.\" This is a wxWidgets manpage page generated from the XML docs .TH wxImage 3wx 2005-02-15 "wxWidgets" "wxWidgets class documentation" .SH NAME wxImage \- A platform-independent image class .SH DESCRIPTION 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. 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. Unlike RGB data, not all images have an alpha channel and before using GetAlpha you should check if this image contains an alpha channel with HasAlpha . Note that currently only images loaded from PNG files with transparency information will have an alpha channel but alpha support will be added to the other formats as well (as well as support for saving images with alpha channel which also isn't implemented). 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 wxInitAllImageHandlers . For loading and saving, always installed. For loading (including alpha support) and saving. For loading and saving. Only for loading, due to legal issues. For loading and saving (see below). For loading and saving (see below). For loading and saving. For loading only. For loading and saving. For loading and saving. For loading and saving. 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. .SH "PARENTS" wxObject .SH "INCLUDE FILES" wx/image.h .SH MEMBERS .SS wxImage () Default constructor. .SS wxImage (const wxImage& image) Copy constructor. .SS wxImage (const wxBitmap& bitmap) (Deprecated form, use wxBitmap::ConvertToImage instead.) Constructs an image from a platform-dependent bitmap. This preserves mask information so that bitmaps and images can be converted back and forth without loss in that respect. .SS wxImage (int widthint heightbool clear = true) Creates an image with the given width and height. If clear is true, the new image will be initialized to black. Otherwise, the image data will be uninitialized. .SS wxImage (int widthint heightunsigned char* databool static_data = false) Creates an image from given data with the given width and height. If static_data is true, then wxImage will not delete the actual image data in its destructor, otherwise it will free it by calling free() . .SS wxImage (const wxString& namelong type = wxBITMAP_TYPE_ANYint index = -1) .SS wxImage (const wxString& nameconst wxString& mimetypeint index = -1) Loads an image from a file. .SS wxImage (wxInputStream& streamlong type = wxBITMAP_TYPE_ANYint index = -1) .SS wxImage (wxInputStream& streamconst wxString& mimetypeint index = -1) Loads an image from an input stream. .SS wxImage (const char** xpmData) Creates an image from XPM data. .SS ~wxImage () Destructor. .SS static void AddHandler (wxImageHandler* handler) Adds a handler to the end of the static list of format handlers. .SS bool CanRead (const wxString& filename) returns true if the current image handlers can read this file .SS static void CleanUpHandlers () Deletes all image handlers. This function is called by wxWidgets on exit. .SS unsigned long ComputeHistogram (wxImageHistogram& histogram) Computes the histogram of the image. histogram is a reference to wxImageHistogram object. wxImageHistogram is a specialization of wxHashMap "template" and is defined as follows: 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); .SS bool ConvertAlphaToMask (unsigned char threshold = 128) If the image has alpha channel, this method converts it to mask. All pixels with alpha value less than 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. .SS wxBitmap ConvertToBitmap () Deprecated, use equivalent wxBitmap constructor (which takes wxImage and depth as its arguments) instead. .SS wxImage ConvertToMono (unsigned char runsigned char gunsigned char b) Returns monochromatic version of the image. The returned image has white colour where the original has (r,g,b) colour and black colour everywhere else. .SS wxImage Copy () Returns an identical copy of the image. .SS bool Create (int widthint heightbool clear = true) Creates a fresh image. If clear is true, the new image will be initialized to black. Otherwise, the image data will be uninitialized. .SS void Destroy () Destroys the image data. .SS bool FindFirstUnusedColour (unsigned char * runsigned char * gunsigned char * bunsigned char startR = 1unsigned char startG = 0unsigned char startB = 0) 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. .SS static wxImageHandler* FindHandler (const wxString& name) Finds the handler with the given name. .SS static wxImageHandler* FindHandler (const wxString& extensionlong imageType) Finds the handler associated with the given extension and type. .SS static wxImageHandler* FindHandler (long imageType) Finds the handler associated with the given image type. .SS static wxImageHandler* FindHandlerMime (const wxString& mimetype) Finds the handler associated with the given MIME type. .SS static wxString GetImageExtWildcard () Iterates all registered wxImageHandler objects, and returns a