# -*- python -*-
'''
pylibgamma — Python 3 wrapper for libgamma
Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
This library is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this library. If not, see .
'''
LIBGAMMA_METHOD_DUMMY = 0
'''
The identifier for the dummy adjustment method.
This method can be configured and is useful for
testing your program's ability to handle errors.
'''
LIBGAMMA_METHOD_X_RANDR = 1
'''
The identifier for the adjustment method with
uses the RandR protocol under the X display server.
'''
LIBGAMMA_METHOD_X_VIDMODE = 2
'''
The identifier for the adjustment method with
uses the VidMode protocol under the X display server.
This is an older alternative to RandR that can
work on some drivers that are not supported by RandR,
however it can only control the primary CRTC per
screen (partition).
'''
LIBGAMMA_METHOD_LINUX_DRM = 3
'''
The identifier for the Direct Rendering Manager
adjustment method that is available in Linux
(built in to the Linux kernel with a userland
library for access) and is a part of the
Direct Rendering Infrastructure. This adjustment
method all work when you are in non-graphical
mode; however a display server cannnot be
started while this is running, but it can be
started while a display server is running.
'''
LIBGAMMA_METHOD_W32_GDI = 4
'''
The identifier for the Graphics Device Interface
adjustment method that is available in Windows.
This method is not well tested; it can be compiled
to be available under X.org using a translation layer.
'''
LIBGAMMA_METHOD_QUARTZ_CORE_GRAPHICS = 5
'''
The identifier for the CoreGraphics adjustment
method that is available in Mac OS X that can
adjust gamma ramps under the Quartz display server.
This method is not well tested; it can be compiled
to be available under X.org using a translation layer.
'''
LIBGAMMA_METHOD_MAX = 5
'''
The index of the last gamma method, neither it
nor any index before it may actually be supported
as it could have been disabled at compile-time
'''
LIBGAMMA_METHOD_COUNT = (LIBGAMMA_METHOD_MAX + 1)
'''
The number adjustment methods provided by this library.
Note however that this includes adjstment methods that
have been removed at compile-time.
'''
class MethodCapabilities:
'''
Capabilities of adjustment methods
---- Integer variables ----
@variable crtc_information OR of the CRTC information fields in `CRTCInformation`
that may (but can fail) be read successfully.
---- Boolean variables ----
@variable default_site_known Whether the default site is known, if true the site is integrated
to the system or can be determined using environment variables.
@variable multiple_sites Whether the adjustment method supports multiple sites rather
than just the default site.
@variable multiple_partitions Whether the adjustment method supports multiple partitions
per site.
@variable multiple_crtcs Whether the adjustment method supports multiple CRTC:s
per partition per site.
@variable partitions_are_graphics_cards Whether the partition to graphics card is a bijection.
@variable site_restore Whether the adjustment method supports `site_restore`.
@variable partition_restore Whether the adjustment method supports `partition_restore`.
@variable crtc_restore Whether the adjustment method supports `crtc_restore`.
@variable identical_gamma_sizes Whether the `red_gamma_size`, `green_gamma_size` and
`blue_gamma_size` fields in `CRTCInformation` will always
have the same values as each other for the adjustment method.
@variable fixed_gamma_size Whether the `red_gamma_size`, `green_gamma_size` and
`blue_gamma_size` fields in `CRTCInformation` will always be
filled with the same value for the adjustment method.
@variable fixed_gamma_depth Whether the `gamma_depth` field in `CRTCInformation` will
always be filled with the same value for the adjustment method.
@variable real Whether the adjustment method will actually perform adjustments.
@variable fake Whether the adjustment method is implement using a translation
layer.
