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 shared by several wxDataViewCtrls. 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
 100 \membersection{wxDataViewModel::wxDataViewModel}\label{wxdataviewmodelwxdataviewmodel}
 101
 102 \func{}{wxDataViewModel}{\void}
 103
 104 Constructor.
 105
 106
 107 \membersection{wxDataViewModel::\destruct{wxDataViewModel}}\label{wxdataviewmodeldtor}
 108
 109 \func{}{\destruct{wxDataViewModel}}{\void}
 110
 111 Destructor. This should not be called directly. Use DecRef() instead.
 112
 113
 114
 115 \membersection{wxDataViewModel::AddNotifier}\label{wxdataviewmodeladdnotifier}
 116
 117 \func{void}{AddNotifier}{\param{wxDataViewModelNotifier* }{notifier}}
 118
 119 Adds a \helpref{wxDataViewModelNotifier}{wxdataviewmodelnotifier}
 120 to the model.
 121
 122
 123 \membersection{wxDataViewModel::Cleared}\label{wxdataviewmodelcleared}
 124
 125 \func{virtual bool}{Cleared}{\void}
 126
 127 Called to inform the model that all data has been deleted.
 128
 129
 130 \membersection{wxDataViewModel::Compare}\label{wxdataviewmodelcompare}
 131
 132 \func{virtual int}{Compare}{\param{const wxDataViewItem\& }{item1}, \param{const wxDataViewItem\& }{item2}, \param{unsigned int }{column}, \param{bool }{ascending}}
 133
 134 The compare function to be used by control. The default compare function
 135 sorts by container and other items separately and in ascending order.
 136 Override this for a different sorting behaviour.
 137
 138 See also \helpref{HasDefaultCompare}{wxdataviewmodelhasdefaultcompare}.
 139
 140
 141 \membersection{wxDataViewModel::GetColumnCount}\label{wxdataviewmodelgetcolumncount}
 142
 143 \constfunc{virtual unsigned int}{GetColumnCount}{\void}
 144
 145 Override this to indicate the number of columns in the model.
 146
 147
 148 \membersection{wxDataViewModel::GetColumnType}\label{wxdataviewmodelgetcolumntype}
 149
 150 \constfunc{virtual wxString}{GetColumnType}{\param{unsigned int }{col}}
 151
 152 Override this to indicate what type of data is stored in the
 153 column specified by {\it col}. This should return a string
 154 indicating the type of data as reported by \helpref{wxVariant}{wxvariant}.
 155
 156
 157 \membersection{wxDataViewModel::GetChildren}\label{wxdataviewmodelgetchildren}
 158
 159 \constfunc{virtual unsigned int}{GetChildren}{\param{const wxDataViewItem\& }{item}, \param{wxDataViewItemArray\& }{children} }
 160
 161 Override this so the control can query the child items of
 162 an item. Returns the number of items.
 163
 164
 165 \membersection{wxDataViewModel::GetParent}\label{wxdataviewmodelgetparent}
 166
 167 \constfunc{virtual wxDataViewItem}{GetParent}{\param{const wxDataViewItem\& }{item}}
 168
 169 Override this to indicate which wxDataViewItem representing the parent
 170 of {\it item} or an invalid wxDataViewItem if the the root item is
 171 the parent item.
 172
 173
 174 \membersection{wxDataViewModel::GetValue}\label{wxdataviewmodelgetvalue}
 175
 176 \constfunc{virtual void}{GetValue}{\param{wxVariant\& }{variant}, \param{const wxDataViewItem\& }{item}, \param{unsigned int }{col}}
 177
 178 Override this to indicate the value of {\it item}
 179 A \helpref{wxVariant}{wxvariant} is used to store the data.
 180
 181
 182
 183 \membersection{wxDataViewModel::HasContainerColumns}\label{wxdataviewmodelhascontainercolumns}
 184
 185 \constfunc{virtual bool}{HasContainerColumns}{\param{const wxDataViewItem\& }{item}}
 186
 187 Override this method to indicate if a container item merely
 188 acts as a headline (or for categorisation) or if it also
 189 acts a normal item with entries for futher columns. By
 190 default returns {\it false}.
 191
 192
 193 \membersection{wxDataViewModel::HasDefaultCompare}\label{wxdataviewmodelhasdefaultcompare}
 194
 195 \constfunc{virtual bool}{HasDefaultCompare}{\void}
 196
 197 Override this to indicate that the model provides a default compare
 198 function that the control should use if no wxDataViewColumn has been
 199 chosen for sorting. Usually, the user clicks on a column header for
 200 sorting, the data will be sorted alphanumerically. If any other
 201 order (e.g. by index or order of appearance) is required, then this
 202 should be used. See also \helpref{wxDataViewIndexListModel}{wxdataviewindexlistmodel}
 203 for a model which makes use of this.