string containing file extension masks suitable for passing to file open/save dialog boxes. .SS unsigned char GetAlpha (int xint y) Returns the alpha value for the given pixel. This function may only be called for the images with alpha channel, use HasAlpha to check for this. The returned value is the opacity of the image, i.e. the value of 0 corresponds to the transparent pixels while the value of 255 -- to the opaque ones. .SS unsigned char * GetAlpha () 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. .SS unsigned char GetBlue (int xint y) Returns the blue intensity at the given coordinate. .SS unsigned char* GetData () 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\ldots 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 wxImage::SetData . .SS unsigned char GetGreen (int xint y) Returns the green intensity at the given coordinate. .SS static int GetImageCount (const wxString& filenamelong type = wxBITMAP_TYPE_ANY) .SS static int GetImageCount (wxInputStream& streamlong type = wxBITMAP_TYPE_ANY) 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. .SS static wxList& GetHandlers () Returns the static list of image format handlers. .SS int GetHeight () Gets the height of the image in pixels. .SS unsigned char GetMaskBlue () Gets the blue value of the mask colour. .SS unsigned char GetMaskGreen () Gets the green value of the mask colour. .SS unsigned char GetMaskRed () Gets the red value of the mask colour. .SS bool GetOrFindMaskColour (unsigned char *runsigned char *gunsigned char *b) 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. .SS const wxPalette& GetPalette () Returns the palette associated with the image. Currently the palette is only used when converting to wxBitmap under Windows. Eventually wxImage handlers will set the palette if one exists in the image file. .SS unsigned char GetRed (int xint y) Returns the red intensity at the given coordinate. .SS wxImage GetSubImage (const wxRect& rect) Returns a sub image of the current one as long as the rect belongs entirely to the image. .SS int GetWidth () Gets the width of the image in pixels. .SS HSVValue (double h = 0.0double s = 0.0double v = 0.0) 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. .SS wxImage::RGBValue HSVtoRGB (const HSVValue & hsv) Converts a color in HSV color space to RGB color space. .SS bool HasAlpha () .SS bool HasMask () Returns true if there is a mask active, false otherwise. .SS wxString GetOption (const wxString& name) Gets a user-defined option. The function is case-insensitive to name . For example, when saving as a JPEG file, the option quality is used, which is a number between 0 and 100 (0 is terrible, 100 is very good). .SS int GetOptionInt (const wxString& name) Gets a user-defined option as an integer. The function is case-insensitive to name . If the given option is not present, the function returns 0. Use wxImage::HasOption is 0 is a possibly valid value for the option. Options for wxPNGHandler wxIMAGE_OPTION_PNG_FORMAT Format for saving a PNG file. wxIMAGE_OPTION_PNG_BITDEPTH Bit depth for every channel (R/G/B/A). Supported values for wxIMAGE_OPTION_PNG_FORMAT: wxPNG_TYPE_COLOUR Stores RGB image. wxPNG_TYPE_GREY Stores grey image, converts from RGB. wxPNG_TYPE_GREY_RED Stores grey image, uses red value as grey. .SS bool HasOption (const wxString& name) Returns true if the given option is present. The function is case-insensitive to name . .SS void InitAlpha () 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 a mask colour, all mask pixels will be completely transparent. .SS static void InitStandardHandlers () .SS static void InsertHandler (wxImageHandler* handler) Adds a handler at the start of the static list of format handlers. .SS bool IsTransparent (int xint yunsigned char threshold = 128) 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 threshold . .SS bool LoadFile (const wxString& namelong type = wxBITMAP_TYPE_ANYint index = -1) .SS bool LoadFile (const wxString& nameconst wxString& mimetypeint index = -1) Loads an image from a file. If no handler type is provided, the library will try to autodetect the format. .SS bool LoadFile (wxInputStream& streamlong typeint index = -1) .SS bool LoadFile (wxInputStream& streamconst wxString& mimetypeint index = -1) Loads an image from an input stream. .SS bool Ok () Returns true if image data is present. .SS RGBValue (unsigned char r = 0unsigned char g = 0unsigned char b = 0) Constructor for RGBValue, an object that contains values for red, green and blud 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. .SS wxImage::HSVValue RGBtoHSV (const RGBValue& rgb) Converts a color in RGB color space to HSV color space. .SS static bool RemoveHandler (const wxString& name) Finds the handler with the given name, and removes it. The handler is not deleted. .SS wxImage Mirror (bool horizontally = true) Returns a mirrored copy of the