regenerated headers to remove @seealso in favour of @see; fixed links to global funct...

[wxWidgets.git] / interface / dc.h

/////////////////////////////////////////////////////////////////////////////
// Name:        dc.h
// Purpose:     interface of wxDC
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/**
    @class wxDC
    @wxheader{dc.h}

    A wxDC is a @e device context onto which graphics and text can be drawn.
    It is intended to represent a number of output devices in a generic way,
    so a window can have a device context associated with it, and a printer also
    has a device context.
    In this way, the same piece of code may write to a number of different devices,
    if the device context is used as a parameter.

    Notice that wxDC is an abstract base class and can't be created directly,
    please use wxPaintDC, wxClientDC,
    wxWindowDC, wxScreenDC,
    wxMemoryDC or wxPrinterDC.

    Please note that in addition to the versions of the methods documented here,
    there are also versions which accept single @c wxPoint parameter instead of
    two @c wxCoord ones or @c wxPoint and @c wxSize instead of four of
    them.

    @library{wxcore}
    @category{dc}

    @see Overview()
*/
class wxDC : public wxObject
{
public:
    /**
        Copy from a source DC to this DC, specifying the destination
        coordinates, size of area to copy, source DC, source coordinates,
        logical function, whether to use a bitmap mask, and mask source position.
        
        @param xdest
            Destination device context x position.
        @param ydest
            Destination device context y position.
        @param width
            Width of source area to be copied.
        @param height
            Height of source area to be copied.
        @param source
            Source device context.
        @param xsrc
            Source device context x position.
        @param ysrc
            Source device context y position.
        @param logicalFunc
            Logical function to use: see SetLogicalFunction().
        @param useMask
            If @true, Blit does a transparent blit using the mask that is associated
        with the bitmap
            selected into the source device context. The Windows implementation does
        the following if MaskBlt cannot be used:
        
        
             Creates a temporary bitmap and copies the destination area into it.
             Copies the source area into the temporary bitmap using the specified
        logical function.
             Sets the masked area in the temporary bitmap to BLACK by ANDing the
            mask bitmap with the temp bitmap with the foreground colour set to WHITE
            and the bg colour set to BLACK.
             Sets the unmasked area in the destination area to BLACK by ANDing the
            mask bitmap with the destination area with the foreground colour set to
        BLACK
            and the background colour set to WHITE.
             ORs the temporary bitmap with the destination area.
             Deletes the temporary bitmap.
        
        
            This sequence of operations ensures that the source's transparent area need
        not be black,
            and logical functions are supported.
            Note: on Windows, blitting with masks can be speeded up considerably by
        compiling
            wxWidgets with the wxUSE_DC_CACHE option enabled. You can also influence
        whether MaskBlt
            or the explicit mask blitting code above is used, by using wxSystemOptions
        and
            setting the no-maskblt option to 1.
        @param xsrcMask
            Source x position on the mask. If both xsrcMask and ysrcMask are -1, xsrc
        and ysrc
            will be assumed for the mask source position. Currently only implemented on
        Windows.
        @param ysrcMask
            Source y position on the mask. If both xsrcMask and ysrcMask are -1, xsrc
        and ysrc
            will be assumed for the mask source position. Currently only implemented on
        Windows.
        
        @remarks There is partial support for Blit in wxPostScriptDC, under X.
        
        @see StretchBlit(), wxMemoryDC, wxBitmap, wxMask
    */
    bool Blit(wxCoord xdest, wxCoord ydest, wxCoord width,
              wxCoord height, wxDC* source,
              wxCoord xsrc, wxCoord ysrc,
              int logicalFunc = wxCOPY,
              bool useMask = false,
              wxCoord xsrcMask = -1,
              wxCoord ysrcMask = -1);

    /**
        Adds the specified point to the bounding box which can be retrieved with
        MinX(), MaxX() and
        MinY(), MaxY() functions.
        
