wxWidgets/docs/latex/wx/image.tex

\section{\class{wxImage}}\label{wximage}

This class encapsulates a platform-independent image. An image can be created
from data, or using the constructor taking a wxBitmap object. 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, and that bitmap drawn on the wxDC, using
wxDC::DrawBitmap.

This class is currently only available under GTK and Windows.

\wxheading{Derived from}

\helpref{wxObject}{wxobject}

\wxheading{See also}

\helpref{wxBitmap}{wxbitmap}

\latexignore{\rtfignore{\wxheading{Members}}}

\membersection{wxImage::wxImage}\label{wximageconstr}

\func{}{wxImage}{\void}

Default constructor.

\func{}{wxImage}{\param{const wxImage\& }{image}}

Copy constructor.

\func{}{wxImage}{\param{const wxBitmap\&}{ bitmap}}

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.

\func{}{wxImage}{\param{int}{ width}, \param{int}{ height}}

Creates an image with the given width and height.

\func{}{wxImage}{\param{const wxString\& }{name}, \param{long}{ type = wxIMAGE\_TYPE\_PNG}}

Loads an image from a file.

\wxheading{Parameters}

\docparam{width}{Specifies the width of the image.}

\docparam{height}{Specifies the height of the image.}

\docparam{name}{This refers to an image filename. Its meaning is determined by the {\it type} parameter.}

\docparam{type}{May be one of the following:

\twocolwidtha{5cm}
\begin{twocollist}
\twocolitem{{\bf \indexit{wxIMAGE\_TYPE\_BMP}}}{Load a Windows bitmap file.}
\twocolitem{{\bf \indexit{wxIMAGE\_TYPE\_PNG}}}{Load a PNG bitmap file.}
\end{twocollist}

The validity of these flags depends on the platform and wxWindows configuration.
If all possible wxWindows settings are used, the loading a BMP (Windows bitmap) file
and a PNG (portable network graphics) file is supported on all platforms that
implement wxImage.}

\wxheading{See also}

\helpref{wxImage::LoadFile}{wximageloadfile}

\membersection{wxImage::\destruct{wxImage}}

\func{}{\destruct{wxImage}}{\void}

Destructor.

\membersection{wxImage::AddHandler}\label{wximageaddhandler}

\func{static void}{AddHandler}{\param{wxImageHandler*}{ handler}}

Adds a handler to the end of the static list of format handlers.

\docparam{handler}{A new image format handler object. There is usually only one instance
of a given handler class in an application session.}

\wxheading{See also}

\helpref{wxImageHandler}{wximagehandler}

\membersection{wxImage::CleanUpHandlers}

\func{static void}{CleanUpHandlers}{\void}

Deletes all image handlers.

This function is called by wxWindows on exit.

\membersection{wxImage::ConvertToBitmap}\label{wximageconverttobitmap}

\constfunc{wxBitmap}{ConvertToBitmap}{\void}

Converts the image to a platform-specific bitmap object. This has to be done
to actually display an image as you cannot draw an image directly on a window.
The resulting bitmap will use the colour depth of the current system which entails
that a (crude) colour reduction has to take place. Especially when converting
to 8-bit (or even less) bitmaps, the routine is slow and will reduce the
quality of the resulting bitmap. A proper set of colour reduction methods has
not yet been written.

\membersection{wxImage::Create}\label{wximagecreate}

\func{bool}{Create}{\param{int}{ width}, \param{int}{ height}}

Creates a fresh image.

\wxheading{Parameters}

\docparam{width}{The width of the image in pixels.}

\docparam{height}{The height of the image in pixels.}

\wxheading{Return value}

TRUE if the call succeeded, FALSE otherwise.

\membersection{wxImage::Destroy}\label{wximagedestroy}

\func{bool}{Destroy}{\void}

Destroys the image data.

\membersection{wxImage::FindHandler}

\func{static wxImageHandler*}{FindHandler}{\param{const wxString\& }{name}}

Finds the handler with the given name.

\func{static wxImageHandler*}{FindHandler}{\param{const wxString\& }{extension}, \param{long}{ imageType}}

Finds the handler associated with the given extension and type.

\func{static wxImageHandler*}{FindHandler}{\param{long }{imageType}}

Finds the handler associated with the given image type.

\docparam{name}{The handler name.}

\docparam{extension}{The file extension, such as ``bmp".}

\docparam{imageType}{The image type, such as wxIMAGE\_TYPE\_BMP.}

\wxheading{Return value}

A pointer to the handler if found, NULL otherwise.

\wxheading{See also}

\helpref{wxImageHandler}{wximagehandler}

\membersection{wxImage::GetBlue}\label{wximagegetblue}

\constfunc{unsigned char}{GetBlue}{\param{int}{ x}, \param{int}{ y}}

Returns the blue intensity at the given coordinate.

\membersection{wxImage::GetData}\label{wximagegetdata}

\constfunc{unsigned char*}{GetData}{\void}

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
chararcters in RGBGBRGB... format.

\membersection{wxImage::GetGreen}\label{wximagegetgreen}

\constfunc{unsigned char}{GetGreen}{\param{int}{ x}, \param{int}{ y}}

Returns the green intensity at the given coordinate.

