[wxWidgets.git] / interface / wx / image.h

/////////////////////////////////////////////////////////////////////////////
// Name:        image.h
// Purpose:     interface of wxImageHandler and wxImage
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/**
    @class wxImageHandler

    This is the base class for implementing image file loading/saving, and
    image creation from data.
    It is used within wxImage and is not normally seen by the application.

    If you wish to extend the capabilities of wxImage, derive a class from
    wxImageHandler and add the handler using wxImage::AddHandler in your
    application initialisation.

    Note that all wxImageHandlers provided by wxWidgets are part of
    the @ref page_libs_wxcore library.
    For details about the default handlers, please see the section
    @ref image_handlers in the wxImage class documentation.


    @section imagehandler_note Note (Legal Issue)

    This software is based in part on the work of the Independent JPEG Group.
    (Applies when wxWidgets is linked with JPEG support.
    wxJPEGHandler uses libjpeg created by IJG.)


    @stdobjects
    ::wxNullImage

    @library{wxcore}
    @category{misc}

    @see wxImage, wxInitAllImageHandlers()
*/
class wxImageHandler : public wxObject
{
public:
    /**
        Default constructor.

        In your own default constructor, initialise the members
        m_name, m_extension and m_type.
    */
    wxImageHandler();

    /**
        Destroys the wxImageHandler object.
    */
    virtual ~wxImageHandler();

    /**
        Gets the file extension associated with this handler.
    */
    const wxString& GetExtension() const;

    /**
        If the image file contains more than one image and the image handler is capable
        of retrieving these individually, this function will return the number of
        available images.

        @param stream
            Opened input stream for reading image data.
            Currently, the stream must support seeking.

        @return Number of available images. For most image handlers, this is 1
                (exceptions are TIFF and ICO formats).
    */
    virtual int GetImageCount(wxInputStream& stream);

    /**
        Gets the MIME type associated with this handler.
    */
    const wxString& GetMimeType() const;

    /**
        Gets the name of this handler.
    */
    const wxString& GetName() const;

    /**
        Gets the image type associated with this handler.
    */
    wxBitmapType GetType() const;

    /**
        Loads a image from a stream, putting the resulting data into @a image.

        If the image file contains more than one image and the image handler is
        capable of retrieving these individually, @a index indicates which image
        to read from the stream.

        @param image
            The image object which is to be affected by this operation.
        @param stream
            Opened input stream for reading image data.
        @param verbose
            If set to @true, errors reported by the image handler will produce
            wxLogMessages.
        @param index
            The index of the image in the file (starting from zero).

        @return @true if the operation succeeded, @false otherwise.

        @see wxImage::LoadFile, wxImage::SaveFile, SaveFile()
    */
    virtual bool LoadFile(wxImage* image, wxInputStream& stream,
                          bool verbose = true, int index = -1);

    /**
        Saves a image in the output stream.

        @param image
            The image object which is to be affected by this operation.
        @param stream
            Opened output stream for writing the data.
        @param verbose
            If set to @true, errors reported by the image handler will produce
            wxLogMessages.

        @return @true if the operation succeeded, @false otherwise.

        @see wxImage::LoadFile, wxImage::SaveFile, LoadFile()
    */
    virtual bool SaveFile(wxImage* image, wxOutputStream& stream,
                          bool verbose = true);

    /**
        Sets the handler extension.

        @param extension
            Handler extension.
    */
    void SetExtension(const wxString& extension);

    /**
        Sets the handler MIME type.

        @param mimetype
            Handler MIME type.
    */
    void SetMimeType(const wxString& mimetype);

    /**
        Sets the handler name.

        @param name
            Handler name.
    */
    void SetName(const wxString& name);
};


/**
    Constant used to indicate the alpha value conventionally defined as
    the complete transparency.
*/
const unsigned char wxIMAGE_ALPHA_TRANSPARENT = 0;

/**
    Constant used to indicate the alpha value conventionally defined as
    the complete opacity.
*/
const unsigned char wxIMAGE_ALPHA_OPAQUE = 0xff;

/**
    @class wxImage

    This class encapsulates a platform-independent image.

    An image can be created from data, or using wxBitmap::ConvertToImage.
    An image can be loaded from a file in a variety of formats, and is extensible
    to new formats via image format handlers. Functions are available to set and
    get image bits, so it can be used for basic image manipulation.

    A wxImage cannot (currently) be drawn directly to a wxDC.
    Instead, a platform-specific wxBitmap object must be created from it using
    the wxBitmap::wxBitmap(wxImage,int depth) constructor.
    This bitmap can then be drawn in a device context, using wxDC::DrawBitmap.

    One colour value of the image may be used as a mask colour which will lead to
    the automatic creation of a wxMask object associated to the bitmap object.


    @section image_alpha Alpha channel support

    Starting from wxWidgets 2.5.0 wxImage supports alpha channel data, that is
    in addition to a byte for the red, green and blue colour components for each
    pixel it also stores a byte representing the pixel opacity.

    An alpha value of 0 corresponds to a transparent pixel (null opacity) while
    a value of 255 means that the pixel is 100% opaque.
    The constants ::wxIMAGE_ALPHA_TRANSPARENT and ::wxIMAGE_ALPHA_OPAQUE can be
    used to indicate those values in a more readable form.

