Color Graphics Language

All measurements are in pixels from the top left corner of the Canvas.

• the top left pixel has the coordinates 0, 0
• x is the distance to the right
• y is the distance down

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

PaintBox Component
The PaintBox component defines a smaller region within the Window where your application can draw. This is useful for maintaining multiple visualizations on the screen at one time. Use it as you would use Form1->Canvas.

• PaintBox1->Canvas->Ellipse(x1, y1, x2, y2);
• PaintBox1->Canvas->MoveTo(x, y);
• PaintBox1->Canvas->LineTo(x, y);
• PaintBox1->Canvas->Rectangle(x1, y1, x2, y2);
• PaintBox1->Canvas->RoundRect(x1, y1, x2, y2, x3, y3);
  where x3 and y3 represent the diameters of curvature of the rounded corners
• PaintBox1->Canvas->TextOut(x, y, "string");
• PaintBox1->Refresh( );
  clears the canvas without resetting the Brush and Pen values

Putting Pixels

• Canvas->Pixels[x][y] = clBlue;
  where any color constant may be used.
• Canvas->Pixels[x][y] = 0xFF0000;
  where a hexadecimal value is given for the Blue, Green, and Red bytes.
• Canvas->Pixels[x][y] = static_cast<TColor>(RGB(red, green, blue));
  where integer values are given for red, green and blue from 0 to 255.
• Canvas->Pixels[x][y] = static_cast<TColor>(colorRamp(range, value));
  only if the colorRamp function is included and integers are given for the range and value.
  

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

Color Constants
Windows recognizes these color constants, representing the corners of the color cube (top row) plus variants (bottom row).

Properties

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

Methods

• Canvas->Ellipse(x1, y1, x2, y2);
• Canvas->MoveTo(x, y);
• Canvas->LineTo(x, y);
• Canvas->Rectangle(x1, y1, x2, y2);
• 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");
• Refresh( );
  clears the canvas without resetting the Brush and Pen values

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]