image. The parameter horizontally indicates the orientation. .SS void Replace (unsigned char r1unsigned char g1unsigned char b1unsigned char r2unsigned char g2unsigned char b2) Replaces the colour specified by r1,g1,b1 by the colour r2,g2,b2 . .SS wxImage & Rescale (int widthint height) 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. Returns the (modified) image itself. .SS wxImage & Resize (const wxSize& sizeconst wxPoint& posint red = -1int green = -1int blue = -1) 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 size and background colour at the position pos relative to the upper left of the new image. If 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. Returns the (modified) image itself. .SS wxImage Rotate (double angleconst wxPoint& rotationCentrebool interpolating = truewxPoint* offsetAfterRotation = NULL) Rotates the image about the given point, by angle radians. Passing true to 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. .SS void RotateHue (double angle) Rotates the hue of each pixel in the image by 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. .SS wxImage Rotate90 (bool clockwise = true) Returns a copy of the image rotated 90 degrees in the direction indicated by clockwise . .SS bool SaveFile (const wxString& nameint type) .SS bool SaveFile (const wxString& nameconst wxString& mimetype) Saves an image in the named file. .SS bool SaveFile (const wxString& name) 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. .SS bool SaveFile (wxOutputStream& streamint type) .SS bool SaveFile (wxOutputStream& streamconst wxString& mimetype) Saves an image in the given stream. .SS wxImage Scale (int widthint height) 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. It may be mentioned that the GTK port uses this function internally to scale bitmaps when using mapping modes in wxDC. Example: // 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; } .SS wxImage Size (const wxSize& sizeconst wxPoint& posint red = -1int green = -1int blue = -1) 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 size and background colour at the position pos relative to the upper left of the new image. If 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. .SS void SetAlpha (unsigned char *alpha = NULLbool static_data = false) 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 static_data parameter is set.to true -- in this case the caller should do it. .SS void SetAlpha (int xint yunsigned char alpha) 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. .SS void SetData (unsigned char*data) 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 malloc() , NOT with 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 wxImage::GetData . .SS void SetMask (bool hasMask = true) Specifies whether there is a mask or not. The area of the mask is determined by the current mask colour. .SS void SetMaskColour (unsigned char redunsigned char greenunsigned char blue) Sets the mask colour for this image (and tells the image to use the mask). .SS bool SetMaskFromImage (const wxImage& maskunsigned char mrunsigned char mgunsigned char mb) 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. .SS void SetOption (const wxString& nameconst wxString& value) .SS void SetOption (const wxString& nameint value) Sets a user-defined option. The function is case-insensitive to name . For example, when saving as a JPEG file, the option quality is used, which is a number between 0 and 100 (0 is terrible, 100 is very good). .SS void SetPalette (const wxPalette& palette) 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). .SS void SetRGB (int xint yunsigned char redunsigned char greenunsigned char blue) Sets the pixel at the given coordinate. This routine performs bounds-checks for the coordinate so it can be considered a safe way to manipulate the data, but in some cases this might be too slow so that the data will have to be set directly. In that case you will have to get access to the image data using the GetData method. .SS void SetRGB (wxRect & rectunsigned char redunsigned char greenunsigned char blue) 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. .SS wxImage& operator = (const wxImage& image) Assignment operator. This operator does not copy any data, but instead passes a pointer to the data in image and increments a reference counter. It is a fast operation. .SS bool operator == (const wxImage& image) Equality operator. This operator tests whether the internal data pointers are equal (a fast test). .SS bool operator != (const wxImage& image) Inequality operator. This operator tests whether the internal data pointers are unequal (a fast test). .SH "SEE ALSO" wxObject wxBitmap wxInitAllImageHandlers .SH "AUTHORS" Documentation content by Julian Smart, Robert Roebling, Vadim Zeitlin, Robin Dunn, et al Conversion to manpage format by Arnout Engelen (http://bzzt.net), bugreports welcome.