    Unlike RGB data, not all images have an alpha channel and before using
    wxImage::GetAlpha you should check if this image contains an alpha channel
    with wxImage::HasAlpha. Note that currently only the PNG format has full
    alpha channel support so only the images loaded from PNG files can have
    alpha and, if you initialize the image alpha channel yourself using
    wxImage::SetAlpha, you should save it in PNG format to avoid losing it.


    @section image_handlers Available image handlers

    The following image handlers are available.
    wxBMPHandler is always installed by default.
    To use other image formats, install the appropriate handler with
    wxImage::AddHandler or call ::wxInitAllImageHandlers().

    - wxBMPHandler: For loading and saving, always installed.
    - wxPNGHandler: For loading (including alpha support) and saving.
    - wxJPEGHandler: For loading and saving.
    - wxGIFHandler: Only for loading, due to legal issues.
    - wxPCXHandler: For loading and saving (see below).
    - wxPNMHandler: For loading and saving (see below).
    - wxTIFFHandler: For loading and saving.
    - wxTGAHandler: For loading only.
    - wxIFFHandler: For loading only.
    - wxXPMHandler: For loading and saving.
    - wxICOHandler: For loading and saving.
    - wxCURHandler: For loading and saving.
    - wxANIHandler: For loading only.

    When saving in PCX format, wxPCXHandler will count the number of different
    colours in the image; if there are 256 or less colours, it will save as 8 bit,
    else it will save as 24 bit.

    Loading PNMs only works for ASCII or raw RGB images.
    When saving in PNM format, wxPNMHandler will always save as raw RGB.


    @library{wxcore}
    @category{gdi}

    @stdobjects
    ::wxNullImage

    @see wxBitmap, wxInitAllImageHandlers(), wxPixelData
*/
class wxImage : public wxObject
{
public:
    class RGBValue
    {
    public:
        /**
            Constructor for RGBValue, an object that contains values for red, green
            and blue which represent the value of a color.

            It is used by wxImage::HSVtoRGB and wxImage::RGBtoHSV, which converts
            between HSV color space and RGB color space.
        */
        RGBValue(unsigned char r=0, unsigned char g=0, unsigned char b=0);
    };

    class HSVValue
    {
    public:
        /**
            Constructor for HSVValue, an object that contains values for hue, saturation
            and value which represent the value of a color.

            It is used by wxImage::HSVtoRGB() and wxImage::RGBtoHSV(), which converts
            between HSV color space and RGB color space.
        */
        HSVValue(double h=0.0, double s=0.0, double v=0.0);
    };

    /**
        Creates an empty wxImage object without an alpha channel.
    */
    wxImage();

    /**
        Creates an image with the given size and clears it if requested.

        Does not create an alpha channel.

        @param width
            Specifies the width of the image.
        @param height
            Specifies the height of the image.
        @param clear
            If @true, initialize the image to black.
    */
    wxImage(int width, int height, bool clear = true);

    /**
        Creates an image from data in memory. If @a static_data is @false
        then the wxImage will take ownership of the data and free it
        afterwards. For this, it has to be allocated with @e malloc.

        @param width
            Specifies the width of the image.
        @param height
            Specifies the height of the image.
        @param data
            A pointer to RGB data
        @param static_data
            Indicates if the data should be free'd after use

    */
    wxImage(int width, int height, unsigned char* data,  bool static_data = false);

    /**
        Creates an image from data in memory. If @a static_data is @false
        then the wxImage will take ownership of the data and free it
        afterwards. For this, it has to be allocated with @e malloc.

        @param width
            Specifies the width of the image.
        @param height
            Specifies the height of the image.
        @param data
            A pointer to RGB data
        @param alpha
            A pointer to alpha-channel data
        @param static_data
            Indicates if the data should be free'd after use

    */
    wxImage(int width, int height, unsigned char* data, unsigned char* alpha,
            bool static_data = false );

    /**
        Creates an image from XPM data.

        @param xpmData
            A pointer to XPM image data.
    */
    wxImage(const char* const* xpmData);

    /**
        Creates an image from a file.

        @param name
            Name of the file from which to load the image.
        @param type
            May be one of the following:
            @li wxBITMAP_TYPE_BMP: Load a Windows bitmap file.
            @li wxBITMAP_TYPE_GIF: Load a GIF bitmap file.
            @li wxBITMAP_TYPE_JPEG: Load a JPEG bitmap file.
            @li wxBITMAP_TYPE_PNG: Load a PNG bitmap file.
            @li wxBITMAP_TYPE_PCX: Load a PCX bitmap file.
            @li wxBITMAP_TYPE_PNM: Load a PNM bitmap file.
            @li wxBITMAP_TYPE_TIF: Load a TIFF bitmap file.
            @li wxBITMAP_TYPE_TGA: Load a TGA bitmap file.
            @li wxBITMAP_TYPE_XPM: Load a XPM bitmap file.
            @li wxBITMAP_TYPE_ICO: Load a Windows icon file (ICO).
            @li wxBITMAP_TYPE_CUR: Load a Windows cursor file (CUR).
            @li wxBITMAP_TYPE_ANI: Load a Windows animated cursor file (ANI).
            @li wxBITMAP_TYPE_ANY: Will try to autodetect the format.
        @param index
            Index of the image to load in the case that the image file contains
            multiple images. This is only used by GIF, ICO and TIFF handlers.
            The default value (-1) means "choose the default image" and is
            interpreted as the first image (index=0) by the GIF and TIFF handler
            and as the largest and most colourful one by the ICO handler.

