Color gradient with different colors and different directions
This tutorial create color gradient with given color range with selected direction.
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Color gradient with different colors and different directions
The RGB macro selects a red, green, blue (RGB) color based on the arguments supplied and the color capabilities of the output device. The intensity for each argument is in the range 0 through 255. If all three intensities are zero, the result is black. If all three intensities are 255, the result is white.
The GetRValue macro retrieves an intensity value for the Red, Green, Blue component of a 32-bit red, green, blue (RGB) value. By calling ColorToRGB to obtain an RGB representation of a color for using with Windows API calls.
Color gradient with different colors and directions.
This is the main procedure doing entire color gradient according to selected colors and direction.
procedure TForm1.Update(Sender: TObject);
Var
Xo, Yo, Max, RC, GC, BC, R, H, W : Integer;
Angle, Radius, XStep, YStep, RStep, GStep, BStep : Real;
Red, Green, Blue, Red1, Green1, Blue1,
Red2, Green2, Blue2 : Integer;
begin
{ Get form size }
H:=Image1.Height;
W:=Image1.Width;
{ Set pen width }
Image1.Canvas.Pen.Width:=1;
{ Set Max count }
Case ComboBox1.ItemIndex Of
0:Max:=H;
1:Max:=W;
2:Begin
Max:=Round(Sqrt((W+1)*(W+1)+(H+1)*(H+1)))+110;
Image1.Canvas.Pen.Width:=2;
{ Set diagonal step size }
If H>W Then
Begin
XStep:=1.0;
YStep:=2*H/Max;
End Else
Begin
YStep:=1.0;
XStep:=2*W/Max;
End;
End;
3:Begin
Max:=360*4;
Image1.Canvas.Pen.Width:=2;
{ Set circle coodinates }
Xo:=W Div 2;
Yo:=H Div 2;
Radius:=Round(Sqrt(Xo*Xo+Yo*Yo));
End;
End;
{ The GetRValue macro retrieves an intensity value for
the Red component of a 32-bit red, green, blue (RGB) value. }
Red1:=GetRValue(Shape1.Brush.Color);
{ The GetRValue macro retrieves an intensity value for
the Green component of a 32-bit red, green, blue (RGB) value. }
Green1:=GetGValue(Shape1.Brush.Color);
{ The GetRValue macro retrieves an intensity value for
the Blue component of a 32-bit red, green, blue (RGB) value. }
Blue1:=GetBValue(Shape1.Brush.Color);
Red2:=GetRValue(Shape2.Brush.Color);
Green2:=GetGValue(Shape2.Brush.Color);
Blue2:=GetBValue(Shape2.Brush.Color);
RStep:=(Red1-Red2)/Max;
GStep:=(Green1-Green2)/Max;
BStep:=(Blue1-Blue2)/Max;
{ Select starting color }
{ Call ColorToRGB to obtain an RGB representation
of a color for using with Windows API calls. }
If ColorToRGB(Shape1.Brush.Color)>ColorToRGB(Shape2.Brush.Color) Then
Begin
Red:=Red1;
Green:=Green1;
Blue:=Blue1;
End Else
Begin
Red:=Red2;
Green:=Green2;
Blue:=Blue2;
End;
{ Set starting color }
RC:=Red;
GC:=Green;
BC:=Blue;
Angle:=0;
For R:=0 To Max Do
Begin
{ set fill color }
{ The RGB macro selects a red, green, blue (RGB) color
based on the arguments supplied and the color capabilities
of the output device.
The intensity for each argument is in the range 0 through 255.
If all three intensities are zero, the result is black.
If all three intensities are 255, the result is white.}
Image1.Canvas.Pen.Color:=RGB(RC,GC,BC);
{ Fill area by drawing lines }
Case ComboBox1.ItemIndex Of
0:Begin
Image1.Canvas.MoveTo(0,R);
Image1.Canvas.LineTo(W,R);
End;
1:Begin
Image1.Canvas.MoveTo(R,0);
Image1.Canvas.LineTo(R,H);
End;
2:Begin
Image1.Canvas.MoveTo(0,Round(R*YStep));
Image1.Canvas.LineTo(Round(R*XStep),0);
End;
3:Begin
Image1.Canvas.MoveTo(Xo,Yo);
Image1.Canvas.LineTo(Xo+Round(Radius*Sin(Angle*(Pi/180))), Yo-Round(Radius*Cos(Angle*(Pi/180))));
End;
End;
{ Change fill color for each color }
RC:=Round(Red+R*RStep);
GC:=Round(Green+R*GStep);
BC:=Round(Blue+R*BStep);
{ Increase angle }
Angle:=Angle+0.25;
End;
End;
Use this one to select color by clicking on shape. And also this will call Update procedure and update color gradient.
procedure TForm1.Shape1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
ColorDialog1.Color:=Shape1.Brush.Color;
If ColorDialog1.Execute Then
Begin
Shape1.Brush.Color:=ColorDialog1.Color;
Update(Self);
End;
end;
procedure TForm1.Shape2MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
ColorDialog1.Color:=Shape2.Brush.Color;
If ColorDialog1.Execute Then
Begin
Shape2.Brush.Color:=ColorDialog1.Color;
Update(Self);
End;
end;
Use this one to update color gradient if user changes direction.
procedure TForm1.ComboBox1Change(Sender: TObject);
begin
Update(Self);
end;
Download This Delphi Tutorials.
Download materials for this article (Delphi - Tutorials)
Color-Gradient-Different-Colors-Directions.zip
File size: 6 KB, File type: zip
Total downloads: 199, Upload date: March 25 - 2009
m stephens :: March 25-2009 :: 11:09 AM
The download link downloads an image and not the source code. Would you please fix this.
Thanks.
Administrator :: March 25-2009 :: 03:37 PM
Hi Stephens, Thanks for bringing this to our attention, we upload the correct source code for download materials.