/// Highest quality but slowest execution time.
wxIMAGE_QUALITY_BICUBIC,
- /// Default image resizing algorithm used by wxImage::Scale().
+ /**
+ Use surrounding pixels to calculate an average that will be used for
+ new pixels. This method is typically used when reducing the size of
+ an image.
+ */
+ wxIMAGE_QUALITY_BOX_AVERAGE,
+
+ /**
+ Default image resizing algorithm used by wxImage::Scale(). Currently
+ the same as wxIMAGE_QUALITY_NEAREST.
+ */
wxIMAGE_QUALITY_NORMAL,
- /// Best image resizing algorithm, currently same as wxIMAGE_QUALITY_BICUBIC.
+ /**
+ Best image resizing algorithm. Since version 2.9.2 this results in
+ wxIMAGE_QUALITY_BOX_AVERAGE being used when reducing the size of the
+ image (meaning that both the new width and height will be smaller than
+ the original size). Otherwise wxIMAGE_QUALITY_BICUBIC is used.
+ */
wxIMAGE_QUALITY_HIGH
};
{
wxPNG_TYPE_COLOUR = 0, ///< Colour PNG image.
wxPNG_TYPE_GREY = 2, ///< Greyscale PNG image converted from RGB.
- wxPNG_TYPE_GREY_RED = 3 ///< Greyscale PNG image using red as grey.
+ wxPNG_TYPE_GREY_RED = 3, ///< Greyscale PNG image using red as grey.
+ wxPNG_TYPE_PALETTE = 4 ///< Palette encoding.
};
/**
the wxBitmap::wxBitmap(wxImage,int depth) constructor.
This bitmap can then be drawn in a device context, using wxDC::DrawBitmap.
+ More on the difference between wxImage and wxBitmap: wxImage is just a
+ buffer of RGB bytes with an optional buffer for the alpha bytes. It is all
+ generic, platform independent and image file format independent code. It
+ includes generic code for scaling, resizing, clipping, and other manipulations
+ of the image data. OTOH, wxBitmap is intended to be a wrapper of whatever is
+ the native image format that is quickest/easiest to draw to a DC or to be the
+ target of the drawing operations performed on a wxMemoryDC. By splitting the
+ responsibilities between wxImage/wxBitmap like this then it's easier to use
+ generic code shared by all platforms and image types for generic operations and
+ platform specific code where performance or compatibility is needed.
+
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.
While all images have RGB data, not all images have an alpha channel. 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.
+ channel with wxImage::HasAlpha. Currently the BMP, PNG, and TIFF format
+ handlers have full alpha channel support for loading so if you want to use
+ alpha you have to use one of these formats. If you initialize the image
+ alpha channel yourself using wxImage::SetAlpha, you should save it in
+ either PNG or TGA format to avoid losing it as these are the only handlers
+ that currently support saving with alpha.
@section image_handlers Available image handlers
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.
+ - wxBMPHandler: For loading (including alpha support) and saving, always installed.
+ - wxPNGHandler: For loading and saving. Includes alpha support.
- wxJPEGHandler: For loading and saving.
- - wxGIFHandler: Only for loading, due to legal issues.
+ - wxGIFHandler: For loading and saving (see below).
- wxPCXHandler: For loading and saving (see below).
- wxPNMHandler: For loading and saving (see below).
- - wxTIFFHandler: For loading and saving.
- - wxTGAHandler: For loading only.
+ - wxTIFFHandler: For loading (including alpha support) and saving.
+ - wxTGAHandler: For loading and saving. Includes alpha support.
- wxIFFHandler: For loading only.
- wxXPMHandler: For loading and saving.
- wxICOHandler: For loading and saving.
Loading PNMs only works for ASCII or raw RGB images.
When saving in PNM format, wxPNMHandler will always save as raw RGB.
+ Saving GIFs requires images of maximum 8 bpp (see wxQuantize), and the alpha channel converted to a mask (see wxImage::ConvertAlphaToMask).
+ Saving an animated GIF requires images of the same size (see wxGIFHandler::SaveAnimation)
@library{wxcore}
@category{gdi}
@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_TIFF: 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).
/**
Gets a user-defined string-valued option.
- Currently the only defined string option is
+ Generic options:
@li @c wxIMAGE_OPTION_FILENAME: The name of the file from which the image
was loaded.