        @see ResetBoundingBox()
    */
    void CalcBoundingBox(wxCoord x, wxCoord y);

    /**
        Clears the device context using the current background brush.
    */
    void Clear();

    /**
        Performs all necessary computations for given platform and context type
        after each change of scale and origin parameters. Usually called automatically
        internally after such changes.
    */
    virtual void ComputeScaleAndOrigin();

    /**
        Displays a cross hair using the current pen. This is a vertical
        and horizontal line the height and width of the window, centred
        on the given point.
    */
    void CrossHair(wxCoord x, wxCoord y);

    /**
        Destroys the current clipping region so that none of the DC is clipped.
        See also SetClippingRegion().
    */
    void DestroyClippingRegion();

    /**
        Convert device X coordinate to logical coordinate, using the current
        mapping mode.
    */
    virtual wxCoord DeviceToLogicalX(wxCoord x);

    /**
        Convert device X coordinate to relative logical coordinate, using the current
        mapping mode but ignoring the x axis orientation.
        Use this function for converting a width, for example.
    */
    virtual wxCoord DeviceToLogicalXRel(wxCoord x);

    /**
        Converts device Y coordinate to logical coordinate, using the current
        mapping mode.
    */
    virtual wxCoord DeviceToLogicalY(wxCoord y);

    /**
        Convert device Y coordinate to relative logical coordinate, using the current
        mapping mode but ignoring the y axis orientation.
        Use this function for converting a height, for example.
    */
    virtual wxCoord DeviceToLogicalYRel(wxCoord y);

    /**
        Draws an arc of a circle, centred on (@e xc, yc), with starting point (@e x1,
        y1)
        and ending at (@e x2, y2).   The current pen is used for the outline
        and the current brush for filling the shape.
        The arc is drawn in an anticlockwise direction from the start point to the end
        point.
    */
    void DrawArc(wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2,
                 wxCoord xc, wxCoord yc);

    /**
        Draw a bitmap on the device context at the specified point. If @a transparent
        is @true and the bitmap has
        a transparency mask, the bitmap will be drawn transparently.
        When drawing a mono-bitmap, the current text foreground colour will be used to
        draw the foreground
        of the bitmap (all bits set to 1), and the current text background colour to
        draw the background
        (all bits set to 0). See also SetTextForeground(),
        SetTextBackground() and wxMemoryDC.
    */
    void DrawBitmap(const wxBitmap& bitmap, wxCoord x, wxCoord y,
                    bool transparent);

    //@{
    /**
        Draws a check mark inside the given rectangle.
    */
    void DrawCheckMark(wxCoord x, wxCoord y, wxCoord width,
                       wxCoord height);
    void DrawCheckMark(const wxRect& rect);
    //@}

    //@{
    /**
        Draws a circle with the given centre and radius.
        
        @see DrawEllipse()
    */
    void DrawCircle(wxCoord x, wxCoord y, wxCoord radius);
    void DrawCircle(const wxPoint& pt, wxCoord radius);
    //@}

    //@{
    /**
        Draws an ellipse contained in the rectangle specified either with the given top
        left corner and the given size or directly. The current pen is used for the
        outline and the current brush for filling the shape.
        
        @see DrawCircle()
    */
    void DrawEllipse(wxCoord x, wxCoord y, wxCoord width,
                     wxCoord height);
    void DrawEllipse(const wxPoint& pt, const wxSize& size);
    void DrawEllipse(const wxRect& rect);
    //@}

    /**
        Draws an arc of an ellipse. The current pen is used for drawing the arc and
        the current brush is used for drawing the pie.
        @a x and @a y specify the x and y coordinates of the upper-left corner of the
        rectangle that contains
        the ellipse.
        @a width and @a height specify the width and height of the rectangle that
        contains
        the ellipse.
        @a start and @a end specify the start and end of the arc relative to the
        three-o'clock
        position from the center of the rectangle. Angles are specified
        in degrees (360 is a complete circle). Positive values mean
        counter-clockwise motion. If @a start is equal to @e end, a
        complete ellipse will be drawn.
    */
    void DrawEllipticArc(wxCoord x, wxCoord y, wxCoord width,
                         wxCoord height,
                         double start,
                         double end);

