wxDC(3)

NAME
wxDC - A wxDC is a "device context" onto which graphics and text can be drawn.

DESCRIPTION

It is intended to represent different output devices and offers a common abstract API for drawing on any of them.

wxWidgets offers an alternative drawing API based on the modern drawing backends GDI+, CoreGraphics, Cairo and Direct2D. See wxGraphicsContext, wxGraphicsRenderer and related classes. There is also a wxGCDC linking the APIs by offering the wxDC API on top of a wxGraphicsContext.

wxDC is an abstract base class and cannot be created directly. Use wxPaintDC, wxClientDC, wxWindowDC, wxScreenDC, wxMemoryDC or wxPrinterDC (not implemented in wx). Notice that device contexts which are associated with windows (i.e. wxClientDC, wxWindowDC and wxPaintDC) use the window font and colours by default (starting with wxWidgets 2.9.0) but the other device context classes use system-default values so you always must set the appropriate fonts and colours before using them.

In addition to the versions of the methods documented below, there are also versions which accept single {X,Y} parameter instead of the two wxCoord ones or {X,Y} and {Width,Height} instead of the four wxCoord parameters.

Beginning with wxWidgets 2.9.0 the entire wxDC code has been reorganized. All platform dependent code (actually all drawing code) has been moved into backend classes which derive from a common wxDCImpl class. The user-visible classes such as wxClientDC and wxPaintDC merely forward all calls to the backend implementation.

Device and logical units

In the wxDC context there is a distinction between logical units and device units.

Device units are the units native to the particular device; e.g. for a screen, a device unit is a pixel. For a printer, the device unit is defined by the resolution of the printer (usually given in DPI: dot-per-inch).

All wxDC functions use instead logical units, unless where explicitly stated. Logical units are arbitrary units mapped to device units using the current mapping mode (see setMapMode/2).

This mechanism allows reusing the same code which prints on e.g. a window on the screen to print on e.g. a paper.

Support for Transparency / Alpha Channel

In general wxDC methods don't support alpha transparency and the alpha component of wx_color() is simply ignored and you need to use wxGraphicsContext for full transparency support. There are, however, a few exceptions: first, under macOS and GTK+ 3 colours with alpha channel are supported in all the normal wxDC-derived classes as they use wxGraphicsContext internally. Second, under all platforms wxSVGFileDC (not implemented in wx) also fully supports alpha channel. In both of these cases the instances of wxPen or wxBrush that are built from wx_color() use the colour's alpha values when stroking or filling.

Support for Transformation Matrix

On some platforms (currently under MSW, GTK+ 3, macOS) wxDC has support for applying an arbitrary affine transformation matrix to its coordinate system (since 3.1.1 this feature is also supported by wxGCDC in all ports). Call CanUseTransformMatrix() (not implemented in wx) to check if this support is available and then call SetTransformMatrix() (not implemented in wx) if it is. If the transformation matrix is not supported, SetTransformMatrix() (not implemented in wx) always simply returns false and doesn't do anything.

This feature is only available when wxUSE_DC_TRANSFORM_MATRIX build option is enabled.

See:

    • Overview dc

    • wxGraphicsContext

wxWidgets docs: wxDC

DATA TYPES

wxDC() :: wx:wx_object().

FUNCTIONS

blit(This, Dest, Size, Source, Src, [Option]) -> boolean() when This :: wxDC(), Dest :: {X :: integer(), Y :: integer()}, Size :: {W :: integer(), H :: integer()}, Source :: wxDC(), Src :: {X :: integer(), Y :: integer()}, Option :: {rop, wx:wx_enum()} | {useMask, boolean()} | {srcPtMask, {X :: integer(), Y :: integer()}}.

    Copy from a source DC to this DC.

    With this method you can specify the destination coordinates and the size of area to copy which will be the same for both the source and target DCs. If you need to apply scaling while copying, use StretchBlit() (not implemented in wx).

    Notice that source DC coordinates xsrc and ysrc are interpreted using the current source DC coordinate system, i.e. the scale, origin position and axis directions are taken into account when transforming them to physical (pixel) coordinates.

    Remark: There is partial support for blit/6 in wxPostScriptDC, under X.

