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{
Abstract mediating views for GUI list controls. This allows you to use
standard list components and make them object-aware. See the demo
application for usage.
}
unit tiListMediators;
{$mode objfpc}{$H+}
interface
uses
Classes,
SysUtils,
tiBaseMediator,
fpg_listview,
fpg_grid,
tiObject;
type
{ Composite mediator for TfpgListView }
TListViewMediator = class(TCustomListMediator)
private
FObserversInTransit: TList;
FView: TfpgListView;
procedure SetView(const AValue: TfpgListView);
protected
function GetSelectedObject: TtiObject; override;
procedure SetSelectedObject(const AValue: TtiObject); override;
procedure CreateColumns; override;
procedure DoCreateItemMediator(AData: TtiObject; ARowIdx: integer); override;
procedure DoDeleteItemMediator(AIndex: Integer; AMediator: TListItemMediator); override;
function GetGuiControl: TComponent; override;
procedure SetGuiControl(const AValue: TComponent); override;
procedure SetupGUIandObject; override;
procedure ClearList; override;
procedure RebuildList; override;
public
constructor CreateCustom(AModel: TtiObjectList; AView: TfpgListView; ADisplayNames: string; AIsObserving: Boolean = True); overload;
constructor CreateCustom(AModel: TtiObjectList; AView: TfpgListView; AOnBeforeSetupField: TOnBeforeSetupField; ADisplayNames: string; AIsObserving: Boolean = True); overload;
class function ComponentClass: TClass; override;
constructor Create; override;
destructor Destroy; override;
procedure HandleSelectionChanged; override;
function GetObjectFromItem(AItem: TfpgLVItem): TtiObject;
published
property View: TfpgListView read FView write SetView;
end;
// for backwards compatibility
TCompositeListViewMediator = TListViewMediator;
{ Composite mediator for TfpgStringGrid }
TStringGridMediator = class(TCustomListMediator)
private
FView: TfpgStringGrid;
procedure DoCreateItemMediator(AData: TtiObject; ARowIdx: integer); override;
procedure DoDeleteItemMediator(AIndex: Integer; AMediator: TListItemMediator); override;
procedure SetView(const AValue: TfpgStringGrid);
protected
function GetSelectedObject: TtiObject; override;
procedure SetSelectedObject(const AValue: TtiObject); override;
procedure CreateColumns; override;
function GetGuiControl: TComponent; override;
procedure SetGuiControl(const AValue: TComponent); override;
procedure SetupGUIandObject; override;
procedure ClearList; override;
procedure RebuildList; override;
public
constructor CreateCustom(AModel: TtiObjectList; AGrid: TfpgStringGrid; ADisplayNames: string; AIsObserving: Boolean = True);
class function ComponentClass: TClass; override;
function GetObjectFromRow(ARow: Integer): TtiObject;
published
property View: TfpgStringGrid read FView write SetView;
property SelectedObject: TtiObject read GetSelectedObject write SetSelectedObject;
end;
// for backwards compatibility
TCompositeStringGridMediator = TStringGridMediator;
{ Used internally for sub-mediators in ListView mediator. Moved to interface
section so it can be overridden. }
TListViewListItemMediator = class(TListItemMediator)
private
FView: TfpgLVItem;
procedure SetupFields; virtual;
public
constructor CreateCustom(AModel: TtiObject; AView: TfpgLVItem; const AFieldsInfo: TtiMediatorFieldInfoList; IsObserving: Boolean = True);
constructor CreateCustom(AModel: TtiObject; AView: TfpgLVItem; AOnBeforeSetupField: TOnBeforeSetupField; const AFieldsInfo: TtiMediatorFieldInfoList; IsObserving: Boolean = True); overload;
procedure BeforeDestruction; override;
procedure Update(ASubject: TtiObject); override;
published
property View: TfpgLVItem read FView;
end;
{ Used internally for sub-mediators in StringGrid mediator. Moved to interface
section so it can be overridden. }
TStringGridRowMediator = class(TListItemMediator)
private
FView: TfpgStringGrid;
FRowIndex: integer;
public
constructor CreateCustom(AModel: TtiObject; AGrid: TfpgStringGrid; const AFieldsInfo: TtiMediatorFieldInfoList; ARowIndex: integer; IsObserving: Boolean = True);
