How to drag report in ppviewer? - delphi

Question

Anyone know how to drag the report in TppViewer? (Delphi 7) i try to use the dagdrop event and dragover event of ppviewer but failed, anyone can help?
procedure Tfrm1.ppviewer1DragOver(Sender, Source: TObject; X,
Y: Integer; State: TDragState; var Accept: Boolean);
begin
inherited;
Accept := Source IS TppViewer;
end;
procedure Tfrm1.ppviewer1DragDrop(Sender, Source: TObject; X,
Y: Integer);
begin
inherited;
if Source is TppViewer then begin
TppViewer(Source).Left := X;
TppViewer(Source).Top := Y;
end;
end;

Answer 1

This answer assumes that you are trying to scroll in the report, by dragging.
TReportPreviewer is the Form
ReportViewer is the ppViewer
Dragging is a Boolean
SaveX, SaveY are Integer
procedure TReportPreviewer.ReportViewerMouseDown(Sender: TObject;
Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
Dragging := true;
SaveX := X;
SaveY := Y;
end;
procedure TReportPreviewer.ReportViewerMouseMove(Sender: TObject;
Shift: TShiftState; X, Y: Integer);
begin
if Dragging then
begin
if ReportViewer.ScrollBox.Visible then
ReportViewer.ScrollBox.HorzScrollBar.Position := ReportViewer.ScrollBox.HorzScrollBar.Position - (X - SaveX);
if ReportViewer.ScrollBox.Visible then
ReportViewer.ScrollBox.VertScrollBar.Position := ReportViewer.ScrollBox.VertScrollBar.Position - (Y - SaveY);
SaveX := X;
SaveY := Y;
end;
end;
procedure TReportPreviewer.ReportViewerMouseUp(Sender: TObject;
Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
Dragging := false;
end;
I tried using ScrollBy instead of moving the scrollbar position, but it seemed to reset for some reason.

Answer 2

Are you trying to drag a report file into the Viewer? if so biased on the following advice:
How to Drop Images from Windows Explorer to a TImage control
Delphi - Drag & Drop with ListView
WM_DROPFILES Message
You can achieve this by using the following code:
procedure TMainForm.FormCreate(Sender: TObject);
begin
//Tell Windows that the Report Viewer accepts files
ShellAPI.DragAcceptFiles(ppViewer1.Handle,True);
Application.OnMessage := ApplicationMessage;
end;
procedure TMainForm.ApplicationMessage(var Msg: TMsg; var Handled: Boolean);
begin
if (Msg.hwnd = ppViewer1.Handle) and (Msg.message = WM_DROPFILES) then
begin
Handled := ReportFileDrop(Msg);
end;
end;
function TMainForm.ReportFileDrop(var Msg: TMsg):Boolean ;
var
numFiles : longInt;
buffer : array[0..MAX_PATH] of char;
l_file:String;
l_filemsg:TWMDROPFILES;
begin
Result := False;
//Convert the TMsg into a TWMDROPFILES record
l_filemsg.Msg := Msg.message;
l_filemsg.Drop := Msg.wParam;
l_filemsg.Unused := Msg.lParam;
l_filemsg.Result := 0;
numFiles := DragQueryFile(l_filemsg.Drop, $FFFFFFFF, nil, 0) ;
if numFiles > 1 then
begin
ShowMessage('You can drop only one file at a time!') ;
end
else
begin
try
DragQueryFile(l_filemsg.Drop, 0, #buffer, sizeof(buffer)) ;
l_file := buffer;
//Only try and load the report if the file has the correct extension
if (Length(l_file) > 0) and (ExtractFileExt(LowerCase(l_file)) = '.rtm') then
begin
//Load the Report
Result := True;
end;
except
//Handle errors
end;
end;
end;