HTML and CSS Reference
In-Depth Information
To move the circle up the screen, we would make
speed
a negative number. To move it left
or right, we would update the
x
instead of the
y
variable. To move the circle diagonally, we
would update both
x
and
y
at the same time.
Example 5-1
shows the complete code needed to create basic movement in a straight line.
Example 5-1. Moving in a straight line
<!doctype html>
<html
<html lang=
"en"
>
<head>
<head>
<meta
<meta charset=
"UTF-8"
>
<title>
<title>
CH5EX1: Moving In A Straight Line
</title>
</title>
<
script src
=
"modernizr.js"
><
/script>
<
script type
=
"text/javascript"
>
window
.
addEventListener
(
'load'
,
eventWindowLoaded
,
false
false
);
function
function
eventWindowLoaded
() {
canvasApp
();
}
function
function
canvasSupport
() {
return
return
Modernizr
.
canvas
;
}
function
function
canvasApp
() {
iif
(
!
canvasSupport
()) {
return
return
;
}
function
function
drawScreen
() {
context
.
fillStyle
=
'#EEEEEE'
;
context
.
fillRect
(
0
,
0
,
theCanvas
.
width
,
theCanvas
.
height
);
//Box
context
.
strokeStyle
=
'#000000'
;
context
.
strokeRect
(
1
,
1
,
theCanvas
.
width
-
2
,
theCanvas
.
height
-
2
);
// Create ball
y
+=
speed
;
context
.
fillStyle
=
"#000000"
;
context
.
beginPath
();