        @remarks Depending on how wxWidgets has been configured and by which
                 handlers have been loaded, not all formats may be available.
                 Any handler other than BMP must be previously initialized with
                wxImage::AddHandler or wxInitAllImageHandlers.

        @note
            You can use GetOptionInt() to get the hotspot when loading cursor files:
            @code
            int hotspot_x = image.GetOptionInt(wxIMAGE_OPTION_CUR_HOTSPOT_X);
            int hotspot_y = image.GetOptionInt(wxIMAGE_OPTION_CUR_HOTSPOT_Y);
            @endcode

        @see LoadFile()
    */
    wxImage(const wxString& name, wxBitmapType type = wxBITMAP_TYPE_ANY, int index = -1);

    /**
        Creates an image from a file using MIME-types to specify the type.

        @param name
            Name of the file from which to load the image.
        @param mimetype
            MIME type string (for example 'image/jpeg')
        @param index
            See description in wxImage(const wxString&, wxBitmapType, int) overload.
    */
    wxImage(const wxString& name, const wxString& mimetype, int index = -1);

    /**
        Creates an image from a stream.

        @param stream
            Opened input stream from which to load the image. Currently,
            the stream must support seeking.
        @param type
            See description in wxImage(const wxString&, wxBitmapType, int) overload.
        @param index
            See description in wxImage(const wxString&, wxBitmapType, int) overload.
    */
    wxImage(wxInputStream& stream, wxBitmapType type = wxBITMAP_TYPE_ANY, int index = -1);

    /**
        Creates an image from a stream using MIME-types to specify the type.

        @param stream
            Opened input stream from which to load the image. Currently,
            the stream must support seeking.
        @param mimetype
            MIME type string (for example 'image/jpeg')
        @param index
            See description in wxImage(const wxString&, wxBitmapType, int) overload.
    */
    wxImage(wxInputStream& stream, const wxString& mimetype, int index = -1);


    /**
        Destructor.

        See @ref overview_refcount_destruct "reference-counted object destruction"
        for more info.
    */
    virtual ~wxImage();

    /**
        Register an image handler.
    */
    static void AddHandler(wxImageHandler* handler);

    /**
        Blurs the image in both horizontal and vertical directions by the
        specified pixel @a blurRadius. This should not be used when using
        a single mask colour for transparency.

        @see BlurHorizontal(), BlurVertical()
    */
    wxImage Blur(int blurRadius) const;

    /**
        Blurs the image in the horizontal direction only. This should not be used
        when using a single mask colour for transparency.

        @see Blur(), BlurVertical()
    */
    wxImage BlurHorizontal(int blurRadius) const;

    /**
        Blurs the image in the vertical direction only. This should not be used
        when using a single mask colour for transparency.

        @see Blur(), BlurHorizontal()
    */
    wxImage BlurVertical(int blurRadius) const;

    /**
        Returns @true if the current image handlers can read this file
    */
    static bool CanRead(const wxString& filename);

    /**
        Deletes all image handlers.
        This function is called by wxWidgets on exit.
    */
    static void CleanUpHandlers();

    /**
        Computes the histogram of the image. @a histogram is a reference to
        wxImageHistogram object. wxImageHistogram is a specialization of
        wxHashMap "template" and is defined as follows:

        @code
        class WXDLLEXPORT wxImageHistogramEntry
        {
        public:
            wxImageHistogramEntry() : index(0), value(0) {}
            unsigned long index;
            unsigned long value;
        };

        WX_DECLARE_EXPORTED_HASH_MAP(unsigned long, wxImageHistogramEntry,
                                    wxIntegerHash, wxIntegerEqual,
                                    wxImageHistogram);
        @endcode

        @return Returns number of colours in the histogram.
    */
    unsigned long ComputeHistogram(wxImageHistogram& histogram) const;

    /**
        If the image has alpha channel, this method converts it to mask.

        All pixels with alpha value less than @a threshold are replaced with mask
        colour and the alpha channel is removed. Mask colour is chosen automatically
        using FindFirstUnusedColour().

        If the image image doesn't have alpha channel, ConvertAlphaToMask() does nothing.

        @return @false if FindFirstUnusedColour returns @false, @true otherwise.
    */
    bool ConvertAlphaToMask(unsigned char threshold = wxIMAGE_ALPHA_THRESHOLD);

    /**
        @deprecated
        Use the equivalent @ref wxBitmap::wxBitmap "wxBitmap constructor"
        (which takes wxImage and depth as its arguments) instead.
    */
    wxBitmap ConvertToBitmap() const;

    /**
        Returns a greyscale version of the image.

        The returned image uses the luminance component of the original to
        calculate the greyscale. Defaults to using the standard ITU-T BT.601
        when converting to YUV, where every pixel equals
        (R * @a lr) + (G * @a lg) + (B * @a lb).
    */
    wxImage ConvertToGreyscale(double lr = 0.299, double lg = 0.587, double lb = 1.114) const;

    /**
        Returns monochromatic version of the image.

