When is TDBGrid.SelectedRows updated in Delphi? - delphi

I want to list some values (ID-s in this case) of the selected rows of a TDBGrid in a TEdit control.
I've tried AfterScroll event, to catch the event after(!) a selection, but it doesn't work if I use the mouse.
If I click on a row with mouse, it doesn't appear in the TDBGrid.SelectedRows collection, only after the next click/selection.
If I do the selection with keyboard, everything works fine.
Do you have any idea, how to solve this?
Simplified code of my solution:
procedure TForm1.ClientDataSet1AfterScroll(DataSet: TDataSet);
begin
edtIDs.Text := string.Join(',', GetSelectedIDs().ToArray) ;
end;
function TForm1.GetSelectedIDs() : TList<string>;
var
i: Integer;
ds: TDataSet;
bmOrig: TBookmark;
begin
FSelectedIDs.Clear();
ds := DBGrid1.DataSource.DataSet;
bmOrig := ds.GetBookmark();
ds.AfterScroll := nil; //switch off AfterScroll event
try
if DBGrid1.SelectedRows.Count > 0 then begin
for i := 0 to DBGrid1.SelectedRows.Count - 1 do begin
ds.GotoBookmark(DBGrid1.SelectedRows.Items[i]);
FSelectedIDs.Add(ds.FindField('ID').AsString);
end;
ds.GotoBookmark(bmOrig);
end;
finally
ds.AfterScroll := ClientDataSet1AfterScroll; //switch on AfterScroll event
ds.FreeBookmark(bmOrig);
end;
Result := FSelectedIDs;
end;

Replace the OnAfterScroll event of the data source by the OnColEnter event of the TDBGrid.
Form the help of TDBGrid.OnColEnter:
Occurs when focus moves to a new cell in the grid.
Write an OnColEnter event handler to take specific action when a new cell has just been selected.
Focus moves to a cell when
The user navigates to the cell using the keyboard. For example, when the user uses the Tab key, or the Home key.
The user clicks the mouse button down in the cell.
The SelectedField or SelectedIndex property is set.
Read the SelectedField or SelectedIndex property to determine which cell was just entered.

Related

How to get the clicked column on TDBGrid.DblClick(Sender: TObject)?

When using the OnDblClick event of a TDBGrid, how can i know what column was double clicked ?
This is easy with the OnCellClick as it has a TColumn parameter, but not on OnDblClick.
During TDBGrid.OnDblClick the dataset is positioned to the clicked record and the column can be retrieved with the TDBGrid.SelectedIndex property. If you are interested in the underlying dataset field, you can directly access it with TDBGrid.SelectedField.
The OnDblClick event doesn't give you any information about the click, in particular where the click was performed, let alone which grid cell was clicked on. So, you will have to determine that information manually.
Try this:
Get the current mouse position within the grid, by passing Mouse.CursorPos to TDBGrid.ScreenToClient()
Then, use TDBGrid.MouseCoord() to determine the row/column indexes of the cell that is underneath the mouse.
Then, check if the cell row/column corresponds to a data cell, and if so then use the TDBGrid.SelectedIndex property to index into the TDBGrid.Columns property.
This is basically the same thing that TDBGrid does internally when firing the OnCellClick event, only it does this in response to a MouseUp event, which provides the mouse coordinates within the grid, thus skipping the 1st step above.
For example:
type
TDBGridAccess = class(TDBGrid)
end;
procedure TMyForm1.DBGrid1DblClick(Sender: TObject);
var
TitleOffset: Byte;
Pt: TPoint;
Cell: TGridCoord;
Column: TColumn;
begin
TitleOffset := Ord(dgTitles in DBGrid1.Options);
Pt := DBGrid1.ScreenToClient(Mouse.CursorPos);
Cell := DBGrid1.MouseCoord(Pt.X, Pt.Y);
if (Cell.X >= TDBGridAccess(DBGrid1).IndicatorOffset) and (Cell.Y >= TitleOffset) then
begin
Column := DBGrid1.Columns[DBGrid1.SelectedIndex];
// use Column as needed...
end;
end;
UPDATE: based on #UweRaabe's comments, you should be able to just use TDBGrid.SelectedIndex by itself:
procedure TMyForm1.DBGrid1DblClick(Sender: TObject);
var
Index: Integer;
Column: TColumn;
begin
Index := DBGrid1.SelectedIndex;
if (Index <> -1) then
begin
Column := DBGrid1.Columns[Index];
// use Column as needed...
end;
end;

