docs/latex/wx/dataviewmodel.tex

   1
   2 \section{\class{wxDataViewModel}}\label{wxdataviewmodel}
   3
   4 wxDataViewModel is the base class for all data model to be
   5 displayed by a \helpref{wxDataViewCtrl}{wxdataviewctrl}.
   6 All other models derive from it and must implement its
   7 pure virtual functions in order to define a complete
   8 data model. In detail, you need to override
   9 \helpref{IsContainer}{wxdataviewmodeliscontainer},
  10 \helpref{GetParent}{wxdataviewmodelgetparent},
  11 \helpref{GetChildren}{wxdataviewmodelgetchildren},
  12 \helpref{GetColumnCount}{wxdataviewmodelgetcolumncount},
  13 \helpref{GetColumnType}{wxdataviewmodelgetcolumntype} and
  14 \helpref{GetValue}{wxdataviewmodelgetvalue} in order to
  15 define the data model which acts as an interface between
  16 your actual data and the wxDataViewCtrl. Since you will
  17 usually also allow the wxDataViewCtrl to change your data
  18 through its graphical interface, you will also have to override
  19 \helpref{SetValue}{wxdataviewmodelsetvalue} which the
  20 wxDataViewCtrl will call when a change to some data has been
  21 commited.
  22
  23 wxDataViewModel (as indeed the entire wxDataViewCtrl
  24 code) is using \helpref{wxVariant}{wxvariant} to store data and
  25 its type in a generic way. wxVariant can be extended to contain
  26 almost any data without changes to the original class.
  27
  28 The data that is presented through this data model is expected
  29 to change at run-time. You need to inform the data model when
  30 a change happened. Depending on what happened you need to call
  31 one of the following methods:
  32 \helpref{ValueChanged}{wxdataviewmodelvaluechanged},
  33 \helpref{ItemAdded}{wxdataviewmodelitemadded},
  34 \helpref{ItemDeleted}{wxdataviewmodelitemdeleted},
  35 \helpref{ItemChanged}{wxdataviewmodelitemchanged},
  36 \helpref{Cleared}{wxdataviewmodelcleared}. There are
  37 plural forms for notification of addition, change
  38 or removal of several item at once. See
  39 \helpref{ItemsAdded}{wxdataviewmodelitemsadded},
  40 \helpref{ItemsDeleted}{wxdataviewmodelitemsdeleted},
  41 \helpref{ItemsChanged}{wxdataviewmodelitemschanged}.
  42
  43 Note that wxDataViewModel does not define the position or
  44 index of any item in the control because different controls
  45 might display the same data differently. wxDataViewModel does
  46 provide a \helpref{Compare}{wxdataviewmodelcompare} method
  47 which the wxDataViewCtrl may use to sort the data either
  48 in conjunction with a column header or without (see
  49 \helpref{HasDefaultCompare}{wxdataviewmodelhasdefaultcompare}).
  50
  51 This class maintains a list of
  52 \helpref{wxDataViewModelNotifier}{wxdataviewmodelnotifier}
  53 which link this class to the specific implementations on the
  54 supported platforms so that e.g. calling
  55 \helpref{ValueChanged}{wxdataviewmodelvaluechanged}
  56 on this model will just call
  57 \helpref{wxDataViewModelNotifier::ValueChanged}{wxdataviewmodelnotifiervaluechanged}
  58 for each notifier that has been added. You can also add
  59 your own notifier in order to get informed about any changes
  60 to the data in the list model.
  61
  62 Currently wxWidgets provides the following models apart
  63 from the base model:
  64 \helpref{wxDataViewIndexListModel}{wxdataviewindexlistmodel},
  65 \helpref{wxDataViewTreeStore}{wxdataviewtreestore}.
  66
  67 Note that wxDataViewModel is reference counted, derives from
  68 \helpref{wxObjectRefData}{wxobjectrefdata} and cannot be deleted
  69 directly as it can be shares by several wxDataViewCtrl. This
  70 implies that you need to decrease the reference count after
  71 associating the model with a control like this:
  72
  73 {\small%
  74 \begin{verbatim}
  75     wxDataViewCtrl *musicCtrl = new wxDataViewCtrl( this, ID_MUSIC_CTRL );
  76     wxDataViewModel *musicModel = new MyMusicModel;
  77     m_musicCtrl->AssociateModel( musicModel );
  78     musicModel->DecRef();  // avoid memory leak !!