        The returned image has white colour where the original has @e (r,g,b)
        colour and black colour everywhere else.
    */
    wxImage ConvertToMono(unsigned char r, unsigned char g, unsigned char b) const;

    /**
        Returns an identical copy of the image.
    */
    wxImage Copy() const;

    /**
        Creates a fresh image.

        If @a clear is @true, the new image will be initialized to black.
        Otherwise, the image data will be uninitialized.

        @param width
            The width of the image in pixels.
        @param height
            The height of the image in pixels.
        @param clear
            If @true, initialize the image data with zeros.

        @return @true if the call succeeded, @false otherwise.
    */
    bool Create(int width, int height, bool clear = true);

    /**
        Destroys the image data.
    */
    void Destroy();

    /**
        Finds the first colour that is never used in the image.
        The search begins at given initial colour and continues by increasing
        R, G and B components (in this order) by 1 until an unused colour is
        found or the colour space exhausted.

        The parameters @a r, @a g, @a b are pointers to variables to save the colour.

        The parameters @a startR, @a startG, @a startB define the initial values
        of the colour.
        The returned colour will have RGB values equal to or greater than these.

        @return Returns @false if there is no unused colour left, @true on success.

        @note
            This method involves computing the histogram, which is a
            computationally intensive operation.
    */
    bool FindFirstUnusedColour(unsigned char* r, unsigned char* g,
                               unsigned char* b, unsigned char startR = 1,
                               unsigned char startG = 0,
                               unsigned char startB = 0) const;

    /**
        Finds the handler with the given name.

        @param name
            The handler name.

        @return A pointer to the handler if found, @NULL otherwise.

        @see wxImageHandler
    */
    static wxImageHandler* FindHandler(const wxString& name);

    /**
        Finds the handler associated with the given extension and type.

        @param extension
            The file extension, such as "bmp".
        @param imageType
            The image type; one of the ::wxBitmapType values.

        @return A pointer to the handler if found, @NULL otherwise.

        @see wxImageHandler
    */
    static wxImageHandler* FindHandler(const wxString& extension,
                                       wxBitmapType imageType);

    /**
        Finds the handler associated with the given image type.

        @param imageType
            The image type; one of the ::wxBitmapType values.

        @return A pointer to the handler if found, @NULL otherwise.

        @see wxImageHandler
    */
    static wxImageHandler* FindHandler(wxBitmapType imageType);

    /**
        Finds the handler associated with the given MIME type.

        @param mimetype
            MIME type.

        @return A pointer to the handler if found, @NULL otherwise.

        @see wxImageHandler
    */
    static wxImageHandler* FindHandlerMime(const wxString& mimetype);

    /**
        Return alpha value at given pixel location.
    */
    unsigned char GetAlpha(int x, int y) const;

    /**
        Returns pointer to the array storing the alpha values for this image.

        This pointer is @NULL for the images without the alpha channel. If the image
        does have it, this pointer may be used to directly manipulate the alpha values
        which are stored as the RGB ones.
    */
    const unsigned char * GetAlpha() const;

    /**
        Returns the blue intensity at the given coordinate.
    */
    unsigned char GetBlue(int x, int y) const;

    /**
        Returns the image data as an array.

        This is most often used when doing direct image manipulation.
        The return value points to an array of characters in RGBRGBRGB... format
        in the top-to-bottom, left-to-right order, that is the first RGB triplet
        corresponds to the pixel first pixel of the first row, the second one ---
        to the second pixel of the first row and so on until the end of the first
        row, with second row following after it and so on.

        You should not delete the returned pointer nor pass it to SetData().
    */
    unsigned char* GetData() const;

    /**
        Returns the green intensity at the given coordinate.
    */
    unsigned char GetGreen(int x, int y) const;

    /**
        Returns the static list of image format handlers.

        @see wxImageHandler
    */
    static wxList GetHandlers();

    /**
        Gets the height of the image in pixels.
    */
    int GetHeight() const;

    //@{
    /**
        If the image file contains more than one image and the image handler is
        capable of retrieving these individually, this function will return the
        number of available images.

        For the overload taking the parameter @a filename, that's the name
        of the file to query.
        For the overload taking the parameter @a stream, that's the ppened input
        stream with image data. Currently, the stream must support seeking.

        The parameter @a type may be one of the following values:
        @li wxBITMAP_TYPE_BMP: Load a Windows bitmap file.
        @li wxBITMAP_TYPE_GIF: Load a GIF bitmap file.
        @li wxBITMAP_TYPE_JPEG: Load a JPEG bitmap file.
        @li wxBITMAP_TYPE_PNG: Load a PNG bitmap file.
        @li wxBITMAP_TYPE_PCX: Load a PCX bitmap file.
        @li wxBITMAP_TYPE_PNM: Load a PNM bitmap file.
        @li wxBITMAP_TYPE_TIF: Load a TIFF bitmap file.
        @li wxBITMAP_TYPE_TGA: Load a TGA bitmap file.
        @li wxBITMAP_TYPE_XPM: Load a XPM bitmap file.
        @li wxBITMAP_TYPE_ICO: Load a Windows icon file (ICO).
        @li wxBITMAP_TYPE_CUR: Load a Windows cursor file (CUR).
        @li wxBITMAP_TYPE_ANI: Load a Windows animated cursor file (ANI).
        @li wxBITMAP_TYPE_ANY: Will try to autodetect the format.

