question on layer setup in Covertflow sample code
question on layer setup in Covertflow sample code
- Subject: question on layer setup in Covertflow sample code
- From: "Wayne Shao" <email@hidden>
- Date: Tue, 17 Jun 2008 08:27:51 -0700
Hi,
I was reading the code (part of Core Animation sample code) and could
not understand the part
that the reflection layer is a sublayer of the desktop image layer.
e.g, in Controller.m
layer = [CALayer layer];
....
desktopImageLayer = [CALayer layer];
....
....
[layer setSublayers:[NSArray arrayWithObject:desktopImageLayer]];
...
CALayer *sublayer = [CALayer layer]; // for reflection
[desktopImageLayer addSublayer:sublayer];
[sublayer addSublayer:gradientLayer];
the image ref will later to set as the content of desktopImageLayer,
and sublayer
layer
|---------- desktopImageLayer
|-------------------------------sublayer
|------------ gradientLayer
if (image != NULL)
{
// main image
[layer setContents:(id)image]; <------ Line A
[layer setBackgroundColor:NULL];
NSArray *sublayers = layer.sublayers;
// reflection
CALayer *sublayer = (CALayer *)[sublayers objectAtIndex:0];
[sublayer setContents:(id)image]; <------------- Line B.
[sublayer setBackgroundColor:NULL];
CGImageRelease (image);
}
Two questions
1) I would think sublayer above should be child of layer (and
sibling of desktopImageLayer). what is the reason for the current
setup?
With this setup, is it true that a sublayer is not geometrically
constraint to be inside the bounds of its superlayer?
2) In Line A noted above, the content of layer is set. What is the
impact of this to its sublayers? Later, the sublayer's content is
also set.
Thanks for any insights on this.
--
Wayne Shao
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