wxErlang

Reference Manual

Version 2.0

Table of Contents

wxGraphicsContext

Module

wxGraphicsContext

Module Summary

Functions for wxGraphicsContext class

Description

A wxGraphicsContext instance is the object that is drawn upon. It is created by a renderer using wxGraphicsRenderer:createContext/2. This can be either directly using a renderer instance, or indirectly using the static convenience create/1 functions of wxGraphicsContext that always delegate the task to the default renderer.

Remark: For some renderers (like Direct2D or Cairo) processing of drawing operations may be deferred (Direct2D render target normally builds up a batch of rendering commands but defers processing of these commands, Cairo operates on a separate surface) so to make drawing results visible you need to update the content of the context by calling wxGraphicsContext::Flush() (not implemented in wx) or by destroying the context.

See: wxGraphicsRenderer:createContext/2, wxGCDC, wxDC

This class is derived (and can use functions) from: wxGraphicsObject

wxWidgets docs: wxGraphicsContext

Data Types

wxGraphicsContext() = wx:wx_object()

Exports

destroy(This :: wxGraphicsContext()) -> ok

Creates a wxGraphicsContext from a wxWindow.

See: wxGraphicsRenderer:createContext/2

create() -> wxGraphicsContext()

Create a lightweight context that can be used only for measuring text.

create(WindowDC) -> wxGraphicsContext()

Types

WindowDC =
    wxWindowDC:wxWindowDC() |
    wxWindow:wxWindow() |
    wxMemoryDC:wxMemoryDC() |
    wxImage:wxImage()

Creates a wxGraphicsContext from a wxWindowDC.

See: wxGraphicsRenderer:createContext/2

createPen(This, Pen) -> wxGraphicsPen:wxGraphicsPen()

Types

This = wxGraphicsContext()
Pen = wxPen:wxPen()

Creates a native pen from a wxPen.

Prefer to use the overload taking wxGraphicsPenInfo (not implemented in wx) unless you already have a wxPen as constructing one only to pass it to this method is wasteful.

createBrush(This, Brush) -> wxGraphicsBrush:wxGraphicsBrush()

Types

This = wxGraphicsContext()
Brush = wxBrush:wxBrush()

Creates a native brush from a wxBrush.

createRadialGradientBrush(This, StartX, StartY, EndX, EndY,
                          Radius, Stops) ->
                             wxGraphicsBrush:wxGraphicsBrush()

Types

This = wxGraphicsContext()
StartX = StartY = EndX = EndY = Radius = number()
Stops = wxGraphicsGradientStops:wxGraphicsGradientStops()

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

createRadialGradientBrush(This, StartX, StartY, EndX, EndY,
                          Radius, OColor, CColor) ->
                             wxGraphicsBrush:wxGraphicsBrush()

Types

This = wxGraphicsContext()
StartX = StartY = EndX = EndY = Radius = number()
OColor = CColor = wx:wx_colour()

Creates a native brush with a radial gradient. The brush originates at (@a startX, @a startY) and ends on a circle around (@a endX, @a endY) with the given @a radius. The gradient may be specified either by its start and end colours @a oColor and @a cColor or by a full set of gradient @a stops. The version taking wxGraphicsGradientStops is new in wxWidgets 2.9.1.

The ability to apply a transformation matrix to the gradient was added in 3.1.3

createLinearGradientBrush(This, X1, Y1, X2, Y2, Stops) ->
                             wxGraphicsBrush:wxGraphicsBrush()

Types

This = wxGraphicsContext()
X1 = Y1 = X2 = Y2 = number()
Stops = wxGraphicsGradientStops:wxGraphicsGradientStops()

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

createLinearGradientBrush(This, X1, Y1, X2, Y2, C1, C2) ->
                             wxGraphicsBrush:wxGraphicsBrush()

Types

This = wxGraphicsContext()
X1 = Y1 = X2 = Y2 = number()
C1 = C2 = wx:wx_colour()

Creates a native brush with a linear gradient. The brush starts at (@a x1, @a y1) and ends at (@a x2, @a y2). Either just the start and end gradient colours (@a c1 and @a c2) or full set of gradient @a stops can be specified. The version taking wxGraphicsGradientStops is new in wxWidgets 2.9.1.