  79     // add columns now
  80 \end{verbatim}
  81 }%
  82
  83 \wxheading{Derived from}
  84
  85 \helpref{wxObjectRefData}{wxobjectrefdata}
  86
  87 \wxheading{Include files}
  88
  89 <wx/dataview.h>
  90
  91 \wxheading{Library}
  92
  93 \helpref{wxAdv}{librarieslist}
  94
  95
  96
  97 \latexignore{\rtfignore{\wxheading{Members}}}
  98
  99 \membersection{wxDataViewModel::wxDataViewModel}\label{wxdataviewmodelwxdataviewmodel}
 100
 101 \func{}{wxDataViewModel}{\void}
 102
 103 Constructor.
 104
 105 \membersection{wxDataViewModel::\destruct{wxDataViewModel}}\label{wxdataviewmodeldtor}
 106
 107 \func{}{\destruct{wxDataViewModel}}{\void}
 108
 109 Destructor. This should not be called directly. Use DecRef() instead.
 110
 111
 112 \membersection{wxDataViewModel::AddNotifier}\label{wxdataviewmodeladdnotifier}
 113
 114 \func{void}{AddNotifier}{\param{wxDataViewModelNotifier* }{notifier}}
 115
 116 Adds a \helpref{wxDataViewModelNotifier}{wxdataviewmodelnotifier}
 117 to the model.
 118
 119 \membersection{wxDataViewModel::Cleared}\label{wxdataviewmodelcleared}
 120
 121 \func{virtual bool}{Cleared}{\void}
 122
 123 Called to inform the model that all data has been deleted.
 124
 125 \membersection{wxDataViewModel::Compare}\label{wxdataviewmodelcompare}
 126
 127 \func{virtual int}{Compare}{\param{const wxDataViewItem\& }{item1}, \param{const wxDataViewItem\& }{item2}, \param{unsigned int }{column}, \param{bool }{ascending}}
 128
 129 The compare function to be used by control. The default compare function
 130 sorts by container and other items separately and in ascending order.
 131 Override this for a different sorting behaviour.
 132
 133 See also \helpref{HasDefaultCompare}{wxdataviewmodelhasdefaultcompare}.
 134
 135 \membersection{wxDataViewModel::GetColumnCount}\label{wxdataviewmodelgetcolumncount}
 136
 137 \constfunc{virtual unsigned int}{GetColumnCount}{\void}
 138
 139 Override this to indicate the number of columns in the model.
 140
 141 \membersection{wxDataViewModel::GetColumnType}\label{wxdataviewmodelgetcolumntype}
 142
 143 \constfunc{virtual wxString}{GetColumnType}{\param{unsigned int }{col}}
 144
 145 Override this to indicate what type of data is stored in the
 146 column specified by {\it col}. This should return a string
 147 indicating the type of data as reported by \helpref{wxVariant}{wxvariant}.
 148
 149 \membersection{wxDataViewModel::GetChildren}\label{wxdataviewmodelgetchildren}
 150
 151 \constfunc{virtual unsigned int}{GetChildren}{\param{const wxDataViewItem\& }{item}, \param{wxDataViewItemArray\& }{children} }
 152
 153 Override this so the control can query the child items of
 154 an item. Returns the number of items.
 155
 156 \membersection{wxDataViewModel::GetParent}\label{wxdataviewmodelgetparent}
 157
 158 \constfunc{virtual wxDataViewItem}{GetParent}{\param{const wxDataViewItem\& }{item}}
 159
 160 Override this to indicate which wxDataViewItem representing the parent
 161 of {\it item} or an invalid wxDataViewItem if the the root item is
 162 the parent item.
 163
 164 \membersection{wxDataViewModel::GetValue}\label{wxdataviewmodelgetvalue}
 165
 166 \constfunc{virtual void}{GetValue}{\param{wxVariant\& }{variant}, \param{const wxDataViewItem\& }{item}, \param{unsigned int }{col}}
 167
 168 Override this to indicate the value of {\it item}
 169 A \helpref{wxVariant}{wxvariant} is used to store the data.
 170
 171
 172 \membersection{wxDataViewModel::HasContainerColumns}\label{wxdataviewmodelhascontainercolumns}
 173
 174 \constfunc{virtual bool}{HasContainerColumns}{\param{const wxDataViewItem\& }{item}}
 175
 176 Override this method to indicate if a container item merely
 177 acts as a headline (or for categorisation) or if it also
 178 acts a normal item with entries for futher columns. By
 179 default returns {\it false}.