    See:

        • wxMemoryDC

        • wxBitmap

        • wxMask
calcBoundingBox(This, X, Y) -> ok when This :: wxDC(), X :: integer(), Y :: integer().

    Adds the specified point to the bounding box which can be retrieved with minX/1, maxX/1 and minY/1, maxY/1 functions.

    See: resetBoundingBox/1
clear(This) -> ok when This :: wxDC().

    Clears the device context using the current background brush.

    Note that setBackground/2 method must be used to set the brush used by clear/1, the brush used for filling the shapes set by setBrush/2 is ignored by it.

    If no background brush was set, solid white brush is used to clear the device context.
crossHair(This, Pt) -> ok when This :: wxDC(), Pt :: {X :: integer(), Y :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
destroyClippingRegion(This) -> ok when This :: wxDC().

    Destroys the current clipping region so that none of the DC is clipped.

    See: setClippingRegion/3
deviceToLogicalX(This, X) -> integer() when This :: wxDC(), X :: integer().

    Convert device X coordinate to logical coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
deviceToLogicalXRel(This, X) -> integer() when This :: wxDC(), X :: integer().

    Convert device X coordinate to relative logical coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.

    Use this for converting a width, for example.
deviceToLogicalY(This, Y) -> integer() when This :: wxDC(), Y :: integer().

    Converts device Y coordinate to logical coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
deviceToLogicalYRel(This, Y) -> integer() when This :: wxDC(), Y :: integer().

    Convert device Y coordinate to relative logical coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.

    Use this for converting a height, for example.
drawArc(This, PtStart, PtEnd, Centre) -> ok when This :: wxDC(), PtStart :: {X :: integer(), Y :: integer()}, PtEnd :: {X :: integer(), Y :: integer()}, Centre :: {X :: integer(), Y :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawBitmap(This, Bmp, Pt, [Option]) -> ok when This :: wxDC(), Bmp :: wxBitmap:wxBitmap(), Pt :: {X :: integer(), Y :: integer()}, Option :: {useMask, boolean()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawCheckMark(This, Rect) -> ok when This :: wxDC(), Rect :: {X :: integer(), Y :: integer(), W :: integer(), H :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawCircle(This, Pt, Radius) -> ok when This :: wxDC(), Pt :: {X :: integer(), Y :: integer()}, Radius :: integer().

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawEllipse(This, Rect) -> ok when This :: wxDC(), Rect :: {X :: integer(), Y :: integer(), W :: integer(), H :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawEllipse(This, Pt, Size) -> ok when This :: wxDC(), Pt :: {X :: integer(), Y :: integer()}, Size :: {W :: integer(), H :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawEllipticArc(This, Pt, Sz, Sa, Ea) -> ok when This :: wxDC(), Pt :: {X :: integer(), Y :: integer()}, Sz :: {W :: integer(), H :: integer()}, Sa :: number(), Ea :: number().

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawIcon(This, Icon, Pt) -> ok when This :: wxDC(), Icon :: wxIcon:wxIcon(), Pt :: {X :: integer(), Y :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawLabel(This, Text, Rect, [Option]) -> ok when This :: wxDC(), Text :: unicode:chardata(), Rect :: {X :: integer(), Y :: integer(), W :: integer(), H :: integer()}, Option :: {alignment, integer()} | {indexAccel, integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawLine(This, Pt1, Pt2) -> ok when This :: wxDC(), Pt1 :: {X :: integer(), Y :: integer()}, Pt2 :: {X :: integer(), Y :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawLines(This, Points, [Option]) -> ok when This :: wxDC(), Points :: [{X :: integer(), Y :: integer()}], Option :: {xoffset, integer()} | {yoffset, integer()}.

    Draws lines using an array of points of size n adding the optional offset coordinate.

    The current pen is used for drawing the lines.
drawPoint(This, Pt) -> ok when This :: wxDC(), Pt :: {X :: integer(), Y :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawPolygon(This, Points, [Option]) -> ok when This :: wxDC(), Points :: [{X :: integer(), Y :: integer()}], Option :: {xoffset, integer()} | {yoffset, integer()} | {fillStyle, wx:wx_enum()}.

    Draws a filled polygon using an array of points of size n, adding the optional offset coordinate.

    The first and last points are automatically closed.

