Title: Simplest way to display dataset record on the fly
Question: Did you ever tried to display current DataSet record on the fly using surface of any kind of TWinControl?
Answer:
There are many possibilities for that.
The following solution does just that in a simplest way.
All what you have to do is add unit to project and implement procedures
Do_TStringGrid and Display_Data every time you want to display data
in current record of TDataSet.
unit DataGrid;
interface
uses
Windows, Controls, Grids, DB, Graphics;
Type
TDataGr = class
private
procedure FStringGridDrawCell(Sender: TObject; ACol, ARow: Integer;
Rect: TRect; State: TGridDrawState);
end;
// Create TStringGrid with current record of ADSet
Procedure Do_TStringGrid(AParent : TWinControl; ADSet : TDataSet);
// Display data
Procedure Display_Data(AParent : TWinControl; ADSet : TDataSet);
implementation
Var
DataGr : TDataGr;
// Display data
Procedure Display_Data(AParent : TWinControl; ADSet : TDataSet);
Var
kCol, kRow, k : Integer;
begin
if AParent.ControlCount = 0 then
Exit;
kCol := 0;
kRow := -1;
with TStringGrid(AParent.Controls[0]) do
for k:=0 to ADSet.FieldList.Count-1 do
begin
Inc(kRow);
Cells[kCol, kRow] := ADSet.FieldList[k].FieldName;
Cells[kCol+1, kRow] := ADSet.FieldByName(ADSet.FieldList[k].FieldName).AsString;
if kRow = RowCount-1 then
begin
kRow := -1;
Inc(kCol, 2);
end;
end;
end;
// Create TStringGrid with current record of ADSet
Procedure Do_TStringGrid(AParent : TWinControl; ADSet : TDataSet);
Var
k : Integer;
begin
while AParent.ControlCount 0 do
AParent.Controls[0].Free;
with TStringGrid.Create(AParent.Owner) do
begin
Parent := AParent;
DefaultRowHeight := 16;
k := (Parent.ClientHeight div (DefaultRowHeight + GridLineWidth)) - 1;
RowCount := k;
Align := alClient;
FixedCols := 0;
FixedRows := 0;
ColCount := 2*((ADSet.FieldList.Count div RowCount)+1);
DefaultColWidth := ClientWidth div ColCount - GridLineWidth;
OnDrawCell := DataGr.FStringGridDrawCell;
end;
// Display data
Display_Data(AParent, ADSet);
end;
procedure TDataGr.FStringGridDrawCell(Sender: TObject; ACol,
ARow: Integer; Rect: TRect; State: TGridDrawState);
begin
if not Odd(ACol) then
Exit;
with TStringGrid(Sender) do
begin
Canvas.FillRect(Rect);
if Cells[ACol, ARow] = '' then
Canvas.Font.Style := []
else
Canvas.Font.Style := [fsBold];
Canvas.TextOut(Rect.Left, Rect.Top, Cells[ACol, ARow]);
end;
end;
end.
Usage:
...
Do_TStringGrid(Panel1, Query1);
to track scrolling data put following line in the AfterScroll event of the TDataSet
...
Display_Data(Panel1, Query1)
I hope this tip can be useful to Database programmers.
NOTES:
1. It is assumed that AParent doesn't have any controls on it. Otherwise one
must search previously created StringGrid in any other manner to destroy it when
it is needed repetedly use procedure Do_TStringGrid. If so replace lines
while AParent.ControlCount 0 do
AParent.Controls[0].Free;
as needed.
2. Second asumption is that all field values can be displyed as strings.
If there are blob fields (i.e. graphics) in the DataSet one must improve the solution.
But these cases seems to be too rarely encountered.