cxgrid highlight (or color) changed cell on form closequery

On closequery of the form I have :
if MessageDlg('Close program ?',
mtConfirmation, [mbYes,mbCancel],0) <> mrYes then CanClose := False
else if DataModule2.mytable.State in [dsEdit,dsInsert] then
if MessageDlg('Save changes ?', mtConfirmation,
[mbYes,mbNo],0) = mrYes then DataModule2.mytable.Post;
Is there a way I can highlight (or color) a changed cell in cxgrid when I trigger my onclosequery event ?
I don't need to know what was changed but just to know which cell was changed so the user can see it so he can easily decide weather to save the changes or not.
It is simple to get the cxGrid to draw a cell (or row) highlighted in some way using the
cxGrid1DBTableView1CustomDrawCell event. And by having a flag that indicates that the OnCloseQuery event is in progress, you can restrict its action to inside that event.
Update The code I originally posted with this answer could not successfully mark more than one cell in the current grid row as changed. The updated code below can do this however; note the comments in the two
procedures.
type
TForm1 = class(TForm)
[...]
public
QueryingClose : Boolean;
end;
procedure TForm1.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
try
QueryingClose := True;
//{cxGrid1.Invalidate{True); Do NOT call Invalidate, because it causes the
// grid's repainting logic to operate in a way which effectively makes it
// impossible to mark more that one cell in the current data row as changed
ShowMessage('Close?');
finally
QueryingClose := False;
end;
end;
procedure TForm1.cxGrid1DBTableView1CustomDrawCell(Sender:
TcxCustomGridTableView; ACanvas: TcxCanvas; AViewInfo:
TcxGridTableDataCellViewInfo; var ADone: Boolean);
var
Field : TField;
MarkCell : Boolean;
S1,
S2 : String;
EC : TcxGridTableEditingController;
begin
if QueryingClose and
(TcxGridDBTableView(Sender).DataController.DataSet.State in[dsEdit, dsInsert]) then begin
Field := TcxGridDBColumn(AViewInfo.Item).DataBinding.Field;
S1 := VarToStr(Field.OldValue);
// When this event is called, the user may be in the middle of editing a cell's contents
// So, the purpose of the following lines is to close the inplace editor being used to do
// this amd post the chamged value back to the TField associated with the cell
EC := TcxGridDBTableView(Sender).Controller.EditingController;
if EC.IsEditing then
EC.HideEdit(True);
S2 := VarToStr(Field.Value);
MarkCell := S1 <> S2;
if MarkCell then
ACanvas.Brush.Color := clLime;
end;
end;
For this to work, your TDataSet-descendant type must support correctly returning the original contents of the fields on their OldValue property; TClientDataSet, which I've used to write/test this code certainly does this but I've no idea what actual TDataSet type you're using.
Hopefully, it should be apparent that you could use these two procedures to
build a list of TFields that have changed values, including the FieldName OldValue, and Value.

Deleting a selected row via mouse click in TStringGrid using delphi

I'm not sure how i would capture the row selected by a mouse click and then press a button to delete that selected row in a stringGrid in delphi.
procedure DeleteRow(Grid: TStringGrid; ARow: Integer);
var
i: Integer;
begin
for i := ARow to Grid.RowCount - 2 do
Grid.Rows[i].Assign(Grid.Rows[i + 1]);
Grid.RowCount := Grid.RowCount - 1;
end;
procedure TManageUsersForm.RemoveRowButtonClick(Sender: TObject);
var
Recordposition : integer;
begin
UserStringGrid.Options := UserStringGrid.Options + [goEditing];
UserStringGrid.Options := UserStringGrid.Options + [goRowSelect];
end;
So the first procedure is for deleting a row and the second makes sure when a user clicks a cell the whole row is highlighted not just that 1 cell.
The mouse click is the most important part!!
Thank You :)
The mouse click is not the most important part. Users can select a row either by keyboard or mouse, it doesn't matter, you'd just want to delete the current row. In the case of a mouse click, or otherwise, you can get the current row by Row.
procedure DeleteCurrentRow(Grid: TStringGrid);
var
i: Integer;
begin
for i := Grid.Row to Grid.RowCount - 2 do
Grid.Rows[i].Assign(Grid.Rows[i + 1]);
Grid.RowCount := Grid.RowCount - 1;
end;
Call it like;
DeleteCurrentRow(UserStringGrid);
I imagine the problem you might be having is to work out which grid row the user has clicked on. One way is:
procedure TForm1.StringGrid1Click(Sender: TObject);
var
StringGrid : TStringGrid;
Row : Integer;
GridRect : TGridRect;
begin
// The Sender argument to StringGrid1Click is actually the StringGrid itself,
// and the following "as" cast lets you assign it to the StringGrid local variable
// in a "type-safe" way, and access its properties and methods via the temporary variable
StringGrid := Sender as TStringGrid;
// Now we can retrieve the use selection
GridRect := StringGrid.Selection;
// and hence the related GridRect
// btw, the value returned for Row automatically takes account of
// the number of FixedRows, if any, of the grid
Row := GridRect.Top;
Caption := IntToStr(Row);
{ ...}
end;
See the OLH about TGridRect.
Hopefully the above will be sufficient to get you going - you've obvious already got most of the way yourself. Or, you could try the method suggested in the other answer, which is a little more "direct" but this way might be a bit more instructive as a "how to". Your choice ...