procedure Update(ASubject: TtiObject); override;
published
property View: TfpgStringGrid read FView;
property RowIndex: integer read FRowIndex;
end;
implementation
{ TListViewMediator }
procedure TListViewMediator.SetView(const AValue: TfpgListView);
begin
FView := AValue;
SetGUIControl(AValue);
end;
function TListViewMediator.GetGuiControl: TComponent;
begin
Result := FView;
end;
procedure TListViewMediator.SetGuiControl(const AValue: TComponent);
begin
FView := AValue as TfpgListView;
inherited SetGuiControl(AValue);
end;
procedure TListViewMediator.SetSelectedObject(const AValue: TtiObject);
var
i: integer;
begin
for i := 0 to FView.Items.Count - 1 do
if TtiObject(FView.Items.Item[i].UserData) = AValue then
begin
FView.ItemIndex := i;
HandleSelectionChanged;
Exit; //==>
end;
end;
function TListViewMediator.GetSelectedObject: TtiObject;
begin
Result := GetObjectFromItem(FView.Items.Item[FView.ItemIndex]);
end;
procedure TListViewMediator.DoCreateItemMediator(AData: TtiObject; ARowIdx: integer);
var
li: TfpgLVItem;
m: TListViewListItemMediator;
begin
DataAndPropertyValid(AData);
{ Create ListItem and Mediator }
FView.BeginUpdate;
try
li := TfpgLVItem.Create(FView.Items);
FView.Items.Add(li);
m := TListViewListItemMediator.CreateCustom(AData, li, OnBeforeSetupField, FieldsInfo, Active);
li.UserData := m;
MediatorList.Add(m);
finally
FView.EndUpdate;
end;
end;
procedure TListViewMediator.DoDeleteItemMediator(AIndex: Integer; AMediator: TListItemMediator);
begin
FView.Items.Delete(FView.Items.IndexOf(TListViewListItemMediator(AMediator).FView));
inherited DoDeleteItemMediator(AIndex, AMediator);
end;
procedure TListViewMediator.CreateColumns;
var
c: integer;
lc: TfpgLVColumn;
lInfo: TtiMediatorFieldInfo;
begin
if (View.Columns.Count<>FieldsInfo.Count) then
View.Columns.Clear;
if View.Columns.Count = 0 then
begin
for c := 0 to FieldsInfo.Count-1 do
begin
lInfo := FieldsInfo[c];
lc := TfpgLVColumn.Create(View.Columns);
lc.AutoSize := False;
lc.Caption := lInfo.Caption;
lc.Width := lInfo.FieldWidth;
lc.Alignment := lInfo.Alignment;
lc.Resizable := True;
View.Columns.Add(lc);
end;
end;
end;
procedure TListViewMediator.SetupGUIandObject;
begin
{ Setup TfpgListView defaults }
FView.Columns.Clear;
FView.Items.Clear;
// FView.ViewStyle := vsReport;
FView.ShowHeaders := True;
// FView.RowSelect := True;
// FView.AutoSize := False;
// FView.ScrollBars := ssAutoBoth;
end;
procedure TListViewMediator.ClearList;
begin
View.Items.Clear;
end;
procedure TListViewMediator.RebuildList;
begin
View.BeginUpdate;
try
CreateColumns;
CreateSubMediators;
finally
View.EndUpdate;
end;
end;
constructor TListViewMediator.CreateCustom(AModel: TtiObjectList; AView: TfpgListView; AOnBeforeSetupField: TOnBeforeSetupField; ADisplayNames: string; AIsObserving: Boolean);
begin
Create; // don't forget this
OnBeforeSetupField := AOnBeforeSetupField;
DisplayNames := ADisplayNames; // Will call ParseDisplaynames.
Subject := AModel;
GUIControl := AView; // Will call SetupGUIandObject;
CreateSubMediators;
Active := AIsObserving; // Will attach/Detach
end;
class function TListViewMediator.ComponentClass: TClass;
begin
Result := TfpgListView;
end;
constructor TListViewMediator.Create;
begin
inherited Create;
FObserversInTransit := TList.Create;
end;
constructor TListViewMediator.CreateCustom(AModel: TtiObjectList; AView: TfpgListView; ADisplayNames: string; AIsObserving: Boolean);
begin
CreateCustom(AModel, AView, nil, ADisplayNames, AIsObserving);
end;
destructor TListViewMediator.Destroy;
begin
IsObserving := False;
FView := nil;
inherited;
end;
procedure TListViewMediator.HandleSelectionChanged;
var
i: integer;
begin
if View.ItemIndex = -1 then
SelectedObject := nil
else
begin
FObserversInTransit.Clear;
{ If an item is already selected, assign the item's List of observers to a
temporary container. This is done so that the same observers can be
assigned to the new item. }
if Assigned(SelectedObject) then
FObserversInTransit.Assign(SelectedObject.ObserverList);
// Assign Newly selected item to SelectedObject Obj.
