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Date Posted: 05:13:10 03/06/02 Wed
Author: Erik
Subject: Re: C++ Problem with Crop
In reply to: Michel 's message, "Re: C++ Problem with Crop" on 10:53:14 03/05/02 Tue

Hi Michel,

thank you very much for the fast reply.
First of all the code is not properly displayed in the
forum think the "> < " is seen as html tags and cut out of the posting.
Second ;)
Your "better approach" is exactly what I need ;)
But somehow it doesnt work ;(

TDibGraphic* Graphic = dynamic_cast..........

is always null (Image->Picture->Graphic has a value)

if I say
TDibGraphic* Graphic = (TDibGraphic*)(Image->Picture->Graphic);

Graphic has a value but Apply causes a Memory Violation.

Thanks

Erik



>
>Hi Erik,
>
>There is a few things I would look at here:
>
>Before trying to obtain the TDibGraphic from
>TImage->Picture->Graphic make sure the graphic
>contained is really a TDibGraphic. For example, it may
>be a TBitmap loaded. To check this, save the return
>value of
>TImage->Picture->Graphic.ClassName() to a variable and
>view it in the debugger. If it is not a class derived
>from TDibGraphic, make use you do "Add to Project" the
>EnReg.Pas unit to register the Envision formats. Also
>check the Envision.Inc file to enable the Envision
>bitmap support if desired.
>
>In,
>
>TDibGraphic *Gr =new TDibGraphic();
>Image1->Picture->Graphic->SaveToStream(strm);
>Gr->NewImage(320,280,ifTrueColor,0,0,0);
>Gr->LoadFromStream(strm);
>
>You should create the appropriate TDibGraphic derived
>class, not the base TDibGraphic class, which does not
>implement LoadFromStream. Also, the NewImage call is
>not necessary because LoadFromStream will take care of
>setting the size.
>
>For example,
>
>Gr = new TBitmapGraphic();
>
>for a BMP file.
>
>Here is a better approach to crop the contents of a
>TImage->Picture->Graphic:
>
>void __fastcall TForm1::CropBtnClick(TObject *Sender)
>{
> TDibGraphic* Graphic =
>dynamic_cast<TDibGraphic*>(Image->Picture->Graphic);
>
> if (Graphic!=NULL)
> {
> // Graphic is a TDibGraphic
> TCropTransform* Transform = new
>TCropTransform;
> try
> {
> Transform->Left = 20;
> Transform->Right = 20;
> Transform->Top = 20;
> Transform->Bottom = 20;
>
>Transform->Apply((TDibGraphic*)Image->Picture->Graphic)
>;
>
> Image->Invalidate();
> }
> __finally
> {
> delete Transform;
> }
> }
>}
>
>Best regards,
>
>Michel
>
>
>
>
>
>
>
>>Hello I have a TImage and i want to
>>crop it.
>>I tried to do it similar like the sourcecode
>>of the delphi example.
>>I got several Memory errors when I tried to
>>map the TImage->Picture->Graphics to TDibGraphic.
>>I didnt find a solution for that so I tried to
>>solve the whole think using stream.
>>This worked fine except that the
>>TDibGraphic->Height and ->Width were zero
>>therefore the crop didnt work.
>>
>>You would do me great favour if you could send
>>me a small C++ sniplet how to use it correctly.
>>
>>Thanks
>>
>>Erik
>>
>>
>>
>> Image1->Picture->LoadFromFile(FileName);
>>
>> TMemoryStream *strm=new TMemoryStream();
>> TCropTransform *Transform = new TCropTransform();
>> TDibGraphic *Gr =new TDibGraphic();
>> Image1->Picture->Graphic->SaveToStream(strm);
>> Gr->NewImage(320,280,ifTrueColor,0,0,0);
>> Gr->LoadFromStream(strm);
>>
>> Transform->Left =75;
>> Transform->Right =75;
>> Transform->Top =25;
>> Transform->Bottom =25;
>> Transform->ApplyOnDest(Gr,Gr);
>> Gr->SaveToStream(strm);
>>
>Image1->Picture->Graphic->LoadFromStream(strm);
>> delete Transform;
>> delete Gr;
>> delete strm;

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