Delphi - ListView or similar with owner draw button - delphi

Question

How do I do create a listview (or similar) with a button on each line? The button needs to be able to have different text/color on each line as required.
I'm sure Virtual Treeview would be perfect for this, but I'm a little lost with it.
Thanks
-Brad

Answer 1

With a virtualtreeview...... add vstButton to your uses and select your Virtualtreeview in the object inspector and set the following events for your tree:
procedure TForm1.VSTCreateEditor(Sender: TBaseVirtualTree; Node: PVirtualNode;
Column: TColumnIndex; out EditLink: IVTEditLink);
begin
EditLink:=TStringEditLink.Create;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
VST.NodeDataSize := SizeOf(TTreeData);
AddRandomNodesToTree(Vst);
end;
procedure TForm1.VSTFreeNode(Sender: TBaseVirtualTree;
Node: PVirtualNode);
var
Data: PTreeData;
begin
Data:=VST.GetNodeData(Node);
if Assigned(Data) then begin
Data^.Column0 := '';
Data^.Column1 := '';
Data^.Column2 := '';
end;
end;
procedure TForm1.VSTGetText(Sender: TBaseVirtualTree;
Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType;
var CellText: string);
var
Data: PTreeData;
begin
Data := VST.GetNodeData(Node);
case Column of
0: CellText := Data^.Column0;
1: CellText := Data^.Column1;
2: CellText := Data^.Column2;
end;
end;
procedure TForm1.VSTNewText(Sender: TBaseVirtualTree; Node: PVirtualNode;
Column: TColumnIndex; NewText: string);
Var
Data: PTreeData;
begin
Data := VST.GetNodeData(Node);
Case Column of
0: Data^.Column0:= NewText;
1: Data^.Column1:= NewText;
2: Data^.Column2:= NewText;
End;
end;
procedure TForm1.VSTPaintText(Sender: TBaseVirtualTree;
const TargetCanvas: TCanvas; Node: PVirtualNode; Column: TColumnIndex;
TextType: TVSTTextType);
Var
Data: PTreeData;
begin
if Odd(Node.Index) then
TargetCanvas.Font.Color:= clRed;
end;
... this assumes the record is:
type
PTreeData = ^TTreeData;
TTreeData = record
Column0: String;
Column1: String;
Column2: String;
end;
...add the following unit:
unit vstButton;
interface
uses
Classes, SysUtils, Forms, Controls, Graphics, Dialogs, VirtualTrees,
messages, windows, StdCtrls, ShlObj;
type
TStringEditLink = class(TInterfacedObject, IVTEditLink)
private
FEdit: TWinControl;
FTree: TVirtualStringTree;
FNode: PVirtualNode;
FColumn: Integer;
FSelectedFolder: string;
protected
procedure ButtonClick(Sender: TObject);
public
destructor Destroy; override;
function BeginEdit: Boolean; stdcall;
function CancelEdit: Boolean; stdcall;
function EndEdit: Boolean; stdcall;
function GetBounds: TRect; stdcall;
function PrepareEdit(Tree: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex): Boolean; stdcall;
procedure ProcessMessage(var Message: TMessage); stdcall;
procedure SetBounds(R: TRect); stdcall;
end;
function GetFolderDialog(Handle: Integer; Caption: string; var strFolder: string): Boolean;
implementation
destructor TStringEditLink.Destroy;
begin
FEdit.Free;
inherited;
end;
procedure TStringEditLink.ButtonClick(Sender: TObject);
var
s: string;
begin
s := 'c:\';
if GetFolderDialog(Application.Handle, 'Select a folder', s) then
FSelectedFolder := s;
FTree.EndEditNode;
FTree.setfocus;
end;
function TStringEditLink.BeginEdit: Boolean;
begin
Result := True;
FSelectedFolder := FTree.Text[FNode, FColumn];
