ab272c0bf8
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@1525 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
112 lines
4.1 KiB
TeX
112 lines
4.1 KiB
TeX
\section{\class{wxBitmapDataObject}}\label{wxbitmapdataobject}
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wxBitmapDataObject is a specialization of wxDataObject for bitmap data. It can be
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used without change to paste data into the \helpref{wxClipboard}{wxclipboard}
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or a \helpref{wxDropSource}{wxdropsource}. A user may wish to derive a new class
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from this class for providing a bitmap on-demand in order to minimize memory consumption
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when offering data in several formats, such as a bitmap and GIF.
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In order to offer bitmap data on-demand \helpref{GetSize}{wxbitmapdataobjectgetsize}
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and \helpref{WriteData}{wxbitmapdataobjectwritedata} will have to be overridden.
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\wxheading{Derived from}
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\helpref{wxDataObject}{wxdataobject}
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\wxheading{See also}
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\helpref{wxDataObject}{wxdataobject}
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\latexignore{\rtfignore{\wxheading{Members}}}
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\membersection{wxBitmapDataObject::wxBitmapDataObject}\label{wxbitmapdataobjectwxbitmapdataobject}
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\func{}{wxBitmapDataObject}{\void}
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Default constructor. Call \helpref{SetBitmap}{wxbitmapdataobjectsettext} later
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or override \helpref{WriteData}{wxbitmapdataobjectwritedata} and
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\helpref{GetSize}{wxbitmapdataobjectgetsize} for providing data on-demand.
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\func{}{wxBitmapDataObject}{\param{const wxBitmap\& }{bitmap}}
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Constructor, passing a bitmap.
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\membersection{wxBitmapDataObject::GetSize}\label{wxbitmapdataobjectgetsize}
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\constfunc{virtual size\_t}{GetSize}{\void}
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Returns the data size. By default, returns the size of the bitmap data
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set in the constructor or using \helpref{SetBitmap}{wxbitmapdataobjectsettext}.
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This can be overridden to provide size data on-demand. Note that you'd
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have to call the inherited GetSize method as this is the only way
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to get to know the transfer size of the bitmap in a platform dependent
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way - a bitmap has different size under GTK and Windows. In practice,
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this would look like this:
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\begin{verbatim}
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size_t MyBitmapDataObject::GetSize()
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{
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// Get bitmap from global container. This container
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// should be able to "produce" data in all formats
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// offered by the application but store it only in
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// one format to reduce memory consumption.
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wxBitmap my_bitmap = my_global_container->GetBitmap();
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// temporarily set bitmap
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SetBitmap( my_bitmap );
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size_t ret = wxBitmapDataObject::GetSize();
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// unset bitmap again
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SetBitmap( wxNullBitmap );
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retrun ret;
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}
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\end{verbatim}
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TODO: Offer a nicer way to do this. Maybe by providing a platform
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dependent function in this class like
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\begin{verbatim}
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size_t GetBitmapSize( const wxBitmap &bitmap )
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\end{verbatim}
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\membersection{wxBitmapDataObject::GetBitmap}\label{wxbitmapdataobjectgettext}
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\constfunc{virtual wxBitmap}{GetBitmap}{\void}
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Returns the bitmap associated with the data object. You may wish to override
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this method when offering data on-demand, but this is not required by
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wxWindows' internals. Use this method to get data in bitmap form from
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the \helpref{wxClipboard}{wxclipboard}.
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\membersection{wxBitmapDataObject::SetBitmap}\label{wxbitmapdataobjectsettext}
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\func{virtual void}{SetBitmap}{\param{const wxBitmap\& }{bitmap}}
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Sets the bitmap associated with the data object. This method is called
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internally when retrieving data from the \helpref{wxClipboard}{wxclipboard}
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and may be used to paste data to the clipboard directly (instead of
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on-demand).
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\membersection{wxBitmapDataObject::WriteData}\label{wxbitmapdataobjectwritedata}
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\constfunc{virtual void}{WriteData}{\param{void}{*dest} }
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Write the data owned by this class to {\it dest}. By default, this
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calls \helpref{WriteBitmap}{wxbitmapdataobjectwritebitmap} with the bitmap
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set in the constructor or using \helpref{SetBitmap}{wxbitmapdataobjectsetbitmap}.
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This can be overridden to provide bitmap data on-demand; in this case
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\helpref{WriteBitmap}{wxbitmapdataobjectwritebitmap} must be called from
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within th overriding WriteData() method.
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\membersection{wxBitmapDataObject::WriteBitmap}\label{wxbitmapdataobjectwritebitmap}
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\constfunc{void}{WriteBitmap}{\param{const wxBitmap\& }{bitmap}\param{void}{*dest} }
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Writes the the bitmap {\it bitmap} to {\it dest}. This method must be called
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from \helpref{WriteData}{wxbitmapdataobjectwritedata}.
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