Graphics Shapes and Primitives

The following subprograms provide the ability to draw shapes, lines, and other graphics primitives.

One concept to understand in this section is the existence of a “current position” of the graphics cursor on the screen. A handful of routines will use this in-memory screen coordinate for drawing. The moveto subroutine can be used to set the position directly. The graphics cursor, however, is never visible on the screen.

arc

C void arc (x, y, stangle, endangle, radius)
Fortran subroutine arc (x, y, stangle, endangle, radius)

Description

Draws a circular arc centered at (x,y) in the current color. The start angle, stangle, and end angle, endangle, are measured in degrees counterclockwise with 0 degrees at 3 o’clock.

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal center of the arc
y	int	integer	Vertical center of the arc
stangle	int	integer	Start angle of the arc in degrees
endangle	int	integer	End angle of the arc in degrees
radius	int	integer	Radius of the circular arc

bar

C void bar (left, top, right, bottom)
Fortran subroutine bar (left, top, right, bottom)

Description

Draws a rectangular, filled bar using the currently selected color and fill pattern.

Parameters

Parameter	C Type	Fortran Type	Description
left	int	integer	Leftmost horizontal bound of the bar
top	int	integer	Topmost vertical bound of the bar
right	int	integer	Righttmost horizontal bound of the bar
bottom	int	integer	Bottommost vertical bound of the bar

bar3d

C void bar3d (left, top, right, bottom, depth, topflag)
Fortran subroutine bar3d (left, top, right, bottom, depth, topflag)

Description

Draws a three-dimensional rectangular, filled bar using the currently selected color and fill pattern. The bar is outlined using the current line color and style.

Parameters

Parameter	C Type	Fortran Type	Description
left	int	integer	Leftmost horizontal bound of the bar
top	int	integer	Topmost vertical bound of the bar
right	int	integer	Righttmost horizontal bound of the bar
bottom	int	integer	Bottommost vertical bound of the bar
depth	int	integer	The third-dimension depth of the bar
topflag	int	integer	One to draw a top on the bar, zero to leave empty

bezier

C void bezier (x1, y1, x2, y2, cx1, cy1, cx2, cy2)
Fortran subroutine bezier (x1, y1, x2, y2, cx1, cy1, cx2, cy2)

Description

Draws a single Bezier segment using the end points specified and two control points to form the curve.

Parameters

Parameter	C Type	Fortran Type	Description
x1	int	integer	X coordinate of the curve’s starting point
y1	int	integer	Y coordinate of the curve’s starting point
x2	int	integer	X coordinate of the curve’s end point
y2	int	integer	Y coordinate of the curve’s end point
cx1	int	integer	X coordinate of the curve’s first control point
cy1	int	integer	Y coordinate of the curve’s first control point
cx2	int	integer	X coordinate of the curve’s second control point
cy2	int	integer	Y coordinate of the curve’s second control point

circle

C void circle (x, y, radius)
Fortran subroutine circle (x, y, radius)

Description

Draws a circle centered at (x,y) with the given radius using the current color

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal center of the circle
y	int	integer	Vertical center of the circle
radius	int	integer	Radius of the circle

drawpoly

C void drawpoly (numpoints, points)
Fortran subroutine drawpoly (numpoints, points)

Description

Draws a polygon of numpoints points using the locations in points. In Fortran, the horizontal positions in the first column, and the vertical position in the second column. In C, the array is one-dimensional with the first horizontal position followed by the first vertical position followed by the second horizontal position, etc.

Parameters

Parameter	C Type	Fortran Type	Description
numpoints	int	integer	The number of points in the polygon
points	int *	integer, dimension(numpoints, 2)	Points of the polygon (see description)

ellipse

C void ellipse (x, y, stangle, endangle, xradius, yradius)
Fortran subroutine ellipse (x, y, stangle, endangle, xradius, yradius)

Description

Draws an ellipse centered at (x,y) with the given radius using the current color. The start angle, stangle, and end angle, endangle, are measured in degrees counterclockwise with 0 degrees at 3 o’clock.

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal center of the ellipse
y	int	integer	Vertical center of the ellipse
stangle	int	integer	Start angle of the arc in degrees
endangle	int	integer	End angle of the arc in degrees
xradius	int	integer	Radius along the horizontal axis
yradius	int	integer	Radius along the vertical axis

fillellipse

C void fillellipse (x, y, xradius, yradius)
Fortran subroutine fillellipse (x, y, xradius, yradius)

Description

Draws a filled ellipse centered at (x,y) with the given radius using the current color.

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal center of the ellipse
y	int	integer	Vertical center of the ellipse
xradius	int	integer	Radius along the horizontal axis
yradius	int	integer	Radius along the vertical axis

fillpoly

C void fillpoly (numpoints, points)
Fortran subroutine fillpoly (numpoints, points)

Description

Draws a filled polygon of numpoints points using the locations in points. In Fortran, the horizontal positions in the first column, and the vertical position in the second column. In C, the array is one-dimensional with the first horizontal position followed by the first vertical position followed by the second horizontal position, etc.

Parameters

Parameter	C Type	Fortran Type	Description
numpoints	int	integer	The number of points in the polygon
points	int *	integer, dimension(numpoints, 2)	Points of the polygon (see description)

floodfill

C void floodfill (x, y, border)
Fortran subroutine floodfill (x, y, border)

Description

Fills in the screen starting at point (x,y) until the color border is encountered.

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal point at which to start flood fill operation
y	int	integer	Vertical point at which to start flood fill operation
border	int	integer	Color at which flood fill is stopped

getarccoords

C void getarccoords ( arccoords )
Fortran subroutine getarccoords ( arccoords )

Description

Retrieves the arc coordinates used for the latest arc drawing request.

