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::GetAttr}\label{wxdataviewmodelgetattr}
 142
 143 \func{bool}{GetAttr}{\param{const wxDataViewItem\& }{item}, \param{unsigned int }{col}, \param{wxDataViewItemAttr\& }{attr}}
 144
 145 Oberride this to indicate that the item has special font attributes.
 146 This only affects the
 147 \helpref{wxDataViewTextRendererText}{wxdataviewtextrendererattr} renderer.
 148
 149 See also \helpref{wxDataViewItemAttr}{wxdataviewitemattr}.
 150
 151 \membersection{wxDataViewModel::GetColumnCount}\label{wxdataviewmodelgetcolumncount}
 152
 153 \constfunc{virtual unsigned int}{GetColumnCount}{\void}
 154
 155 Override this to indicate the number of columns in the model.
 156
 157
 158 \membersection{wxDataViewModel::GetColumnType}\label{wxdataviewmodelgetcolumntype}
 159
 160 \constfunc{virtual wxString}{GetColumnType}{\param{unsigned int }{col}}
 161
 162 Override this to indicate what type of data is stored in the
 163 column specified by {\it col}. This should return a string
 164 indicating the type of data as reported by \helpref{wxVariant}{wxvariant}.
 165
 166
 167 \membersection{wxDataViewModel::GetChildren}\label{wxdataviewmodelgetchildren}
 168
 169 \constfunc{virtual unsigned int}{GetChildren}{\param{const wxDataViewItem\& }{item}, \param{wxDataViewItemArray\& }{children} }
 170
 171 Override this so the control can query the child items of
 172 an item. Returns the number of items.
 173
 174
 175 \membersection{wxDataViewModel::GetParent}\label{wxdataviewmodelgetparent}
 176
 177 \constfunc{virtual wxDataViewItem}{GetParent}{\param{const wxDataViewItem\& }{item}}
 178
 179 Override this to indicate which wxDataViewItem representing the parent
 180 of {\it item} or an invalid wxDataViewItem if the the root item is
 181 the parent item.
 182
 183
 184 \membersection{wxDataViewModel::GetValue}\label{wxdataviewmodelgetvalue}
 185
 186 \constfunc{virtual void}{GetValue}{\param{wxVariant\& }{variant}, \param{const wxDataViewItem\& }{item}, \param{unsigned int }{col}}
 187
 188 Override this to indicate the value of {\it item}
 189 A \helpref{wxVariant}{wxvariant} is used to store the data.
 190
 191
 192
 193 \membersection{wxDataViewModel::HasContainerColumns}\label{wxdataviewmodelhascontainercolumns}
 194
 195 \constfunc{virtual bool}{HasContainerColumns}{\param{const wxDataViewItem\& }{item}}
 196
 197 Override this method to indicate if a container item merely
 198 acts as a headline (or for categorisation) or if it also
 199 acts a normal item with entries for futher columns. By
 200 default returns {\it false}.
 201
 202
 203 \membersection{wxDataViewModel::HasDefaultCompare}\label{wxdataviewmodelhasdefaultcompare}
 204
 205 \constfunc{virtual bool}{HasDefaultCompare}{\void}
 206
 207 Override this to indicate that the model provides a default compare
 208 function that the control should use if no wxDataViewColumn has been
 209 chosen for sorting. Usually, the user clicks on a column header for
 210 sorting, the data will be sorted alphanumerically. If any other
 211 order (e.g. by index or order of appearance) is required, then this
 212 should be used. See also \helpref{wxDataViewIndexListModel}{wxdataviewindexlistmodel}
 213 for a model which makes use of this.
 214
 215
 216 \membersection{wxDataViewModel::IsContainer}\label{wxdataviewmodeliscontainer}
 217
 218 \constfunc{virtual bool}{IsContainer}{\param{const wxDataViewItem\& }{item}}
 219
 220 Override this to indicate of {\it item} is a container, i.e. if
 221 it can have child items.
