Graphics DrawingCanvas canvas = new DrawingCanvas( ); Note: - - PowerPoint PPT Presentation

Graphics

DrawingCanvas canvas = new DrawingCanvas( );

Note: DrawingCanvas is not a standard API class; it must be downloaded from the class webpage.

made up

• f pixels

Java’s (wacky) coordinate system

x axis y axis

(0,0) (x,y)

the larger the y the farther down the pixel is on the DrawingCanvas

Shapes

Graphics object

To draw in Java we must first get a Graphics

• bject from the DrawingCanvas:

import java.awt.Graphics; . . . Graphics g = canvas.getGraphics();

Graphics methods Examples

void drawLine (int x1, int y1, int x2, int y2) g.drawLine(50, 25, 180, 220);

(x1,y1) (x2,y2)

Graphics methods Examples

void drawLine (int x1, int y1, int x2, int y2) g.drawRect(30, 70, 150, 100);

(x,y) width

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

height

Graphics methods Examples

void drawLine (int x1, int y1, int x2, int y2) g.fillRect(30, 70, 150, 100);

(x,y) width

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

height

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

Graphics methods Examples

void drawLine (int x1, int y1, int x2, int y2) g.drawOval(30, 70, 150, 100);

(x,y) width

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

height

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

Graphics methods Examples

void drawLine (int x1, int y1, int x2, int y2) g.fillOval(30, 70, 150, 100);

(x,y) width

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

height

void fillRect (int x, int y, int width, int height) void drawOval (int x, int y, int width, int height) void fillOval (int x, int y, int width, int height)

Graphics methods Examples

void drawLine (int x1, int y1, int x2, int y2) g.drawArc(30, 70, 150, 100, 45, 180);

(x,y) width

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

height

void fillRect (int x, int y, int width, int height) void drawOval (int x, int y, int width, int height) void fillOval (int x, int y, int width, int height) void drawArc (int x, int y, int width, int height, int startAngle, int arcAngle)

startAngle arcAngle

Graphics methods Examples

void drawLine (int x1, int y1, int x2, int y2) g.drawString(“I love java!”, 100, 50);

(x,y)

void drawRect (int x, int y, int width, int height) void fillRect (int x, int y, int width, int height) void drawOval (int x, int y, int width, int height) void fillOval (int x, int y, int width, int height) void drawArc (int x, int y, int width, int height, int startAngle, int arcAngle) void drawString (String s, int x, int y)

Graphics methods Examples

void drawLine (int x1, int y1, int x2, int y2) import java.awt.Polygon; // create Polygon object Polygon p = new Polygon(); p.addPoint(150,150); p.addPoint(250,100); p.addPoint(325,125); p.addPoint(375,225); p.addPoint(450,250); p.addPoint(275,375); g.drawPolygon(p); // draw Polygon void drawRect (int x, int y, int width, int height) void fillRect (int x, int y, int width, int height) void drawOval (int x, int y, int width, int height) void fillOval (int x, int y, int width, int height) void drawArc (int x, int y, int width, int height, int startAngle, int arcAngle) void drawString (String s, int x, int y) void drawPolygon (Polygon p)

red green blue R G B

values

0..255

Java predefined colors java.awt.Color

Color.black (0, 0, 0) Color.red (255, 0, 0 ) Color.green (0, 255, 0) Color.blue (0, 0, 255) Color.magenta (255, 0, 255) Color.yellow (255, 255, 0) Color.cyan (0, 255, 255) Color.white (255,255,255)

Color.

• range

Color. pink

Color.lightGray Color.gray Color.darkGray

g.setColor(Color.red); g.fillRect(30, 70, 150, 100);

Graphics methods

void drawLine (int x1, int y1, int x2, int y2) void drawRect (int x, int y, int width, int height) void fillRect (int x, int y, int width, int height) void drawOval (int x, int y, int width, int height) void fillOval (int x, int y, int width, int height) void drawArc (int x, int y, int width, int height, int startAngle, int arcAngle) void drawString （String s, int x, int y) void setColor (Color c)

// Create Color Object using RGB value Color mycolor = new Color(255,0,0); // Create Color Object using floats. [0.0,1.0] //Color mycolor = new Color(1.0, 0.0, 0.0); g.setColor(mycolor); g.fillRect(30, 70, 150, 100);

Graphics methods

void drawLine (int x1, int y1, int x2, int y2) void drawRect (int x, int y, int width, int height) void fillRect (int x, int y, int width, int height) void drawOval (int x, int y, int width, int height) void fillOval (int x, int y, int width, int height) void drawArc (int x, int y, int width, int height, int startAngle, int arcAngle) void drawString （String s, int x, int y) void setColor (Color c)

Graphics methods Examples

void drawLine (int x1, int y1, int x2, int y2) canvas.setBackground(Color.yellow); g.setColor(Color.red); g.fillRect(30, 70, 150, 100); void drawRect (int x, int y, int width, int height) void fillRect (int x, int y, int width, int height) void drawOval (int x, int y, int width, int height) void fillOval (int x, int y, int width, int height) void drawArc (int x, int y, int width, int height, int startAngle, int arcAngle) void setcolor (Color c)

DrawingCanvas method

void setBackground (Color c) void drawString （String s, int x, int y)

How do we access the Graphics object?

import java.awt.Graphics ; import java.awt.Color ; class DrawingExample { public static void main (String[] args) { } }

instantiate DrawingCanvas object

DrawingCanvas canvas = new DrawingCanvas( ); Graphics g = canvas.getGraphics( ); g.drawLine(10, 50, 25, 100);

call drawing methods

Let’s try it… download DrawingCanvas.java

get Graphics object for drawing