        @return Number of available images. For most image handlers, this is 1
                (exceptions are TIFF and ICO formats).
    */
    static int GetImageCount(const wxString& filename,
                             wxBitmapType type = wxBITMAP_TYPE_ANY);
    static int GetImageCount(wxInputStream& stream,
                             wxBitmapType type = wxBITMAP_TYPE_ANY);
    //@}

    /**
        Iterates all registered wxImageHandler objects, and returns a string containing
        file extension masks suitable for passing to file open/save dialog boxes.

        @return The format of the returned string is @c "(*.ext1;*.ext2)|*.ext1;*.ext2".
                It is usually a good idea to prepend a description before passing
                the result to the dialog.
                Example:
                @code
                wxFileDialog FileDlg( this, "Choose Image", ::wxGetCwd(), "",
                                      _("Image Files ") + wxImage::GetImageExtWildcard(),
                                      wxFD_OPEN );
                @endcode

        @see wxImageHandler
    */
    static wxString GetImageExtWildcard();

    /**
        Gets the blue value of the mask colour.
    */
    unsigned char GetMaskBlue() const;

    /**
        Gets the green value of the mask colour.
    */
    unsigned char GetMaskGreen() const;

    /**
        Gets the red value of the mask colour.
    */
    unsigned char GetMaskRed() const;

    /**
        Gets a user-defined option. The function is case-insensitive to @a name.

        For example, when saving as a JPEG file, the option @b quality is
        used, which is a number between 0 and 100 (0 is terrible, 100 is very good).

        @see SetOption(), GetOptionInt(), HasOption()
    */
    wxString GetOption(const wxString& name) const;

    /**
        Gets a user-defined option as an integer.
        The function is case-insensitive to @a name.
        If the given option is not present, the function returns 0.
        Use HasOption() is 0 is a possibly valid value for the option.

        Options for wxPNGHandler:
        @li wxIMAGE_OPTION_PNG_FORMAT: Format for saving a PNG file.
        @li wxIMAGE_OPTION_PNG_BITDEPTH: Bit depth for every channel (R/G/B/A).

        Supported values for wxIMAGE_OPTION_PNG_FORMAT:
        @li wxPNG_TYPE_COLOUR: Stores RGB image.
        @li wxPNG_TYPE_GREY: Stores grey image, converts from RGB.
        @li wxPNG_TYPE_GREY_RED: Stores grey image, uses red value as grey.

        @see SetOption(), GetOption()
    */
    int GetOptionInt(const wxString& name) const;

    /**
        Get the current mask colour or find a suitable unused colour that could be
        used as a mask colour. Returns @true if the image currently has a mask.
    */
    bool GetOrFindMaskColour(unsigned char* r, unsigned char* g,
                             unsigned char* b) const;

    /**
        Returns the palette associated with the image.
        Currently the palette is only used when converting to wxBitmap under Windows.

        Some of the wxImage handlers have been modified to set the palette if
        one exists in the image file (usually 256 or less colour images in
        GIF or PNG format).
    */
    const wxPalette& GetPalette() const;

    /**
        Returns the red intensity at the given coordinate.
    */
    unsigned char GetRed(int x, int y) const;

    /**
        Returns a sub image of the current one as long as the rect belongs entirely
        to the image.
    */
    wxImage GetSubImage(const wxRect& rect) const;

    /**
        Gets the type of image found by LoadFile() or specified with SaveFile().

        @since 2.9.0
    */
    wxBitmapType GetType() const;

    /**
        Gets the width of the image in pixels.

        @see GetHeight()
    */
    int GetWidth() const;

    /**
        Converts a color in HSV color space to RGB color space.
    */
    static wxImage::RGBValue HSVtoRGB(const wxImage::HSVValue& hsv);

    /**
        Returns @true if this image has alpha channel, @false otherwise.

        @see GetAlpha(), SetAlpha()
    */
    bool HasAlpha() const;

    /**
        Returns @true if there is a mask active, @false otherwise.
    */
    bool HasMask() const;

    /**
        Returns @true if the given option is present.
        The function is case-insensitive to @a name.

        @see SetOption(), GetOption(), GetOptionInt()
    */
    bool HasOption(const wxString& name) const;

    /**
        Initializes the image alpha channel data.

        It is an error to call it if the image already has alpha data.
        If it doesn't, alpha data will be by default initialized to all pixels
        being fully opaque. But if the image has a mask colour, all mask pixels
        will be completely transparent.
    */
    void InitAlpha();

    /**
        Internal use only. Adds standard image format handlers.
        It only install wxBMPHandler for the time being, which is used by wxBitmap.

        This function is called by wxWidgets on startup, and shouldn't be called by
        the user.

        @see wxImageHandler, wxInitAllImageHandlers(), wxQuantize
    */
    static void InitStandardHandlers();

    /**
        Adds a handler at the start of the static list of format handlers.

        @param handler
            A new image format handler object. There is usually only one instance
            of a given handler class in an application session.

