Merge pull request #41 from snappr/master

Less Precise Line Chart

@@ -97,11 +97,13 @@
 -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
 {
     [self touchPoint:touches withEvent:event];
+    [self touchKeyPoint:touches withEvent:event];
 }
 
 -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
 {
     [self touchPoint:touches withEvent:event];
+    [self touchKeyPoint:touches withEvent:event];
 }
 
 -(void)touchPoint:(NSSet *)touches withEvent:(UIEvent *)event
@@ -109,26 +111,59 @@
     //Get the point user touched
     UITouch *touch = [touches anyObject];
     CGPoint touchPoint = [touch locationInView:self];
-    for (UIBezierPath *path in _chartPath) {
-        CGPathRef originalPath = path.CGPath;
-        CGPathRef strokedPath = CGPathCreateCopyByStrokingPath(originalPath, NULL, 3.0, kCGLineCapRound, kCGLineJoinRound, 3.0);
-        BOOL pathContainsPoint = CGPathContainsPoint(strokedPath, NULL, touchPoint, NO);
-        if (pathContainsPoint)
-        {
-            [_delegate userClickedOnLinePoint:touchPoint lineIndex:[_chartPath indexOfObject:path]];
-            for (NSArray *linePointsArray in _pathPoints) {
-                for (NSValue *val in linePointsArray) {
-                    CGPoint p = [val CGPointValue];
-                    if (p.x + 3.0 > touchPoint.x && p.x - 3.0 < touchPoint.x && p.y + 3.0 > touchPoint.y && p.y - 3.0 < touchPoint.y ) {
-                        //Call the delegate and pass the point and index of the point
-                        [_delegate userClickedOnLineKeyPoint:touchPoint lineIndex:[_pathPoints indexOfObject:linePointsArray] andPointIndex:[linePointsArray indexOfObject:val]];
+    
+    for (int p = _pathPoints.count - 1; p >= 0; p--) {
+        NSArray *linePointsArray = _pathPoints[p];
+        
+        for (int i = 0; i < linePointsArray.count - 1; i += 1) {
+            CGPoint p1 = [linePointsArray[i] CGPointValue];
+            CGPoint p2 = [linePointsArray[i+1] CGPointValue];
+            
+            // Closest distance from point to line
+            float distance = fabsf(((p2.x - p1.x)*(touchPoint.y - p1.y))-((p1.x-touchPoint.x)*(p1.y-p2.y)));
+            distance /= hypot(p2.x-p1.x, p1.y-p2.y);
+            
+            if (distance <= 5.0) {
+                // Conform to delegate parameters, figure out what bezier path this CGPoint belongs to.
+                for (UIBezierPath *path in _chartPath) {
+                    BOOL pointContainsPath = CGPathContainsPoint(path.CGPath, NULL, p1, NO);
+                    
+                    if (pointContainsPath) {
+                        [_delegate userClickedOnLinePoint:touchPoint lineIndex:[_chartPath indexOfObject:path]];
+                        return;
                     }
                 }
             }
-            
         }
     }
+}
+
+-(void)touchKeyPoint:(NSSet *)touches withEvent:(UIEvent *)event
+{
+    //Get the point user touched
+    UITouch *touch = [touches anyObject];
+    CGPoint touchPoint = [touch locationInView:self];
     
+    for (int p = _pathPoints.count - 1; p >= 0; p--) {
+        NSArray *linePointsArray = _pathPoints[p];
+        
+        for (int i = 0; i < linePointsArray.count - 1; i += 1) {
+            CGPoint p1 = [linePointsArray[i] CGPointValue];
+            CGPoint p2 = [linePointsArray[i+1] CGPointValue];
+            
+            float distanceToP1 = fabsf(hypot(touchPoint.x - p1.x, touchPoint.y - p1.y));
+            float distanceToP2 = hypot(touchPoint.x - p2.x, touchPoint.y - p2.y);
+            
+            float distance = MIN(distanceToP1, distanceToP2);
+            
+            if (distance <= 10.0) {
+                [_delegate userClickedOnLineKeyPoint:touchPoint
+                                           lineIndex:p
+                                       andPointIndex:(distance == distanceToP2 ? i+1 : i)];
+                return;
+            }
+        }
+    }
 }
 
 -(void)strokeChart