    /**
        Draw an icon on the display (does nothing if the device context is PostScript).
        This can be the simplest way of drawing bitmaps on a window.
    */
    void DrawIcon(const wxIcon& icon, wxCoord x, wxCoord y);

    //@{
    /**
        Draw optional bitmap and the text into the given rectangle and aligns it as
        specified
        by alignment parameter; it also will emphasize the character with the given
        index if
        it is != -1 and return the bounding rectangle if required.
    */
    virtual void DrawLabel(const wxString& text,
                           const wxBitmap& image,
                           const wxRect& rect,
                           int alignment = wxALIGN_LEFT | wxALIGN_TOP,
                           int indexAccel = -1,
                           wxRect* rectBounding = NULL);
    void DrawLabel(const wxString& text, const wxRect& rect,
                   int alignment = wxALIGN_LEFT | wxALIGN_TOP,
                   int indexAccel = -1);
    //@}

    /**
        Draws a line from the first point to the second. The current pen is used
        for drawing the line. Note that the point (x2, y2) is not part of the
        line and is not drawn by this function (this is consistent with the behaviour
        of many other toolkits).
    */
    void DrawLine(wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2);

    //@{
    /**
        This method uses a list of wxPoints, adding the optional offset
        coordinate. The programmer is responsible for deleting the list
        of points.
    */
    void DrawLines(int n, wxPoint points[], wxCoord xoffset = 0,
                   wxCoord yoffset = 0);
    void DrawLines(const wxPointList* points,
                   wxCoord xoffset = 0,
                   wxCoord yoffset = 0);
    //@}

    /**
        Draws a point using the color of the current pen. Note that the other
        properties of the pen are not used, such as width etc..
    */
    void DrawPoint(wxCoord x, wxCoord y);

    /**
        Draws two or more filled polygons using an array of @e points, adding the
        optional offset coordinates.
        Notice that for the platforms providing a native implementation
        of this function (Windows and PostScript-based wxDC currently), this is more
        efficient than using DrawPolygon() in a loop.
        @a n specifies the number of polygons to draw, the array @e count of size
        @a n specifies the number of points in each of the polygons in the
        @e points array.
        The last argument specifies the fill rule: @b wxODDEVEN_RULE (the default)
        or @b 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.
        The polygons maybe disjoint or overlapping. Each polygon specified in a call to
        @b DrawPolyPolygon must be closed. Unlike polygons created by the
        DrawPolygon() member function, the polygons created by
        @b DrawPolyPolygon are not closed automatically.
    */
    void DrawPolyPolygon(int n, int count[], wxPoint points[],
                         wxCoord xoffset = 0,
                         wxCoord yoffset = 0,
                         int fill_style = wxODDEVEN_RULE);

    //@{
    /**
        This method draws a filled polygon using a list of wxPoints,
        adding the optional offset coordinate.
        The last argument specifies the fill rule: @b wxODDEVEN_RULE (the
        default) or @b 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.
        The programmer is responsible for deleting the list of points.
        Note that wxWidgets automatically closes the first and last points.
    */
    void DrawPolygon(int n, wxPoint points[], wxCoord xoffset = 0,
                     wxCoord yoffset = 0,
                     int fill_style = wxODDEVEN_RULE);
    void DrawPolygon(const wxPointList* points,
                     wxCoord xoffset = 0,
                     wxCoord yoffset = 0,
                     int fill_style = wxODDEVEN_RULE);
    //@}

    /**
        Draws a rectangle with the given top left corner, and with the given
        size.  The current pen is used for the outline and the current brush
        for filling the shape.
    */
    void DrawRectangle(wxCoord x, wxCoord y, wxCoord width,
                       wxCoord height);

    /**
        Draws the text rotated by @a angle degrees.
        @b NB: Under Win9x only TrueType fonts can be drawn by this function. In
        particular, a font different from @c wxNORMAL_FONT should be used as the
        latter is not a TrueType font. @c wxSWISS_FONT is an example of a font
        which is.
        