        @see wxImageHandler
    */
    static void InsertHandler(wxImageHandler* handler);

    /**
        Returns @true if image data is present.
    */
    bool IsOk() const;

    /**
        Returns @true if the given pixel is transparent, i.e. either has the mask
        colour if this image has a mask or if this image has alpha channel and alpha
        value of this pixel is strictly less than @a threshold.
    */
    bool IsTransparent(int x, int y,
                       unsigned char threshold = wxIMAGE_ALPHA_THRESHOLD) const;

    /**
        Loads an image from an input stream.

        @param stream
            Opened input stream from which to load the image.
            Currently, the stream must support seeking.
        @param type
            May be one of the following:
            @li wxBITMAP_TYPE_BMP: Load a Windows bitmap file.
            @li wxBITMAP_TYPE_GIF: Load a GIF bitmap file.
            @li wxBITMAP_TYPE_JPEG: Load a JPEG bitmap file.
            @li wxBITMAP_TYPE_PNG: Load a PNG bitmap file.
            @li wxBITMAP_TYPE_PCX: Load a PCX bitmap file.
            @li wxBITMAP_TYPE_PNM: Load a PNM bitmap file.
            @li wxBITMAP_TYPE_TIF: Load a TIFF bitmap file.
            @li wxBITMAP_TYPE_TGA: Load a TGA bitmap file.
            @li wxBITMAP_TYPE_XPM: Load a XPM bitmap file.
            @li wxBITMAP_TYPE_ICO: Load a Windows icon file (ICO).
            @li wxBITMAP_TYPE_CUR: Load a Windows cursor file (CUR).
            @li wxBITMAP_TYPE_ANI: Load a Windows animated cursor file (ANI).
            @li wxBITMAP_TYPE_ANY: Will try to autodetect the format.
        @param index
            Index of the image to load in the case that the image file contains
            multiple images. This is only used by GIF, ICO and TIFF handlers.
            The default value (-1) means "choose the default image" and is
            interpreted as the first image (index=0) by the GIF and TIFF handler
            and as the largest and most colourful one by the ICO handler.

        @return @true if the operation succeeded, @false otherwise.
                If the optional index parameter is out of range, @false is
                returned and a call to wxLogError() takes place.

        @remarks Depending on how wxWidgets has been configured, not all formats
                 may be available.

        @note
            You can use GetOptionInt() to get the hotspot when loading cursor files:
            @code
            int hotspot_x = image.GetOptionInt(wxIMAGE_OPTION_CUR_HOTSPOT_X);
            int hotspot_y = image.GetOptionInt(wxIMAGE_OPTION_CUR_HOTSPOT_Y);
            @endcode

        @see SaveFile()
    */
    bool LoadFile(wxInputStream& stream, wxBitmapType type, int index = -1);

    /**
        Loads an image from a file.
        If no handler type is provided, the library will try to autodetect the format.

        @param name
            Name of the file from which to load the image.
        @param type
            See the description in the LoadFile(wxInputStream&, wxBitmapType, int) overload.
        @param index
            See the description in the LoadFile(wxInputStream&, wxBitmapType, int) overload.
    */
    virtual bool LoadFile(const wxString& name,
                          wxBitmapType type = wxBITMAP_TYPE_ANY,
                          int index = -1);

    /**
        Loads an image from a file.
        If no handler type is provided, the library will try to autodetect the format.

        @param name
            Name of the file from which to load the image.
        @param mimetype
            MIME type string (for example 'image/jpeg')
        @param index
            See the description in the LoadFile(wxInputStream&, wxBitmapType, int) overload.
    */
    virtual bool LoadFile(const wxString& name, const wxString& mimetype,
                          int index = -1);


    /**
        Loads an image from an input stream.

        @param stream
            Opened input stream from which to load the image.
            Currently, the stream must support seeking.
        @param mimetype
            MIME type string (for example 'image/jpeg')
        @param index
            See the description in the LoadFile(wxInputStream&, wxBitmapType, int) overload.
    */
    virtual bool LoadFile(wxInputStream& stream, const wxString& mimetype,
                          int index = -1);

    /**
        Returns a mirrored copy of the image.
        The parameter @a horizontally indicates the orientation.
    */
    wxImage Mirror(bool horizontally = true) const;

    /**
        Copy the data of the given @a image to the specified position in this image.
    */
    void Paste(const wxImage& image, int x, int y);

    /**
        Converts a color in RGB color space to HSV color space.
    */
    static wxImage::HSVValue RGBtoHSV(const wxImage::RGBValue& rgb);

    /**
        Finds the handler with the given name, and removes it.
        The handler is not deleted.

        @param name
            The handler name.

        @return @true if the handler was found and removed, @false otherwise.

        @see wxImageHandler
    */
    static bool RemoveHandler(const wxString& name);

    /**
        Replaces the colour specified by @e r1,g1,b1 by the colour @e r2,g2,b2.
    */
    void Replace(unsigned char r1, unsigned char g1,
                 unsigned char b1, unsigned char r2,
                 unsigned char g2, unsigned char b2);

    /**
        Changes the size of the image in-place by scaling it: after a call to this
        function,the image will have the given width and height.

        For a description of the @a quality parameter, see the Scale() function.
        Returns the (modified) image itself.

        @see Scale()
    */
    wxImage& Rescale(int width, int height,
                    int quality = wxIMAGE_QUALITY_NORMAL);

    /**
        Changes the size of the image in-place without scaling it by adding either a
        border with the given colour or cropping as necessary.

