Hello,
I am trying to get drag and drop to work but I am not an expert with all this low level GTK2 api. In the end I want to be able to drag files from my application to the file manager. My application is displaying a list of items (that represent files) in the scrollbox (I have essentially emulated a custom drawn listview for my needs from scratch) and then the user should be able to drag from the scrollbox to the file manager or to the desktop and this other application shold then behave as if files were dropped.
For this purpose I have started a new empty project to play with the gtk2 API (and maybe later do the same also for windows once I have worked out how this goes). This is what I have so far (and it is NOT working):
unit Unit1;
{$mode objfpc}{$H+}
interfaceuses
Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, ExtCtrls,
StdCtrls;type
{ TForm1 }
TForm1 = class(TForm)
Button1: TButton;
ScrollBox1: TScrollBox;
procedure FormCreate(Sender: TObject);
procedure SetupDragDrop;
private
{ private declarations }
public
{ public declarations }
end;
var
Form1: TForm1;
implementation
uses
glib2, gtk2, gdk2;
{$R *.lfm}{ TForm1 }
procedure drag_begin(para1: TGtkSignalFuncProc); cdecl;
begin
writeln('drag_begin');
end;
procedure drag_end(para1: TGtkSignalFuncProc); cdecl;
begin
writeln('drag_end');
end;
procedure drag_data_get(para1: TGtkSignalFuncProc); cdecl;
begin
writeln('drag_data_get');
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
SetupDragDrop;
end;
procedure TForm1.SetupDragDrop;
var
Widget: PGtkWidget;
TargetEntry: TGtkTargetEntry;
begin
// is it ok to assume that the handle is the PGtkWidget?
// none of them seem to work :-(
//Widget := PGtkWidget(Form1.Handle);
//Widget := PGtkWidget(Button1.Handle);
Widget := PGtkWidget(ScrollBox1.Handle);
with TargetEntry do begin
target := 'what do i have to put here for dragging files?';
info := 0; // <-- what is this?
flags := 0; // <-- maybe the wrong flags?
end;
// is this correct?
gtk_drag_source_set(Widget, GDK_BUTTON1_MASK, @TargetEntry, 1,
GDK_ACTION_COPY);
// or is the way I connect the signals wrong?
g_signal_connect(Widget, 'drag-begin', @drag_begin, nil);
g_signal_connect(Widget, 'drag-end', @drag_end, nil);
g_signal_connect(Widget, 'drag-data-get', @drag_end, nil);
// what else is missing? None of my callbacks will ever be called :-(
end;
end.Its a simple empty application with just a button and a TScrollBox (ideally I want to have the scrollbox as drag source, some GTK tutorials use buttons in their examples as drag source so I assume at least with the button it should work once I get it working at all?
Unfortunately the above code does not seem to do
of the callbacks are called, the cursor does not change when I attempt to drag, I assume I am missing something esential. It would be nice if someone could help me modify the above at least to the point where at least *something* will happen and maybe also answer some of the questions embedded in the code, maybe then I can figure out the rest on my own.
Bernd