        @see DrawText()
    */
    void DrawRotatedText(const wxString& text, wxCoord x, wxCoord y,
                         double angle);

    /**
        Draws a rectangle with the given top left corner, and with the given
        size.  The corners are quarter-circles using the given radius. The
        current pen is used for the outline and the current brush for filling
        the shape.
        If @a radius is positive, the value is assumed to be the
        radius of the rounded corner. If @a radius is negative,
        the absolute value is assumed to be the @e proportion of the smallest
        dimension of the rectangle. This means that the corner can be
        a sensible size relative to the size of the rectangle, and also avoids
        the strange effects X produces when the corners are too big for
        the rectangle.
    */
    void DrawRoundedRectangle(wxCoord x, wxCoord y, wxCoord width,
                              wxCoord height,
                              double radius);

    //@{
    /**
        Draws a three-point spline using the current pen.
    */
    void DrawSpline(int n, wxPoint points[]);
    void DrawSpline(const wxPointList* points);
    void DrawSpline(wxCoord x1, wxCoord y1, wxCoord x2,
                    wxCoord y2,
                    wxCoord x3,
                    wxCoord y3);
    //@}

    /**
        Draws a text string at the specified point, using the current text font,
        and the current text foreground and background colours.
        The coordinates refer to the top-left corner of the rectangle bounding
        the string. See GetTextExtent() for how
        to get the dimensions of a text string, which can be used to position the
        text more precisely.
        @b NB: under wxGTK the current
        @ref getlogicalfunction() "logical function" is used by this function
        but it is ignored by wxMSW. Thus, you should avoid using logical functions
        with this function in portable programs.
    */
    void DrawText(const wxString& text, wxCoord x, wxCoord y);

    /**
        Ends a document (only relevant when outputting to a printer).
    */
    void EndDoc();

    /**
        Ends a document page (only relevant when outputting to a printer).
    */
    void EndPage();

    /**
        Flood fills the device context starting from the given point, using
        the @e current brush colour, and using a style:
         wxFLOOD_SURFACE: the flooding occurs until a colour other than the given
        colour is encountered.
         wxFLOOD_BORDER: the area to be flooded is bounded by the given colour.
        Returns @false if the operation failed.
        @e Note: The present implementation for non-Windows platforms may fail to find
        colour borders if the pixels do not match the colour exactly. However the
        function will still return @true.
    */
    bool FloodFill(wxCoord x, wxCoord y, const wxColour& colour,
                   int style = wxFLOOD_SURFACE);

    /**
        Gets the brush used for painting the background (see wxDC::SetBackground).
    */
    const wxBrush GetBackground() const;

    /**
        Returns the current background mode: @c wxSOLID or @c wxTRANSPARENT.
        
        @see SetBackgroundMode()
    */
    int GetBackgroundMode() const;

    /**
        Gets the current brush (see wxDC::SetBrush).
    */
    const wxBrush GetBrush() const;

    /**
        Gets the character height of the currently set font.
    */
    wxCoord GetCharHeight();

    /**
        Gets the average character width of the currently set font.
    */
    wxCoord GetCharWidth();

    /**
        Gets the rectangle surrounding the current clipping region.
    */
    void GetClippingBox(wxCoord x, wxCoord y, wxCoord width,
                        wxCoord height);

    /**
        Returns the depth (number of bits/pixel) of this DC.
        