    The last argument specifies the fill rule: wxODDEVEN_RULE (the default) or wxWINDING_RULE.

    The current pen is used for drawing the outline, and the current brush for filling the shape. Using a transparent brush suppresses filling.
drawRectangle(This, Rect) -> ok when This :: wxDC(), Rect :: {X :: integer(), Y :: integer(), W :: integer(), H :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawRectangle(This, Pt, Sz) -> ok when This :: wxDC(), Pt :: {X :: integer(), Y :: integer()}, Sz :: {W :: integer(), H :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawRotatedText(This, Text, Point, Angle) -> ok when This :: wxDC(), Text :: unicode:chardata(), Point :: {X :: integer(), Y :: integer()}, Angle :: number().

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawRoundedRectangle(This, Rect, Radius) -> ok when This :: wxDC(), Rect :: {X :: integer(), Y :: integer(), W :: integer(), H :: integer()}, Radius :: number().

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawRoundedRectangle(This, Pt, Sz, Radius) -> ok when This :: wxDC(), Pt :: {X :: integer(), Y :: integer()}, Sz :: {W :: integer(), H :: integer()}, Radius :: number().

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
drawText(This, Text, Pt) -> ok when This :: wxDC(), Text :: unicode:chardata(), Pt :: {X :: integer(), Y :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
endDoc(This) -> ok when This :: wxDC().

    Ends a document (only relevant when outputting to a printer).
endPage(This) -> ok when This :: wxDC().

    Ends a document page (only relevant when outputting to a printer).
floodFill(This, Pt, Col, [Option]) -> boolean() when This :: wxDC(), Pt :: {X :: integer(), Y :: integer()}, Col :: wx:wx_colour(), Option :: {style, wx:wx_enum()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
getBackground(This) -> wxBrush:wxBrush() when This :: wxDC().

    Gets the brush used for painting the background.

    See: setBackground/2
getBackgroundMode(This) -> integer() when This :: wxDC().

    Returns the current background mode: wxPENSTYLE\_SOLID or wxPENSTYLE\_TRANSPARENT.

    See: setBackgroundMode/2
getBrush(This) -> wxBrush:wxBrush() when This :: wxDC().

    Gets the current brush.

    See: setBrush/2
getCharHeight(This) -> integer() when This :: wxDC().

    Gets the character height of the currently set font.
getCharWidth(This) -> integer() when This :: wxDC().

    Gets the average character width of the currently set font.
getClippingBox(This) -> Result when Result :: {X :: integer(), Y :: integer(), Width :: integer(), Height :: integer()}, This :: wxDC().

    Gets the rectangle surrounding the current clipping region. If no clipping region is set this function returns the extent of the device context. @remarks Clipping region is given in logical coordinates. @param x If non-<span class='literal'>NULL</span>, filled in with the logical horizontal coordinate of the top left corner of the clipping region if the function returns true or 0 otherwise. @param y If non-<span class='literal'>NULL</span>, filled in with the logical vertical coordinate of the top left corner of the clipping region if the function returns true or 0 otherwise. @param width If non-<span class='literal'>NULL</span>, filled in with the width of the clipping region if the function returns true or the device context width otherwise. @param height If non-<span class='literal'>NULL</span>, filled in with the height of the clipping region if the function returns true or the device context height otherwise.

    Return: true if there is a clipping region or false if there is no active clipping region (note that this return value is available only since wxWidgets 3.1.2, this function didn't return anything in the previous versions).
getFont(This) -> wxFont:wxFont() when This :: wxDC().

    Gets the current font.

    Notice that even although each device context object has some default font after creation, this method would return a ?wxNullFont initially and only after calling setFont/2 a valid font is returned.
getLayoutDirection(This) -> wx:wx_enum() when This :: wxDC().

    Gets the current layout direction of the device context.

    On platforms where RTL layout is supported, the return value will either be wxLayout_LeftToRight or wxLayout_RightToLeft. If RTL layout is not supported, the return value will be wxLayout_Default.

    See: setLayoutDirection/2
getLogicalFunction(This) -> wx:wx_enum() when This :: wxDC().

    Gets the current logical function.

    See: setLogicalFunction/2
getMapMode(This) -> wx:wx_enum() when This :: wxDC().

