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{
fpGUI - Free Pascal GUI Toolkit
Copyright (C) 2006 - 2010 See the file AUTHORS.txt, included in this
distribution, for details of the copyright.
See the file COPYING.modifiedLGPL, included in this distribution,
for details about redistributing fpGUI.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Description:
Database support classes. This serves as an example of how someone
could implement DB aware components for fpGUI.
}
unit fpgui_db;
{$mode objfpc}{$H+}
// If enabled it outputs debug information for this unit
{.$Define DEBUG}
interface
uses
Classes,
db,
fpg_widget,
fpg_label{, fpg_edit};
type
TfpgFieldDataLink = class(TDataLink)
private
FWidget: TfpgWidget;
FField: TField;
FFieldName: string;
FOnDataChange: TNotifyEvent;
function GetCanModify: Boolean;
procedure SetFieldName(const AFieldName: string);
procedure UpdateField;
protected
procedure ActiveChanged; override;
procedure RecordChanged(AField: TField); override;
public
constructor Create(AWidget: TfpgWidget);
property CanModify: Boolean read GetCanModify;
property Field: TField read FField;
property FieldName: string read FFieldName write SetFieldName;
property Widget: TfpgWidget read FWidget write FWidget;
property OnDataChange: TNotifyEvent read FOnDataChange write FOnDataChange;
end;
TfpgDBLabel = class(TfpgCustomLabel)
private
FDataLink: TfpgFieldDataLink;
function GetDataField: String;
function GetField: TField;
procedure SetDataField(const ADataField: String);
function GetDataSource: TDataSource;
procedure SetDataSource(ADataSource: TDataSource);
procedure DataChange(Sender: TObject);
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
property Field: TField read GetField;
published
property AutoSize;
property BackgroundColor;
property DataField: string read GetDataField write SetDataField;
property DataSource: TDataSource read GetDataSource write SetDataSource;
property Enabled;
property FontDesc;
property Text;
property TextColor;
end;
{
// TfpgEdit needs to be refactor some more first!!
TfpgDBEdit = class(TfpgCustomEdit)
private
FDataLink: TfpgFieldDataLink;
function GetDataField: string;
function GetDataSource: TDataSource;
function GetField: TField;
function GetReadOnly: Boolean;
procedure SetDataField(const ADataField: string);
procedure SetDataSource(const ADataSource: TDataSource);
procedure DataChange(Sender: TObject);
procedure SetReadOnly(const AValue: Boolean);
protected
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
property Field: TField read GetField;
published
property DataField: string read GetDataField write SetDataField;
property DataSource: TDataSource read GetDataSource write SetDataSource;
property Enabled;
property BackgroundColor;
property Color;
property FontDesc;
property Text;
property ReadOnly: Boolean read GetReadOnly write SetReadOnly default False;
end;
}
implementation
{ TfpgFieldDataLink }
function TfpgFieldDataLink.GetCanModify: Boolean;
begin
Result := not ReadOnly and (Field <> nil) and Field.CanModify;
end;
procedure TfpgFieldDataLink.SetFieldName(const AFieldName: string);
begin
if AFieldName <> FieldName then
begin
FFieldName := AFieldName;
UpdateField;
end;
end;
procedure TfpgFieldDataLink.UpdateField;
begin
{$IFDEF DEBUG} WriteLn('## UpdateField. DataSet: ', DataSource.DataSet.ClassName); {$ENDIF}
FField := DataSource.DataSet.FindField(FieldName);
if Assigned(OnDataChange) then
OnDataChange(Self);
end;
procedure TfpgFieldDataLink.ActiveChanged;
begin
inherited ActiveChanged;
UpdateField;
end;
procedure TfpgFieldDataLink.RecordChanged(AField: TField);
begin
inherited RecordChanged(AField);
if Assigned(OnDataChange) then
OnDataChange(Self);
end;
constructor TfpgFieldDataLink.Create(AWidget: TfpgWidget);
begin
inherited Create;
FWidget := AWidget;
end;
{ TfpgDBLabel }
function TfpgDBLabel.GetDataField: String;
begin
Result := FDataLink.FieldName;
end;
function TfpgDBLabel.GetField: TField;
begin
Result := FDataLink.Field;
end;
procedure TfpgDBLabel.SetDataField(const ADataField: String);
begin
FDataLink.FieldName := ADataField;
end;
function TfpgDBLabel.GetDataSource: TDataSource;
begin
Result := FDataLink.DataSource;
end;
procedure TfpgDBLabel.SetDataSource(ADataSource: TDataSource);
begin
FDataLink.DataSource := ADataSource;
end;
procedure TfpgDBLabel.DataChange(Sender: TObject);
begin
{$IFDEF DEBUG} Write(Classname + '.DataChange'); {$ENDIF}
if Assigned(FDataLink.Field) then
begin
Text := FDataLink.Field.DisplayText;
{$IFDEF DEBUG} WriteLn(' new text: "', Text, '"'); {$ENDIF}
end
else
begin
Text := '';
{$IFDEF DEBUG} WriteLn('DataLink has no data'); {$ENDIF}
end;
end;
constructor TfpgDBLabel.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FDataLink := TfpgFieldDataLink.Create(Self);
FDataLink.OnDataChange := @DataChange;
end;
destructor TfpgDBLabel.Destroy;
begin
FDataLink.Free;
inherited Destroy;
end;
end.
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