Graphics Reference
In-Depth Information
//calculate clipping bounds
CGRect bounds =
self
.
scrollView
.bounds;
bounds.origin =
self
.
scrollView
.contentOffset;
bounds =
CGRectInset
(bounds, -
SIZE
/
2
, -
SIZE
/
2
);
//add existing layers to pool
[
self
.
recyclePool
addObjectsFromArray
:
self
.
scrollView
.layer.sublayers];
//disable animation
[CATransaction
begin
];
[CATransaction
setDisableActions
:
YES
];
//create layers
NSInteger recycled =
0
;
NSMutableArray *visibleLayers = [NSMutableArray
array
];
for
(
int
z =
DEPTH
-
1
; z >=
0
; z--)
{
//increase bounds size to compensate for perspective
CGRect adjusted = bounds;
adjusted.size.width /=
PERSPECTIVE
(z*
SPACING
);
adjusted.size.height /=
PERSPECTIVE
(z*
SPACING
);
adjusted.origin.x -= (adjusted.size.width - bounds.size.width) /
2
;
adjusted.origin.y -= (adjusted.size.height - bounds.size.height) /
2
;
for
(
int
y =
0
; y <
HEIGHT
; y++)
{
//check if vertically outside visible rect
if
(y*
SPACING
< adjusted.origin.y ||
y*
SPACING
>= adjusted.origin.y + adjusted.size.height)
{
continue
;
}
for
(
int
x =
0
; x <
WIDTH
; x++)
{
//check if horizontally outside visible rect
if
(x*
SPACING
< adjusted.origin.x ||
x*
SPACING
>= adjusted.origin.x + adjusted.size.width)
{
continue
;
}
//recycle layer if available
CALayer *layer = [
self
.
recyclePool
anyObject
];
if
(layer)
{