Why don't child controls of a TStringGrid work properly?

I am placing checkboxes (TCheckBox) in a string grid (TStringGrid) in the first column. The checkboxes show fine, positioned correctly, and respond to mouse by glowing when hovering over them. When I click them, however, they do not toggle. They react to the click, and highlight, but finally, the actual Checked property does not change. What makes it more puzzling is I don't have any code changing these values once they're there, nor do I even have an OnClick event assigned to these checkboxes. Also, I'm defaulting these checkboxes to be unchecked, but when displayed, they are checked.
The checkboxes are created along with each record which is added to the list, and is referenced inside a record pointer which is assigned to the object in the cell where the checkbox is to be placed.
String grid hack for cell highlighting:
type
THackStringGrid = class(TStringGrid); //used later...
Record containing checkbox:
PImageLink = ^TImageLink;
TImageLink = record
...other stuff...
Checkbox: TCheckbox;
ShowCheckbox: Bool;
end;
Creation/Destruction of checkbox:
function NewImageLink(const AFilename: String): PImageLink;
begin
Result:= New(PImageLink);
...other stuff...
Result.Checkbox:= TCheckbox.Create(nil);
Result.Checkbox.Caption:= '';
end;
procedure DestroyImageLink(AImageLink: PImageLink);
begin
AImageLink.Checkbox.Free;
Dispose(AImageLink);
end;
Adding rows to grid:
//...after clearing grid...
//L = TStringList of original filenames
if L.Count > 0 then
lstFiles.RowCount:= L.Count + 1
else
lstFiles.RowCount:= 2; //in case there are no records
for X := 0 to L.Count - 1 do begin
S:= L[X];
Link:= NewImageLink(S); //also creates checkbox
Link.Checkbox.Parent:= lstFiles;
Link.Checkbox.Visible:= Link.ShowCheckbox;
Link.Checkbox.Checked:= False;
Link.Checkbox.BringToFront;
lstFiles.Objects[0,X+1]:= Pointer(Link);
lstFiles.Cells[1, X+1]:= S;
end;
Grid's OnDrawCell Event Handler:
procedure TfrmMain.lstFilesDrawCell(Sender: TObject; ACol, ARow: Integer;
Rect: TRect; State: TGridDrawState);
var
Link: PImageLink;
CR: TRect;
begin
if (ARow > 0) and (ACol = 0) then begin
Link:= PImageLink(lstFiles.Objects[0,ARow]); //Get record pointer
CR:= lstFiles.CellRect(0, ARow); //Get cell rect
Link.Checkbox.Width:= Link.Checkbox.Height;
Link.Checkbox.Left:= CR.Left + (CR.Width div 2) - (Link.Checkbox.Width div 2);
Link.Checkbox.Top:= CR.Top;
if not Link.Checkbox.Visible then begin
lstFiles.Canvas.Brush.Color:= lstFiles.Color;
lstFiles.Canvas.Brush.Style:= bsSolid;
lstFiles.Canvas.Pen.Style:= psClear;
lstFiles.Canvas.FillRect(CR);
if lstFiles.Row = ARow then
THackStringGrid(lstFiles).DrawCellHighlight(CR, State, ACol, ARow);
end;
end;
end;
Here's how it looks when clicking...
What could be causing this? It's definitely not changing the Checked property anywhere in my code. There's some strange behavior coming from the checkboxes themselves when placed in a grid.
EDIT
I did a brief test, I placed a regular TCheckBox on the form. Check/unchecks fine. Then, in my form's OnShow event, I changed the Checkbox's Parent to this grid. This time, I get the same behavior, not toggling when clicked. Therefore, it seems that a TCheckBox doesn't react properly when it has another control as its parent. How to overcome this?
TStringGrid's WMCommand handler doesn't allow children controls to handle messages (except for InplaceEdit).
So you can use e.g. an interposed class (based on code by Peter Below) or draw controls by hands, as some people have adviced. Here is the code of the interposed class:
uses
Grids;
type
TStringGrid = class(Grids.TStringGrid)
private
procedure WMCommand(var AMessage: TWMCommand); message WM_COMMAND;
end;
implementation
procedure TStringGrid.WMCommand(var AMessage: TWMCommand);
begin
if EditorMode and (AMessage.Ctl = InplaceEditor.Handle) then
inherited
else
if AMessage.Ctl <> 0 then
begin
AMessage.Result := SendMessage(AMessage.Ctl, CN_COMMAND,
TMessage(AMessage).WParam, TMessage(AMessage).LParam);
end;
end;
In Delphi7 at least I do this:
You need to draw a checkbox on the cell, and keep it in sync with an array of boolean (here fChecked[]) that indicates the state of the checkbox in each row. Then, in the DrawCell part of the TStringGrid:
var
cbstate: integer;
begin
...
if fChecked[Arow] then cbState:=DFCS_CHECKED else cbState:=DFCS_BUTTONCHECK;
DrawFrameControl(StringGrid.canvas.handle, Rect, DFC_BUTTON, cbState);
...
end;
To get the checkbox to respond to the space-bar, use the KeyDown event, and force a repaint:
if (Key = VK_SPACE) And (col=ColWithCheckBox) then begin
fChecked[row]:=not fChecked[row];
StringGrid.Invalidate;
key:=0;
end;
A similar approach is needed for the OnClick method.
Can u use VirtualTreeView in toReportMode (TListView emulating) mode instead of grid ?
Can u use TDBGrid over some in-memory table like NexusDB or TClientDataSet ?
Ugly approach would be presenting checkbox like a letter with a custom font - like WinDings or http://fortawesome.github.com/Font-Awesome
This latter is most easy to implement, yet most ugly to see and most inflexible to maintain - business logic gets intermixed into VCL event handlers