\membersection{wxImage::GetRed}\label{wximagegetred}

\constfunc{unsigned char}{GetRed}{\param{int}{ x}, \param{int}{ y}}

Returns the red intensity at the given coordinate.

\membersection{wxImage::GetHandlers}

\func{static wxList\&}{GetHandlers}{\void}

Returns the static list of image format handlers.

\wxheading{See also}

\helpref{wxImageHandler}{wximagehandler}

\membersection{wxImage::GetHeight}\label{wximagegetheight}

\constfunc{int}{GetHeight}{\void}

Gets the height of the image in pixels.

\membersection{wxImage::GetMaskBlue}\label{wximagegetmaskblue}

\constfunc{unsigned char}{GetMaskBlue}{\void}

Gets the blue value of the mask colour.

\membersection{wxImage::GetMaskGreen}\label{wximagegetmaskgreen}

\constfunc{unsigned char}{GetMaskGreen}{\void}

Gets the green value of the mask colour.

\membersection{wxImage::GetMaskRed}\label{wximagegetmaskred}

\constfunc{unsigned char}{GetMaskRed}{\void}

Gets the red value of the mask colour.

\membersection{wxImage::GetWidth}\label{wximagegetwidth}

\constfunc{int}{GetWidth}{\void}

Gets the width of the image in pixels.

\wxheading{See also}

\helpref{wxImage::GetHeight}{wximagegetheight}

\membersection{wxImage::HasMask}\label{wximagehasmask}

\constfunc{bool}{HasMask}{\void}

Returns TRUE if there is a mask active, FALSE otherwise.

\membersection{wxImage::InitStandardHandlers}

\func{static void}{InitStandardHandlers}{\void}

Adds the standard image format handlers, which, depending on wxWindows
configuration, can be handlers for Windows BMP (loading) and PNG
(loading and saving) file formats.

This function is called by wxWindows on startup.

\wxheading{See also}

\helpref{wxImageHandler}{wximagehandler}

\membersection{wxImage::InsertHandler}

\func{static void}{InsertHandler}{\param{wxImageHandler*}{ handler}}

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

\docparam{handler}{A new image format handler object. There is usually only one instance
of a given handler class in an application session.}

\wxheading{See also}

\helpref{wxImageHandler}{wximagehandler}

\membersection{wxImage::LoadFile}\label{wximageloadfile}

\func{bool}{LoadFile}{\param{const wxString\&}{ name}, \param{long}{ type}}

Loads an image from a file.

\wxheading{Parameters}

\docparam{name}{A filename.
The meaning of {\it name} is determined by the {\it type} parameter.}

\docparam{type}{One of the following values:

\twocolwidtha{5cm}
\begin{twocollist}
\twocolitem{{\bf wxIMAGE\_TYPE\_BMP}}{Load a Windows image file.}
\twocolitem{{\bf wxIMAGE\_TYPE\_PNG}}{Load a PNG image file.}
\end{twocollist}

The validity of these flags depends on the platform and wxWindows configuration.}

\wxheading{Return value}

TRUE if the operation succeeded, FALSE otherwise.

\wxheading{See also}

\helpref{wxImage::SaveFile}{wximagesavefile}

\membersection{wxImage::Ok}\label{wximageok}

\constfunc{bool}{Ok}{\void}

Returns TRUE if image data is present.

\membersection{wxImage::RemoveHandler}

\func{static bool}{RemoveHandler}{\param{const wxString\& }{name}}

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

\docparam{name}{The handler name.}

\wxheading{Return value}

TRUE if the handler was found and removed, FALSE otherwise.

\wxheading{See also}

\helpref{wxImageHandler}{wximagehandler}

\membersection{wxImage::SaveFile}\label{wximagesavefile}

\func{bool}{SaveFile}{\param{const wxString\& }{name}, \param{int}{ type}}

Saves a image in the named file.

\wxheading{Parameters}

\docparam{name}{A filename. The meaning of {\it name} is determined by the {\it type} parameter.}

\docparam{type}{Currently only one type can be used:

\twocolwidtha{5cm}
\begin{twocollist}
\twocolitem{{\bf wxIMAGE\_TYPE\_PNG}}{Save a PNG image file.}
\end{twocollist}

The validity of these flags depends on the platform and wxWindows configuration
as well as user-added handlers.}

\wxheading{Return value}

TRUE if the operation succeeded, FALSE otherwise.

\wxheading{Remarks}

Depending on how wxWindows has been configured, not all formats may be available.

\wxheading{See also}

\helpref{wxImage::LoadFile}{wximageloadfile}

\membersection{wxImage::Scale}\label{wximagescale}

\func{wxImage}{Scale}{\param{int}{ width}, \param{int}{ 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 do blit a wxMemoryDC into another wxMemoryDC. Windows can such scaling
itself, but on GTK scaling bitmaps is done using this routine 
internally.

\membersection{wxImage::SetData}\label{wximagesetdata}

\func{void}{SetData}{\param{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.

