BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  TImage repaint() issue in C++ Builder 6.0          BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) View previous topic :: View next topic   Author Message Chad Guest Posted: Wed May 25, 2005 4:07 am    Post subject: TImage repaint() issue in C++ Builder 6.0 I just finished upgrading from C++ Builder 3 to C++ Builder 6. One of the programs I wrote under Builder 3 performs a simple image editing task. The changes are applied to the TBitmap held by a TImage component, and the repaint() function of the TImage component is then called. The image is rather large (around 1500x1500). When compiled under Bulder 3 the operation occurs quickly and smoothly. Under Builder 6 repaint() ocurrs slowly enough that I can see the repaint occur. Since repaint is called everytime the bitmap is updated, the result is a flickering appearance to the bitmap whenever the user edits it. How can I update the bitmap and refresh the TImage component (so the udates are actually displayed) without having an annoying flicker effect? Thanks Chad Back to top Mark Jacobs Guest Posted: Wed May 25, 2005 11:39 am    Post subject: Re: TImage repaint() issue in C++ Builder 6.0 Chad wrote: Quote: I just finished upgrading from C++ Builder 3 to C++ Builder 6. One of the programs I wrote under Builder 3 performs a simple image editing task. The changes are applied to the TBitmap held by a TImage component, and the repaint() function of the TImage component is then called. The image is rather large (around 1500x1500). When compiled under Bulder 3 the operation occurs quickly and smoothly. Under Builder 6 repaint() ocurrs slowly enough that I can see the repaint occur. Since repaint is called everytime the bitmap is updated, the result is a flickering appearance to the bitmap whenever the user edits it. How can I update the bitmap and refresh the TImage component (so the udates are actually displayed) without having an annoying flicker effect? Thanks I use the following on my image zoomer, and it is very smooth :- Image1->Canvas->CopyRect(Rect(0,0,Image1->Width,Image1->Height),mjbitmp->Canvas, Rect(xd/fac,yd/fac,xu/fac,yu/fac)); Image1->Repaint(); Also, try putting DoubleBuffered=true; in your main form's constructor. I use BCB5. -- Mark Jacobs http://www.dkcomputing.co.uk Back to top Chad Guest Posted: Thu May 26, 2005 10:33 pm    Post subject: Re: TImage repaint() issue in C++ Builder 6.0 Thanks. The DoubleBuffered property was the key. Apparently the program was trying to first repaint the underlying control before repainting the TImage object. This fixed the problem Just a quick note about DoubleBuffered for anyone else with the same question. The DoubleBuffered property is part of the TWinControl object. TImage does not decend from this object and does not have this property. DoubleBuffered should be set to true for the PARENT of the TImage object. If the TImage lies directly on the form, than set the form's DoubleBuffered property to true. If the TImage lies on a TPanel (as in my case) setting the TForm's DoubleBuffered property won't work. You must set the TPanel's DoubleBuffered property to true to eliminate flicker. Again, Thanks. Chad Back to top Mark Jacobs Guest Posted: Fri May 27, 2005 11:36 am    Post subject: Re: TImage repaint() issue in C++ Builder 6.0 Chad wrote: Quote: Thanks. The DoubleBuffered property was the key. Apparently the program was trying to first repaint the underlying control before repainting the TImage object. This fixed the problem Just a quick note about DoubleBuffered for anyone else with the same question. The DoubleBuffered property is part of the TWinControl object. TImage does not decend from this object and does not have this property. DoubleBuffered should be set to true for the PARENT of the TImage object. If the TImage lies directly on the form, than set the form's DoubleBuffered property to true. If the TImage lies on a TPanel (as in my case) setting the TForm's DoubleBuffered property won't work. You must set the TPanel's DoubleBuffered property to true to eliminate flicker. You're welcome. Thanks for the invaluable feedback about using the parent control. 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