    Gets the current mapping mode for the device context.

    See: setMapMode/2
getMultiLineTextExtent(This, String) -> {W :: integer(), H :: integer()} when This :: wxDC(), String :: unicode:chardata().

    Gets the dimensions of the string using the currently selected font.

    string is the text string to measure.

    Return: The text extent as a {Width,Height} object.

    Note: This function works with both single-line and multi-line strings.

    See:

        • wxFont

        • setFont/2

        • getPartialTextExtents/2

        • getTextExtent/3
getMultiLineTextExtent(This, String, [Option]) -> {W :: integer(), H :: integer(), HeightLine :: integer()} when This :: wxDC(), String :: unicode:chardata(), Option :: {font, wxFont:wxFont()}.

    Gets the dimensions of the string using the currently selected font.

    string is the text string to measure, heightLine, if non NULL, is where to store the height of a single line.

    The text extent is set in the given w and h pointers.

    If the optional parameter font is specified and valid, then it is used for the text extent calculation, otherwise the currently selected font is used.

    If string is empty, its horizontal extent is 0 but, for convenience when using this function for allocating enough space for a possibly multi-line string, its vertical extent is the same as the height of an empty line of text. Please note that this behaviour differs from that of getTextExtent/3.

    Note: This function works with both single-line and multi-line strings.

    See:

        • wxFont

        • setFont/2

        • getPartialTextExtents/2

        • getTextExtent/3
getPPI(This) -> {W :: integer(), H :: integer()} when This :: wxDC().

    Returns the resolution of the device in pixels per inch.
getPartialTextExtents(This, Text) -> Result when Result :: {Res :: boolean(), Widths :: [integer()]}, This :: wxDC(), Text :: unicode:chardata().

    Fills the widths array with the widths from the beginning of text to the corresponding character of text.

    The generic version simply builds a running total of the widths of each character using getTextExtent/3, however if the various platforms have a native API function that is faster or more accurate than the generic implementation then it should be used instead.

    See:

        • getMultiLineTextExtent/3

        • getTextExtent/3
getPen(This) -> wxPen:wxPen() when This :: wxDC().

    Gets the current pen.

    See: setPen/2
getPixel(This, Pos) -> Result when Result :: {Res :: boolean(), Colour :: wx:wx_colour4()}, This :: wxDC(), Pos :: {X :: integer(), Y :: integer()}.

    Gets in colour the colour at the specified location.

    This method isn't available for wxPostScriptDC or wxMetafileDC (not implemented in wx) nor for any DC in wxOSX port and simply returns false there.

    Note: Setting a pixel can be done using drawPoint/2.

    Note: This method shouldn't be used with wxPaintDC as accessing the DC while drawing can result in unexpected results, notably in wxGTK.
getSize(This) -> {W :: integer(), H :: integer()} when This :: wxDC().

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
getSizeMM(This) -> {W :: integer(), H :: integer()} when This :: wxDC().

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
getTextBackground(This) -> wx:wx_colour4() when This :: wxDC().

    Gets the current text background colour.

    See: setTextBackground/2
getTextExtent(This, String) -> {W :: integer(), H :: integer()} when This :: wxDC(), String :: unicode:chardata().

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
getTextExtent(This, String, [Option]) -> Result when Result :: {W :: integer(), H :: integer(), Descent :: integer(), ExternalLeading :: integer()}, This :: wxDC(), String :: unicode:chardata(), Option :: {theFont, wxFont:wxFont()}.

    Gets the dimensions of the string using the currently selected font.

    string is the text string to measure, descent is the dimension from the baseline of the font to the bottom of the descender, and externalLeading is any extra vertical space added to the font by the font designer (usually is zero).

    The text extent is returned in w and h pointers or as a {Width,Height} object depending on which version of this function is used.

    If the optional parameter font is specified and valid, then it is used for the text extent calculation. Otherwise the currently selected font is.

    If string is empty, its extent is 0 in both directions, as expected.

    Note: This function only works with single-line strings.

    See:

        • wxFont

        • setFont/2

        • getPartialTextExtents/2

        • getMultiLineTextExtent/3
getTextForeground(This) -> wx:wx_colour4() when This :: wxDC().