        @see wxDisplayDepth()
    */
    int GetDepth() const;

    /**
        Gets the current font. Notice that even although each device context object has
        some default font after creation, this method would return a @c wxNullFont
        initially and only after calling SetFont() a valid
        font is returned.
    */
    const wxFont GetFont() const;

    /**
        Gets the current layout direction of the device context. On platforms where RTL
        layout
        is supported, the return value will either be @c wxLayout_LeftToRight or
        @c wxLayout_RightToLeft. If RTL layout is not supported, the return value will
        be @c wxLayout_Default.
        
        @see SetLayoutDirection()
    */
    wxLayoutDirection GetLayoutDirection() const;

    /**
        Gets the current logical function (see wxDC::SetLogicalFunction).
    */
    int GetLogicalFunction();

    /**
        Gets the @e mapping mode for the device context (see wxDC::SetMapMode).
    */
    int GetMapMode();

    //@{
    /**
        Gets the dimensions of the string using the currently selected font.
        @a string is the text string to measure, @e heightLine, if non @NULL,
        is where to store the height of a single line.
        The text extent is returned in @a w and @a h pointers (first form) or as
        a wxSize object (second form).
        If the optional parameter @a font is specified and valid, then it is used
        for the text extent calculation. Otherwise the currently selected font is.
        Note that this function works both with single-line and multi-line strings.
        
        @see wxFont, SetFont(), GetPartialTextExtents(), GetTextExtent()
    */
    void GetMultiLineTextExtent(const wxString& string, wxCoord* w,
                                wxCoord* h,
                                wxCoord* heightLine = NULL,
                                wxFont* font = NULL) const;
    const wxSize  GetMultiLineTextExtent(const wxString& string) const;
    //@}

    /**
        Returns the resolution of the device in pixels per inch.
    */
    wxSize GetPPI() const;

    /**
        Fills the @a widths array with the widths from the beginning of
        @a text to the corresponding character of @e text.  The generic
        version simply builds a running total of the widths of each character
        using GetTextExtent(), 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(), GetTextExtent()
    */
    bool GetPartialTextExtents(const wxString& text,
                               wxArrayInt& widths) const;

    /**
        Gets the current pen (see wxDC::SetPen).
    */
    const wxPen GetPen() const;

    /**
        Gets in @a colour the colour at the specified location.
        Not available for wxPostScriptDC or wxMetafileDC.
        Note that setting a pixel can be done using DrawPoint().
    */
    bool GetPixel(wxCoord x, wxCoord y, wxColour* colour);

    //@{
    /**
        This gets the horizontal and vertical resolution in device units. It can be
        used to scale graphics to fit the page.
        For example, if @e maxX and @e maxY
        represent the maximum horizontal and vertical 'pixel' values used in your
        application, the following code will scale the graphic to fit on the
        printer page:
        
        
        @b GetSize()
        
        Returns a Wx::Size
        
        @b GetSizeWH()
        
        Returns a 2-element list
          @c ( width, height )
    */
    void GetSize(wxCoord* width, wxCoord* height) const;
    const wxSize  GetSize() const;
    //@}

    //@{
    /**
        Returns the horizontal and vertical resolution in millimetres.
    */
    void GetSizeMM(wxCoord* width, wxCoord* height) const;
    const wxSize  GetSizeMM() const;
    //@}

    /**
        Gets the current text background colour (see wxDC::SetTextBackground).
    */
    const wxColour GetTextBackground() const;

    //@{
    /**
        Gets the dimensions of the string using the currently selected font.
        @a string is the text string to measure, @a descent is the
        dimension from the baseline of the font to the bottom of the
        descender, and @a externalLeading is any extra vertical space added
        to the font by the font designer (usually is zero).
        The text extent is returned in @a w and @a h pointers (first form) or as
        a wxSize object (second form).
        If the optional parameter @a font is specified and valid, then it is used
        for the text extent calculation. Otherwise the currently selected font is.
        Note that this function only works with single-line strings.
        