'''
def __init__(self, crtc_information : int = 0, booleans : int = 0):
'''
Constructor
@param crtc_information The value for `CRTCInformation`
@param booleans The value for each booleanic variable
'''
self.crtc_information = crtc_information
self.default_site_known = (booleans & (1 << 0)) != 0
self.multiple_sites = (booleans & (1 << 1)) != 0
self.multiple_partitions = (booleans & (1 << 2)) != 0
self.multiple_crtcs = (booleans & (1 << 3)) != 0
self.partitions_are_graphics_cards = (booleans & (1 << 4)) != 0
self.site_restore = (booleans & (1 << 5)) != 0
self.partition_restore = (booleans & (1 << 6)) != 0
self.crtc_restore = (booleans & (1 << 7)) != 0
self.identical_gamma_sizes = (booleans & (1 << 8)) != 0
self.fixed_gamma_size = (booleans & (1 << 9)) != 0
self.fixed_gamma_depth = (booleans & (1 << 10)) != 0
self.real = (booleans & (1 << 11)) != 0
self.fake = (booleans & (1 << 12)) != 0
class CRTCInformation:
'''
Cathode ray tube controller information data structure.
@variable edid:bytes The Extended Display Identification Data associated with
the attached monitor. This is raw byte array that is usually
128 bytes long.
@variable edid_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable width_mm:int The phyical width, in millimetres, of the viewport of the
attached monitor, as reported by the adjustment method. This
value may be incorrect, which is a known issue with the X
server where it is the result of the X server attempting
the estimate the size on its own.
Zero means that its is not applicable, which is the case
for projectors.
@variable width_mm_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable height_mm:int The phyical height, in millimetres, of the viewport of the
attached monitor, as reported by the adjustment method. This
value may be incorrect, which is a known issue with the X
server where it is the result of the X server attempting
the estimate the size on its own.
Zero means that its is not applicable, which is the case
for projectors.
@variable height_mm_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable width_mm_edid:int The phyical width, in millimetres, of the viewport of the
attached monitor, as reported by it the monitor's Extended
Display Information Data. This value can only contain whole
centimetres, which means that the result is always zero
modulus ten. However, this could change with revisions of
the EDID structure.
Zero means that its is not applicable, which is the case
for projectors.
@variable width_mm_edid_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable height_mm_edid:int The phyical height, in millimetres, of the viewport of the
attached monitor, as reported by it the monitor's Extended
Display Information Data. This value can only contain whole
centimetres, which means that the result is always zero
modulus ten. However, this could change with revisions of
the EDID structure.
Zero means that its is not applicable, which is the case
for projectors.
@variable height_mm_edid_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable red_gamma_size:int The size of the encoding axis of the red gamma ramp.
@variable green_gamma_size:int The size of the encoding axis of the green gamma ramp.
@variable blue_gamma_size:int The size of the encoding axis of the blue gamma ramp.
@variable gamma_size_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable gamma_depth:int The bit-depth of the value axes of gamma ramps,
-1 for single precision floating point, and -2 for
double precision floating point.
@variable gamma_depth_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable gamma_support:int Non-zero gamma ramp adjustments are supported.
@variable gamma_support_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable subpixel_order:int The layout of the subpixels.
You cannot count on this value — especially for CRT:s —
but it is provided anyway as a means of distinguishing monitors.
@variable subpixel_order_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable active:bool Whether there is a monitors connected to the CRTC.
@variable active_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable connector_name:str The name of the connector as designated by the display
server or as give by this library in case the display
server lacks this feature.
@variable connector_name_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable connector_type:int The type of the connector that is associated with the CRTC.
@variable connector_type_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
@variable gamma_red:float The gamma characteristics of the monitor as reported
in its Extended Display Information Data. The value
holds the value for the red channel. If you do not have
and more accurate measurement of the gamma for the
monitor this could be used to give a rought gamma
correction; simply divide the value with 2.2 and use
the result for the red channel in the gamma correction.
@variable gamma_green:float The gamma characteristics of the monitor as reported
in its Extended Display Information Data. The value
holds the value for the green channel. If you do not have
and more accurate measurement of the gamma for the
monitor this could be used to give a rought gamma
correction; simply divide the value with 2.2 and use
the result for the green channel in the gamma correction.