    Gets the current text foreground colour.

    See: setTextForeground/2
getUserScale(This) -> {X :: number(), Y :: number()} when This :: wxDC().

    Gets the current user scale factor.

    See: setUserScale/3
gradientFillConcentric(This, Rect, InitialColour, DestColour) -> ok when This :: wxDC(), Rect :: {X :: integer(), Y :: integer(), W :: integer(), H :: integer()}, InitialColour :: wx:wx_colour(), DestColour :: wx:wx_colour().

    Fill the area specified by rect with a radial gradient, starting from initialColour at the centre of the circle and fading to destColour on the circle outside.

    The circle is placed at the centre of rect.

    Note: Currently this function is very slow, don't use it for real-time drawing.
gradientFillConcentric(This, Rect, InitialColour, DestColour, CircleCenter) -> ok when This :: wxDC(), Rect :: {X :: integer(), Y :: integer(), W :: integer(), H :: integer()}, InitialColour :: wx:wx_colour(), DestColour :: wx:wx_colour(), CircleCenter :: {X :: integer(), Y :: integer()}.

    Fill the area specified by rect with a radial gradient, starting from initialColour at the centre of the circle and fading to destColour on the circle outside.

    circleCenter are the relative coordinates of centre of the circle in the specified rect.

    Note: Currently this function is very slow, don't use it for real-time drawing.
gradientFillLinear(This, Rect, InitialColour, DestColour, [Option]) -> ok when This :: wxDC(), Rect :: {X :: integer(), Y :: integer(), W :: integer(), H :: integer()}, InitialColour :: wx:wx_colour(), DestColour :: wx:wx_colour(), Option :: {nDirection, wx:wx_enum()}.

    Fill the area specified by rect with a linear gradient, starting from initialColour and eventually fading to destColour.

    The nDirection specifies the direction of the colour change, default is to use initialColour on the left part of the rectangle and destColour on the right one.
isOk(This) -> boolean() when This :: wxDC().

    Returns true if the DC is ok to use.
logicalToDeviceX(This, X) -> integer() when This :: wxDC(), X :: integer().

    Converts logical X coordinate to device coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
logicalToDeviceXRel(This, X) -> integer() when This :: wxDC(), X :: integer().

    Converts logical X coordinate to relative device coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.

    Use this for converting a width, for example.
logicalToDeviceY(This, Y) -> integer() when This :: wxDC(), Y :: integer().

    Converts logical Y coordinate to device coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
logicalToDeviceYRel(This, Y) -> integer() when This :: wxDC(), Y :: integer().

    Converts logical Y coordinate to relative device coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.

    Use this for converting a height, for example.
maxX(This) -> integer() when This :: wxDC().

    Gets the maximum horizontal extent used in drawing commands so far.
maxY(This) -> integer() when This :: wxDC().

    Gets the maximum vertical extent used in drawing commands so far.
minX(This) -> integer() when This :: wxDC().

    Gets the minimum horizontal extent used in drawing commands so far.
minY(This) -> integer() when This :: wxDC().

    Gets the minimum vertical extent used in drawing commands so far.
resetBoundingBox(This) -> ok when This :: wxDC().

    Resets the bounding box: after a call to this function, the bounding box doesn't contain anything.

    See: calcBoundingBox/3
setAxisOrientation(This, XLeftRight, YBottomUp) -> ok when This :: wxDC(), XLeftRight :: boolean(), YBottomUp :: boolean().

    Sets the x and y axis orientation (i.e. the direction from lowest to highest values on the axis).

    The default orientation is x axis from left to right and y axis from top down.
setBackground(This, Brush) -> ok when This :: wxDC(), Brush :: wxBrush:wxBrush().

    Sets the current background brush for the DC.
setBackgroundMode(This, Mode) -> ok when This :: wxDC(), Mode :: integer().

    mode may be one of wxPENSTYLE\_SOLID and wxPENSTYLE\_TRANSPARENT.

    This setting determines whether text will be drawn with a background colour or not.
setBrush(This, Brush) -> ok when This :: wxDC(), Brush :: wxBrush:wxBrush().

    Sets the current brush for the DC.

