void __fastcall TForm1::Button1Click(TObject *Sender)
{
float Step;
TRect BandRect; //Panel hat kein Canvas
TControlCanvas *PanelCanvas = new TControlCanvas;
PanelCanvas->Control=Panel1;
Step=(float)Panel1->ClientHeight / 256; //256 Farbbänder
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); // horizontale Bänder
PanelCanvas->Brush->Color = RGB(0, 0, 255-i); // blauer Gradient
PanelCanvas->FillRect(BandRect);
}
delete PanelCanvas;
}