\membersection{wxImage::SetMask}\label{wximagesetmask}

\func{void}{SetMask}{\param{bool}{ hasMask = TRUE}}

Specifies whether there is a mask or not. The area of the mask is determined by the current mask colour.

\membersection{wxImage::SetMaskColour}\label{wximagesetmaskcolour}

\func{void}{SetMaskColour}{\param{unsigned char }{red}, \param{unsigned char }{blue}, \param{unsigned char }{green}}

Sets the mask colour for this image.

\membersection{wxImage::SetRGB}\label{wximagesetrgb}

\func{void}{SetRGB}{\param{int }{x}, \param{int }{y}, \param{unsigned char }{red}, \param{unsigned char }{blue}, \param{unsigned char }{green}}

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 have to get that data by calling GetData().

\membersection{wxImage::operator $=$}

\func{wxImage\& }{operator $=$}{\param{const wxImage\& }{image}}

Assignment operator. This operator does not copy any data, but instead
passes a pointer to the data in {\it image} and increments a reference
counter. It is a fast operation.

\wxheading{Parameters}

\docparam{image}{Image to assign.}

\wxheading{Return value}

Returns 'this' object.

\membersection{wxImage::operator $==$}

\func{bool}{operator $==$}{\param{const wxImage\& }{image}}

Equality operator. This operator tests whether the internal data pointers are
equal (a fast test).

\wxheading{Parameters}

\docparam{image}{Image to compare with 'this'}

\wxheading{Return value}

Returns TRUE if the images were effectively equal, FALSE otherwise.

\membersection{wxImage::operator $!=$}

\func{bool}{operator $!=$}{\param{const wxImage\& }{image}}

Inequality operator. This operator tests whether the internal data pointers are
unequal (a fast test).

\wxheading{Parameters}

\docparam{image}{Image to compare with 'this'}

\wxheading{Return value}

Returns TRUE if the images were unequal, FALSE otherwise.

\section{\class{wxImageHandler}}\label{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 \helpref{wxImage::AddHandler}{wximageaddhandler} in your
application initialisation.

\wxheading{Derived from}

\helpref{wxObject}{wxobject}

\wxheading{See also}

\helpref{wxImage}{wximage}

\latexignore{\rtfignore{\wxheading{Members}}}

\membersection{wxImageHandler::wxImageHandler}\label{wximagehandlerconstr}

\func{}{wxImageHandler}{\void}

Default constructor. In your own default constructor, initialise the members
m\_name, m\_extension and m\_type.

\membersection{wxImageHandler::\destruct{wxImageHandler}}

\func{}{\destruct{wxImageHandler}}{\void}

Destroys the wxImageHandler object.

\membersection{wxImageHandler::GetName}

\constfunc{wxString}{GetName}{\void}

Gets the name of this handler.

\membersection{wxImageHandler::GetExtension}

\constfunc{wxString}{GetExtension}{\void}

Gets the file extension associated with this handler.

\membersection{wxImageHandler::GetType}

\constfunc{long}{GetType}{\void}

Gets the image type associated with this handler.

\membersection{wxImageHandler::LoadFile}\label{wximagehandlerloadfile}

\func{bool}{LoadFile}{\param{wxImage* }{image}, \param{const wxString\&}{ name}}

Loads a image from a file or resource, putting the resulting data into {\it image}.

\wxheading{Parameters}

\docparam{image}{The image object which is to be affected by this operation.}

\docparam{name}{Either a filename or a Windows resource name.
The meaning of {\it name} is determined by the {\it type} parameter.}

\wxheading{Return value}

TRUE if the operation succeeded, FALSE otherwise.

\wxheading{See also}

\helpref{wxImage::LoadFile}{wximageloadfile}\\
\helpref{wxImage::SaveFile}{wximagesavefile}\\
\helpref{wxImageHandler::SaveFile}{wximagehandlersavefile}

\membersection{wxImageHandler::SaveFile}\label{wximagehandlersavefile}

\func{bool}{SaveFile}{\param{wxImage* }{image}, \param{const wxString\& }{name}}

Saves a image in the named file.

\wxheading{Parameters}

\docparam{image}{The image object which is to be affected by this operation.}

\docparam{name}{A filename. The meaning of {\it name} is determined by the {\it type} parameter.}

\wxheading{Return value}

TRUE if the operation succeeded, FALSE otherwise.

\wxheading{See also}

\helpref{wxImage::LoadFile}{wximageloadfile}\\
\helpref{wxImage::SaveFile}{wximagesavefile}\\
\helpref{wxImageHandler::LoadFile}{wximagehandlerloadfile}

\membersection{wxImageHandler::SetName}

\func{void}{SetName}{\param{const wxString\& }{name}}

Sets the handler name.

\wxheading{Parameters}

\docparam{name}{Handler name.}

\membersection{wxImageHandler::SetExtension}

\func{void}{SetExtension}{\param{const wxString\& }{extension}}

Sets the handler extension.

\wxheading{Parameters}

\docparam{extension}{Handler extension.}

\membersection{wxImageHandler::SetType}

\func{void}{SetType}{\param{long }{type}}

Sets the handler type.

\wxheading{Parameters}

\docparam{name}{Handler type.}