 204
 205
 206 \membersection{wxDataViewModel::IsContainer}\label{wxdataviewmodeliscontainer}
 207
 208 \constfunc{virtual bool}{IsContainer}{\param{const wxDataViewItem\& }{item}}
 209
 210 Override this to indicate of {\it item} is a container, i.e. if
 211 it can have child items.
 212
 213
 214 \membersection{wxDataViewModel::ItemAdded}\label{wxdataviewmodelitemadded}
 215
 216 \func{virtual bool}{ItemAdded}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItem\& }{item}}
 217
 218 Call this to inform the model that an item has been added
 219 to the data.
 220
 221
 222 \membersection{wxDataViewModel::ItemChanged}\label{wxdataviewmodelitemchanged}
 223
 224 \func{virtual bool}{ItemChanged}{\param{const wxDataViewItem\& }{item}}
 225
 226 Call this to inform the model that an item has changed.
 227
 228 This will eventually emit a wxEVT\_DATAVIEW\_ITEM\_VALUE\_CHANGED
 229 event (in which the column fields will not be set) to the user.
 230
 231
 232 \membersection{wxDataViewModel::ItemDeleted}\label{wxdataviewmodelitemdeleted}
 233
 234 \func{virtual bool}{ItemDeleted}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItem\& }{item}}
 235
 236 Call this to inform the model that an item has been deleted from the data.
 237
 238
 239 \membersection{wxDataViewModel::ItemsAdded}\label{wxdataviewmodelitemsadded}
 240
 241 \func{virtual bool}{ItemsAdded}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItemArray\& }{items}}
 242
 243 Call this to inform the model that several items have been added
 244 to the data.
 245
 246
 247 \membersection{wxDataViewModel::ItemsChanged}\label{wxdataviewmodelitemschanged}
 248
 249 \func{virtual bool}{ItemsChanged}{\param{const wxDataViewItemArray\& }{items}}
 250
 251 Call this to inform the model that several items have changed.
 252
 253 This will eventually emit wxEVT\_DATAVIEW\_ITEM\_VALUE\_CHANGED
 254 events (in which the column fields will not be set) to the user.
 255
 256
 257 \membersection{wxDataViewModel::ItemsDeleted}\label{wxdataviewmodelitemsdeleted}
 258
 259 \func{virtual bool}{ItemsDeleted}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItemArray\& }{items}}
 260
 261 Call this to inform the model that several items have been deleted.
 262
 263
 264 \membersection{wxDataViewModel::RemoveNotifier}\label{wxdataviewmodelremovenotifier}
 265
 266 \func{void}{RemoveNotifier}{\param{wxDataViewModelNotifier* }{notifier}}
 267
 268 Remove the {\it notifier} from the list of notifiers.
 269
 270
 271 \membersection{wxDataViewModel::Resort}\label{wxdataviewmodelresort}
 272
 273 \func{virtual void}{Resort}{\void}
 274
 275 Call this to initiate a resort after the sort function has
 276 been changed.
 277
 278
 279 \membersection{wxDataViewModel::SetValue}\label{wxdataviewmodelsetvalue}
 280
 281 \func{virtual bool}{SetValue}{\param{const wxVariant\& }{variant}, \param{const wxDataViewItem\& }{item}, \param{unsigned int }{col}}
 282
 283 This gets called in order to set a value in the data model.
 284 The most common scenario is that the wxDataViewCtrl calls
 285 this method after the user changed some data in the view.
 286 Afterwards \helpref{ValueChanged}{wxdataviewmodelvaluechanged}
 287 has to be called!
 288
 289
 290 \membersection{wxDataViewModel::ValueChanged}\label{wxdataviewmodelvaluechanged}
 291
 292 \func{virtual bool}{ValueChanged}{\param{const wxDataViewItem\& }{item}, \param{unsigned int }{col}}
 293
 294 Call this to inform this model that a value in the model has
 295 been changed. This is also called from wxDataViewCtrl's
 296 internal editing code, e.g. when editing a text field
 297 in the control.
 298
 299 This will eventually emit a wxEVT\_DATAVIEW\_ITEM\_VALUE\_CHANGED
 300 event to the user.
 301