在 iPhone 上實現小畫家基本功能

.h

UIImageView *drawImage_;

CGPoint lastPoint_;

.m

-(id) init

{

if( (self=[super init])) {

        drawImage_ = [[[UIImageView alloc]initWithImage:nil]autorelease];

        drawImage_.frame = CGRectMake(0, 50, 320,400);

        [[[CCDirector sharedDirector]openGLView] addSubview:drawImage_];

        self.isTouchEnabled = YES;

}

return self;

}

- (void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event

{

    UITouch *touch = [touches anyObject];

    lastPoint_ = [touch locationInView:drawImage_];    

}

- (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event

{

    UITouch *touch = [touches anyObject];

    CGPoint currentPoint = [touch locationInView:drawImage_];

    UIGraphicsBeginImageContext(drawImage_.frame.size);

    

    [drawImage_.image drawInRect:CGRectMake(0, 0, drawImage_.frame.size.width, drawImage_.frame.size.height)];

    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound); 

    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);

    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0,0.0,0.0, 1.0);

    CGContextBeginPath(UIGraphicsGetCurrentContext());

    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint_.x, lastPoint_.y);

    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);

    CGContextStrokePath(UIGraphicsGetCurrentContext());

    drawImage_.image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    lastPoint_ = currentPoint;

}