 222
 223
 224 \membersection{wxDataViewModel::ItemAdded}\label{wxdataviewmodelitemadded}
 225
 226 \func{virtual bool}{ItemAdded}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItem\& }{item}}
 227
 228 Call this to inform the model that an item has been added
 229 to the data.
 230
 231
 232 \membersection{wxDataViewModel::ItemChanged}\label{wxdataviewmodelitemchanged}
 233
 234 \func{virtual bool}{ItemChanged}{\param{const wxDataViewItem\& }{item}}
 235
 236 Call this to inform the model that an item has changed.
 237
 238 This will eventually emit a wxEVT\_DATAVIEW\_ITEM\_VALUE\_CHANGED
 239 event (in which the column fields will not be set) to the user.
 240
 241
 242 \membersection{wxDataViewModel::ItemDeleted}\label{wxdataviewmodelitemdeleted}
 243
 244 \func{virtual bool}{ItemDeleted}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItem\& }{item}}
 245
 246 Call this to inform the model that an item has been deleted from the data.
 247
 248
 249 \membersection{wxDataViewModel::ItemsAdded}\label{wxdataviewmodelitemsadded}
 250
 251 \func{virtual bool}{ItemsAdded}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItemArray\& }{items}}
 252
 253 Call this to inform the model that several items have been added
 254 to the data.
 255
 256
 257 \membersection{wxDataViewModel::ItemsChanged}\label{wxdataviewmodelitemschanged}
 258
 259 \func{virtual bool}{ItemsChanged}{\param{const wxDataViewItemArray\& }{items}}
 260
 261 Call this to inform the model that several items have changed.
 262
 263 This will eventually emit wxEVT\_DATAVIEW\_ITEM\_VALUE\_CHANGED
 264 events (in which the column fields will not be set) to the user.
 265
 266
 267 \membersection{wxDataViewModel::ItemsDeleted}\label{wxdataviewmodelitemsdeleted}
 268
 269 \func{virtual bool}{ItemsDeleted}{\param{const wxDataViewItem\& }{parent}, \param{const wxDataViewItemArray\& }{items}}
 270
 271 Call this to inform the model that several items have been deleted.
 272
 273
 274 \membersection{wxDataViewModel::RemoveNotifier}\label{wxdataviewmodelremovenotifier}
 275
 276 \func{void}{RemoveNotifier}{\param{wxDataViewModelNotifier* }{notifier}}
 277
 278 Remove the {\it notifier} from the list of notifiers.
 279
 280
 281 \membersection{wxDataViewModel::Resort}\label{wxdataviewmodelresort}
 282
 283 \func{virtual void}{Resort}{\void}
 284
 285 Call this to initiate a resort after the sort function has
 286 been changed.
 287
 288
 289 \membersection{wxDataViewModel::SetValue}\label{wxdataviewmodelsetvalue}
 290
 291 \func{virtual bool}{SetValue}{\param{const wxVariant\& }{variant}, \param{const wxDataViewItem\& }{item}, \param{unsigned int }{col}}
 292
 293 This gets called in order to set a value in the data model.
 294 The most common scenario is that the wxDataViewCtrl calls
 295 this method after the user changed some data in the view.
 296 Afterwards \helpref{ValueChanged}{wxdataviewmodelvaluechanged}
 297 has to be called!
 298
 299
 300 \membersection{wxDataViewModel::ValueChanged}\label{wxdataviewmodelvaluechanged}
 301
 302 \func{virtual bool}{ValueChanged}{\param{const wxDataViewItem\& }{item}, \param{unsigned int }{col}}
 303
 304 Call this to inform this model that a value in the model has
 305 been changed. This is also called from wxDataViewCtrl's
 306 internal editing code, e.g. when editing a text field
 307 in the control.
 308
 309 This will eventually emit a wxEVT\_DATAVIEW\_ITEM\_VALUE\_CHANGED
 310 event to the user.
 311