View Source wxDC (wx v2.4.3)
A wxDC
is a "device context"
onto which graphics and text can be drawn.
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:
wxWidgets docs: wxDC
Summary
Functions
Copy from a source DC to this DC.
Clears the device context using the current background brush.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Destroys the current clipping region so that none of the DC is clipped.
Convert device
X coordinate to logical coordinate, using the current mapping mode, user
scale factor, device origin and axis orientation.
Convert device
X coordinate to relative logical coordinate, using the current mapping
mode and user scale factor but ignoring the axis orientation.
Converts device
Y coordinate to logical coordinate, using the current mapping mode,
user scale factor, device origin and axis orientation.
Convert device
Y coordinate to relative logical coordinate, using the current mapping
mode and user scale factor but ignoring the axis orientation.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Equivalent to drawBitmap(This, Bmp, Pt, [])
.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Equivalent to drawLabel(This, Text, Rect, [])
.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Equivalent to drawLines(This, Points, [])
.
Draws lines using an array of points of size n
adding the optional offset coordinate.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Equivalent to drawPolygon(This, Points, [])
.
Draws a filled polygon using an array of points of size n
, adding the optional offset
coordinate.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Ends a document (only relevant when outputting to a printer).
Ends a document page (only relevant when outputting to a printer).
Equivalent to floodFill(This, Pt, Col, [])
.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Gets the brush used for painting the background.
Returns the current background mode: wxPENSTYLE\_SOLID
or wxPENSTYLE\_TRANSPARENT
.
Gets the current brush.
Gets the character height of the currently set font.
Gets the average character width of the currently set font.
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.
Gets the current font.
Gets the current layout direction of the device context.
Gets the current logical function.
Gets the current mapping mode for the device context.
Gets the dimensions of the string using the currently selected font.
Gets the dimensions of the string using the currently selected font.
Fills the widths
array with the widths from the beginning of text
to the
corresponding character of text
.
Gets the current pen.
Gets in colour
the colour at the specified location.
Returns the resolution of the device in pixels per inch.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Gets the current text background colour.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Gets the dimensions of the string using the currently selected font.
Gets the current text foreground colour.
Gets the current user scale factor.
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.
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.
Fill the area specified by rect
with a linear gradient, starting from initialColour
and eventually fading to destColour
.
Returns true if the DC is ok to use.
Converts logical X coordinate to device coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
Converts logical X coordinate to relative device coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.
Converts logical Y coordinate to device coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
Converts logical Y coordinate to relative device coordinate, using the current mapping mode and user scale factor but ignoring the axis orientation.
Gets the maximum horizontal extent used in drawing commands so far.
Gets the maximum vertical extent used in drawing commands so far.
Gets the minimum horizontal extent used in drawing commands so far.
Gets the minimum vertical extent used in drawing commands so far.
Resets the bounding box: after a call to this function, the bounding box doesn't contain anything.
Sets the x and y axis orientation (i.e. the direction from lowest to highest values on the axis).
Sets the current background brush for the DC.
mode
may be one of wxPENSTYLE\_SOLID
and wxPENSTYLE\_TRANSPARENT
.
Sets the current brush for the DC.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Sets the device origin (i.e. the origin in pixels after scaling has been applied).
Sets the current font for the DC.
Sets the current layout direction for the device context.
Sets the current logical function for the device context.
The mapping mode of the device context defines the unit of measurement used to convert logical
units to device
units.
If this is a window DC or memory DC, assigns the given palette to the window or bitmap associated with the DC.
Sets the current pen for the DC.
Sets the current text background colour for the DC.
Sets the current text foreground colour for the DC.
Sets the user scaling factor, useful for applications which require 'zooming'.
Starts a document (only relevant when outputting to a printer).
Starts a document page (only relevant when outputting to a printer).
Types
-type wxDC() :: wx:wx_object().
Functions
-spec blit(This, Dest, Size, Source, Src) -> boolean() when This :: wxDC(), Dest :: {X :: integer(), Y :: integer()}, Size :: {W :: integer(), H :: integer()}, Source :: wxDC(), Src :: {X :: integer(), Y :: integer()}.
Equivalent to blit(This, Dest, Size, Source, Src, [])
.
-spec 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:
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
-spec 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.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
-spec destroyClippingRegion(This) -> ok when This :: wxDC().
Destroys the current clipping region so that none of the DC is clipped.
See: setClippingRegion/3
Convert device
X coordinate to logical coordinate, using the current mapping mode, user
scale factor, device origin and axis orientation.
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.
Converts device
Y coordinate to logical coordinate, using the current mapping mode,
user scale factor, device origin and axis orientation.
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.
-spec 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.
-spec drawBitmap(This, Bmp, Pt) -> ok when This :: wxDC(), Bmp :: wxBitmap:wxBitmap(), Pt :: {X :: integer(), Y :: integer()}.
