Draw a gradient fill on a form

Author: Doctor Nam

implementation

{$R *.DFM}

procedure FillGradientRect(Canvas: TCanvas; Recty: TRect; fbcolor, fecolor: TColor; fcolors: Integer);

var

i, j, h, w, fcolor: Integer;

R, G, B: Longword;

beginRGBvalue, RGBdifference: array[0..2] of Longword;

begin

beginRGBvalue[0] := GetRvalue(colortoRGB(FBcolor));

beginRGBvalue[1] := GetGvalue(colortoRGB(FBcolor));

beginRGBvalue[2] := GetBvalue(colortoRGB(FBcolor));

RGBdifference[0] := GetRvalue(colortoRGB(FEcolor)) - beginRGBvalue[0];

RGBdifference[1] := GetGvalue(colortoRGB(FEcolor)) - beginRGBvalue[1];

RGBdifference[2] := GetBvalue(colortoRGB(FEcolor)) - beginRGBvalue[2];

Canvas.pen.Style := pssolid;

Canvas.pen.mode := pmcopy;

j := 0;

h := recty.Bottom - recty.Top;

w := recty.Right - recty.Left;

for i := fcolors downto 0 do

begin

recty.Left := muldiv(i - 1, w, fcolors);

recty.Right := muldiv(i, w, fcolors);

if fcolors1 then

begin

R := beginRGBvalue[0] + muldiv(j, RGBDifference[0], fcolors);

G := beginRGBvalue[1] + muldiv(j, RGBDifference[1], fcolors);

B := beginRGBvalue[2] + muldiv(j, RGBDifference[2], fcolors);

end;

Canvas.Brush.Color := RGB(R, G, B);

patBlt(Canvas.Handle, recty.Left, recty.Top, Recty.Right - recty.Left, h, patcopy);

Inc(j);

end;

end;

//case 1

procedure TForm1.FormPaint(Sender: TObject);

begin

FillGradientRect(Form1.Canvas, rect(0, 0, Width, Height), $FF0000, $00000, $00FF);

end;

//case 2

procedure TForm1.FormPaint(Sender: TObject);

var

Row, Ht: Word;

IX: Integer;

begin

iX := 200;

Ht := (ClientHeight + 512) div 256;

for Row := 0 to 512 do

begin

with Canvas do

begin

Brush.Color := RGB(Ix, 0, row);

FillRect(Rect(0, Row * Ht, ClientWidth, (Row + 1) * Ht));

IX := (IX - 1);

end;

end;

end;

{

Note, that the OnResize event should also call the FormPaint

method if this form is allowed to be resizable.

This is because if it is not called then when the

window is resized the gradient will not match the rest of the form.

}

stopniowa zmiana koloru okienka...