@variable gamma_blue:float The gamma characteristics of the monitor as reported
in its Extended Display Information Data. The value
holds the value for the blue channel. If you do not have
and more accurate measurement of the gamma for the
monitor this could be used to give a rought gamma
correction; simply divide the value with 2.2 and use
the result for the blue channel in the gamma correction.
@variable gamma_error:int Zero on success, positive it holds the value `errno` had
when the reading failed, otherwise (negative) the value
of an error identifier provided by this library.
'''
def __init__(self):
'''
Constructor
'''
pass
LIBGAMMA_CONNECTOR_TYPE_Unknown = 0
'''
The adjustment method does not know the connector's type
(This could be considered an error).
'''
LIBGAMMA_CONNECTOR_TYPE_VGA = 1
'''
Video Graphics Array (VGA).
'''
LIBGAMMA_CONNECTOR_TYPE_DVI = 2
'''
Digital Visual Interface, unknown type.
'''
LIBGAMMA_CONNECTOR_TYPE_DVII = 3
'''
Digital Visual Interface, integrated (DVI-I).
'''
LIBGAMMA_CONNECTOR_TYPE_DVID = 4
'''
Digital Visual Interface, digital only (DVI-D).
'''
LIBGAMMA_CONNECTOR_TYPE_DVIA = 5
'''
Digital Visual Interface, analogue only (DVI-A).
'''
LIBGAMMA_CONNECTOR_TYPE_Composite = 6
'''
Composite video.
'''
LIBGAMMA_CONNECTOR_TYPE_SVIDEO = 7
'''
Separate Video (S-video).
'''
LIBGAMMA_CONNECTOR_TYPE_LVDS = 8
'''
Low-voltage differential signaling (LVDS).
'''
LIBGAMMA_CONNECTOR_TYPE_Component = 9
'''
Component video, usually separate cables for each channel.
'''
LIBGAMMA_CONNECTOR_TYPE_9PinDIN = 10
'''
9 pin DIN (Deutsches Institut für Normung) connector.
'''
LIBGAMMA_CONNECTOR_TYPE_DisplayPort = 11
'''
DisplayPort.
'''
LIBGAMMA_CONNECTOR_TYPE_HDMI = 12
'''
High-Definition Multimedia Interface (HDMI), unknown type.
'''
LIBGAMMA_CONNECTOR_TYPE_HDMIA = 13
'''
High-Definition Multimedia Interface, type A (HDMI-A).
'''
LIBGAMMA_CONNECTOR_TYPE_HDMIB = 14
'''
High-Definition Multimedia Interface, type B (HDMI-B).
'''
LIBGAMMA_CONNECTOR_TYPE_TV = 15
'''
Television, unknown connector.
'''
LIBGAMMA_CONNECTOR_TYPE_eDP = 16
'''
Embedded DisplayPort (eDP).
'''
LIBGAMMA_CONNECTOR_TYPE_VIRTUAL = 17
'''
A virtual connector.
'''
LIBGAMMA_CONNECTOR_TYPE_DSI = 18
'''
Display Serial Interface (DSI).
'''
LIBGAMMA_CONNECTOR_TYPE_LFP = 19
'''
LFP connector.
(If you know what this is add it to Wikipedia.)
'''
LIBGAMMA_CONNECTOR_TYPE_COUNT = 20
'''
The number of `LIBGAMMA_CONNECTOR_*` values defined.
'''
LIBGAMMA_SUBPIXEL_ORDER_UNKNOWN = 0
'''
The adjustment method does not know the order of the subpixels.
(This could be considered an error.)
'''
LIBGAMMA_SUBPIXEL_ORDER_NONE = 1
'''
There are no subpixels in the monitor.
'''
LIBGAMMA_SUBPIXEL_ORDER_HORIZONTAL_RGB = 2
'''
The subpixels are ordered red, green and then blue, from left to right.
'''
LIBGAMMA_SUBPIXEL_ORDER_HORIZONTAL_BGR = 3
'''
The subpixels are ordered blue, green and then red, from left to right.
