Graphics Reference
In-Depth Information
LISTING 4-5
Continued
- (
void
)legThree:(
id
)sender
{
CGPathAddLineToPoint
(starPath,
NULL
, 144.0, 210.0);
[[[window
contentView
]
layer
]
setNeedsDisplay
];
}
- (
void
)legFour:(
id
)sender
{
CGPathAddLineToPoint
(starPath,
NULL
, 298.0, 99.0);
[[[window
contentView
]
layer
]
setNeedsDisplay
];
}
- (
void
)legFive:(
id
)sender
{
CGPathCloseSubpath
(starPath);
[[[window
contentView
]
layer
]
setNeedsDisplay
];
}
When we call
-setNeedsDisplay
on the root layer,
-drawLayer
gets called and the path in
its current state gets drawn to the layer, as shown in Listing 4-6.
LISTING 4-6
Draw the Path We Have Been Building at Each Timer Call
- (
void
)drawLayer:(
CALayer
*)layer
inContext:(
CGContextRef
)context
{
if
( layer == [[window
contentView
]
layer
] )
{
CGColorRef
white =
CGColorCreateGenericRGB
(1.0, 1.0, 1.0, 1.0);
CGContextSetStrokeColorWithColor
(context, white);
CFRelease
(white);
CGContextBeginPath
(context);
CGContextAddPath
(context, starPath);
CGContextSetLineWidth
(context, 3.0);
CGContextStrokePath
(context);
}
}
