wxWidgets/interface/wx/colour.h

/////////////////////////////////////////////////////////////////////////////
// Name:        colour.h
// Purpose:     interface of wxColour
// Author:      wxWidgets team
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////



/**
    Flags for wxColour -> wxString conversion (see wxColour::GetAsString).
*/
///@{
enum {
    wxC2S_NAME             = 1,   // return colour name, when possible
    wxC2S_CSS_SYNTAX       = 2,   // return colour in rgb(r,g,b) syntax
    wxC2S_HTML_SYNTAX      = 4    // return colour in #rrggbb syntax
};

///@}

const unsigned char wxALPHA_TRANSPARENT = 0;
const unsigned char wxALPHA_OPAQUE = 0xff;

/**
    @class wxColour

    A colour is an object representing a combination of Red, Green, and Blue
    (RGB) intensity values and an Alpha value, and is used to determine
    drawing colours. See the entry for wxColourDatabase for how a pointer to a predefined,
    named colour may be returned instead of creating a new colour.

    Valid RGB values are in the range 0 to 255.

    You can retrieve the current system colour settings with wxSystemSettings.


    @section colour_accessors Channel Accessor Functions

    Note that this class provides pairs of functions for each of the colour
    channels, i.e. red, green, blue and alpha values. The one word functions
    Red(), Green(), Blue() and Alpha() return the values of type @c unsigned @c
    char, while GetRed(), GetGreen(), GetBlue() and GetAlpha() returns the same
    value as @c unsigned @c int. According to the C++ integer promotion rules,
    the result of any arithmetic expression involving the former will be
    (signed) @c int, while that of the latter will be @c unsigned, which is
    what would be commonly expected, so the latter family of functions should
    be typically preferred (but they are only available since wxWidgets 3.1.6).


    @library{wxcore}
    @category{gdi}

    @stdobjects
    - ::wxNullColour - An empty, invalid colour.
    - ::wxTransparentColour - Valid but fully transparent colour (new in 2.9.1).
    - ::wxBLACK
    - ::wxBLUE
    - ::wxCYAN
    - ::wxGREEN
    - ::wxYELLOW
    - ::wxLIGHT_GREY
    - ::wxRED
    - ::wxWHITE

    @see wxColourDatabase, wxPen, wxBrush, wxColourDialog, wxSystemSettings
*/
class wxColour : public wxObject
{
public:

    /**
        Default constructor.
    */
    wxColour();

    /**
        @param red
            The red value.
        @param green
            The green value.
        @param blue
            The blue value.
        @param alpha
            The alpha value. Alpha values range from 0 (wxALPHA_TRANSPARENT) to
            255 (wxALPHA_OPAQUE).
    */
    wxColour(unsigned char red, unsigned char green, unsigned char blue,
             unsigned char alpha = wxALPHA_OPAQUE);

    /**
        @param colourName
            The colour name.
    */
    wxColour(const wxString& colourName);

    /**
        @param colRGB
            A packed RGB value.
    */
    wxColour(unsigned long colRGB);

    /**
        Copy constructor.
    */
    wxColour(const wxColour& colour);

    /**
        Returns the alpha value, on platforms where alpha is not yet supported, this
        always returns wxALPHA_OPAQUE.

        @see GetAlpha()
    */
    virtual unsigned char Alpha() const;

    /**
        Returns the blue intensity.

        @see GetBlue()
    */
    virtual unsigned char Blue() const;

    /**
        Returns the alpha value, on platforms where alpha is not yet supported, this
        always returns wxALPHA_OPAQUE.

        @since 3.1.6
     */
    unsigned int GetAlpha() const;

    /**
        Returns the blue intensity as unsigned int.

        @since 3.1.6
     */
    unsigned int GetBlue() const;

    /**
        Returns the green intensity as unsigned int.

        @since 3.1.6
     */
    unsigned int GetGreen() const;

    /**
        Returns the red intensity as unsigned int.

