+
+ @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.
+
+