        @see wxFont, SetFont(), GetPartialTextExtents(),
             GetMultiLineTextExtent()
    */
    void GetTextExtent(const wxString& string, wxCoord* w,
                       wxCoord* h,
                       wxCoord* descent = NULL,
                       wxCoord* externalLeading = NULL,
                       const wxFont* font = NULL) const;
    const wxSize  GetTextExtent(const wxString& string) const;
    //@}

    /**
        Gets the current text foreground colour (see wxDC::SetTextForeground).
    */
    const wxColour GetTextForeground() const;

    /**
        Gets the current user scale factor (set by wxDC::SetUserScale).
    */
    void GetUserScale(double x, double y);

    //@{
    /**
        Fill the area specified by rect with a radial gradient, starting from
        @a initialColour at the centre of the circle and fading to @a destColour
        on the circle outside.
        @a circleCenter are the relative coordinates of centre of the circle in
        the specified @e rect. If not specified, the cercle is placed at the
        centre of rect.
        @b Note: Currently this function is very slow, don't use it for
        real-time drawing.
    */
    void GradientFillConcentric(const wxRect& rect,
                                const wxColour& initialColour,
                                const wxColour& destColour);
    void GradientFillConcentric(const wxRect& rect,
                                const wxColour& initialColour,
                                const wxColour& destColour,
                                const wxPoint& circleCenter);
    //@}

    /**
        Fill the area specified by @a rect with a linear gradient, starting from
        @a initialColour and eventually fading to @e destColour. The
        @a nDirection specifies the direction of the colour change, default is to
        use @a initialColour on the left part of the rectangle and
        @a destColour on the right one.
    */
    void GradientFillLinear(const wxRect& rect,
                            const wxColour& initialColour,
                            const wxColour& destColour,
                            wxDirection nDirection = wxEAST);

    /**
        Returns @true if the DC is ok to use.
    */
    bool Ok();

    /**
        Converts logical X coordinate to device coordinate, using the current
        mapping mode.
    */
    virtual wxCoord LogicalToDeviceX(wxCoord x);

    /**
        Converts logical X coordinate to relative device coordinate, using the current
        mapping mode but ignoring the x axis orientation.
        Use this for converting a width, for example.
    */
    virtual wxCoord LogicalToDeviceXRel(wxCoord x);

    /**
        Converts logical Y coordinate to device coordinate, using the current
        mapping mode.
    */
    virtual wxCoord LogicalToDeviceY(wxCoord y);

    /**
        Converts logical Y coordinate to relative device coordinate, using the current
        mapping mode but ignoring the y axis orientation.
        Use this for converting a height, for example.
    */
    virtual wxCoord LogicalToDeviceYRel(wxCoord y);

    /**
        Gets the maximum horizontal extent used in drawing commands so far.
    */
    wxCoord MaxX();

    /**
        Gets the maximum vertical extent used in drawing commands so far.
    */
    wxCoord MaxY();

    /**
        Gets the minimum horizontal extent used in drawing commands so far.
    */
    wxCoord MinX();

    /**
        Gets the minimum vertical extent used in drawing commands so far.
    */
    wxCoord MinY();

    /**
        Resets the bounding box: after a call to this function, the bounding box
        doesn't contain anything.
        
        @see CalcBoundingBox()
    */
    void ResetBoundingBox();

    /**
        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.
        
        @param xLeftRight
            True to set the x axis orientation to the natural
            left to right orientation, @false to invert it.
        @param yBottomUp
            True to set the y axis orientation to the natural
            bottom up orientation, @false to invert it.
    */
    void SetAxisOrientation(bool xLeftRight, bool yBottomUp);

    /**
        Sets the current background brush for the DC.
    */
    void SetBackground(const wxBrush& brush);

    /**
        @a mode may be one of wxSOLID and wxTRANSPARENT. This setting determines
        whether text will be drawn with a background colour or not.
    */
    void SetBackgroundMode(int mode);

    /**
        Sets the current brush for the DC.
        If the argument is wxNullBrush, 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 also wxBrush.
        See also wxMemoryDC for the interpretation of colours
        when drawing into a monochrome bitmap.
    */
    void SetBrush(const wxBrush& brush);

    //@{
    /**
        Sets the clipping region for this device context to the intersection of the
        given region described by the parameters of this method and the previously set
        clipping region. You should call
        DestroyClippingRegion() if you want to set
        the clipping region exactly to the region specified.
        The clipping region is an area to which drawing is restricted. Possible uses
        for the clipping region are for clipping text or for speeding up window redraws
        when only a known area of the screen is damaged.
        
