mcs/class/Managed.Windows.Forms/System.Windows.Forms/Binding.cs

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   6 // permit persons to whom the Software is furnished to do so, subject to
   7 // the following conditions:
   8 //
   9 // The above copyright notice and this permission notice shall be
  10 // included in all copies or substantial portions of the Software.
  11 //
  12 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  13 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  14 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  15 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  16 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  17 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  18 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  19 //
  20 // Copyright (c) 2004-2005 Novell, Inc.
  21 //
  22 // Authors:
  23 //      Peter Bartok    pbartok@novell.com
  24 //      Jackson Harper  jackson@ximian.com
  25 //
  26
  27
  28 using System.ComponentModel;
  29
  30 namespace System.Windows.Forms {
  31
  32         [TypeConverter (typeof (ListBindingConverter))]
  33         public class Binding {
  34
  35                 private string property_name;
  36                 private object data_source;
  37                 private string data_member;
  38                 private BindingMemberInfo binding_member_info;
  39                 private Control control;
  40
  41                 private BindingManagerBase manager;
  42                 private PropertyDescriptor prop_desc;
  43                 private PropertyDescriptor is_null_desc;
  44                 private object data;
  45
  46                 private EventDescriptor changed_event;
  47                 private EventHandler property_value_changed_handler;
  48                 private object event_current; // The manager.Current as far as the changed_event knows
  49
  50                 #region Public Constructors
  51                 public Binding (string propertyName, object dataSource, string dataMember)
  52                 {
  53                         property_name = propertyName;
  54                         data_source = dataSource;
  55                         data_member = dataMember;
  56                         binding_member_info = new BindingMemberInfo (dataMember);
  57                 }
  58                 #endregion      // Public Constructors
  59
  60                 #region Public Instance Properties
  61                 public BindingManagerBase BindingManagerBase {
  62                         get {
  63                                 return manager;
  64                         }
  65                 }
  66
  67                 public BindingMemberInfo BindingMemberInfo {
  68                         get {
  69                                 return binding_member_info;
  70                         }
  71                 }
  72
  73                 [DefaultValue (null)]
  74                 public Control Control {
  75                         get {
  76                                 return control;
  77                         }
  78                 }
  79
  80                 public object DataSource {
  81                         get {
  82                                 return data_source;
  83                         }
  84                 }
  85
  86                 [MonoTODO]
  87                 public bool IsBinding {
  88                         get {
  89                                 return false;
  90                         }
  91                 }
  92
  93                 [DefaultValue ("")]
  94                 public string PropertyName {
  95                         get {
  96                                 return property_name;
  97                         }
  98                 }
  99                 #endregion      // Public Instance Properties
 100
 101                 #region Protected Instance Methods
 102                 protected virtual void OnFormat (ConvertEventArgs cevent)
 103                 {
 104                         if (Format!=null)
 105                                 Format (this, cevent);
 106                 }
 107
 108                 protected virtual void OnParse (ConvertEventArgs cevent)
 109                 {
 110                         if (Parse!=null)
 111                                 Parse (this, cevent);
 112                 }
 113                 #endregion      // Protected Instance Methods
 114
 115
 116                 internal void SetControl (Control control)
 117                 {
 118                         if (control == this.control)
 119                                 return;
 120
 121                         prop_desc = TypeDescriptor.GetProperties (control).Find (property_name, false);
 122
 123                         if (prop_desc == null)
 124                                 throw new ArgumentException (String.Concat ("Cannot bind to property '", property_name, "' on target control."));
 125                         if (prop_desc.IsReadOnly)
 126                                 throw new ArgumentException (String.Concat ("Cannot bind to property '", property_name, "' because it is read only."));
 127
 128                         control.Validating += new CancelEventHandler (ControlValidatingHandler);
 129
 130                         this.control = control;
 131                 }
 132
 133                 internal void Check (BindingContext binding_context)
 134                 {
 135                         if (control == null)
 136                                 return;
 137
 138                         manager = control.BindingContext [data_source, property_name];
 139                         manager.AddBinding (this);
 140
 141                         WirePropertyValueChangedEvent ();
 142
 143                         is_null_desc = TypeDescriptor.GetProperties (manager.Current).Find (property_name + "IsNull", false);
 144
 145                         PullData ();
 146                         PushData ();
 147                 }
 148
 149                 internal void PushData ()
 150                 {
 151                         prop_desc.SetValue (control, data);
 152                 }
 153
 154                 internal void PullData ()
 155                 {
 156                         if (is_null_desc != null) {
 157                                 bool is_null = (bool) is_null_desc.GetValue (manager.Current);
 158                                 if (is_null) {
 159                                         data = Convert.DBNull;
 160                                         return;
 161                                 }
 162                         }
 163
 164                         PropertyDescriptor pd = TypeDescriptor.GetProperties (manager.Current).Find (data_member, true);
 165                         data = pd.GetValue (manager.Current);
 166                 }
 167
 168                 internal void UpdateIsBinding ()
 169                 {
 170                         PushData ();
 171                 }
 172
 173                 private void CurrentChangedHandler ()
 174                 {
 175                         if (changed_event != null) {
 176                                 changed_event.RemoveEventHandler (event_current, property_value_changed_handler);
 177                                 WirePropertyValueChangedEvent ();
 178                         }
 179                 }
 180
 181                 private void WirePropertyValueChangedEvent ()
 182                 {
 183                         EventDescriptor changed_event = TypeDescriptor.GetEvents (manager.Current).Find (property_name + "Changed", false);
 184                         if (changed_event == null)
 185                                 return;
 186                         property_value_changed_handler = new EventHandler (PropertyValueChanged);
 187                         changed_event.AddEventHandler (manager.Current, property_value_changed_handler);
 188
 189                         event_current = manager.Current;
 190                 }
 191
 192                 private void PropertyValueChanged (object sender, EventArgs e)
 193                 {
 194                         PullData ();
 195                         PushData ();
 196                 }
 197
 198                 private void ControlValidatingHandler (object sender, CancelEventArgs e)
 199                 {
 200                         PullData ();
 201                 }
 202
 203                 #region Events
 204                 public event ConvertEventHandler Format;
 205                 public event ConvertEventHandler Parse;
 206                 #endregion      // Events
 207         }
 208 }