        The image is pasted into a new image with the given @a size and background
        colour at the position @a pos relative to the upper left of the new image.

        If @a red = green = blue = -1 then use either the  current mask colour
        if set or find, use, and set a suitable mask colour for any newly exposed
        areas.

        @return The (modified) image itself.

        @see Size()
    */
    wxImage& Resize(const wxSize& size, const wxPoint& pos, int red = -1,
                    int green = -1, int blue = -1);

    /**
        Rotates the image about the given point, by @a angle radians.

        Passing @true to @a interpolating results in better image quality, but is slower.

        If the image has a mask, then the mask colour is used for the uncovered
        pixels in the rotated image background. Else, black (rgb 0, 0, 0) will be used.

        Returns the rotated image, leaving this image intact.
    */
    wxImage Rotate(double angle, const wxPoint& rotationCentre,
                   bool interpolating = true,
                   wxPoint* offsetAfterRotation = NULL) const;

    /**
        Returns a copy of the image rotated 90 degrees in the direction
        indicated by @a clockwise.
    */
    wxImage Rotate90(bool clockwise = true) const;

    /**
        Rotates the hue of each pixel in the image by @e angle, which is a double in
        the range of -1.0 to +1.0, where -1.0 corresponds to -360 degrees and +1.0
        corresponds to +360 degrees.
    */
    void RotateHue(double angle);

    /**
        Saves an image in the given stream.

        @param stream
            Opened output stream to save the image to.
        @param mimetype
            MIME type.

        @return @true if the operation succeeded, @false otherwise.

        @remarks Depending on how wxWidgets has been configured, not all formats
                 may be available.

        @note
            You can use SetOption() to set the hotspot when saving an image
            into a cursor file (default hotspot is in the centre of the image):
            @code
            image.SetOption(wxIMAGE_OPTION_CUR_HOTSPOT_X, hotspotX);
            image.SetOption(wxIMAGE_OPTION_CUR_HOTSPOT_Y, hotspotY);
            @endcode

        @see LoadFile()
    */
    virtual bool SaveFile(wxOutputStream& stream,
                          const wxString& mimetype) const;

    /**
        Saves an image in the named file.

        @param name
            Name of the file to save the image to.
        @param type
            Currently these types can be used:
            @li wxBITMAP_TYPE_BMP: Save a BMP image file.
            @li wxBITMAP_TYPE_JPEG: Save a JPEG image file.
            @li wxBITMAP_TYPE_PNG: Save a PNG image file.
            @li wxBITMAP_TYPE_PCX: Save a PCX image file
                (tries to save as 8-bit if possible, falls back to 24-bit otherwise).
            @li wxBITMAP_TYPE_PNM: Save a PNM image file (as raw RGB always).
            @li wxBITMAP_TYPE_TIFF: Save a TIFF image file.
            @li wxBITMAP_TYPE_XPM: Save a XPM image file.
            @li wxBITMAP_TYPE_ICO: Save a Windows icon file (ICO).
                The size may be up to 255 wide by 127 high. A single image is saved
                in 8 colors at the size supplied.
            @li wxBITMAP_TYPE_CUR: Save a Windows cursor file (CUR).
    */
    virtual bool SaveFile(const wxString& name, wxBitmapType type) const;

    /**
        Saves an image in the named file.

        @param name
            Name of the file to save the image to.
        @param mimetype
            MIME type.
    */
    virtual bool SaveFile(const wxString& name, const wxString& mimetype) const;

    /**
        Saves an image in the named file.

        File type is determined from the extension of the file name.
        Note that this function may fail if the extension is not recognized!
        You can use one of the forms above to save images to files with
        non-standard extensions.

        @param name
            Name of the file to save the image to.
    */
    virtual bool SaveFile(const wxString& name) const;

    /**
        Saves an image in the given stream.

        @param stream
            Opened output stream to save the image to.
        @param type
            MIME type.
    */
    virtual bool SaveFile(wxOutputStream& stream, wxBitmapType type) const;

    /**
        Returns a scaled version of the image.

        This is also useful for scaling bitmaps in general as the only other way
        to scale bitmaps is to blit a wxMemoryDC into another wxMemoryDC.

        The parameter @a quality determines what method to use for resampling the image.
        Can be one of the following:
        - wxIMAGE_QUALITY_NORMAL: Uses the normal default scaling method of pixel
                                  replication
        - wxIMAGE_QUALITY_HIGH: Uses bicubic and box averaging resampling methods
                                for upsampling and downsampling respectively

        It should be noted that although using @c wxIMAGE_QUALITY_HIGH produces much nicer
        looking results it is a slower method. Downsampling will use the box averaging
        method which seems to operate very fast. If you are upsampling larger images using
        this method you will most likely notice that it is a bit slower and in extreme
        cases it will be quite substantially slower as the bicubic algorithm has to process a
        lot of data.

        It should also be noted that the high quality scaling may not work as expected
        when using a single mask colour for transparency, as the scaling will blur the
        image and will therefore remove the mask partially. Using the alpha channel
        will work.

