Makes drawing more smoothly

Example/JotDemo/ExampleViewController.m

@@ -172,4 +172,4 @@ - (void)jotViewController:(JotViewController *)jotViewController isEditingText:(
     self.toggleDrawingButton.hidden = isEditing;
 }
 
-@end
+@end

Example/Podfile

@@ -18,4 +18,4 @@ target 'JotDemoTests', :exclusive => true do
   pod 'Expecta'
   pod 'Expecta+Snapshots'
   pod 'OCMockito'
-end
+end

Example/Podfile.lock

@@ -33,4 +33,4 @@ SPEC CHECKSUMS:
   OCMockito: 4981140c9a9ec06c31af40f636e3c0f25f27e6b2
   Specta: cf3e4188cf35375c3ee2cd03f8db8f1f4ef98234
 
-COCOAPODS: 0.38.2
+COCOAPODS: 0.38.2

jot/JotDrawView.m

@@ -15,6 +15,19 @@
 CGFloat const kJotInitialVelocity = 220.f;
 CGFloat const kJotRelativeMinStrokeWidth = 0.4f;
 
+static inline CGRect calcRect(CGPoint p1,CGPoint p2, CGPoint p3, CGPoint p4){
+    CGFloat x1,y1,x2,y2,width,height;
+    x1 = MIN(MIN(p1.x, p2.x), MIN(p3.x, p4.x));
+    x2 = MAX(MAX(p1.x, p2.x), MAX(p3.x, p4.x));
+
+    y1 = MIN(MIN(p1.y, p2.y), MIN(p3.y, p4.y));
+    y2 = MAX(MAX(p1.y, p2.y), MAX(p3.y, p4.y));
+
+    width  = x2 - x1 + 15;
+    height = y2 - y1 + 15;
+    return CGRectMake(MAX(x1 - 10, 0), MAX(y1 - 10, 0),  width,  height);
+}
+
 @interface JotDrawView ()
 
 @property (nonatomic, strong) UIImage *cachedImage;
@@ -132,6 +145,7 @@ - (void)drawTouchMovedToPoint:(CGPoint)touchPoint
             self.lastVelocity = velocity;
         }
 
+
         self.pointsArray[0] = self.pointsArray[3];
         self.pointsArray[1] = self.pointsArray[4];
 
@@ -156,6 +170,8 @@ - (void)drawTouchEnded
 
 - (void)drawBitmap
 {
+    CGRect rect = calcRect(self.bezierPath.startPoint, self.bezierPath.controlPoint1, self.bezierPath.controlPoint2, self.bezierPath.endPoint);
+
     UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, [UIScreen mainScreen].scale);
 
     if (self.cachedImage) {
@@ -173,18 +189,21 @@ - (void)drawBitmap
         [touchPoint.strokeColor setFill];
         [JotTouchBezier jotDrawBezierPoint:[touchPoint CGPointValue]
                                  withWidth:touchPoint.strokeWidth];
+
+        CGFloat pointWidth = touchPoint.strokeWidth;
+        CGPoint point = touchPoint.CGPointValue;
+        rect = CGRectMake(point.x - pointWidth, point.y - pointWidth, pointWidth * 2.f, pointWidth * 2.f);
     }
 
     self.cachedImage = UIGraphicsGetImageFromCurrentImageContext();
     UIGraphicsEndImageContext();
-    [self setNeedsDisplay];
+
+    [self setNeedsDisplayInRect:rect];
 }
 
 - (void)drawRect:(CGRect)rect
 {
-    [self.cachedImage drawInRect:rect];
-
-    [self.bezierPath jotDrawBezier];
+    [self.cachedImage drawAtPoint:CGPointZero];
 }
 
 - (CGFloat)strokeWidthForVelocity:(CGFloat)velocity

jot/JotTouchBezier.m

@@ -9,6 +9,11 @@
 #import "JotTouchBezier.h"
 
 NSUInteger const kJotDrawStepsPerBezier = 300;
+CGFloat const kJotBezierShadow = 0.65f;
+
+static inline CGFloat pointLength(const CGPoint point1, const CGPoint point2){
+    return sqrt(pow(point1.x - point2.x, 2) + pow(point1.y - point2.y, 2));
+}
 
 @implementation JotTouchBezier
 
@@ -34,11 +39,26 @@ - (void)jotDrawBezier
     } else {
         [self.strokeColor setFill];
 
+        CGFloat minWidth = self.startWidth;
         CGFloat widthDelta = self.endWidth - self.startWidth;
 
-        for (NSUInteger i = 0; i < kJotDrawStepsPerBezier; i++) {
+        CGFloat length = pointLength(self.startPoint, self.controlPoint1)
+                        + pointLength(self.controlPoint1, self.controlPoint2)
+                        + pointLength(self.controlPoint2, self.endPoint);
+
+        CGFloat drawSteps = MAX(MIN(length,kJotDrawStepsPerBezier),10);
+
+        CGContextRef context = UIGraphicsGetCurrentContext();
+        if (!context) {
+            return;
+        }
+
+        // Set shadow makes bezier path more smoothly
+        CGContextSetShadowWithColor(context, CGSizeMake(0, 0), kJotBezierShadow, self.strokeColor.CGColor);
+
+        for (NSUInteger i = 0; i < drawSteps; i++) {
 
-            CGFloat t = ((CGFloat)i) / (CGFloat)kJotDrawStepsPerBezier;
+            CGFloat t = ((CGFloat)i) / (CGFloat)drawSteps;
             CGFloat tt = t * t;
             CGFloat ttt = tt * t;
             CGFloat u = 1.f - t;
@@ -56,8 +76,27 @@ - (void)jotDrawBezier
             y += ttt * self.endPoint.y;
 
             CGFloat pointWidth = self.startWidth + (ttt * widthDelta);
+            minWidth = MIN(pointWidth, minWidth);
+
             [self.class jotDrawBezierPoint:CGPointMake(x, y) withWidth:pointWidth];
         }
+
+        // Draw a min width bezier, in case of drawSteps is not enough
+        CGFloat span = 0.0f;
+        CGPoint startPoint = CGPointMake(self.startPoint.x, self.startPoint.y + span);
+        CGPoint controlPoint1 = CGPointMake(self.controlPoint1.x, self.controlPoint1.y + span);
+        CGPoint controlPoint2 = CGPointMake(self.controlPoint2.x, self.controlPoint2.y + span);
+        CGPoint endPoint = CGPointMake(self.endPoint.x, self.endPoint.y + span);
+
+        [self.strokeColor setStroke];
+        CGContextSetLineWidth(context, minWidth);
+        CGContextSetAllowsAntialiasing(context, true);
+        CGContextSetLineCap(context, kCGLineCapRound);
+        CGContextSetLineJoin(context, kCGLineJoinRound);
+        CGContextMoveToPoint(context, startPoint.x, startPoint.y);
+        CGContextAddCurveToPoint(context, controlPoint1.x, controlPoint1.y,
+                                 controlPoint2.x, controlPoint2.y, endPoint.x, endPoint.y);
+        CGContextStrokePath(context);
     }
 }