'''
LIBGAMMA_SUBPIXEL_ORDER_VERTICAL_RGB = 4
'''
The subpixels are ordered red, green and then blue, from the top down.
'''
LIBGAMMA_SUBPIXEL_ORDER_VERTICAL_BGR = 5
'''
The subpixels are ordered blue, green and then red, from the top down.
'''
LIBGAMMA_SUBPIXEL_ORDER_COUNT = 6
'''
The number of `LIBGAMMA_SUBPIXEL_ORDER_*` values defined.
'''
LIBGAMMA_CRTC_INFO_EDID = 1 << 0
'''
For a `CRTCInformation` fill in the
values for `edid` and `edid_length` and report errors to `edid_error`.
'''
LIBGAMMA_CRTC_INFO_WIDTH_MM = 1 << 1
'''
For a `CRTCInformation` fill in the
value for `width_mm` and report errors to `width_mm_error`.
'''
LIBGAMMA_CRTC_INFO_HEIGHT_MM = 1 << 2
'''
For a `CRTCInformation` fill in the
value for `height_mm` and report errors to `height_mm_error`.
'''
LIBGAMMA_CRTC_INFO_WIDTH_MM_EDID = 1 << 3
'''
For a `CRTCInformation` fill in the
value for `width_mm_edid` and report errors to `width_mm_edid_error`.
'''
LIBGAMMA_CRTC_INFO_HEIGHT_MM_EDID = 1 << 4
'''
For a `CRTCInformation` fill in the
value for `height_mm_edid` and report errors to `height_mm_edid_error`.
'''
LIBGAMMA_CRTC_INFO_GAMMA_SIZE = 1 << 5
'''
For a `CRTCInformation` fill in the
values for `red_gamma_size`, `green_gamma_size` and `blue_gamma_size`.
and report errors to `gamma_size_error`
'''
LIBGAMMA_CRTC_INFO_GAMMA_DEPTH = 1 << 6
'''
For a `CRTCInformation` fill in the
value for `gamma_depth` and report errors to `gamma_depth_error`.
'''
LIBGAMMA_CRTC_INFO_GAMMA_SUPPORT = 1 << 7
'''
For a `CRTCInformation` fill in the
value for `gamma_support` and report errors to `gamma_support_error`.
'''
LIBGAMMA_CRTC_INFO_SUBPIXEL_ORDER = 1 << 8
'''
For a `CRTCInformation` fill in the
value for `subpixel_order` and report errors to `subpixel_order_error`.
'''
LIBGAMMA_CRTC_INFO_ACTIVE = 1 << 9
'''
For a `CRTCInformation` fill in the
value for `active` and report errors to `active_error`.
'''
LIBGAMMA_CRTC_INFO_CONNECTOR_NAME = 1 << 10
'''
For a `CRTCInformation` fill in the
value for `connector_name` and report errors to `connector_name_error`.
'''
LIBGAMMA_CRTC_INFO_CONNECTOR_TYPE = 1 << 11
'''
For a `CRTCInformation` fill in the
value for `connector_type` and report errors to `connector_type_error`.
'''
LIBGAMMA_CRTC_INFO_GAMMA = 1 << 12
'''
For a `CRTCInformation` fill in the
values for `gamma_red`, `gamma_green` and `gamma_blue`
and report errors to `gamma_error`.
'''
LIBGAMMA_CRTC_INFO_COUNT = 13
'''
The number of `LIBGAMMA_CRTC_INFO_*` values defined.
'''
LIBGAMMA_CRTC_INFO_MACRO_EDID_VIEWPORT = LIBGAMMA_CRTC_INFO_WIDTH_MM_EDID |
LIBGAMMA_CRTC_INFO_HEIGHT_MM_EDID
'''
Macro for both `CRTCInformation` fields
that can specify the size of the monitor's viewport
as specified in the monitor's Extended Display
Information Data.
