CS 106B Libraries: extgraph.h File Reference

#define Bold 1

#define Italic 2

#define Normal 0

The constants Bold and Italic are used in the SetStyle command to specify the desired text style. They may also be used in combination by adding these constants together, as in Bold + Italic. The constant Normal indicates the default style.

void DefineColor	(	string	name,
		double	red,
		double	green,
		double	blue
	)

This function allows the client to define a new color name by supplying intensity levels for the colors red, green, and blue, which are the primary colors of light. The color values are provided as real numbers between 0 and 1, indicating the intensity of that color. For example, the predefined color Magenta has full intensity red and blue but no green and is therefore defined as:

DefineColor("Magenta", 1, 0, 1);

DefineColor allows you to create intermediate colors on many displays, although the results vary significantly depending on the hardware. For example, the following usually gives a reasonable approximation of brown:

DefineColor("Brown", .35, .20, .05);

void DrawEllipticalArc	(	double	rx,
		double	ry,
		double	start,
		double	sweep
	)

This procedure draws an elliptical arc. It is exactly the same in its operation as DrawArc in the graphics.h interface, except that the radius is different along the two axes.

void DrawNamedPicture ( string name )

This function looks for a image file with the specified name in the "Pictures" subdirectory of the project. It displays this image in the graphics window so that the lower left corner of the image appears at the current point. The function generates an error if the named picture cannot be found. Note that, although the interface presented here is the same for all systems, the format used for the resource itself may not be supported across all platforms. The ones that are guaranteed to work are bitmaps (.bmp), GIFs (.gif), and JPEGs (.jpg.) Others may work, but those are the only ones that are guaranteed.

void DrawTextString ( string text )

This function displays the string text at the current point in the current font and size. The current point is updated so that the next DrawTextString command would continue from the next character position. The string may not include the newline character.

void EndFilledRegion ( )

void ExitGraphics ( )

The ExitGraphics function closes the graphics window and exits from the application without waiting for any additional user interaction.

bool GetEraseMode ( )

This function returns the current state of the erase mode flag.

string GetFont ( )

This function returns the current font name as a string.

double GetFontAscent ( )

These functions return properties of the current font that are used to calculate how to position text vertically on the page. The ascent of a font is the distance from the baseline to the top of the largest character; the descent is the maximum distance any character extends below the baseline. The height is the total distance between two lines of text, including the interline space (which is called leading).

Examples: To change the value of y so that it indicates the next text line, you need to execute

y -= GetFontHeight();

To center text vertically around the coordinate y, you need to start the pen at

y - GetFontAscent() / 2

double GetFontDescent ( )

double GetFontHeight ( )

double GetFullScreenHeight ( )

double GetFullScreenWidth ( )

These functions return the height and width of the entire display screen, not the graphics window. Their only significant use is for applications that need to adjust the size of the graphics window based on available screen space. These functions may be called before InitGraphics has been called.

double GetMouseX ( )

These functions return the x and y coordinates of the mouse, respectively. The coordinate values are real numbers measured in inches from the origin and therefore match the drawing coordinates.

double GetMouseY ( )

string GetPenColor ( )

This function returns the current pen color as a string.

double GetPictureHeight ( string name )

double GetPictureWidth ( string name )

These functions return the width and height (in inches) of the named picture, as described in the comments for DrawNamedPicture.

int GetPointSize ( )

This function returns the current point size.

int GetStyle ( )

This function returns the current style.

string GetWindowTitle ( )

This function returns the title of the graphics window. If the implementation does not support titles, this call returns the empty string.

double GetXResolution ( )

These functions return the number of pixels per inch along each of the coordinate directions and are useful for applications in which it is important for short distances to be represented uniformly in terms of dot spacing. Even though the x and y resolutions are the same for most displays, clients should not rely on this property.

Note: Lines in the graphics library are one pixel unit wide and have a length that is always one pixel longer than you might expect. For example, the function call

DrawLine(2 / GetXResolution(), 0);

draws a line from the current point to the point two pixels further right, which results in a line of three pixels.

double GetYResolution ( )

bool MouseButtonIsDown ( )

This function returns true if the mouse button is currently down. For maximum compatibility among implementations, the mouse is assumed to have one button. If the mouse has more than one button, this function returns true if any button is down.

void Pause ( double seconds )

The Pause function updates the graphics window and then pauses for the indicated number of seconds. This function is useful for animation where the motion would otherwise be too fast.

void RestoreGraphicsState ( )

void SaveGraphicsState ( )

The SaveGraphicsState function saves the current graphics state (the current pen position, the font, the point size, and the erase mode flag) internally, so that they can be restored by the next RestoreGraphicsState call. These two functions must be used in pairs but may be nested to any depth.

void SetEraseMode ( bool mode )

The SetEraseMode function sets the value of the internal erasing flag. Setting this flag is similar to setting the color to "White" in its effect but does not affect the current color setting. When erase mode is set to false, normal drawing is restored, using the current color.