        @since 3.1.6
     */
    unsigned int GetRed() const;

    /**
        Converts this colour to a wxString using the given flags.

        The supported flags are @c wxC2S_NAME, to obtain the colour name
        (e.g. wxColour(255,0,0) == "red"), @c wxC2S_CSS_SYNTAX, to obtain
        the colour in the "rgb(r,g,b)" or "rgba(r,g,b,a)" syntax
        (e.g. wxColour(255,0,0,85) == "rgba(255,0,0,0.333)"), and
        @c wxC2S_HTML_SYNTAX, to obtain the colour as "#" followed by 6
        hexadecimal digits (e.g. wxColour(255,0,0) == "#FF0000").

        This function returns empty string if the colour is not initialized
        (see IsOk()). Otherwise, the returned string is always non-empty, but
        the function asserts if the colour has alpha channel (i.e. is non
        opaque) but @c wxC2S_CSS_SYNTAX (which is the only one supporting
        alpha) is not specified in @a flags.

        @note For non-solid (i.e. non-RGB) colour this function returns
        "rgb(??, ?? ??)" or "#??????".

        @since 2.7.0
    */
    virtual wxString GetAsString(long flags = wxC2S_NAME | wxC2S_CSS_SYNTAX) const;

    ///@{
    /**
        Sets the RGB or RGBA colour values from a single 32 bit value.

        The arguments @a colRGB and @a colRGBA should be of the form 0x00BBGGRR
        and 0xAABBGGRR respectively where @c 0xRR, @c 0xGG, @c 0xBB and @c 0xAA
        are the values of the red, green, blue and alpha components.

        Notice the right-to-left order of components!

        @see GetRGB(), GetRGBA()

        @since 2.9.1
    */
    void SetRGB(wxUint32 colRGB);
    void SetRGBA(wxUint32 colRGBA);
    ///@}

    ///@{
    /**
        Gets the RGB or RGBA colour values as a single 32 bit value.

        The returned value is of the same form as expected by SetRGB() and
        SetRGBA().

        Notice that GetRGB() returns the value with 0 as its highest byte
        independently of the value actually returned by Alpha(). So for a fully
        opaque colour, the return value of GetRGBA() is @c 0xFFBBGGRR while
        that of GetRGB() is @c 0x00BBGGRR.

        @since 2.9.1
    */
    wxUint32 GetRGB() const;
    wxUint32 GetRGBA() const;
    ///@}

    /**
        Return the perceived brightness of the colour.

        This value is computed using the simple @code 0.299*R + 0.587*G + 0.114*B @endcode
        formula with the coefficients taken from the RGB to
        YIQ conversion formula and @c R, @c G and @c B being the values of the
        corresponding colour channels normalized to 0..1 range, so that the
        return value is 0 for black and 1 for white.

        @since 3.1.3
     */
    double GetLuminance() const;

    /**
        Returns a pixel value which is platform-dependent.
        On Windows, a COLORREF is returned.
        On X, an allocated pixel value is returned.
        If the pixel is invalid (on X, unallocated), @c -1 is returned.
    */
    wxIntPtr GetPixel() const;

    /**
        Returns the green intensity.

        @see GetGreen()
    */
    virtual unsigned char Green() const;

    /**
        Returns @true if the colour object is valid (the colour has been initialised
        with RGB values).
    */
    virtual bool IsOk() const;

    /**
        Returns the red intensity.

        @see GetRed()
    */
    virtual unsigned char Red() const;

    /**
        Returns @true if the color can be described using RGB values, i.e. is solid,
        @false if it is a pattern (currently only possible on macOS)

        @since 3.1.2
    */
    virtual bool IsSolid() const;
    ///@{
    /**
        Sets the RGB intensity values using the given values (first overload),
        extracting them from the packed long (second overload), using the given
        string (third overload).