'''
LIBGAMMA_CRTC_INFO_MACRO_EDID = LIBGAMMA_CRTC_INFO_EDID |
LIBGAMMA_CRTC_INFO_MACRO_EDID_VIEWPORT |
LIBGAMMA_CRTC_INFO_GAMMA
'''
Macro for all `CRTCInformation` fields
that can be filled if the adjustment method have
support for reading the monitors' Extended Display
Information Data.
'''
LIBGAMMA_CRTC_INFO_MACRO_VIEWPORT = LIBGAMMA_CRTC_INFO_WIDTH_MM |
LIBGAMMA_CRTC_INFO_HEIGHT_MM
'''
Macro for both `CRTCInformation` fields
that can specify the size of the monitor's viewport
as provided by the adjustment method without this
library having to parse the monitor's Extended Display
Information Data.
'''
LIBGAMMA_CRTC_INFO_MACRO_RAMP = LIBGAMMA_CRTC_INFO_GAMMA_SIZE |
LIBGAMMA_CRTC_INFO_GAMMA_DEPTH
'''
Macro for the `CRTCInformation` fields
that specifies the CRTC's gamma ramp sizes and gamma
ramp depth.
'''
LIBGAMMA_CRTC_INFO_MACRO_CONNECTOR = LIBGAMMA_CRTC_INFO_CONNECTOR_NAME |
LIBGAMMA_CRTC_INFO_CONNECTOR_TYPE
'''
Macro for the `CRTCInformation` fields
that specifies the CRTC's connector type and the
partition unique name of the connector.
'''
LIBGAMMA_CRTC_INFO_MACRO_ACTIVE = LIBGAMMA_CRTC_INFO_MACRO_EDID |
LIBGAMMA_CRTC_INFO_MACRO_VIEWPORT |
LIBGAMMA_CRTC_INFO_SUBPIXEL_ORDER |
LIBGAMMA_CRTC_INFO_ACTIVE
'''
Macro for the `CRTCInformation` fields
that required there is a monitor attached to the connector,
and that status itself.
'''
class GammaRamps:
'''
Gamma ramp structure.
'''
def __init__(self, red_size : int, green_size : int = ..., blue_size : int = ..., *, depth : int = 16):
'''
Constructor.
@param red_size The number of stops in the gamma ramp for the red channel
@param green_size The number of stops in the gamma ramp for the green channel, `...` for `red_size`
@param blue_size The number of stops in the gamma ramp for the blue channel, `...` for `green_size`
@param depth The depth of the gamma ramps
'''
if green_size is ...: green_size = red_size
if blue_size is ...: blue_size = green_size
self.__depth = depth
if depth not in (8, 16, 32, 64, -1, -2):
raise ValueError('invalid gamma ramp depth')
if depth == 8: ramp_struct = libgamma_native_gamma_ramps8_create (red_size, green_size, blue_size)
elif depth == 16: ramp_struct = libgamma_native_gamma_ramps16_create(red_size, green_size, blue_size)
elif depth == 32: ramp_struct = libgamma_native_gamma_ramps32_create(red_size, green_size, blue_size)
elif depth == 64: ramp_struct = libgamma_native_gamma_ramps64_create(red_size, green_size, blue_size)
elif depth == -1: ramp_struct = libgamma_native_gamma_rampsf_create (red_size, green_size, blue_size)
elif depth == -2: ramp_struct = libgamma_native_gamma_rampsd_create (red_size, green_size, blue_size)
if isinstance(ramp_struct, int):
import c
error = OSError()
error.errno = ramp_struct
error.strerror = c.strerror(error.errno)
raise error
(self.__ramps, red, green, blue) = ramp_struct
class Ramp:
'''
A gamma ramp for one single channel.
'''
def __init__(self, ramp, size : int, depth : int):
'''
Constructor.
@param ramp The gamma ramp.
@param size The number of stops in the gamma ramp.
@param depth The depth of the gamma ramp.