The matrix parameter was added in wxWidgets 3.1.3

createFont(This, Font) -> wxGraphicsFont:wxGraphicsFont()

Types

This = wxGraphicsContext()
Font = wxFont:wxFont()
createFont(This, SizeInPixels, Facename) ->
              wxGraphicsFont:wxGraphicsFont()
createFont(This, Font, Facename :: [Option]) ->
              wxGraphicsFont:wxGraphicsFont()

Types

This = wxGraphicsContext()
Font = wxFont:wxFont()
Option = {col, wx:wx_colour()}

Creates a native graphics font from a wxFont and a text colour.

Remark: For Direct2D graphics fonts can be created from TrueType fonts only.

createFont(This, SizeInPixels, Facename, Options :: [Option]) ->
              wxGraphicsFont:wxGraphicsFont()

Types

This = wxGraphicsContext()
SizeInPixels = number()
Facename = unicode:chardata()
Option = {flags, integer()} | {col, wx:wx_colour()}

Creates a font object with the specified attributes.

The use of overload taking wxFont is preferred, see wxGraphicsRenderer:createFont/4 for more details.

Remark: For Direct2D graphics fonts can be created from TrueType fonts only.

Since: 2.9.3

createMatrix(This) -> wxGraphicsMatrix:wxGraphicsMatrix()

Types

This = wxGraphicsContext()
createMatrix(This, Options :: [Option]) ->
                wxGraphicsMatrix:wxGraphicsMatrix()

Types

This = wxGraphicsContext()
Option =
    {a, number()} |
    {b, number()} |
    {c, number()} |
    {d, number()} |
    {tx, number()} |
    {ty, number()}

Creates a native affine transformation matrix from the passed in values.

The default parameters result in an identity matrix.

createPath(This) -> wxGraphicsPath:wxGraphicsPath()

Types

This = wxGraphicsContext()

Creates a native graphics path which is initially empty.

clip(This, Region) -> ok

Types

This = wxGraphicsContext()
Region = wxRegion:wxRegion()

Sets the clipping region to the intersection of the given region and the previously set clipping region.

The clipping region is an area to which drawing is restricted.

Remark:

clip(This, X, Y, W, H) -> ok

Types

This = wxGraphicsContext()
X = Y = W = H = number()

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

resetClip(This) -> ok

Types

This = wxGraphicsContext()

Resets the clipping to original shape.

drawBitmap(This, Bmp, X, Y, W, H) -> ok

Types

This = wxGraphicsContext()
Bmp = wxBitmap:wxBitmap()
X = Y = W = H = number()

Draws the bitmap.

In case of a mono bitmap, this is treated as a mask and the current brushed is used for filling.

drawEllipse(This, X, Y, W, H) -> ok

Types

This = wxGraphicsContext()
X = Y = W = H = number()

Draws an ellipse.

drawIcon(This, Icon, X, Y, W, H) -> ok

Types

This = wxGraphicsContext()
Icon = wxIcon:wxIcon()
X = Y = W = H = number()

Draws the icon.

drawLines(This, Points) -> ok

Types

This = wxGraphicsContext()
Points = [{X :: float(), Y :: float()}]
drawLines(This, Points, Options :: [Option]) -> ok

Types

This = wxGraphicsContext()
Points = [{X :: float(), Y :: float()}]
Option = {fillStyle, wx:wx_enum()}

Draws a polygon.

drawPath(This, Path) -> ok

Types

This = wxGraphicsContext()
Path = wxGraphicsPath:wxGraphicsPath()
drawPath(This, Path, Options :: [Option]) -> ok

Types

This = wxGraphicsContext()
Path = wxGraphicsPath:wxGraphicsPath()
Option = {fillStyle, wx:wx_enum()}

Draws the path by first filling and then stroking.

drawRectangle(This, X, Y, W, H) -> ok

Types

This = wxGraphicsContext()
X = Y = W = H = number()

Draws a rectangle.

