PAN Gesture for a Line

C4WorkSpace.m

//
//  C4WorkSpace.m
//  linePAN
//
//  Created by moi on 12-09-29.
//  Copyright (c) 2012 moi. All rights reserved.
//

/*
 One of the main problems in trying to drag a LINE is that, by default, you cannot add gestures to lines.

 The reason is that there is "nothing" to hit-test... This is an issue that arises from the CAShapeLayer, or more specifically the UIBezier path. Bezier paths that are straight lines cannot be hit-test because they "sort of" have NO area to hit...
 
 To move a line with a gesture, you can ADD the line to an invisible shape.
 This example will show you how to do this.
 */

#import "C4WorkSpace.h"

@implementation C4WorkSpace {
    C4Shape *line;
}

-(void)setup {
    //create the line
    CGPoint p[2] = {CGPointMake(0, 0),CGPointMake(100, 100)};
    line = [C4Shape line:p];
    
    //create a shape the size of the line's frame
    C4Shape *backgroundShape = [C4Shape rect:line.frame];
    backgroundShape.fillColor = [UIColor clearColor];
    backgroundShape.lineWidth = 0.0f;

    //add the line to the shape
    [backgroundShape addShape:line];
    
    //add the gesture recognizer to the SHAPE
    [backgroundShape addGesture:PAN name:@"pan" action:@"move:"];
    [self.canvas addShape:backgroundShape];
}
					
@end