        Example:
        @code
        // get the bitmap from somewhere
        wxBitmap bmp = ...;

        // rescale it to have size of 32*32
        if ( bmp.GetWidth() != 32 || bmp.GetHeight() != 32 )
        {
            wxImage image = bmp.ConvertToImage();
            bmp = wxBitmap(image.Scale(32, 32));

            // another possibility:
            image.Rescale(32, 32);
            bmp = image;
        }
        @endcode

        @see Rescale()
    */
    wxImage Scale(int width, int height,
                  int quality = wxIMAGE_QUALITY_NORMAL) const;

    /**
       This function is similar to SetData() and has similar restrictions.

        The pointer passed to it may however be @NULL in which case the function
        will allocate the alpha array internally -- this is useful to add alpha
        channel data to an image which doesn't have any.

        If the pointer is not @NULL, it must have one byte for each image pixel
        and be allocated with malloc().
        wxImage takes ownership of the pointer and will free it unless @a static_data
        parameter is set to @true -- in this case the caller should do it.
    */
    void SetAlpha(unsigned char* alpha = NULL,
                  bool static_data = false);

    /**
        Sets the alpha value for the given pixel.
        This function should only be called if the image has alpha channel data,
        use HasAlpha() to check for this.
    */
    void SetAlpha(int x, int y, unsigned char alpha);

    /**
        Sets the image data without performing checks.

        The data given must have the size (width*height*3) or results will be
        unexpected. Don't use this method if you aren't sure you know what you
        are doing.

        The data must have been allocated with @c malloc(), @b NOT with
        @c operator new.

        After this call the pointer to the data is owned by the wxImage object,
        that will be responsible for deleting it.
        Do not pass to this function a pointer obtained through GetData().
    */
    void SetData(unsigned char* data);

    /**
        Specifies whether there is a mask or not.

        The area of the mask is determined by the current mask colour.
    */
    void SetMask(bool hasMask = true);

    /**
        Sets the mask colour for this image (and tells the image to use the mask).
    */
    void SetMaskColour(unsigned char red, unsigned char green,
                       unsigned char blue);

    /**
        Sets image's mask so that the pixels that have RGB value of mr,mg,mb in
        mask will be masked in the image.

        This is done by first finding an unused colour in the image, setting
        this colour as the mask colour and then using this colour to draw all
        pixels in the image who corresponding pixel in mask has given RGB value.

        The parameter @a mask is the mask image to extract mask shape from.
        It must have the same dimensions as the image.

        The parameters @a mr, @a mg, @a mb are the RGB values of the pixels in
        mask that will be used to create the mask.

        @return Returns @false if mask does not have same dimensions as the image
                or if there is no unused colour left. Returns @true if the mask
                was successfully applied.

        @note
            Note that this method involves computing the histogram, which is a
            computationally intensive operation.
    */
    bool SetMaskFromImage(const wxImage& mask, unsigned char mr,
                          unsigned char mg,
                          unsigned char mb);

    //@{
    /**
        Sets a user-defined option. The function is case-insensitive to @a name.

        For example, when saving as a JPEG file, the option @b quality is
        used, which is a number between 0 and 100 (0 is terrible, 100 is very good).

        @see GetOption(), GetOptionInt(), HasOption()
    */
    void SetOption(const wxString& name, const wxString& value);
    void SetOption(const wxString& name, int value);
    //@}

    /**
        Associates a palette with the image.

        The palette may be used when converting wxImage to wxBitmap (MSW only at present)
        or in file save operations (none as yet).
    */
    void SetPalette(const wxPalette& palette);

    /**
        Sets the colour of the pixels within the given rectangle.

        This routine performs bounds-checks for the coordinate so it can be considered
        a safe way to manipulate the data.
    */
    void SetRGB(wxRect& rect, unsigned char red,
                unsigned char green,
                unsigned char blue);

    /**
        Set the type of image returned by GetType().

        This method is mostly used internally by the library but can also be
        called from the user code if the image was created from data in the
        given bitmap format without using LoadFile() (which would set the type
        correctly automatically).

        Notice that the image must be created before this function is called.

        @since 2.9.0

        @param type
            One of bitmap type constants, @c wxBITMAP_TYPE_INVALID is a valid
            value for it and can be used to reset the bitmap type to default
            but @c wxBITMAP_TYPE_MAX is not allowed here.
    */
    void SetType(wxBitmapType type);

    /**
        Returns a resized version of this image without scaling it by adding either a
        border with the given colour or cropping as necessary.

        The image is pasted into a new image with the given @a size and background
        colour at the position @a pos relative to the upper left of the new image.

        If @a red = green = blue = -1 then the areas of the larger image not covered
        by this image are made transparent by filling them with the image mask colour
        (which will be allocated automatically if it isn't currently set).

        Otherwise, the areas will be filled with the colour with the specified RGB components.

        @see Resize()
    */
    wxImage Size(const wxSize& size, const wxPoint& pos, int red = -1,
                 int green = -1, int blue = -1) const;

    /**
        Assignment operator, using @ref overview_refcount "reference counting".

        @param image
            Image to assign.

        @return Returns 'this' object.
    */
    wxImage& operator=(const wxImage& image);
};

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

/** @ingroup group_funcmacro_appinitterm */
//@{

/**
    Initializes all available image handlers. For a list of available handlers,
    see wxImage.

    @see wxImage, wxImageHandler

    @header{wx/image.h}
*/
void wxInitAllImageHandlers();

//@}