Creating an ios paint application - ios

Question

I'm trying to create a simple paint app.
- (void)handleSingleTap:(UIPanGestureRecognizer *)recognizer
{
CGPoint location = [recognizer locationInView:[recognizer.view superview]];
NSLog(#"Test");
CGFloat ok = 40;
self.sheet.test = ok;
[self.sheet addPoint: location];
//Do stuff here...
}
This function draws lines but when I lift up my finger and replace it there is a "straight line" from the last point to the next one. How can I skip this?

Answer 1

Try controlling it using UIGestureRecognizerStateEnded
if(recognizer.state == UIGestureRecognizerStateEnded){
//Drawing Ends.
isDrawn = NO;
}
with your comments, I understood that you are controlling your line drawing method with a variable isDrawn.
if(recognier.state == UIGestureStateBegan){
[self moveToPoint:point]; // declare the point variable in the header file.
isDrawn = YES;
//Drawing Starts
}

Answer 2

Hope below code snippet helps
typedef NS_ENUM(NSInteger, PenType){
kPenTypeGreen,
kPenTypeCyan,
kPenTypeRed,
kPenTypePurple,
kPenTypeErase
};
#interface MCStylus() {
PenType penType;
CGPoint lastPoint;
CGPoint secondLastPoint;
NSInteger currentStylistPageIndex;
NSMutableArray *arrayOfStylistImages;
}
#property (nonatomic, strong) IBOutlet UIImageView *handwritingView;
#property (nonatomic, strong) UIImageView *drawImage;
- (void)initializeUI {
arrayOfStylistImages = [[NSMutableArray alloc] init];
[arrayOfStylistImages addObject:[[UIImage alloc] init]];
self.drawImage = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, self.handwritingView.frame.size.width, self.handwritingView.frame.size.height)];
self.drawImage.userInteractionEnabled = true;
self.handwritingView.backgroundColor = [UIColor whiteColor];
self.handwritingView.layer.cornerRadius = 5.0f;
self.handwritingView.layer.borderColor = [UIColor colorWithWhite:230.0f/255.0f alpha:1.0].CGColor;
self.handwritingView.layer.borderWidth = 2.0f;
self.handwritingView.clipsToBounds = true;
[self.handwritingView addSubview:self.drawImage];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
NSArray *allTouches = [touches allObjects];
int count = [allTouches count];
if(count==1){
UITouch *touch = [touches anyObject];
lastPoint = [touch locationInView:self.handwritingView];
secondLastPoint = lastPoint;
}
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesMoved:touches withEvent:event];
NSArray *allTouches = [touches allObjects];
int count = [allTouches count];
if(count==1){
UITouch *touch = [touches anyObject];
CGPoint currentPoint = [touch locationInView:self.handwritingView];
UIGraphicsBeginImageContext(self.handwritingView.frame.size);
if(self.drawImage.image!=NULL)
[self.drawImage.image drawInRect:CGRectMake(0, 0, self.handwritingView.frame.size.width, self.handwritingView.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2.0);
switch (penType) {
case kPenTypeGreen:
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 1.0, 0.0, 1.0);
break;
case kPenTypeCyan:
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.0, 1.0, 1.0);
break;
case kPenTypeRed:
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
break;
case kPenTypePurple:
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.5, 0.2, 0.3, 1.0);
break;
case kPenTypeErase:
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 6.0 * (self.handwritingView.frame.size.height/350));
CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeClear);
CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(),[UIColor clearColor].CGColor);
break;
default:
break;
}
CGPoint mid1 = CGPointMake((lastPoint.x+secondLastPoint.x)/2, (lastPoint.y + secondLastPoint.y)/2);
CGPoint mid2 = CGPointMake((lastPoint.x+currentPoint.x)/2, (lastPoint.y+currentPoint.y)/2);
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), mid1.x, mid1.y);
CGContextAddQuadCurveToPoint(UIGraphicsGetCurrentContext(),lastPoint.x, lastPoint.y,mid2.x,mid2.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
self.drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
secondLastPoint = lastPoint;
lastPoint = currentPoint;
}
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
[super touchesEnded:touches withEvent:event];
if(self.drawImage.image!=NULL)
[arrayOfStylistImages replaceObjectAtIndex:currentStylistPageIndex withObject:self.drawImage.image];
}