+ Options specific to wxGIFHandler:
+ @li @c wxIMAGE_OPTION_GIF_COMMENT: The comment text that is read from
+ or written to the GIF file. In an animated GIF each frame can have
+ its own comment. If there is only a comment in the first frame of
+ a GIF it will not be repeated in other frames.
+
@param name
The name of the option, case-insensitive.
@return
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.
+ Use HasOption() if 0 is a possibly valid value for the option.
Generic options:
@li @c wxIMAGE_OPTION_MAX_WIDTH and @c wxIMAGE_OPTION_MAX_HEIGHT: If either
the resulting PNG file. Use this option if your application produces
images with small size variation.
+ Options specific to wxTIFFHandler:
+ @li @c wxIMAGE_OPTION_TIFF_BITSPERSAMPLE: Number of bits per
+ sample (channel). Currently values of 1 and 8 are supported. A
+ value of 1 results in a black and white image. A value of 8 (the
+ default) can mean greyscale or RGB, depending on the value of
+ @c wxIMAGE_OPTION_TIFF_SAMPLESPERPIXEL.
+ @li @c wxIMAGE_OPTION_TIFF_SAMPLESPERPIXEL: Number of samples
+ (channels) per pixel. Currently values of 1 and 3 are supported.
+ A value of 1 results in either a greyscale (by default) or black and
+ white image, depending on the value of
+ @c wxIMAGE_OPTION_TIFF_BITSPERSAMPLE. A value of 3 (the default)
+ will result in an RGB image.
+ @li @c wxIMAGE_OPTION_TIFF_COMPRESSION: Compression type. By default
+ it is set to 1 (COMPRESSION_NONE). Typical other values are
+ 5 (COMPRESSION_LZW) and 7 (COMPRESSION_JPEG). See tiff.h for more
+ options.
+ @li @c wxIMAGE_OPTION_TIFF_PHOTOMETRIC: Specifies the photometric
+ interpretation. By default it is set to 2 (PHOTOMETRIC_RGB) for RGB
+ images and 0 (PHOTOMETRIC_MINISWHITE) for greyscale or black and
+ white images. It can also be set to 1 (PHOTOMETRIC_MINISBLACK) to
+ treat the lowest value as black and highest as white.
+ If you want a greyscale image it is also sufficient to only specify
+ @c wxIMAGE_OPTION_TIFF_PHOTOMETRIC and set it to either
+ PHOTOMETRIC_MINISWHITE or PHOTOMETRIC_MINISBLACK. The other values
+ are taken care of.
+
+ @note
+ Be careful when combining the options @c wxIMAGE_OPTION_TIFF_SAMPLESPERPIXEL,
+ @c wxIMAGE_OPTION_TIFF_BITSPERSAMPLE, and @c wxIMAGE_OPTION_TIFF_PHOTOMETRIC.
+ While some measures are taken to prevent illegal combinations and/or
+ values, it is still easy to abuse them and come up with invalid
+ results in the form of either corrupted images or crashes.
+
@param name
The name of the option, case-insensitive.
@return
@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_TIFF: 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).
/**
Register an image handler.
- See @ref image_handlers for a list of the available handlers.
+
+ Typical example of use:
+ @code
+ wxImage::AddHandler(new wxPNGHandler);
+ @endcode
+
+ See @ref image_handlers for a list of the available handlers. You can
+ also use ::wxInitAllImageHandlers() to add handlers for all the image
+ formats supported by wxWidgets at once.
+
+ @param handler
+ A heap-allocated handler object which will be deleted by wxImage
+ if it is removed later by RemoveHandler() or at program shutdown.
*/
static void AddHandler(wxImageHandler* handler);
/**
Finds the handler with the given name, and removes it.
- The handler is not deleted.
+
+ The handler is also deleted.
@param name
The handler name.
@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_TIFF: 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).
//@{
/**
- Initializes all available image handlers. For a list of available handlers,
- see wxImage.
- If you don't need/want all image handlers loaded
+ Initializes all available image handlers.
+
+ This function calls wxImage::AddHandler() for all the available image
+ handlers (see @ref image_handlers for the full list). Calling it is the
+ simplest way to initialize wxImage but it creates and registers even the
+ handlers your program may not use. If you want to avoid the overhead of
+ doing this you need to call wxImage::AddHandler() manually just for the
+ handlers that you do want to use.
@see wxImage, wxImageHandler
projects / wxWidgets.git / blobdiff