Parameters

Parameter	C Type	Fortran Type	Description
arccoords	arccoordstype *	type(arccoordstype), intent(out)	Pointer to the structure to fill with the arc details

getdpi

C int getdpi ( )
Fortran function getdpi ( )

Description

Retrieves the current system logical pixels per inch (measured in the vertical axis). Note that the application should call setapplicationdpiaware() if the application wishes to perform true dots-per-inch calculations. Otherwise, the operating system will shield the application from retrieving the true dots-per-inch.

Return Value

C int
Fortran integer

The logical pixels per inch in the vertical direction. This measurement should be identical to the horizontal direction in most cases.

getpixel

C int getpixel ( x, y )
Fortran function getpixel ( x, y )

Description

Retrieves the color as an RGB triplet at the pixel at the specified coordinates

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal point at which to query the pixel color
y	int	integer	Vertical point at which to query the pixel color

Return Value

C int
Fortran integer

The color of the pixel as an RGB triplet

getx

C int getx ( )
Fortran function getx ( )

Description

Retrieves the current horizontal graphics cursor position

Return Value

C int
Fortran integer

The horizontal position of the graphics cursor

gety

C int gety ( )
Fortran function gety ( )

Description

Retrieves the current vertical graphics cursor position

Return Value

C int
Fortran integer

The vertical position of the graphics cursor

line

C void line (x1, y1, x2, y2)
Fortran subroutine line (x1, y1, x2, y2)

Description

Draws a line using the current color from point (x1,y1) to point (x2,y2).

Parameters

Parameter	C Type	Fortran Type	Description
x1	int	integer	Horizontal coordinate of the start point of the line
y1	int	integer	Vertical coordinate of the start point of the line
x2	int	integer	Horizontal coordinate of the end point of the line
y2	int	integer	Vertical coordinate of the end point of the line

linerel

C void linerel (dx, dy)
Fortran subroutine linerel (dx, dy)

Description

Draws a line from the current position to a point that is distanced dx horizontally and dy vertically from the current position using the current color. The current position is moved to this new offset after the drawing operation.

Parameters

Parameter	C Type	Fortran Type	Description
dx	int	integer	Horizontal offset of the end point of the line
dy	int	integer	Vertical offset of the end point of the line

lineto

C void lineto (x, y)
Fortran subroutine lineto (x, y)

Description

Draws a line from the current position to the point (x, y) using the current color. The current position is moved to this new offset after the drawing operation.

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal coordinate of the end point of the line
y	int	integer	Vertical coordinate of the end point of the line

moverel

C void moverel ( int dx, int dy )
Fortran subroutine moverel ( int dx, int dy )

Description

Moves the graphics cursor a specifed distance in the horizontal and vertical positions from the current position.

Parameters

Parameter	C Type	Fortran Type	Description
dx	int	integer	Horizontal distance relative to the current position
dy	int	integer	Vertical distance relative to the current position

moveto

C void moveto (x, y)
Fortran subroutine moveto (x, y)

Description

Sets the current position to be used with subsequent relative graphics operations.

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal coordinate of the current position
y	int	integer	Vertical coordinate of the current position

pieslice

C void pieslice (x, y, stangle, endangle, radius)
Fortran subroutine pieslice (x, y, stangle, endangle, radius)

Description

Draws a filled circular arc centered at (x,y) in the current color, appearing in the shape of a pie slice. The start angle, stangle, and end angle, endangle, are measured in degrees counterclockwise with 0 degrees at 3 o’clock.

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal center of the arc
y	int	integer	Vertical center of the arc
stangle	int	integer	Start angle of the arc in degrees
endangle	int	integer	End angle of the arc in degrees
radius	int	integer	Radius of the circular arc

putpixel

C void putpixel (x, y, color)
Fortran subroutine putpixel (x, y, color)

Description

Draws a single pixel at (x, y) using the color color.

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal coordinate of the pixel
y	int	integer	Vertical coordinate of the pixel
color	int	integer	The color of the pixel

rectangle

C void rectangle (left, top, right, bottom)
Fortran subroutine rectangle (left, top, right, bottom)

Description

Draws an unfilled rectangle with vertices located at (left, top) and (right, bottom)

Parameters

Parameter	C Type	Fortran Type	Description
left	int	integer	Leftmost horizontal bound of the rectangle
top	int	integer	Topmost vertical bound of the rectangle
right	int	integer	Righttmost horizontal bound of the rectangle
bottom	int	integer	Bottommost vertical bound of the rectangle

scaledpi

C int getdpi ( int x )
Fortran function getdpi ( x )

Description

Scales the argument to the current screen dots-per-inch based on the reference value of 96. Note that the application should call setapplicationdpiaware() if the application wishes to perform true dots-per-inch calculations. Otherwise, the operating system will shield the application from retrieving the true dots-per-inch.

Parameter	C Type	Fortran Type	Description
x	int	integer	Value to scale to true dots per inch

Return Value

C int
Fortran integer

The scaled value.

sector

C void sector (x, y, stangle, endangle, xradius, yradius)
Fortran subroutine sector (x, y, stangle, endangle, xradius, yradius)

Description

Draws a filled elliptical shape, similar to a pie slice, centered at (x,y) with the given radius using the current color. The start angle, stangle, and end angle, endangle, are measured in degrees counterclockwise with 0 degrees at 3 o’clock.

Parameters

Parameter	C Type	Fortran Type	Description
x	int	integer	Horizontal center of the sector
y	int	integer	Vertical center of the sector
stangle	int	integer	Start angle of the arc in degrees
endangle	int	integer	End angle of the arc in degrees
xradius	int	integer	Radius along the horizontal axis
yradius	int	integer	Radius along the vertical axis