SelectedObject := TtiObject(View.Items.Item[View.ItemIndex].UserData);
{ If an object was selected, copy the old item's observer List
to the new item's observer List. }
if FObserversInTransit.Count > 0 then
SelectedObject.ObserverList.Assign(FObserversInTransit);
{ Set the Observers Subject property to the selected object }
for i := 0 to SelectedObject.ObserverList.Count - 1 do
TMediatorView(SelectedObject.ObserverList.Items[i]).Subject :=
SelectedObject;
// execute the NotifyObservers event to update the observers.
SelectedObject.NotifyObservers;
end;
end;
function TListViewMediator.GetObjectFromItem(AItem: TfpgLVItem): TtiObject;
begin
if (AItem = nil) or (AItem.UserData = nil) then
Result := nil
else
Result := TListItemMediator(AItem.UserData).Model;
end;
{ TListViewListItemMediator }
procedure TListViewListItemMediator.SetupFields;
var
c: integer;
lMemberName: string;
lValue: string;
begin
lMemberName := FFieldsInfo[0].PropName;
lValue := Model.PropValue[lMemberName];
if Assigned(OnBeforeSetupField) then
OnBeforeSetupField(Model, lMemberName, lValue);
FView.Caption := lValue;
for c := 1 to FFieldsInfo.Count - 1 do
begin
lMemberName := FFieldsInfo[c].PropName;
lValue := Model.PropValue[lMemberName];
if Assigned(OnBeforeSetupField) then
OnBeforeSetupField(Model, lMemberName, lValue);
FView.SubItems.Add(lValue);
end;
end;
constructor TListViewListItemMediator.CreateCustom(AModel: TtiObject; AView: TfpgLVItem; const AFieldsInfo: TtiMediatorFieldInfoList; IsObserving: Boolean);
begin
CreateCustom(AModel, AView, nil, AFieldsInfo, IsObserving);
end;
constructor TListViewListItemMediator.CreateCustom(AModel: TtiObject; AView: TfpgLVItem; AOnBeforeSetupField: TOnBeforeSetupField; const AFieldsInfo: TtiMediatorFieldInfoList; IsObserving: Boolean);
begin
inherited Create;
Model := AModel;
FView := AView;
FFieldsInfo := AFieldsInfo;
OnBeforeSetupField := AOnBeforeSetupField;
SetupFields;
Active := IsObserving; // Will attach
end;
procedure TListViewListItemMediator.BeforeDestruction;
begin
Model.DetachObserver(self);
Model := nil;
FView := nil;
inherited BeforeDestruction;
end;
procedure TListViewListItemMediator.Update(ASubject: TtiObject);
var
c: integer;
lMemberName: string;
lValue: string;
begin
Assert(Model = ASubject);
lMemberName := FFieldsInfo[0].PropName;
lValue := Model.PropValue[lMemberName];
if Assigned(OnBeforeSetupField) then
OnBeforeSetupField(Model, lMemberName, lValue);
FView.Caption := lValue;
for c := 1 to FFieldsInfo.Count - 1 do
begin
lMemberName := FFieldsInfo[c].PropName;
lValue := Model.PropValue[lMemberName];
if Assigned(OnBeforeSetupField) then
OnBeforeSetupField(Model, lMemberName, lValue);
FView.SubItems[c - 1] := lValue;
end;
end;
{ TStringGridMediator }
function TStringGridMediator.GetSelectedObject: TtiObject;
begin
Result := GetObjectFromRow(FView.FocusRow);
end;
procedure TStringGridMediator.SetSelectedObject(const AValue: TtiObject);
var
i: integer;
begin
for i := 0 to FView.RowCount - 1 do
if TtiObject(FView.Objects[0, i]) = AValue then
begin
FView.FocusRow := i;
Exit; //==>
end;
end;
procedure TStringGridMediator.SetView(const AValue: TfpgStringGrid);
begin
SetGUIControl(AValue);
end;
function TStringGridMediator.GetGuiControl: TComponent;
begin
Result := fView;
end;
procedure TStringGridMediator.SetGuiControl(const AValue: TComponent);
begin
FView := AValue as TfpgStringGrid;
end;
procedure TStringGridMediator.DoCreateItemMediator(AData: TtiObject; ARowIdx: integer);
var
i: integer;
lFieldName: string;
lMediatorView: TStringGridRowMediator;
begin
FView.BeginUpdate;
try
if ARowIdx = FView.RowCount then // In case of add notification
FView.RowCount := FView.RowCount+1;
for i := 0 to FieldsInfo.Count - 1 do
begin
lFieldName := FieldsInfo[i].PropName;
FView.Cells[i, ARowIdx] := AData.PropValue[lFieldName]; // set Cell text
end;
lMediatorView := TStringGridRowMediator.CreateCustom(AData, FView, FieldsInfo, ARowIdx, Active);
FView.Objects[0, ARowIdx] := lMediatorView; // set Object reference inside grid. It used to be AData.