drawRoundedRectangle(This, X, Y, W, H, Radius) -> ok

Types

This = wxGraphicsContext()
X = Y = W = H = Radius = number()

Draws a rounded rectangle.

drawText(This, Str, X, Y) -> ok

Types

This = wxGraphicsContext()
Str = unicode:chardata()
X = Y = number()

Draws text at the defined position.

drawText(This, Str, X, Y, Angle) -> ok
drawText(This, Str, X, Y, BackgroundBrush) -> ok

Types

This = wxGraphicsContext()
Str = unicode:chardata()
X = Y = number()
BackgroundBrush = wxGraphicsBrush:wxGraphicsBrush()

Draws text at the defined position.

drawText(This, Str, X, Y, Angle, BackgroundBrush) -> ok

Types

This = wxGraphicsContext()
Str = unicode:chardata()
X = Y = Angle = number()
BackgroundBrush = wxGraphicsBrush:wxGraphicsBrush()

Draws text at the defined position.

fillPath(This, Path) -> ok

Types

This = wxGraphicsContext()
Path = wxGraphicsPath:wxGraphicsPath()
fillPath(This, Path, Options :: [Option]) -> ok

Types

This = wxGraphicsContext()
Path = wxGraphicsPath:wxGraphicsPath()
Option = {fillStyle, wx:wx_enum()}

Fills the path with the current brush.

strokePath(This, Path) -> ok

Types

This = wxGraphicsContext()
Path = wxGraphicsPath:wxGraphicsPath()

Strokes along a path with the current pen.

getPartialTextExtents(This, Text) -> [number()]

Types

This = wxGraphicsContext()
Text = unicode:chardata()

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

getTextExtent(This, Text) -> Result

Types

Result =
    {Width :: number(),
     Height :: number(),
     Descent :: number(),
     ExternalLeading :: number()}
This = wxGraphicsContext()
Text = unicode:chardata()

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

rotate(This, Angle) -> ok

Types

This = wxGraphicsContext()
Angle = number()

Rotates the current transformation matrix (in radians).

scale(This, XScale, YScale) -> ok

Types

This = wxGraphicsContext()
XScale = YScale = number()

Scales the current transformation matrix.

translate(This, Dx, Dy) -> ok

Types

This = wxGraphicsContext()
Dx = Dy = number()

Translates the current transformation matrix.

getTransform(This) -> wxGraphicsMatrix:wxGraphicsMatrix()

Types

This = wxGraphicsContext()

Gets the current transformation matrix of this context.

setTransform(This, Matrix) -> ok

Types

This = wxGraphicsContext()
Matrix = wxGraphicsMatrix:wxGraphicsMatrix()

Sets the current transformation matrix of this context.

concatTransform(This, Matrix) -> ok

Types

This = wxGraphicsContext()
Matrix = wxGraphicsMatrix:wxGraphicsMatrix()

Concatenates the passed in transform with the current transform of this context.

setBrush(This, Brush) -> ok

Types

This = wxGraphicsContext()
Brush = wxGraphicsBrush:wxGraphicsBrush() | wxBrush:wxBrush()

Sets the brush for filling paths.

setFont(This, Font) -> ok

Types

This = wxGraphicsContext()
Font = wxGraphicsFont:wxGraphicsFont()

Sets the font for drawing text.

setFont(This, Font, Colour) -> ok

Types

This = wxGraphicsContext()
Font = wxFont:wxFont()
Colour = wx:wx_colour()

Sets the font for drawing text.

Remark: For Direct2D only TrueType fonts can be used.

setPen(This, Pen) -> ok

Types

This = wxGraphicsContext()
Pen = wxPen:wxPen() | wxGraphicsPen:wxGraphicsPen()

Sets the pen used for stroking.

strokeLine(This, X1, Y1, X2, Y2) -> ok

Types

This = wxGraphicsContext()
X1 = Y1 = X2 = Y2 = number()

Strokes a single line.

strokeLines(This, Points) -> ok

Types

This = wxGraphicsContext()
Points = [{X :: float(), Y :: float()}]

Stroke lines connecting all the points.

Unlike the other overload of this function, this method draws a single polyline and not a number of disconnected lines.

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