Round Cornered Views

Custom NSView with rounded corner:

To draw a custom view with its one or more corners round, all you need to do is draw a bezier path of the required shape in the view’s drawRect: method.
Also, this can be used to customize any NSView subclassed objects as  NSTextView, NSTextField etc.
Here I present the code to create a text field with any one round corner as shown in the image below. The code can be easily changed to create more than one round corners of a view.

Round Cornered Views

These are four different text fields in the figure each with its different corner rounded. You can create  similar text field using the code below.

1.  Top Left Corner Round.

// Set the background color of your view to transparent and no focus ring as it will be of rectangular shape.

[self setBackgroundColor:[NSColor clearColor]];

[self setFocusRingType:NSFocusRingTypeNone];

// Set the corner curve radius

[NSGraphicsContext saveGraphicsState];

CGFloat cornerRadius = 20;

              Drawing the bezier path

// Draw top left round corner

NSBezierPath *path = [NSBezierPath bezierPath];

[path moveToPoint:NSMakePoint(NSMinX(self.bounds), NSMaxY(self.bounds))];

// Draw side border and a top-left rounded corner

NSPoint topLeftCorner = NSMakePoint(NSMinX(self.bounds), NSMinY(self.bounds));

[path lineToPoint:NSMakePoint(NSMinX(self.bounds), NSMinY(self.bounds) + cornerRadius)];

[path curveToPoint:NSMakePoint(NSMinX(self.bounds) + cornerRadius, NSMinY(self.bounds)) controlPoint1:topLeftCorner

controlPoint2:topLeftCorner];

// Draw top border, right border and bottom border

[path lineToPoint:NSMakePoint(NSMaxX(self.bounds), NSMinY(self.bounds))];

[path lineToPoint:NSMakePoint(NSMaxX(self.bounds), NSMaxY(self.bounds))];

[path lineToPoint:NSMakePoint(NSMinX(self.bounds), NSMaxY(self.bounds))];

              Set color and fill the path

[[NSColor redColor]set];

[path fill];

[NSGraphicsContext restoreGraphicsState];

All you need is copy the above code in the drawRect: method of your custom text field (i.e subclass of NSTextField) to get a text field with top left corner round (first text field in the image above).

2. Top Right Corner Round

Now , to create a text field with its top right corner rounded, the code will be same but you only need to draw the bezier path a bit differently. The points where the curve will be drawn this time is top right corner. So the steps to draw the bezier path in this case are:

// Draw top right round corner

NSBezierPath *path = [NSBezierPath bezierPath];

[path moveToPoint:NSMakePoint(NSMinX(self.bounds), NSMinY(self.bounds))];

// Draw top border and a top-right rounded corner

NSPoint topRightCorner = NSMakePoint(NSMaxX(self.bounds), NSMinY(self.bounds));

[path lineToPoint:NSMakePoint(NSMaxX(self.bounds)-cornerRadius, NSMinY(self.bounds))];

[path curveToPoint:NSMakePoint(NSMaxX(self.bounds), NSMinY(self.bounds)+cornerRadius)

controlPoint1:topRightCorner

controlPoint2:topRightCorner];

// Draw right border, bottom border and left border

[path lineToPoint:NSMakePoint(NSMaxX(self.bounds), NSMaxY(self.bounds))];

[path lineToPoint:NSMakePoint(NSMinX(self.bounds), NSMaxY(self.bounds))];

[path lineToPoint:NSMakePoint(NSMinX(self.bounds), NSMinY(self.bounds))];

Similarly the bezier path for Bottom Left Round corner and Bottom Right Round corner can be drawn as:

3. Bottom Left Corner Round

// Draw bottom left round corner

NSBezierPath *path = [NSBezierPath bezierPath];

[path moveToPoint:NSMakePoint(NSMaxX(self.bounds), NSMaxY(self.bounds))];

// Draw left border and a bottom-left rounded corner

NSPoint bottomLeftCorner = NSMakePoint(NSMinX(self.bounds), NSMaxY(self.bounds));

[path lineToPoint:NSMakePoint(NSMinX(self.bounds)+cornerRadius, NSMaxY(self.bounds))];

[path curveToPoint:NSMakePoint(NSMinX(self.bounds), NSMaxY(self.bounds)-cornerRadius)

controlPoint1:bottomLeftCorner

controlPoint2:bottomLeftCorner];

// Draw bottom border, right border and top border

[path lineToPoint:NSMakePoint(NSMinX(self.bounds), NSMinY(self.bounds))];

[path lineToPoint:NSMakePoint(NSMaxX(self.bounds), NSMinY(self.bounds))];

[path lineToPoint:NSMakePoint(NSMaxX(self.bounds), NSMaxY(self.bounds))];

4. Bottom Right Corner Round

// Draw bottom right round corner

NSBezierPath *path = [NSBezierPath bezierPath];

[path moveToPoint:NSMakePoint(NSMaxX(self.bounds), NSMinY(self.bounds))];

// Draw bottom border and a bottom-right rounded corner

NSPoint bottomRightCorner = NSMakePoint(NSMaxX(self.bounds), NSMaxY(self.bounds));

[path lineToPoint:NSMakePoint(NSMaxX(self.bounds), NSMaxY(self.bounds)-cornerRadius)];

[path curveToPoint:NSMakePoint(NSMaxX(self.bounds)-cornerRadius, NSMaxY(self.bounds))

controlPoint1:bottomRightCorner

controlPoint2:bottomRightCorner];

// Draw right border, top border and left border

[path lineToPoint:NSMakePoint(NSMinX(self.bounds), NSMaxY(self.bounds))];

[path lineToPoint:NSMakePoint(NSMinX(self.bounds), NSMinY(self.bounds))];

[path lineToPoint:NSMakePoint(NSMaxX(self.bounds), NSMinY(self.bounds))];

This way you can draw a custom view with any of its corner round.

Written By: Neha Gupta, Software Engineer, Mindfire Solutions