        @see DestroyClippingRegion(), wxRegion
    */
    void SetClippingRegion(wxCoord x, wxCoord y, wxCoord width,
                           wxCoord height);
    void SetClippingRegion(const wxPoint& pt, const wxSize& sz);
    void SetClippingRegion(const wxRect& rect);
    void SetClippingRegion(const wxRegion& region);
    //@}

    /**
        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.
    */
    void SetDeviceOrigin(wxCoord x, wxCoord y);

    /**
        Sets the current font for the DC. It must be a valid font, in particular you
        should not pass @c wxNullFont to this method.
        See also wxFont.
    */
    void SetFont(const wxFont& font);

    /**
        Sets the current layout direction for the device context. @a dir may be either
        @c wxLayout_Default, @c wxLayout_LeftToRight or @c wxLayout_RightToLeft.
        
        @see GetLayoutDirection()
    */
    void SetLayoutDirection(wxLayoutDirection dir);

    /**
        Sets the current logical function for the device context.  This determines how
        a source pixel (from a pen or brush colour, or source device context if
        using wxDC::Blit) combines with a destination pixel in the
        current device context.
        The possible values
        and their meaning in terms of source and destination pixel values are
        as follows:
        
        The default is wxCOPY, which simply draws with the current colour.
        The others combine the current colour and the background using a
        logical operation.  wxINVERT is commonly used for drawing rubber bands or
        moving outlines, since drawing twice reverts to the original colour.
    */
    void SetLogicalFunction(int function);

    /**
        The @e 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 @e user scale (see
        wxDC::SetUserScale) 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.
        The mapping mode can be one of the following:
        
        wxMM_TWIPS
        
        Each logical unit is 1/20 of a point, or 1/1440 of
          an inch.
        
        wxMM_POINTS
        
        Each logical unit is a point, or 1/72 of an inch.
        
        wxMM_METRIC
        
        Each logical unit is 1 mm.
        
        wxMM_LOMETRIC
        
        Each logical unit is 1/10 of a mm.
        
        wxMM_TEXT
        
        Each logical unit is 1 device pixel.
    */
    void SetMapMode(int int);

    /**
        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 for further details.
    */
    void SetPalette(const wxPalette& palette);

    /**
        Sets the current pen for the DC.
        If the argument is wxNullPen, the current pen is selected out of the device
        context (leaving wxDC without any valid pen), allowing the current brush to
        be destroyed safely.
        See also wxMemoryDC for the interpretation of colours
        when drawing into a monochrome bitmap.
    */
    void SetPen(const wxPen& pen);

    /**
        Sets the current text background colour for the DC.
    */
    void SetTextBackground(const wxColour& colour);

    /**
        Sets the current text foreground colour for the DC.
        See also wxMemoryDC for the interpretation of colours
        when drawing into a monochrome bitmap.
    */
    void SetTextForeground(const wxColour& colour);

    /**
        Sets the user scaling factor, useful for applications which require
        'zooming'.
    */
    void SetUserScale(double xScale, double yScale);

    /**
        Starts a document (only relevant when outputting to a printer).
        Message is a message to show while printing.
    */
    bool StartDoc(const wxString& message);

    /**
        Starts a document page (only relevant when outputting to a printer).
    */
    bool StartPage();

    /**
        Copy from a source DC to this DC, specifying the destination
        coordinates, destination size, source DC, source coordinates,
        size of source area to copy, logical function, whether to use a bitmap mask,
        and mask source position.
        