MediatorList.Add(lMediatorView);
finally
FView.EndUpdate;
end;
end;
procedure TStringGridMediator.DoDeleteItemMediator(AIndex: Integer; AMediator: TListItemMediator);
begin
FView.DeleteRow(AIndex);
inherited DoDeleteItemMediator(AIndex, AMediator);
end;
procedure TStringGridMediator.CreateColumns;
var
i: integer;
lColumnTotalWidth: integer;
begin
lColumnTotalWidth := 0;
for i := 0 to FieldsInfo.Count - 1 do
begin
FView.ColumnWidth[i] := FieldsInfo[i].FieldWidth;
FView.ColumnTitle[i] := FieldsInfo[i].Caption;
FView.Columns[i].Alignment := FieldsInfo[i].Alignment;
//resize the last column to fill the grid.
if i = FieldsInfo.Count - 1 then
begin
if FView.Width > (lColumnTotalWidth + 10) then
FView.ColumnWidth[i] := FView.Width - (lColumnTotalWidth + 10);
end
else
lColumnTotalWidth := lColumnTotalWidth + FView.ColumnWidth[i] + 20;
end;
end;
procedure TStringGridMediator.SetupGUIandObject;
begin
//Setup default properties for the StringGrid
FView.RowSelect := True;
FView.ColumnCount := FieldsInfo.Count;
if ShowDeleted then
FView.RowCount := Model.Count
else
FView.RowCount := Model.CountNotDeleted;
end;
procedure TStringGridMediator.ClearList;
begin
MediatorList.Clear;
if Assigned(View) then
View.RowCount := 1; {$Note Double check if this is desired. Shouldn't it be 0 instead. }
end;
procedure TStringGridMediator.RebuildList;
begin
// writeln('--- TStringGridMediator.RebuildList');
{ This rebuilds the whole list. Not very efficient. }
View.BeginUpdate;
try
SetupGUIandObject;
MediatorList.Clear;
// for i := View.ColumnCount-1 downto 0 do
// View.DeleteColumn(i);
CreateSubMediators;
finally
View.EndUpdate;
end;
end;
constructor TStringGridMediator.CreateCustom(AModel: TtiObjectList; AGrid: TfpgStringGrid; ADisplayNames: string; AIsObserving: Boolean);
begin
inherited Create;
DisplayNames := ADisplayNames;
Subject := AModel;
GUIControl := AGrid;
CreateSubMediators;
IsObserving := AIsObserving;
end;
class function TStringGridMediator.ComponentClass: TClass;
begin
Result := TfpgStringGrid;
end;
function TStringGridMediator.GetObjectFromRow(ARow: Integer): TtiObject;
var
O: TObject;
begin
if FView.RowCount = 0 then
begin
Result := nil;
Exit;
end;
if FView.FocusRow = -1 then
Result := nil
else
begin
O := FView.Objects[0, ARow];
if O <> nil then
Result := TListItemMediator(O).Model
else
Result := nil;
end;
end;
{ TStringGridRowMediator }
constructor TStringGridRowMediator.CreateCustom(AModel: TtiObject; AGrid: TfpgStringGrid; const AFieldsInfo: TtiMediatorFieldInfoList; ARowIndex: integer; IsObserving: Boolean);
begin
inherited Create;
Model := AModel;
FView := AGrid;
FFieldsInfo := AFieldsInfo;
FRowIndex := ARowIndex;
Active := IsObserving; // Will attach
end;
procedure TStringGridRowMediator.Update(ASubject: TtiObject);
var
i: integer;
lvalue, lFieldName: string;
begin
Assert(Model = ASubject);
for i := 0 to FFieldsInfo.Count - 1 do
begin
lFieldName := FFieldsInfo[I].PropName;
lValue := Model.PropValue[lFieldName];
if Assigned(OnBeforeSetupField) then
OnBeforeSetupField(Model, lFieldName, lValue);
FView.Cells[i, FRowIndex] := lValue;
end;
end;
end.
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