1.52.4 Get methods

display <-contained_in: -> display_manager

Implements visual<-contained_in protocol.

display <-contains: -> chain

Implements visual<-contains protocol.

display <-convert: any -> display

Convert a graphical to the display it is shown on, or accept an already-existing display object.

display <-depth: -> bits_per_pixel=int

Bits used to represent a display pixel. Returns 32 (RGBA) on all current platforms; preserved for compatibility with code that branched on colour depth.

display <-size: -> size

Pixel size of the display: equivalent to display<-area.

display <-width: -> int

Pixel width of the display: equivalent to display<-area.

display <-height: -> int

Pixel height of the display: equivalent to display<-area.

display <-system_theme: -> {light,dark}

The OS system theme as reported by SDL_GetSystemTheme(). On Windows, a contrast theme with a dark window background also counts as dark. Fails if the platform cannot tell.

display <-theme: -> name

The SWI-Prolog theme for the xpce user interface: the class variable display.theme or, if that is @default, display<-system_theme. library(pce_theme) applies this theme when xpce starts and, if the class variable is @default, when the desktop switches between light and dark.

display <-paste: which=[{primary,clipboard}] -> string

Return the textual content of the indicated selection (defaults to clipboard). Pair with display->copy and display->selection.

See also

- display->copy
- display<-selection

display <-selection: which=[name], target=[name], type=[type] -> any

Query the value of a system selection. which defaults to primary; common alternatives are clipboard and secondary. target is the requested MIME-like type (default text; utf8_string for explicit UTF-8). For the clipboard, target may also be image, returning an image from PNG, JPEG or another image format on the clipboard, or svg, returning the SVG document as a string. type is the xpce type the returned value should be coerced to via type<-check. It defaults to image for the target image and string otherwise.

See also

- display<-selection_targets
- display<-paste

display <-selection_targets: which=[{primary,clipboard}] -> chain

New chain with the MIME types of the data in the selection (default clipboard), e.g., 'text/plain;charset=utf-8' or 'image/png'. This allows a paste command to decide what to paste.

display <-has_screen_keyboard_support: -> bool

@on when SDL reports the platform has an on-screen keyboard.

display <-screen_keyboard_shown: -> bool

@on when the on-screen keyboard is currently visible.

display <-input_devices: -> chain

Chain of input_device objects known to xpce. It holds at least @mouse_device and @keyboard_device. Other devices are added when the window system reports them. The chain should not be modified.

When a device is added or removed, e.g., a gamepad is plugged in, the window with the keyboard focus of each frame receives a device_added or device_removed event, whose event<-device is the device.

display <-power_state: -> {unknown,on_battery,no_battery,charging,charged}

Whether the system runs on a battery and, if so, whether it is charging.

display <-battery_percent: -> 0..100

The charge of the battery. Fails if this is unknown, e.g., if the system has no battery.

display <-battery_seconds: -> int

The estimated number of seconds the battery lasts. Fails if this is unknown.

display <-preferred_locales: -> chain

New chain with the user's preferred locales, most preferred first, as names such as en_US or nl.

display <-bell_sound: -> sound

The sound display->bell plays: the file of display.bell_sound or else a tone (see sound->tone) of display.bell_pitch Hz that lasts display.bell_duration seconds.

display <-sound_file_extensions: -> chain

New chain with the (lower case) extensions of the sound files sound->load can load, e.g., wav, mp3, ogg and flac. This is only wav if xpce is built without SDL3_sound.

display <-image_save_formats: -> chain

New chain with the formats image->save can write, e.g., png, jpeg and gif. Whether webp and avif are included depends on how SDL_image was built.

display <-video_decoders: -> chain

New chain with the names of the common video codecs class video can play, e.g., h264, hevc, av1 and vp9. Empty if xpce is built without video support.

display <-video_encoders: -> chain

New chain with the names of the common video codecs class video_writer can write. This depends on how the video library was built.

display <-video_backend: -> name*

The library used for video: ffmpeg, media_foundation or avfoundation, or @nil if xpce is built without video support.

display <-cameras: -> chain

New chain holding the names of the available cameras. The first call starts the support for cameras, which may ask the user for permission.

See also

class camera

display <-gamepads: -> chain

New chain holding the connected gamepads. The first call starts the support for gamepads: as this may be slow and, on some systems, asks the user for permission, xpce only does so if the application asks for gamepads. Without this call there are no gamepad events.

See also

class gamepad

display <-sdl_test_gamepad: {rumble_low,rumble_high,red,green,blue} -> num

For testing only. The last rumble (0..1) or LED colour (0..255) sent to the virtual gamepad of display->sdl_test_gamepad.