Problem with TeeCreateBitmap when there is A/V

[davidnovo]

Hello,

In TeeCreateMetafile you create the bitmap and assign to the result on the first line. Then do a bunch of stuff, including setting the size of the bitmap. Problem is if there is an exception (lets say setting the size too big) you will always leak a bitmap because the result of the function is undefined and if there is an exception in teh method.

i.e.

Code: Select all

bmp:=nil;
try
  bmp:=TeeCreateBitmap(someSize);
  .. do some stuff with bitmap
finally
  bmp.free
end

if there was an exception in TeeCreateBitmap (i.e. somesize was too large) it will jump to the finally, but bmp won't be assigned because the result of the function will be invalid and bmp will still be nil. You need to put a try except inside teeCreateBitmap to prevent a leak in this case.

[Yeray]

Hi David,

I'm not sure to understand it. I see no TeeCreateBitmap function with a single argument. I can see one without arguments and one with several (minimum a TColor and a TRect). See the signatures:

Code: Select all

Function TCustomTeePanel.TeeCreateBitmap:TBitmap;

Code: Select all

Function TCustomTeePanel.TeeCreateBitmap(ABackColor:TColor; Const Rect:TRect;
                                         APixelFormat:{$IFNDEF CLX}Graphics.{$ENDIF}TPixelFormat=
                                         {$IFDEF CLX}TeePixelFormat{$ELSE}pfDevice{$ENDIF};
                                         ADpi:Integer=0):TBitmap;

With the first one you can do as follows:

Code: Select all

procedure TForm1.FormCreate(Sender: TObject);
var tmp: TBitmap;
begin
 Chart1.AddSeries(TLineSeries);
 Chart1[0].FillSampleValues(10);

 tmp:=Chart1.TeeCreateBitmap;
end;

Isn't it what you want?

[davidnovo]

Hello Yeray....

I am talking about the one with several. I was working from memory so messed it up.

if you do

Code: Select all

try
  tmp:=chart1.TeeCreateBitmap(clRed,Rect(0,0,100000,00000))
finally
  tmp.Free
end;

you will not really free the bitmap. That is because TeeCreateBitmap will raise an exception and not return the bitmap it created. There is no way for me as a user to make sure I don't have a memory leak in the event that there is an exception in TeeCreateBitmap.

[Yeray]

Hi David,

I guess you meant 100000 as Bottom parameter, where you wrote 00000.
What about this:

Code: Select all

uses Series, Types;

procedure TForm1.FormCreate(Sender: TObject);
begin
  with Chart1.AddSeries(TPieSeries) do FillSampleValues();
end;

procedure TForm1.Button1Click(Sender: TObject);
var tmp: TBitmap;
    tmpRect: TRect;
begin
  tmp:=nil;
  tmpRect:=Rect(0,0,100000,100000);
//  tmpRect:=Rect(0,0,Chart1.Width,Chart1.Height);

  try
    try
      tmp:=Chart1.TeeCreateBitmap(clRed,tmpRect);
      tmp.SaveToFile('C:\tmp\test.bmp');
    except
      on E : EOutOfResources do
        ShowMessage(E.ClassName+' error raised, with message : '+E.Message);
    end;
  finally
    if tmp <> nil then
      tmp.Free;
  end;
end;

[davidnovo]

Yes I did. But really any size that is too big will do it.

But that is just an example of an easy way to reproduce it. ANY Exception that happens to be raised inside TeeCreateBitmap will do this.

[Yeray]

Hi David,

I've added it to the wish list to be studied for inclusion in future releases (TV52015328).
In the meanwhile you could use the mentioned workaround.

[davidnovo]

Hello,

In your sample code, you check for tmp<>nil then call tmp.Free. The tmp<>nil check is not necessary. You can call .Free on a nil object.

Second, your workaround simply will not work. Just because tmp=nil does not mean the bitmap was not leaked.

our code is even simpler than your worklaround

rect:=some big rectc
tmp:=nil;
try
tmp:=chart1.TeeCreateBitmap(clNone,someBigRect)
finally
tmp.Free
end

and that will still generate a memory leak if there is an Exception in TeeCreateBitmp because a bitmap is created in TeeCreateBitmap and NOT passed back as the result. Since it is not passed back, there is nothing for me to free. There is no workaround that I can do that will result in non memory leak. You have to free the created bitmap in TeeCreateBitmap.

[Yeray]

Hi David,

Excuse me, I haven't understood well what you were trying to explain. I've clarified the explanation of the enhancement request.

I recommend you to be aware at this forum or subscribe to our RSS news feed for new release announcements and what's implemented on them.