 180
 181 \membersection{wxDataViewModel::HasDefaultCompare}\label{wxdataviewmodelhasdefaultcompare}
 182
 183 \constfunc{virtual bool}{HasDefaultCompare}{\void}
 184
 185 Override this to indicate that the model provides a default compare
 186 function that the control should use if no wxDataViewColumn has been
 187 chosen for sorting. Usually, the user clicks on a column header for
 188 sorting, the data will be sorted alphanumerically. If any other
 189 order (e.g. by index or order of appearance) is required, then this
 190 should be used. See also \helpref{wxDataViewIndexListModel}{wxdataviewindexlistmodel}
 191 for a model which makes use of this.
 192
 193 \membersection{wxDataViewModel::IsContainer}\label{wxdataviewmodeliscontainer}
 194
 195 \constfunc{virtual bool}{IsContainer}{\param{const wxDataViewItem\& }{item}}
 196
 197 Override this to indicate of {\it item} is a container, i.e. if
 198 it can have child items.
 199
 200 \membersection{wxDataViewModel::ItemAdded}\label{wxdataviewmodelitemadded}
 201
 202 \func{virtual bool}{ItemAdded}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItem\& }{item}}
 203
 204 Call this to inform the model that an item has been added
 205 to the data.
 206
 207 \membersection{wxDataViewModel::ItemChanged}\label{wxdataviewmodelitemchanged}
 208
 209 \func{virtual bool}{ItemChanged}{\param{const wxDataViewItem\& }{item}}
 210
 211 Call this to inform the model that an item has changed.
 212
 213 This will eventually emit a wxEVT\_DATAVIEW\_ITEM\_VALUE\_CHANGED
 214 event (in which the column fields will not be set) to the user.
 215
 216 \membersection{wxDataViewModel::ItemsAdded}\label{wxdataviewmodelitemsadded}
 217
 218 \func{virtual bool}{ItemsAdded}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItemArray\& }{items}}
 219
 220 Call this to inform the model that several items have been added
 221 to the data.
 222
 223 \membersection{wxDataViewModel::ItemsChanged}\label{wxdataviewmodelitemschanged}
 224
 225 \func{virtual bool}{ItemsChanged}{\param{const wxDataViewItemArray\& }{items}}
 226
 227 Call this to inform the model that several items have changed.
 228
 229 This will eventually emit wxEVT\_DATAVIEW\_ITEM\_VALUE\_CHANGED
 230 events (in which the column fields will not be set) to the user.
 231
 232 \membersection{wxDataViewModel::ItemsDeleted}\label{wxdataviewmodelitemsdeleted}
 233
 234 \func{virtual bool}{ItemsDeleted}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItemArray\& }{items}}
 235
 236 Call this to inform the model that several items have been deleted.
 237
 238 \membersection{wxDataViewModel::RemoveNotifier}\label{wxdataviewmodelremovenotifier}
 239
 240 \func{void}{RemoveNotifier}{\param{wxDataViewModelNotifier* }{notifier}}
 241
 242 Remove the {\it notifier} from the list of notifiers.
 243
 244 \membersection{wxDataViewModel::Resort}\label{wxdataviewmodelresort}
 245
 246 \func{virtual void}{Resort}{\void}
 247
 248 Call this to initiate a resort after the sort function has
 249 been changed.
 250
 251 \membersection{wxDataViewModel::SetValue}\label{wxdataviewmodelsetvalue}
 252
 253 \func{virtual bool}{SetValue}{\param{const wxVariant\& }{variant}, \param{const wxDataViewItem\& }{item}, \param{unsigned int }{col}}
 254
 255 This gets called in order to set a value in the data model.
 256 The most common scenario is that the wxDataViewCtrl calls
 257 this method after the user changed some data in the view.
 258 Afterwards \helpref{ValueChanged}{wxdataviewmodelvaluechanged}
 259 has to be called!
 260
 261 \membersection{wxDataViewModel::ValueChanged}\label{wxdataviewmodelvaluechanged}
 262
 263 \func{virtual bool}{ValueChanged}{\param{const wxDataViewItem\& }{item}, \param{unsigned int }{col}}
 264
 265 Call this to inform this model that a value in the model has
 266 been changed. This is also called from wxDataViewCtrl's
 267 internal editing code, e.g. when editing a text field
 268 in the control.
 269
 270 This will eventually emit a wxEVT\_DATAVIEW\_ITEM\_VALUE\_CHANGED
 271 event to the user.
 272