DotNet Interop - Platform Bug?

james_cs

I have a very simple piece of DotNet. I am trying to create a rectangle to show on a report. The code works the first two times it is run and then fails with the message

A call to System.Drawing.Graphics.FillRectangle failed with this message: Parameter is not valid.

Variables

Name	DataType	Subtype	Length
LocalImage	DotNet	System.Drawing.Image.'System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'	
LocalImageFormat	DotNet	System.Drawing.Imaging.ImageFormat.'System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'	
Bitmap	DotNet	System.Drawing.Bitmap.'System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'	
Graphics	DotNet	System.Drawing.Graphics.'System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'	
Brushes	DotNet	System.Drawing.Brushes.'System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'	
InStr	InStream		

GlobalTempPicture happens to be a temporary item record (table 27) but could be a TempBLOB


Code

GlobalTempPicture.DELETEALL;

Bitmap := Bitmap.Bitmap(300,50);
LocalImage := Bitmap;
Graphics := Graphics.FromImage(LocalImage);

//This line fails - I don;'t know why
Graphics.FillRectangle(Brushes.Green,0,0,300,50);


GlobalTempPicture.Picture.CREATEINSTREAM(InStr);
LocalImage.Save(InStr,LocalImageFormat.Jpeg);
GlobalTempPicture.INSERT;

it makes no difference if I clear all the variables. I can't see that I am doing anything wrong - is this a bug?

If anyone would like the object then please let me know.

thanks in advance!

James

kaspermoerch

I figured out why we get the error.

A comment in this article led me to the answer.

The reason it fails is because the brush (in this case a system-defined brush) gets disposed after the first run. This means that Brushes.Green now refers to null and null is not an acceptable parameter for FillRectangle.

The following code works:

CLEAR(Item);
Item.DELETEALL;

Bitmap := Bitmap.Bitmap(300,50);
Graphics := Graphics.FromImage(Bitmap);
SolidBrush := SolidBrush.SolidBrush(Color.Green);
Graphics.FillRectangle(SolidBrush,0,0,300,50);

Item.Picture.CREATEINSTREAM(InputStream);
Bitmap.Save(InputStream,ImageFormat.Jpeg);
Item.INSERT;

Variables are the same as you use with these added:

Color DotNet System.Drawing.Color.'System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'	
SolidBrush DotNet System.Drawing.SolidBrush.'System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'

archer89

dou you run clear(<dotnet variable>) at the end of your code ?

oki

I think, you have to create a brush first, assign the color to it and then pass it to your function.
Hope, it helps
Oki

james_cs

I'm sorry to say that neither of these responses take the matter further. As stated - clearing the variables made no difference. Also defining the brush as a separate variable is completely equivalent to passing the Brushes enum through.

Equivalent code works well in C# but this C/SIDE code fails after the first two successful runs. I don't know why.

kaspermoerch

I have been testing your code example and I get the exact same error.

My test do show though that it sometimes crashes on the first pass.

I will keep testing various options to see if I can get something working.

kaspermoerch

I figured out why we get the error.

A comment in this article led me to the answer.

The reason it fails is because the brush (in this case a system-defined brush) gets disposed after the first run. This means that Brushes.Green now refers to null and null is not an acceptable parameter for FillRectangle.

The following code works:

CLEAR(Item);
Item.DELETEALL;

Bitmap := Bitmap.Bitmap(300,50);
Graphics := Graphics.FromImage(Bitmap);
SolidBrush := SolidBrush.SolidBrush(Color.Green);
Graphics.FillRectangle(SolidBrush,0,0,300,50);

Item.Picture.CREATEINSTREAM(InputStream);
Bitmap.Save(InputStream,ImageFormat.Jpeg);
Item.INSERT;

Variables are the same as you use with these added:

Color DotNet System.Drawing.Color.'System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'	
SolidBrush DotNet System.Drawing.SolidBrush.'System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'

mdPartnerNL

good catch

james_cs

That's amazing - I have no idea why it works but it does work. I was under the impression that Brushes was a static and required neither to be created nor disposed. I can confirm that using the SolidBrush does not produce the same error though.

kaspermoerch - I would be interested to understand how you figured out that the Brushes was being disposed but that is probably a different discussion!

Many thanks for spending your time looking at this.