'''
self.__size = size
self.__ramp = ramp
if depth == 8: fs = (libgamma_native_gamma_ramps8_get, libgamma_native_gamma_ramps8_set)
elif depth == 16: fs = (libgamma_native_gamma_ramps16_get, libgamma_native_gamma_ramps16_set)
elif depth == 32: fs = (libgamma_native_gamma_ramps32_get, libgamma_native_gamma_ramps32_set)
elif depth == 64: fs = (libgamma_native_gamma_ramps64_get, libgamma_native_gamma_ramps64_set)
elif depth == -1: fs = (libgamma_native_gamma_rampsf_get, libgamma_native_gamma_rampsf_set)
elif depth == -2: fs = (libgamma_native_gamma_rampsd_get, libgamma_native_gamma_rampsd_set)
(self.__get, self.__set) = fs
@property
def size(self) -> int:
'''
Get the number of stops in the gamma ramp.
@return The number of stops in the gamma ramp.
'''
return self.__size
@size.setter
def size(self, value : int):
'''
It is not possible to change this attribute, but a setter is
required for the getter to function.
'''
raise AttributeError('cannot resize ramp')
def __len__(self) -> int:
'''
Get the number of stops in the gamma ramp.
@return The number of stops in the gamma ramp.
'''
return self.__size
def __getitem__(self, indices):
'''
Read the gamma ramp.
@param indices:slice The stops to read.
@return :list The values of the read stops.
-- OR --
@param indices:int The index of the stop to read.
@return :int|float The value of the read stop.
'''
if isinstance(indices, slice):
start = indices.start
stop = indices.stop
step = indices.step
if start is None: start = 0
elif start < 0: start += self.__size
if stop is None: stop = self.__size
elif stop < 0: stop += self.__size
if step is None: step = 1
return [self.__get(self.__ramp, i) for i in range(start, stop, step)]
else:
if indices < 0:
indices += self.__size
return self.__get(self.__ramp, indices)
def __setitem__(self, indices, values):
'''
Modify the gamma ramp.
@param indices:slice The stops to modify.
@param values:itr The values for the selected stops.
-- OR --
@param indices:int The index of the stop to modify.
@param values:int|float The new value for the stop.
'''
if isinstance(indices, slice):
start = indices.start
stop = indices.stop
step = indices.step
if start is None: start = 0
elif start < 0: start += self.__size
if stop is None: stop = self.__size
elif stop < 0: stop += self.__size
if step is None: step = 1
indices = list(range(start, stop, step))
if not len(indices) == len(values):
raise ValueError('cannot resize ramp')
for index, value in zip(indices, values):
self.__set(self.__ramp, index, value)
else:
if indices < 0:
indices += self.__size
self.__set(self.__ramp, indices, values)
self.red = Ramp(red, red_size, depth)
self.green = Ramp(green, green_size, depth)
self.blue = Ramp(blue, blue_size, depth)
def __del__(self):
'''
This function is called when the object is not longer in use.
'''
if self.__depth == 8: libgamma_native_gamma_ramps8_free(self.__ramps)
elif self.__depth == 16: libgamma_native_gamma_ramps16_free(self.__ramps)
elif self.__depth == 32: libgamma_native_gamma_ramps32_free(self.__ramps)
elif self.__depth == 64: libgamma_native_gamma_ramps64_free(self.__ramps)
elif self.__depth == -1: libgamma_native_gamma_rampsf_free(self.__ramps)
elif self.__depth == -2: libgamma_native_gamma_rampsd_free(self.__ramps)
@property
def size(self) -> tuple:
'''
Get the ramps' sizes.
@return :(red:int, green:int, blue:int) The size of each individual ramp.
'''
return (self.red.size, self.green.size, self.blue.size)
@size.setter
def size(self, value):
'''
It is not possible to change this attribute, but a setter is
required for the getter to function.
'''
raise AttributeError('cannot resize ramps')
@property
def depth(self) -> int:
'''
Get the depth of ramps.
@return :int The ramps' depth in bits and -1 for single precision floating
point and -2 for doublesingle precision floating point
'''
return self.__depth
@size.setter
def depth(self, value):
'''
It is not possible to change this attribute, but a setter is
required for the getter to function.
'''
raise AttributeError('cannot change depth')