void SetFont ( string font )

This function sets a new font according to the font string, which is case-independent. Different systems support different fonts, although common ones like "Times" and "Courier" are often supported. Initially, the font is set to "Default" which is always supported, although the underlying font is system dependent. If the font name is unrecognized, no error is generated, and the font remains unchanged. If you need to detect this condition, you can call GetFont to see if the change took effect. By not generating an error in this case, programs become more portable.

void SetPenColor ( string color )

This function sets the color of the pen used for any drawing, including lines, text, and filled regions. The color is a string, which will ordinarily be one of the following predefined color names:

Black, Dark Gray, Gray, Light Gray, White, Red, Yellow, Green, Cyan, Blue, Magenta

The first line corresponds to standard gray scales and the second to the primary and secondary colors of light. The built-in set is limited to these colors because they are likely to be the same on all hardware devices. For finer color control, you can use the DefineColor function to create new color names as well.

void SetPenColorRGB	(	double	red,
		double	green,
		double	blue
	)

This function sets the color of the pen used for any drawing, including lines, text, and filled regions. The color is specified by supplying intensity levels for the colors red, green, and blue, which are the primary colors of light. The color values are provided as real numbers between 0 and 1, indicating the intensity of that color. This version is useful when you don't need to keep the color around under a defined name (for that, use DefineColor below).

void SetPointSize ( int size )

This function sets a new point size. If the point size is not supported for a particular font, the closest existing size is selected.

void SetStyle ( int style )

This function establishes the current style properties for text based on the parameter style, which is an integer representing the sum of any of the text style constants.

void SetWindowSize	(	double	width,
		double	height
	)

This function sets the window size to the indicated dimensions, if possible. This function should be called before the graphics window is created by InitGraphics. Attempts to change the size of an existing window are ignored by most implementations. This function should be used sparingly because it reduces the portability of applications, particularly if the client requests more space than is available on the screen.

void SetWindowTitle ( string title )

This function sets the title of the graphics window, if such an operation is possible on the display. If it is not possible for a particular implementation, the call is simply ignored. This function may be called prior to the InitGraphics call to set the initial name of the window.

void StartFilledRegion ( double density )

These calls make it possible to draw filled shapes on the display. After calling StartFilledRegion, any calls to DrawLine and DrawArc are used to create a shape definition and do not appear on the screen until EndFilledRegion is called. The lines and arcs must be consecutive, in the sense that each new element must start where the last one ended. MovePen calls may occur at the beginning or the end of the region, but not in the interior. When EndFilledRegion is called, the entire region appears on the screen, with its interior filled in. The density parameter is a number between 0 and 1 and indicates how the dot density to be used for the fill pattern. If density is 1, the shape will be filled in a solid color; if it is 0, the fill will be invisible. In between, the implementation will use a dot pattern that colors some of the screen dots but not others.

double TextStringWidth ( string text )

This function returns the width of the text string if displayed at the current font and size.

void UpdateDisplay ( )

This function initiates an immediate update of the graphics window and is necessary for animation. Ordinarily, the graphics window is only updated when the program waits for user input.

void WaitForMouseDown ( )

The WaitForMouseDown function waits until the mouse button is pressed and then returns. WaitForMouseUp waits for the button to be released.

void WaitForMouseUp ( )

extgraph.h File Reference

Defines

Functions

Define Documentation

Function Documentation


Defines
#define	Normal 0
#define	Bold 1
#define	Italic 2
Functions
void	DrawEllipticalArc (double rx, double ry, double start, double sweep)
void	StartFilledRegion (double density)
void	EndFilledRegion ()
void	DrawTextString (string text)
double	TextStringWidth (string text)
void	SetFont (string font)
string	GetFont ()
void	SetPointSize (int size)
int	GetPointSize ()
void	SetStyle (int style)
int	GetStyle ()
double	GetFontAscent ()
double	GetFontDescent ()
double	GetFontHeight ()
double	GetMouseX ()
double	GetMouseY ()
bool	MouseButtonIsDown ()
void	WaitForMouseDown ()
void	WaitForMouseUp ()
void	SetPenColor (string color)
void	SetPenColorRGB (double red, double green, double blue)
string	GetPenColor ()
void	DefineColor (string name, double red, double green, double blue)
void	DrawNamedPicture (string name)
double	GetPictureWidth (string name)
double	GetPictureHeight (string name)
void	SetEraseMode (bool mode)
bool	GetEraseMode ()
void	SetWindowTitle (string title)
string	GetWindowTitle ()
void	UpdateDisplay ()
void	Pause (double seconds)
void	ExitGraphics ()
void	SaveGraphicsState ()
void	RestoreGraphicsState ()
double	GetFullScreenWidth ()
double	GetFullScreenHeight ()
void	SetWindowSize (double width, double height)
double	GetXResolution ()
double	GetYResolution ()