Equivalent to drawBitmap(This, Bmp, Pt, [])
.
-spec 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.
-spec 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.
-spec 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.
-spec 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.
-spec 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.
-spec 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.
-spec 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.
-spec drawLabel(This, Text, Rect) -> ok when This :: wxDC(), Text :: unicode:chardata(), Rect :: {X :: integer(), Y :: integer(), W :: integer(), H :: integer()}.
Equivalent to drawLabel(This, Text, Rect, [])
.
-spec 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.
-spec 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.
-spec drawLines(This, Points) -> ok when This :: wxDC(), Points :: [{X :: integer(), Y :: integer()}].
Equivalent to drawLines(This, Points, [])
.
-spec 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.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
-spec drawPolygon(This, Points) -> ok when This :: wxDC(), Points :: [{X :: integer(), Y :: integer()}].
Equivalent to drawPolygon(This, Points, [])
.
-spec 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.
-spec 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.
-spec 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.
-spec 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.
-spec 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.
-spec 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.
-spec 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.
-spec endDoc(This) -> ok when This :: wxDC().
Ends a document (only relevant when outputting to a printer).
-spec endPage(This) -> ok when This :: wxDC().
Ends a document page (only relevant when outputting to a printer).
-spec floodFill(This, Pt, Col) -> boolean() when This :: wxDC(), Pt :: {X :: integer(), Y :: integer()}, Col :: wx:wx_colour().
Equivalent to floodFill(This, Pt, Col, [])
.
-spec 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.
-spec getBackground(This) -> wxBrush:wxBrush() when This :: wxDC().
Gets the brush used for painting the background.
See: setBackground/2
Returns the current background mode: wxPENSTYLE\_SOLID
or wxPENSTYLE\_TRANSPARENT
.
See: setBackgroundMode/2
-spec getBrush(This) -> wxBrush:wxBrush() when This :: wxDC().
Gets the current brush.
See: setBrush/2
Gets the character height of the currently set font.
Gets the average character width of the currently set font.
-spec 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).
-spec 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.
-spec 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
-spec getLogicalFunction(This) -> wx:wx_enum() when This :: wxDC().
Gets the current logical function.
See: setLogicalFunction/2
-spec getMapMode(This) -> wx:wx_enum() when This :: wxDC().
Gets the current mapping mode for the device context.
See: setMapMode/2
-spec 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:
-spec 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:
-spec 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:
-spec getPen(This) -> wxPen:wxPen() when This :: wxDC().
Gets the current pen.
See: setPen/2
-spec 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.
Returns the resolution of the device in pixels per inch.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
-spec getTextBackground(This) -> wx:wx_colour4() when This :: wxDC().
Gets the current text background colour.
See: setTextBackground/2
-spec 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.
-spec 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:
-spec getTextForeground(This) -> wx:wx_colour4() when This :: wxDC().
Gets the current text foreground colour.
See: setTextForeground/2
Gets the current user scale factor.
See: setUserScale/3
-spec 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)
View Source-spec 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.
-spec gradientFillLinear(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().
Equivalent to gradientFillLinear(This, Rect, InitialColour, DestColour, [])
.
-spec 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.
Returns true if the DC is ok to use.
Converts logical X coordinate to device coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
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.
Converts logical Y coordinate to device coordinate, using the current mapping mode, user scale factor, device origin and axis orientation.
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.
Gets the maximum horizontal extent used in drawing commands so far.
Gets the maximum vertical extent used in drawing commands so far.
Gets the minimum horizontal extent used in drawing commands so far.
Gets the minimum vertical extent used in drawing commands so far.
-spec 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
-spec 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.
-spec setBackground(This, Brush) -> ok when This :: wxDC(), Brush :: wxBrush:wxBrush().
Sets the current background brush for the DC.
mode
may be one of wxPENSTYLE\_SOLID
and wxPENSTYLE\_TRANSPARENT
.
This setting determines whether text will be drawn with a background colour or not.
-spec 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:
-spec 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.
-spec 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.
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.
-spec 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
-spec setLayoutDirection(This, Dir) -> ok when This :: wxDC(), Dir :: wx:wx_enum().
Sets the current layout direction for the device context.
See: getLayoutDirection/1
-spec 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.
-spec 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.
-spec 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
-spec 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
-spec setTextBackground(This, Colour) -> ok when This :: wxDC(), Colour :: wx:wx_colour().
Sets the current text background colour for the DC.
-spec setTextForeground(This, Colour) -> ok when This :: wxDC(), Colour :: wx:wx_colour().
Sets the current text foreground colour for the DC.
See: wxMemoryDC
-spec setUserScale(This, XScale, YScale) -> ok when This :: wxDC(), XScale :: number(), YScale :: number().
Sets the user scaling factor, useful for applications which require 'zooming'.
-spec 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.
-spec startPage(This) -> ok when This :: wxDC().
Starts a document page (only relevant when outputting to a printer).