waba.fx
Class Graphics

java.lang.Object
  |
  +--waba.fx.Graphics

public class Graphics

extends Object

Graphics draws on a surface.

Surfaces are objects that implement the ISurface interface. MainWindow and Image are both examples of surfaces.

Here is an example that uses Graphics to draw a line:

 public class MyProgram extends MainWindow
 {
 public void onPaint(Graphics g)
  {
  g.setColor(0, 0, 255);
  g.drawLine(0, 0, 10, 10);
 ...
 

Field Summary

static int	DRAW_AND The constant for a draw operation that AND's the source with the destination.
static int	DRAW_OR The constant for a draw operation that OR's the source with the destination.
static int	DRAW_OVER The constant for a draw operation that draws the source over the destination.
static int	DRAW_XOR The constant for a draw operation that XOR's the source with the destination.

Constructor Summary

Graphics(ISurface surface)
Constructs a graphics object which can be used to draw on the given surface.

Method Summary

void	clearClip() Clears the current clipping rectangle.
void	copyRect(ISurface surface, int x, int y, int width, int height, int dstX, int dstY)
void	drawCursor(int x, int y, int width, int height) Draws a cursor by XORing the given rectangular area on the surface.
void	drawDots(int x1, int y1, int x2, int y2) Draws a dotted line at the given coordinates.
void	drawImage(Image image, int x, int y) Draws an image at the given x and y coordinates.
void	drawLine(int x1, int y1, int x2, int y2) Draws a line at the given coordinates.
void	drawPolygon(int[] x, int[] y, int count) Draws the outline of a polygon with the given coordinates.
void	drawRect(int x, int y, int width, int height) Draws a rectangle at the given coordinates.
void	drawText(char[] chars, int start, int count, int x, int y) Draws text at the given coordinates.
void	drawText(String s, int x, int y) Draws text at the given coordinates.
void	fillPolygon(int[] x, int[] y, int count) Draws a filled polygon with the given coordinates.
void	fillRect(int x, int y, int width, int height) Fills a rectangular area with the current color.
void	free() Frees any system resources (native device contexts) associated with the graphics object.
Rect	getClip(Rect r) Sets the x, y, width and height coordinates in the rectangle passed to the current clip coordinates.
void	setClip(int x, int y, int width, int height) Sets a clipping rectangle.
void	setColor(int r, int g, int b) Sets the current color for drawing operations.
void	setDrawOp(int drawOp)
void	setFont(Font font) Sets the current font for operations that draw text.
void	translate(int x, int y) Translates the origin of the current coordinate system by the given x and y values.

Methods inherited from class java.lang.Object

equals, hashCode, toString

Field Detail

DRAW_OVER

public static final int DRAW_OVER

The constant for a draw operation that draws the source over the destination.

DRAW_AND

public static final int DRAW_AND

The constant for a draw operation that AND's the source with the destination. Commonly used to create image masks.

DRAW_OR

public static final int DRAW_OR

The constant for a draw operation that OR's the source with the destination. Commonly used with image masks.

DRAW_XOR

public static final int DRAW_XOR

The constant for a draw operation that XOR's the source with the destination.

Constructor Detail

Graphics

public Graphics(ISurface surface)

Constructs a graphics object which can be used to draw on the given surface. For the sake of the methods in this class, the given surface is known as the "current surface".

If you are trying to create a graphics object for drawing in a subclass of control, use the createGraphics() method in the Control class. It creates a graphics object and translated the origin to the origin of the control.

Method Detail

clearClip

public void clearClip()

Clears the current clipping rectangle. This allows drawing to occur anywhere on the current surface.

copyRect

public void copyRect(ISurface surface,
                     int x,
                     int y,
                     int width,
                     int height,
                     int dstX,
                     int dstY)

free

public void free()

Frees any system resources (native device contexts) associated with the graphics object. After calling this function, the graphics object can no longer be used to draw. Calling this method is not required since any system resources allocated will be freed when the object is garbage collected. However, if a program uses many graphics objects, free() should be called whenever one is no longer needed to prevent allocating too many system resources before garbage collection can occur.

drawText

public void drawText(char[] chars,
                     int start,
                     int count,
                     int x,
                     int y)

Draws text at the given coordinates. The x and y coordinates specify the upper left hand corner of the text's bounding box.

Parameters:

chars - the character array to display

start - the start position in array

count - the number of characters to display

x - the left coordinate of the text's bounding box

y - the top coordinate of the text's bounding box

drawImage

public void drawImage(Image image,
                      int x,
                      int y)

Draws an image at the given x and y coordinates.

drawCursor

public void drawCursor(int x,
                       int y,
                       int width,
                       int height)

Draws a cursor by XORing the given rectangular area on the surface. Since it is XORed, calling the method a second time with the same parameters will erase the cursor.

drawLine

public void drawLine(int x1,
                     int y1,
                     int x2,
                     int y2)

Draws a line at the given coordinates. The drawing includes both endpoints of the line.

drawRect

public void drawRect(int x,
                     int y,
                     int width,
                     int height)

Draws a rectangle at the given coordinates.

drawDots

public void drawDots(int x1,
                     int y1,
                     int x2,
                     int y2)

Draws a dotted line at the given coordinates. Dotted lines must be either horizontal or vertical, they can't be drawn at arbitrary angles.

drawPolygon

public void drawPolygon(int[] x,
                        int[] y,
                        int count)

Draws the outline of a polygon with the given coordinates. The polygon is automatically closed, you should not duplicate the start point to close the polygon.

Parameters:

x - x vertex coordinates

y - y vertex coordinates

count - number of vertices

fillPolygon

public void fillPolygon(int[] x,
                        int[] y,
                        int count)

Draws a filled polygon with the given coordinates. The polygon is automatically closed, you should not duplicate the start point to close the polygon. The polygon is filled according to Jordan's rule - a point is inside if a horizontal line to the point intersects the polygon an odd number of times. This function is not implemented for the PalmOS VM. Under PalmOS only the outline of the polygon is drawn.

Parameters:

x - x vertex coordinates

y - y vertex coordinates

count - number of vertices

drawText

public void drawText(String s,
                     int x,
                     int y)

Draws text at the given coordinates. The x and y coordinates specify the upper left hand corner of the text.

fillRect

public void fillRect(int x,
                     int y,
                     int width,
                     int height)

Fills a rectangular area with the current color.

setClip

public void setClip(int x,
                    int y,
                    int width,
                    int height)

Sets a clipping rectangle. Anything drawn outside of the rectangular area specified will be clipped. Setting a clip overrides any previous clip.

getClip

public Rect getClip(Rect r)

Sets the x, y, width and height coordinates in the rectangle passed to the current clip coordinates. To reduce the use of temporary objects during drawing, this method does not allocate its own rectangle object. If there is no current clip, null will be returned and the rectangle passed will remain unchanged. Upon success, the rectangle passed to the method will be returned.

setColor

public void setColor(int r,
                     int g,
                     int b)

Sets the current color for drawing operations.

Parameters:

r - the red value (0..255)

g - the green value (0..255)

b - the blue value (0..255)

setDrawOp

public void setDrawOp(int drawOp)

setFont

public void setFont(Font font)

Sets the current font for operations that draw text.

translate

public void translate(int x,
                      int y)

Translates the origin of the current coordinate system by the given x and y values.