Why there is a black ouline while using eraser? - iphone

Question

Please see the attached image. I have created an app in which user can draw with multiple images but when I am using the Clear Color in order to erase the drawing it is showing the black border around the erased path. I have used UIBezierPath for drawing. Is this an issue with UIBezierPath or it can be resolved by any other way? Please let me know if you want code snippet! I will post that here.
Edit: Code has been added! Please ignore the irrelevant code.
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
if(isFirstTapp)
{
isFirstTapp=NO;
[self.spooleteView removeHandView];
}
isdraw=YES;
mouseSwapped=NO;
UITouch *touch = [touches anyObject];
lastPoint=[touch locationInView:self];
//UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[currentPath moveToPoint:p];
currentPath.flatness = 10.0;
NSMutableDictionary *dict=[[NSMutableDictionary alloc]init];
UIBezierPath *myPath=[[UIBezierPath alloc]init];
myPath.lineCapStyle=kCGLineJoinRound;
[dict setObject:myPath forKey:#"Path"];
colorTag= [[AppHelper userDefaultsForKey:#"ColorTag"]intValue];
self.selectedColor = [brushColor objectAtIndex:colorTag];
if(isErase)
{
myPath.lineWidth=30.0;
self.selectedColor = [UIColor whiteColor];
}
else
{
if([mode isEqualToString:#"morsecode"])
myPath.lineWidth=10.0;
else
myPath.lineWidth=5.0;
}
//[dict setObject:[brushColor objectAtIndex:colorTag] forKey:#"Colors"];
[dict setObject:self.selectedColor forKey:#"Colors"];
[myArr addObject:dict];
currentPath=myPath;
currentPath.flatness = 0.1;
currentPath.lineJoinStyle = kCGLineJoinRound;
currentDict=dict;
[myPath moveToPoint:lastPoint];
[myPath release];
[dict release];
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
if(!istapped)
{
if([mode isEqualToString:#"morsecode"])
{
mouseSwapped=YES;
UITouch *mytouch=[[touches allObjects] objectAtIndex:0];
currentPoint=[mytouch locationInView:self];
[currentPath addLineToPoint:currentPoint];
[self setNeedsDisplay];
}
}
// UITouch *touch = [touches anyObject];
// CGPoint p = [touch locationInView:self];
// [currentPath addLineToPoint:p];
// [self setNeedsDisplay];
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
if(!istapped)
{
mouseSwapped=YES;
UITouch *objTouch=[[touches allObjects] objectAtIndex:0];
if (!mouseSwapped&&(objTouch.tapCount==1))
{
lastPoint=currentPoint;
}
}
if(isErase)
{
if ([myArr count]>50)
{
[myArr removeAllObjects];
}
}
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[currentPath addLineToPoint:p];
[self drawBitmap]; // (3)
[self setNeedsDisplay];
[currentPath removeAllPoints]; //(4)
}
- (void)drawRect:(CGRect)rect
{
[self.incrementalImage drawInRect:rect]; // (3)
[currentPath stroke];
//[self.incrementalImage drawInRect:rect];
for (NSMutableDictionary *dictionary in myArr)
{
UIBezierPath *_path = [dictionary objectForKey:#"Path"];
self.selectedColor = [dictionary objectForKey:#"Colors"];
[self.selectedColor setStroke];
[_path stroke];
[_path strokeWithBlendMode:kCGBlendModeCopy alpha:1.0];
_path.lineCapStyle = kCGLineJoinRound;
if([mode isEqualToString:#"morsecode"])
{
if (!isErase)
{
const float p[2] = {1,15.9};
[_path setLineDash:p count:2 phase:0.9];
}
else
{
self.selectedColor = [UIColor whiteColor];
}
}
}
}
- (void)drawBitmap // (3)
{
UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, 0.0);
[self.selectedColor setStroke];
if (!self.incrementalImage) // first draw; paint background white by ...
{
UIBezierPath *rectpath = [UIBezierPath bezierPathWithRect:self.bounds]; // enclosing bitmap by a rectangle defined by another UIBezierPath object
[[UIColor clearColor] setFill];
[rectpath fill]; // filling it with white
}
[self.incrementalImage drawAtPoint:CGPointZero];
[currentPath stroke];
self.incrementalImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}

Answer 1

I have found the reason of that issue. It was because of the second line of the following function.
- (void)drawRect:(CGRect)rect
{
[self.incrementalImage drawInRect:rect]; // (3)
[currentPath stroke];
i.e., [currentPath stroke];
I have commented that and now there is no black border around the path.
I hope this will help other.