        When using third form, Set() accepts: colour names (those listed in
        wxColourDatabase), the CSS-like @c "rgb(r,g,b)" or @c "rgba(r,g,b,a)" syntax
        (case insensitive) and the HTML-like syntax: @c "#" followed by 6 hexadecimal
        digits for red, green, blue components.

        Returns @true if the conversion was successful, @false otherwise.

        @since 2.7.0
    */
    void Set(unsigned char red, unsigned char green,
             unsigned char blue,
             unsigned char alpha = wxALPHA_OPAQUE);
    void Set(unsigned long RGB);
    bool Set(const wxString& str);
    ///@}

    /**
        Tests the inequality of two colours by comparing individual red, green, blue
        intensities and alpha values.
    */
    bool operator !=(const wxColour& colour) const;

    /**
        Assignment operator.

        @see wxColourDatabase
    */
    wxColour& operator=(const wxColour& colour);

    /**
        Tests the equality of two colours by comparing individual red, green, blue
        intensities and alpha values.
    */
    bool operator ==(const wxColour& colour) const;

    /**
        Assigns the same value to @a r, @a g, @a b: 0 if @a on is @c false, 255 otherwise.
        @since 2.9.0
    */
    static void MakeMono(unsigned char* r, unsigned char* g, unsigned char* b, bool on);

    /**
        Create a disabled (dimmed) colour from (in/out) rgb parameters.
        @since 2.9.0
    */
    static void MakeDisabled(unsigned char* r, unsigned char* g, unsigned char* b, unsigned char brightness = 255);

    /**
        Make a disabled version of this colour.

        This method modifies the object in place and returns the object itself.

        @since 2.9.5
     */
    wxColour& MakeDisabled(unsigned char brightness = 255);

    /**
        Create a grey colour from (in/out) rgb parameters using integer arithmetic.
        @since 2.9.0
    */
    static void MakeGrey(unsigned char* r, unsigned char* g, unsigned char* b);

    /**
        Create a grey colour from (in/out) rgb parameters using floating point arithmetic.
        Defaults to using the standard ITU-T BT.601 when converting to YUV, where every pixel equals
        (R * @a weight_r) + (G * @a weight_g) + (B * @a weight_b).
        @since 2.9.0
    */
    static void MakeGrey(unsigned char* r, unsigned char* g, unsigned char* b,
                         double weight_r, double weight_g, double weight_b);

    /**
        Blend colour, taking alpha into account.
        @since 2.9.0
    */
    static unsigned char AlphaBlend(unsigned char fg, unsigned char bg, double alpha);

    /**
        Utility function that simply darkens or lightens a color, based on the specified 
        percentage @a ialpha. @a ialpha of 0 would be make the color completely black, 
        200 completely white and 100 would not change the color.
        @since 2.9.0
    */
    static void ChangeLightness(unsigned char* r, unsigned char* g, unsigned char* b, int ialpha);

    /**
        wxColour wrapper for ChangeLightness(r,g,b,ialpha).
        @since 2.9.0
    */
    wxColour ChangeLightness(int ialpha) const;
};


/** @name Predefined colors. */
///@{
wxColour wxNullColour;
wxColour wxTransparentColour;
wxColour* wxBLACK;
wxColour* wxBLUE;
wxColour* wxCYAN;
wxColour* wxGREEN;
wxColour* wxYELLOW;
wxColour* wxLIGHT_GREY;
wxColour* wxRED;
wxColour* wxWHITE;
///@}



// ============================================================================
// Global functions/macros
// ============================================================================

/** @addtogroup group_funcmacro_misc */
///@{

/**
    Converts string to a wxColour best represented by the given string. Returns
    @true on success.

    @see wxToString(const wxColour&)

    @header{wx/colour.h}
*/
bool wxFromString(const wxString& string, wxColour* colour);

/**
    Converts the given wxColour into a string.

    @see wxFromString(const wxString&, wxColour*)

    @header{wx/colour.h}
*/
wxString wxToString(const wxColour& colour);

///@}