Закраска окна градиентном

void __fastcall TForm1::FormPaint(TObject *Sender)
{
        HDC hdc = GetDC(Handle);
        TRIVERTEX vert[2];
        GRADIENT_RECT gRect;
        vert[0].x = 0;
        vert[0].y = 0;
        vert[0].Red = 0xff00;
        vert[0].Green = 0x0000;
        vert[0].Blue = 0x0000;
        vert[0].Alpha = 0x0000;
 
        vert[1].x = Width;
        vert[1].y = Height;
        vert[1].Red = 0x0000;
        vert[1].Green = 0x0000;
        vert[1].Blue = 0xff00;
        vert[1].Alpha = 0x0000;
        gRect.UpperLeft = 0;
        gRect.LowerRight = 1;
        GradientFill(hdc, vert, 2, &gRect, 1, GRADIENT_FILL_RECT_V);
        ReleaseDC(Handle, hdc);
}

float Step; 
TRect BandRect; 
//A panel doesn't have a canvas property. Create one.
TControlCanvas *PanelCanvas=new TControlCanvas; 
PanelCanvas->Control=Panel1; 
 
Step=(float)Panel1->ClientHeight/256;  //256 bandes de couleur 
for(int i=0;i<256;i++) 
{ 
  BandRect.Left=0; 
  BandRect.Top=(int)(i*Step); 
  BandRect.Right=Panel1->ClientWidth+1; 
  BandRect.Bottom=(int)((i+1)*Step);  // bandes horizontales 
  PanelCanvas->Brush->Color=RGB(0,0,255-i); // bandes bleues 
  PanelCanvas->FillRect(BandRect); 
} 
delete PanelCanvas;