diff -r 000000000000 -r e9f7ba4718e1 Source/Piece.m
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Source/Piece.m	Fri Mar 07 11:43:02 2008 -0800
@@ -0,0 +1,132 @@
+/*  This code is based on Apple's "GeekGameBoard" sample code, version 1.0.
+    http://developer.apple.com/samplecode/GeekGameBoard/
+    Copyright © 2007 Apple Inc. Copyright © 2008 Jens Alfke. All Rights Reserved.
+
+    Redistribution and use in source and binary forms, with or without modification, are permitted
+    provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright notice, this list of conditions
+      and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright notice, this list of
+      conditions and the following disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 
+    FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRI-
+    BUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
+    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
+    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 
+    THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+#import "Piece.h"
+#import "QuartzUtils.h"
+
+
+@implementation Piece
+
+
+- (id) initWithImageNamed: (NSString*)imageName
+                    scale: (CGFloat)scale
+{
+    self = [super init];
+    if (self != nil) {
+        self.imageName = imageName;
+        [self setImage: GetCGImageNamed(imageName) scale: scale];
+        self.zPosition = kPieceZ;
+    }
+    return self;
+}
+
+
+- (id) initWithCoder: (NSCoder*)decoder
+{
+    self = [super initWithCoder: decoder];
+    if( self ) {
+        self.imageName = [decoder decodeObjectForKey: @"imageName"];
+        // (actual image (self.contents) was already restord by superclass)
+    }
+    return self;
+}
+
+- (void) encodeWithCoder: (NSCoder*)coder
+{
+    [super encodeWithCoder: coder];
+    [coder encodeObject: _imageName forKey: @"imageName"];
+}
+
+
+- (void) dealloc
+{
+    [_imageName release];
+    [super dealloc];
+}
+
+
+- (NSString*) description
+{
+    return [NSString stringWithFormat: @"%@[%@]", 
+            [self class],
+            _imageName.lastPathComponent.stringByDeletingPathExtension];
+}
+
+
+@synthesize imageName=_imageName;
+
+
+- (void) setImage: (CGImageRef)image scale: (CGFloat)scale
+{
+    self.contents = (id) image;
+    self.contentsGravity = @"resize";
+    self.minificationFilter = kCAFilterLinear;
+    int width = CGImageGetWidth(image), height = CGImageGetHeight(image);
+    if( scale > 0 ) {
+        if( scale >= 4.0 )
+            scale /= MAX(width,height);             // interpret scale as target dimensions
+        width = ceil( width * scale);
+        height= ceil( height* scale);
+    }
+    self.bounds = CGRectMake(0,0,width,height);
+    self.imageName = nil;
+}
+
+- (void) setImage: (CGImageRef)image
+{
+    CGSize size = self.bounds.size;
+    [self setImage: image scale: MAX(size.width,size.height)];
+}
+
+- (void) setImageNamed: (NSString*)name
+{
+    [self setImage: GetCGImageNamed(name)];
+    self.imageName = name;
+}
+
+
+- (BOOL)containsPoint:(CGPoint)p
+{
+    // Overrides CGLayer's implementation,
+    // returning YES only for pixels at which this layer's alpha is at least 0.5.
+    // This takes into account the opacity, bg color, and background image's alpha channel.
+    if( ! [super containsPoint: p] )
+        return NO;
+    float opacity = self.opacity;
+    if( opacity < 0.5 )
+        return NO;
+    float thresholdAlpha = 0.5 / self.opacity;
+    
+    CGColorRef bg = self.backgroundColor;
+    float alpha = bg ?CGColorGetAlpha(bg) :0.0;
+    if( alpha < thresholdAlpha ) {
+        CGImageRef image = (CGImageRef)self.contents;
+        if( image ) {
+            // Note: This makes the convenient assumption that the image entirely fills the bounds.
+            alpha = MAX(alpha, GetPixelAlpha(image, self.bounds.size, p));
+        }
+    }
+    return alpha >= thresholdAlpha;
+}
+
+
+@end