Graphics Commands

Color Graphics Language

Color Theoryxxxxxxx
Understanding Color Spaces

Color is represented by three variables, with values from 0 to 255:
red, green, blue.

The gamut of color is often displayed as a color cube with three dimensions:
red, green, blue.

The 8 corners of the color cube are shown in the rightmost column ->

RED value	GREEN value	BLUE value	Result	Notation	BGRX hex code
255	255	255	WHITE	W	0xFFFFFF
255	0	0	RED	Additive Primaries: RGB	0x0000FF
0	255	0	GREEN		0x00FF00
0	0	255	BLUE		0xFF0000
0	255	255	CYAN	SubtractiveX Primaries: CMY	0xFFFF00
255	0	255	MAGENTA		0xFF00FF
255	255	0	YELLOW		0x00FFFF
0	0	0	BLACK	K	0x000000

Color Constants
Windows recognizes these color constants, representing the corners of the color cube (top row), plus darker variants (bottom row).
Windows also recognizes other colors (see the color combo-box in the properties tab of most visual components).

clRed additive primary RED	clLime additive primary GREEN	clBlue additive primary BLUE	clAqua subtractive primary CYAN	clFuchsia subtractive primary MAGENTA	clYellow subtractive primary YELLOW	clBlack BLACK	clWhite WHITE
clMaroon	clGreen	clNavy	clTeal	clPurple	clOlive	clGray	clSilver

All coordinates on your display are measured in pixels from the top left corner of the component.

the top left pixel has the coordinates 0, 0
x is the distance to the right or east
y is the distance down or south

Form Component
The Form component is the entire Window of your application. You can draw anywhere on a Window using Form1->Canvas.

PaintBox Component
The PaintBox component defines a smaller region within the Window on which your application can draw.
All measurements are relative to the top left corner of the PaintBox.
A PaintBox is useful for maintaining multiple visualizations on the screen at one time. Use it as you would use Form1->Canvas.

Canvas Shape Methods

Canvas->Ellipse(x1, y1, x2, y2);
where x1 and y1 represent the top left corner of the object, and x2 and y2 the bottom right
Canvas->MoveTo(x, y);
moves the cursor to x and y in order to begin a LineTo() command
Canvas->LineTo(x, y);
draws a line to x and y
Canvas->Rectangle(x1, y1, x2, y2);
where x1 and y1 represent the top left corner of the shape and x2 and y2 the bottom right
Canvas->RoundRect(x1, y1, x2, y2, x3, y3);
where x3 and y3 represent the diameters of curvature of the rounded corners
Canvas->TextOut(x, y, "string");
writes the specified string beginning at position x and y
Refresh( );
clears the canvas without resetting the Brush and Pen values

Canvas Polygons and Polylines

TPoint points[6];
creates an array of six TPoint objects with elements numbered from 0 to 5
points[0].x = 40; points[0].y = 10;
points[1].x = 20; points[1].y = 60;
points[2].x = 70; points[2].y = 30;
points[3].x = 10; points[3].y = 30;
points[4].x = 60; points[4].y = 60;
points[5].x = 40; points[5].y = 10;
fills the array with x and y values
Canvas->Polyline(points,5);
draws a line with the current Pen color beginning with points element [0] and ending with points element [5]
Canvas->Polygon(points, 5);
draws a line with the current Pen color and fills it with the current Brush color beginning with points element [0] and ending with points element [5]

Canvas Puting Pixels

Canvas->Pixels[x][y] = clBlue;
puts a blue pixel at coordinate x and y.
any color constant designated by the prefix letters (not numerals) "cl" may be used.
Canvas->Pixels[x][y] = 0xFF0000;
puts a pixel at coordinate x and y given by the hexadecimal byte values of its Blue, Green, and Red coordinates in the color cube.
Canvas->Pixels[x][y] = static_cast<TColor>(RGB(red, green, blue));
puts a pixel at coordinate x and y given by the decimal (0-255) byte values of its Blue, Green, and Red coordinates in the color cube.
Canvas->Pixels[x][y] = static_cast<TColor>(colorRamp(range, value));
puts a pixel at coordinate x and y given by the a numerical value along a range of numerical values (see colorRamp()).

Getting Pixels

int color, red, green, blue;
declares variables to receive colors
color = Form1->Canvas->Pixels[X][Y];
retrieves the RGB color triplet
red = GetRValue(color);
retrieves the Red color component
green = GetGValue(color);
retrieves the Green color component
blue = GetBValue(color);
retrieves the Blue color component

Properties

Canvas->Pen->Color = clBlack;
where Pen is the outline color. Black is the default
Canvas->Pen->Style = psSolid;
where Style can be psSolid, psClear, psDash, psDot, psDashDot or psDashDotDot. Solid is the default
Canvas->Pen->Width = 1;
if Width is greater than one, then Style may revert to psSolid. One is the default
Canvas->Brush->Color = clWhite;
where Brush is the fill color. White is the default
Canvas->Brush->Style = bsSolid;
where Style can be bsSolid, bsClear, bsHorizontal, bsVertical, bsFDiagonal, bsBDiagonal, bsCross or bsDiagonalCross. Solid is the default