explained. + + 3. 18 March 2005 - BrianP + Added screen_number to eglChooseModeMESA(). + Fix off by one mistake in value range for ORIGIN attributes + Added Issues section + + 4. 21 March 2005 - BrianP + Removed eglScreenAttribsMESA(). + Added eglScreenPositionMESA() to set screen origin. + Replaced EGL_SCREEN_X/Y_OFFSET_MESA with EGL_SCREEN_POSITION_MESA. + Replaced EGL_PHYSICAL_WIDTH/HEIGHT_MESA with EGL_PHYSICAL_SIZE_MESA. + Use EGL_OPTIMAL_MESA as a new mode attribute. (Michel Danzer) + Added a few more issues. + + 5. 6 April 2005 - BrianP + More language for eglGetModeStringMESA(). + Added issues 10, 11, 12, 13, 14. + Updated issue 3 discussion about mode sorting. + + 6. 22 April 2005 - BrianP + Fixed "LDC" typo. + Added issues 15, 16. + Changed dependency on EGL 1.1 to EGL 1.0 + s/EGL_NUM_SCREENS_MESA/EGL_SCREEN_COUNT_MESA/ + Added eglQueryDisplayMESA() to New Functions section. + Clarified language for the EGL_SCREEN_COUNT_MESA query. + + 7. 29 April 2005 - BrianP + Added EGLScreenMESA type and eglGetScreensMESA() function. [J. Smirl]. + Replaced EGLint screen_number parameters with EGLScreenMESA screen. + Added issue 17 (pixel-accurate panning) + + 8. 2 May 2005 - BrianP + Removed eglQueryDisplayMESA. + Fixed a few more EGLint -> EGLScreenMESA changes. + + 9. 20 May 2005 - BrianP + Fixed a few typos. + Updated some open issues text. + + 10. 10 August 2005 - BrianP + Added EGL_SCREEN_POSITION_GRANULARITY_MESA. + |