TButton(FEdit).CAption := FTree.Text[FNode, FColumn];
FEdit.Show;
FEdit.SetFocus;
end;
function TStringEditLink.CancelEdit: Boolean;
begin
Result := True;
FEdit.Hide;
FTree.EndEditNode;
FTree.setfocus;
end;
function TStringEditLink.EndEdit: Boolean;
var
S: WideString;
begin
Result := True;
FTree.Text[FNode, FColumn] := FSelectedFolder;
FTree.InvalidateNode(FNode);
FEdit.Hide;
FTree.SetFocus;
end;
function TStringEditLink.GetBounds: TRect;
begin
Result := FEdit.BoundsRect;
end;
function TStringEditLink.PrepareEdit(Tree: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex): Boolean;
begin
Result := True;
FTree := Tree as TVirtualStringTree;
FNode := Node;
FColumn := Column;
FEdit.Free;
FEdit := nil;
FEdit := TButton.Create(nil);
with FEdit as TButton do
begin
Visible := False;
Parent := Tree;
Font.Color := FTree.Colors.HeaderHotColor;
OnClick := ButtonClick;
end;
end;
procedure TStringEditLink.ProcessMessage(var Message: TMessage);
begin
FEdit.WindowProc(Message);
end;
procedure TStringEditLink.SetBounds(R: TRect);
var
Dummy: Integer;
begin
FTree.Header.Columns.GetColumnBounds(FColumn, Dummy, R.Right);
FEdit.BoundsRect := R;
end;
//------------------------------------------------------------------------------\\
function BrowseCallbackProc(hwnd: HWND; uMsg: UINT; lParam: LPARAM; lpData: LPARAM): Integer; stdcall;
begin
if (uMsg = BFFM_INITIALIZED) then
SendMessage(hwnd, BFFM_SETSELECTION, 1, lpData);
BrowseCallbackProc := 0;
end;
function GetFolderDialog(Handle: Integer; Caption: string; var strFolder: string): Boolean;
const
BIF_STATUSTEXT = $0004;
BIF_NEWDIALOGSTYLE = $0040;
BIF_RETURNONLYFSDIRS = $0080;
BIF_SHAREABLE = $0100;
BIF_USENEWUI = BIF_EDITBOX or BIF_NEWDIALOGSTYLE;
var
BrowseInfo: TBrowseInfo;
ItemIDList: PItemIDList;
JtemIDList: PItemIDList;
Path: PChar;
begin
Result := False;
Path := StrAlloc(MAX_PATH);
SHGetSpecialFolderLocation(Handle, CSIDL_DRIVES, JtemIDList);
with BrowseInfo do
begin
hwndOwner := GetActiveWindow;
pidlRoot := JtemIDList;
SHGetSpecialFolderLocation(hwndOwner, CSIDL_DRIVES, JtemIDList);
{ return display name of item selected }
pszDisplayName := StrAlloc(MAX_PATH);
{ set the title of dialog }
lpszTitle := PChar(Caption);//'Select the folder';
{ flags that control the return stuff }
lpfn := #BrowseCallbackProc;
{ extra info that's passed back in callbacks }
lParam := LongInt(PChar(strFolder));
end;
ItemIDList := SHBrowseForFolder(BrowseInfo);
if (ItemIDList <> nil) then
if SHGetPathFromIDList(ItemIDList, Path) then
begin
strFolder := Path;
Result := True
end;
end;
End.
the above code is based upon code found at this website:
http://wiki.freepascal.org/VirtualTreeview_Example_for_Lazarus
If you look at the unit vstButton, to get a TEdit, or TCombo...etc... just replace any TButton reference with TEdit or TCombo etc... adjust events for it etc... The above link code actually uses a TCombo
that website helped me alot to learn how to use the virtualtreeview
the above code will insert a Tbutton into every cell, and when you click on the button it will open a BrowseForFolder dialog and insert the result back into the virtualtreeview cell
Hope this helps
did you want a button visible in a cell column all the time? Could simulate the button with an image... like a dropdown mark on one side of the cell