Delphi throbber - delphi

Question

What is the best solution to show that the application is doing something?
I tried showing a progress indicator, but it did not work.
UPDATE: -------------
A progress bar works fine, but isn't what I want.
I want to show a throbber, like what Web browsers use, so as long as something is being updated it keeps turning.
Cursor can also be in crHourGlass mode.

Answer 1

Try this:
AnimateUnit
unit AnimateUnit;
interface
uses
Windows, Classes;
type
TFrameProc = procedure(const theFrame: ShortInt) of object;
TFrameThread = class(TThread)
private
{ Private declarations }
FFrameProc: TFrameProc;
FFrameValue: ShortInt;
procedure SynchedFrame();
protected
{ Protected declarations }
procedure Frame(const theFrame: ShortInt); virtual;
public
{ Public declarations }
constructor Create(theFrameProc: TFrameProc; CreateSuspended: Boolean = False); reintroduce; virtual;
end;
TAnimateThread = class(TFrameThread)
private
{ Private declarations }
protected
{ Protected declarations }
procedure Execute(); override;
public
{ Public declarations }
end;
var
AnimateThread: TAnimateThread;
implementation
{ TFrameThread }
constructor TFrameThread.Create(theFrameProc: TFrameProc; CreateSuspended: Boolean = False);
begin
inherited Create(CreateSuspended);
FreeOnTerminate := True;
FFrameProc := theFrameProc;
end;
procedure TFrameThread.SynchedFrame();
begin
if Assigned(FFrameProc) then FFrameProc(FFrameValue);
end;
procedure TFrameThread.Frame(const theFrame: ShortInt);
begin
FFrameValue := theFrame;
try
Sleep(0);
finally
Synchronize(SynchedFrame);
end;
end;
{ TAnimateThread }
procedure TAnimateThread.Execute();
var
I: ShortInt;
begin
while (not Self.Terminated) do
begin
Frame(0);
for I := 1 to 8 do
begin
if (not Self.Terminated) then
begin
Sleep(120);
Frame(I);
end;
end;
Frame(0);
end;
end;
end.
Unit1
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ExtCtrls, ImgList;
type
TForm1 = class(TForm)
ImageList1: TImageList;
Image1: TImage;
Button1: TButton;
Button2: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
procedure UpdateFrame(const theFrame: ShortInt);
end;
var
Form1: TForm1;
implementation
uses
AnimateUnit;
{$R *.DFM}
procedure TForm1.UpdateFrame(const theFrame: ShortInt);
begin
Image1.Picture.Bitmap.Handle := 0;
try
ImageList1.GetBitmap(theFrame, Image1.Picture.Bitmap);
finally
Image1.Update();
end;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
AnimateThread := TAnimateThread.Create(UpdateFrame);
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
AnimateThread.Terminate();
end;
end.
The Images

Answer 2

You are probably running your time consuming task in the main thread.
One option is to move it to a background thread which will allow your message queue to be serviced. You need it to be serviced in order for your progress bar, and indeed any UI, to work.

Answer 3

Answer to the updated question:
generate an animated gif e.g. here
add a GIF library to your environment (JEDI JVCL+JCL)
insert a TImage and load the generated gif
make it visible if you need it

Answer 4

A indicator is OK. You have to call Application.ProcessMessages after changing it.

Answer 5

"What is the best solution to show that that application is doing something?" - set mouse cursor to crHourGlass? or to create another form/frame/etc which attentions the user that the application is 'doing' something, and he needs to wait.

Answer 6

From your lengthy task, you can occasionally update a visual indicator, like a progress bar or anything else. However, you need to redraw the changes immediately by calling Update on the control that provides the feedback.
Don't use Application.ProcessMessages as this will introduce possible reentrancy issues.