Transcript Intro to Graphics

• Please open JCreator and follow these steps:
Configure  Options
JDK Tools
Choose Run Applet from drop-down
Click Default, then Edit
Click the 3 dots next to the Command box,
then find your jdk folder, then bin, then select
appletviewer.
6) OK, Apply, OK
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Intro to Graphics
• Graphics are often created using an applet
• An applet is simply a Java program that is embedded in
an HTML document, and (usually) is designed to be
Web-accessible
• You must compile an applet file before embedding it in
an HTML file (the HTML file only takes the bytecode,
which can then be run using any browser – this is one of
Java’s major advantages over other languages)
• Applet files…
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Have no main
Import 2 or more packages
Must extend the class called Applet
Once embedded, can be viewed with a browser or appletviewer
• To draw graphics, define the paint method that is
inherited from Applet
• The paint method accepts one parameter, of type
Graphics
• Using the Graphics object, you can draw using
methods such as drawRect( ), drawOval( ),
drawLine( ), etc.
• Java uses an xy-coordinate system, with the top-left
corner being the origin (0,0)
• When drawing shapes, you pass parameters specifying
where to begin the shape, and how far to draw it.
• Example:
page.drawRect(100,100,80,50) /* draws a rectangle starting
at (100,100) and with length=80 and height=50. page is the
Graphics object */
• Demo….GraphicsDemo
• To draw a line: drawLine(startX,startY,endX,endY)
// note how this is different from rectangles!
– Demo…
• To draw an oval, you specify the dimensions of its
bounding rectangle, the rectangle that it would fit
into
• To draw a circle: the bounding rectangle must have
equal sides (a square)
– Demo…
• To draw an arc (part of a circle): like drawing an
oval, but also give the starting angle and the
measure of the angle
– Demo…
• To write text: drawString(String,x,y) // x,y is
bottom left with Strings!!
• Demo….
• The Color class has a bunch of predefined
colors, such as Color.yellow and Color.red (see
list on p 106)
• You can set the background by simply typing
setBackground(Color), but to set a shape’s
color, you must use the Graphics object (i.e.
page.setColor(Color.Blue) )
Assignments
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Copy & Paste Snowman from the student folder
P. 118 # 14 (try to avoid using MID and TOP)
P. 118 # 15
Create a drawing of your own – be creative, and
experiment with all of the methods of the
Graphics class that we learned.