        @param xdest
            Destination device context x position.
        @param ydest
            Destination device context y position.
        @param dstWidth
            Width of destination area.
        @param dstHeight
            Height of destination area.
        @param source
            Source device context.
        @param xsrc
            Source device context x position.
        @param ysrc
            Source device context y position.
        @param srcWidth
            Width of source area to be copied.
        @param srcHeight
            Height of source area to be copied.
        @param logicalFunc
            Logical function to use: see SetLogicalFunction().
        @param useMask
            If @true, Blit does a transparent blit using the mask that is associated
        with the bitmap
            selected into the source device context. The Windows implementation does
        the following if MaskBlt cannot be used:
        
        
             Creates a temporary bitmap and copies the destination area into it.
             Copies the source area into the temporary bitmap using the specified
        logical function.
             Sets the masked area in the temporary bitmap to BLACK by ANDing the
            mask bitmap with the temp bitmap with the foreground colour set to WHITE
            and the background colour set to BLACK.
             Sets the unmasked area in the destination area to BLACK by ANDing the
            mask bitmap with the destination area with the foreground colour set to
        BLACK
            and the background colour set to WHITE.
             ORs the temporary bitmap with the destination area.
             Deletes the temporary bitmap.
        
        
            This sequence of operations ensures that the source's transparent area need
        not be black,
            and logical functions are supported.
            Note: on Windows, blitting with masks can be speeded up considerably by
        compiling
            wxWidgets with the wxUSE_DC_CACHE option enabled. You can also influence
        whether MaskBlt
            or the explicit mask blitting code above is used, by using wxSystemOptions
        and
            setting the no-maskblt option to 1.
        @param xsrcMask
            Source x position on the mask. If both xsrcMask and ysrcMask are -1, xsrc
        and ysrc
            will be assumed for the mask source position. Currently only implemented on
        Windows.
        @param ysrcMask
            Source y position on the mask. If both xsrcMask and ysrcMask are -1, xsrc
        and ysrc
            will be assumed for the mask source position. Currently only implemented on
        Windows.
        
        @remarks There is partial support for Blit in wxPostScriptDC, under X.
    */
    bool StretchBlit(wxCoord xdest, wxCoord ydest, wxCoord dstWidth,
                     wxCoord dstHeight,
                     wxDC* source, wxCoord xsrc,
                     wxCoord ysrc,
                     wxCoord srcWidth,
                     wxCoord srcHeight,
                     int logicalFunc = wxCOPY,
                     bool useMask = false,
                     wxCoord xsrcMask = -1,
                     wxCoord ysrcMask = -1);
};



/**
    @class wxDCClipper
    @wxheader{dc.h}

    wxDCClipper is a small helper class for setting a clipping region on a
    wxDC and unsetting it automatically. An object of wxDCClipper
    class is typically created on the stack so that it is automatically destroyed
    when the object goes out of scope. A typical usage example:

    @code
    void MyFunction(wxDC& dc)
        {
            wxDCClipper clip(rect);
            ... drawing functions here are affected by clipping rect ...
        }

        void OtherFunction()
        {
            wxDC dc;
            MyFunction(dc);
            ... drawing functions here are not affected by clipping rect ...
        }
    @endcode

    @library{wxcore}
    @category{gdi}

    @see wxDC::SetClippingRegion
*/
class wxDCClipper
{
public:
    //@{
    /**
        Sets the clipping region to the specified region @a r or rectangle specified
        by either a single @a rect parameter or its position (@a x and @e y)
        and size (@a w ad @e h).
        The clipping region is automatically unset when this object is destroyed.
    */
    wxDCClipper(wxDC& dc, const wxRegion& r);
    wxDCClipper(wxDC& dc, const wxRect& rect);
    wxDCClipper(wxDC& dc, int x, int y, int w, int h);
    //@}
};