Delphi Popup Menu Checks

I am using a popup menu in Delphi. I want to use it in a "radio group" fashion where if the user selects an item it is checked and the other items are not checked. I tried using the AutoCheck property, but this allows multiple items to be checked. Is there a way to set the popup menu so that only one item can be checked?
To treat the popup (or any other) menu items like radio group items, set the 'RadioItem' property to true for each item you want to have in the radio group.
Instead of showing a checkmark, it will show a bullet by the selected item, but it will work the way you want, and the visual cue will actually match a windows standard.
Zartog is right, but if you want to keep the checkbox, assign this event to every item in the popup menu.
Note that this code is a little hairy looking because it does not depend on knowing the name of your popup menu (hence, looking it up with "GetParentComponent").
procedure TForm2.OnPopupItemClick(Sender: TObject);
var
i : integer;
begin
with (Sender as TMenuItem) do begin
//if they just checked something...
if Checked then begin
//go through the list and *un* check everything *else*
for i := 0 to (GetParentComponent as TPopupMenu).Items.Count - 1 do begin
if i <> MenuIndex then begin //don't uncheck the one they just clicked!
(GetParentComponent as TPopupMenu).Items[i].Checked := False;
end; //if not the one they just clicked
end; //for each item in the popup
end; //if we checked something
end; //with
end;
You can assign the event at runtime to every popup box on your form like this (if you want to do that):
procedure TForm2.FormCreate(Sender: TObject);
var
i,j: integer;
begin
inherited;
//look for any popup menus, and assign our custom checkbox handler to them
if Sender is TForm then begin
with (Sender as TForm) do begin
for i := 0 to ComponentCount - 1 do begin
if (Components[i] is TPopupMenu) then begin
for j := 0 to (Components[i] as TPopupMenu).Items.Count - 1 do begin
(Components[i] as TPopupMenu).Items[j].OnClick := OnPopupItemClick;
end; //for every item in the popup list we found
end; //if we found a popup list
end; //for every component on the form
end; //with the form
end; //if we are looking at a form
end;
In response to a comment below this answer: If you want to require at least one item to be checked, then use this instead of the first code block. You may want to set a default checked item in the oncreate event.
procedure TForm2.OnPopupItemClick(Sender: TObject);
var
i : integer;
begin
with (Sender as TMenuItem) do begin
//go through the list and make sure *only* the clicked item is checked
for i := 0 to (GetParentComponent as TPopupMenu).Items.Count - 1 do begin
(GetParentComponent as TPopupMenu).Items[i].Checked := (i = MenuIndex);
end; //for each item in the popup
end; //with
end;
To enlarge on Zartog's post: Popup menus in Delphi (from at least D6) have a GroupIndex property which allow you to have multiple sets of radio items within a menu. Set GroupIndex to 1 for the first group, 2 for a second etc.
So:
Set AutoCheck = True
Set RadioItem = True
Set GroupIndex if you need more than one group of radio items

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