How to Clear a Bitmap in VCL












0















How to clear a bitmap that was declared in the .cpp as follows:



Graphics::TBitmap * Bitmap1 = new Graphics::TBitmap;


All the examples I find are for Firemonkey and there it seems quite simple



MyBitmap = new TBitmap(0,0);

...





MyBitmap->Clear(claWhite);


or



MyBitmap->ClearRect(MyRect);


But Clear() and ClearRect() are not members of TBitmap in VCL



I expect I should delete Bitmap1; in order to clear it, but then how to re-declare it, so that it is still global to all methods in the form?



Thanks in advance.






c++builder vcl rad-studio







share|improve this question



























    0















    How to clear a bitmap that was declared in the .cpp as follows:



    Graphics::TBitmap * Bitmap1 = new Graphics::TBitmap;


    All the examples I find are for Firemonkey and there it seems quite simple



    MyBitmap = new TBitmap(0,0);
    
...
    

    

    
MyBitmap->Clear(claWhite);


    or



    MyBitmap->ClearRect(MyRect);


    But Clear() and ClearRect() are not members of TBitmap in VCL



    I expect I should delete Bitmap1; in order to clear it, but then how to re-declare it, so that it is still global to all methods in the form?



    Thanks in advance.






    c++builder vcl rad-studio







    share|improve this question

























      0












      0








      0








      How to clear a bitmap that was declared in the .cpp as follows:



      Graphics::TBitmap * Bitmap1 = new Graphics::TBitmap;


      All the examples I find are for Firemonkey and there it seems quite simple



      MyBitmap = new TBitmap(0,0);
      
...
      

      

      
MyBitmap->Clear(claWhite);


      or



      MyBitmap->ClearRect(MyRect);


      But Clear() and ClearRect() are not members of TBitmap in VCL



      I expect I should delete Bitmap1; in order to clear it, but then how to re-declare it, so that it is still global to all methods in the form?



      Thanks in advance.






      c++builder vcl rad-studio







      share|improve this question














      How to clear a bitmap that was declared in the .cpp as follows:



      Graphics::TBitmap * Bitmap1 = new Graphics::TBitmap;


      All the examples I find are for Firemonkey and there it seems quite simple



      MyBitmap = new TBitmap(0,0);
      
...
      

      

      
MyBitmap->Clear(claWhite);


      or



      MyBitmap->ClearRect(MyRect);


      But Clear() and ClearRect() are not members of TBitmap in VCL



      I expect I should delete Bitmap1; in order to clear it, but then how to re-declare it, so that it is still global to all methods in the form?



      Thanks in advance.






      c++builder vcl rad-studio




      c++builder vcl rad-studio






      share|improve this question













      share|improve this question











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      asked Nov 13 '18 at 14:10









      BarryKBarryK

      94




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          You don't need to delete and recreate the TBitmap. Simply draw a new image over top of it, for instance by using its Canvas->FillRect() method (that is essentially what the FMX examples are doing), eg:



          Bitmap1->Brush->Color = clWhite;
          
Bitmap1->Canvas->FillRect(Rect(0, 0, Bitmap1->Width, Bitmap1->Height));





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            You don't need to delete and recreate the TBitmap. Simply draw a new image over top of it, for instance by using its Canvas->FillRect() method (that is essentially what the FMX examples are doing), eg:



            Bitmap1->Brush->Color = clWhite;
            
Bitmap1->Canvas->FillRect(Rect(0, 0, Bitmap1->Width, Bitmap1->Height));





            share|improve this answer




























              1














              You don't need to delete and recreate the TBitmap. Simply draw a new image over top of it, for instance by using its Canvas->FillRect() method (that is essentially what the FMX examples are doing), eg:



              Bitmap1->Brush->Color = clWhite;
              
Bitmap1->Canvas->FillRect(Rect(0, 0, Bitmap1->Width, Bitmap1->Height));





              share|improve this answer


























                1












                1








                1







                You don't need to delete and recreate the TBitmap. Simply draw a new image over top of it, for instance by using its Canvas->FillRect() method (that is essentially what the FMX examples are doing), eg:



                Bitmap1->Brush->Color = clWhite;
                
Bitmap1->Canvas->FillRect(Rect(0, 0, Bitmap1->Width, Bitmap1->Height));





                share|improve this answer













                You don't need to delete and recreate the TBitmap. Simply draw a new image over top of it, for instance by using its Canvas->FillRect() method (that is essentially what the FMX examples are doing), eg:



                Bitmap1->Brush->Color = clWhite;
                
Bitmap1->Canvas->FillRect(Rect(0, 0, Bitmap1->Width, Bitmap1->Height));






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 13 '18 at 20:16









                Remy LebeauRemy Lebeau

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                334k18254450






























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