    If the argument is ?wxNullBrush (or another invalid brush; see wxBrush:isOk/1), the current brush is selected out of the device context (leaving wxDC without any valid brush), allowing the current brush to be destroyed safely.

    See:

        • wxBrush

        • wxMemoryDC
setClippingRegion(This, Rect) -> ok when This :: wxDC(), Rect :: {X :: integer(), Y :: integer(), W :: integer(), H :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
setClippingRegion(This, Pt, Sz) -> ok when This :: wxDC(), Pt :: {X :: integer(), Y :: integer()}, Sz :: {W :: integer(), H :: integer()}.

    This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
setDeviceOrigin(This, X, Y) -> ok when This :: wxDC(), X :: integer(), Y :: integer().

    Sets the device origin (i.e. the origin in pixels after scaling has been applied).

    This function may be useful in Windows printing operations for placing a graphic on a page.
setFont(This, Font) -> ok when This :: wxDC(), Font :: wxFont:wxFont().

    Sets the current font for the DC.

    If the argument is ?wxNullFont (or another invalid font; see wxFont:isOk/1), the current font is selected out of the device context (leaving wxDC without any valid font), allowing the current font to be destroyed safely.

    See: wxFont
setLayoutDirection(This, Dir) -> ok when This :: wxDC(), Dir :: wx:wx_enum().

    Sets the current layout direction for the device context.

    See: getLayoutDirection/1
setLogicalFunction(This, Function) -> ok when This :: wxDC(), Function :: wx:wx_enum().

    Sets the current logical function for the device context.

    Note: This function is not fully supported in all ports, due to the limitations of the underlying drawing model. Notably, wxINVERT which was commonly used for drawing rubber bands or other moving outlines in the past, is not, and will not, be supported by wxGTK3 and wxMac. The suggested alternative is to draw temporarily objects normally and refresh the (affected part of the) window to remove them later.

    It determines how a source pixel (from a pen or brush colour, or source device context if using blit/6) combines with a destination pixel in the current device context. Text drawing is not affected by this function.

    See ?wxRasterOperationMode enumeration values for more info.

    The default is wxCOPY, which simply draws with the current colour. The others combine the current colour and the background using a logical operation.
setMapMode(This, Mode) -> ok when This :: wxDC(), Mode :: wx:wx_enum().

    The mapping mode of the device context defines the unit of measurement used to convert logical units to device units.

    Note that in X, text drawing isn't handled consistently with the mapping mode; a font is always specified in point size. However, setting the user scale (see setUserScale/3) scales the text appropriately. In Windows, scalable TrueType fonts are always used; in X, results depend on availability of fonts, but usually a reasonable match is found.

    The coordinate origin is always at the top left of the screen/printer.

    Drawing to a Windows printer device context uses the current mapping mode, but mapping mode is currently ignored for PostScript output.
setPalette(This, Palette) -> ok when This :: wxDC(), Palette :: wxPalette:wxPalette().

    If this is a window DC or memory DC, assigns the given palette to the window or bitmap associated with the DC.

    If the argument is ?wxNullPalette, the current palette is selected out of the device context, and the original palette restored.

    See: wxPalette
setPen(This, Pen) -> ok when This :: wxDC(), Pen :: wxPen:wxPen().

    Sets the current pen for the DC.

    If the argument is ?wxNullPen (or another invalid pen; see wxPen:isOk/1), the current pen is selected out of the device context (leaving wxDC without any valid pen), allowing the current pen to be destroyed safely.

    See: wxMemoryDC
setTextBackground(This, Colour) -> ok when This :: wxDC(), Colour :: wx:wx_colour().

    Sets the current text background colour for the DC.
setTextForeground(This, Colour) -> ok when This :: wxDC(), Colour :: wx:wx_colour().

    Sets the current text foreground colour for the DC.

    See: wxMemoryDC
setUserScale(This, XScale, YScale) -> ok when This :: wxDC(), XScale :: number(), YScale :: number().

    Sets the user scaling factor, useful for applications which require 'zooming'.
startDoc(This, Message) -> boolean() when This :: wxDC(), Message :: unicode:chardata().

    Starts a document (only relevant when outputting to a printer).

    message is a message to show while printing.
startPage(This) -> ok when This :: wxDC().

    Starts a document page (only relevant when outputting to a printer).