How to draw a rounded rectangle in Core Graphics / Quartz 2D?
I need to draw an outline for a rounded rectangle. I know I can make lines and arcs, but maybe there is also a function for rounded rects?
Solution 1:
Instead of making your own path out of lines and arcs, you can use
[UIBezierPath bezierPathWithRoundedRect:cornerRadius:]
or
[UIBezierPath bezierPathWithRoundedRect:byRoundingCorners:cornerRadii:]
(the second one lets you specify which corners are rounded)
Available in iOS 3.2 or later.
Solution 2:
There is no prepackaged way to this, you must combine arcs in order to do this, apples quartzdemo project shows the code to do this, here is a reference Quartz Demo and here is the code they provide
// As a bonus, we'll combine arcs to create a round rectangle!
// Drawing with a white stroke color
CGContextRef context=UIGraphicsGetCurrentContext()
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
// If you were making this as a routine, you would probably accept a rectangle
// that defines its bounds, and a radius reflecting the "rounded-ness" of the rectangle.
CGRect rrect = CGRectMake(210.0, 90.0, 60.0, 60.0);
CGFloat radius = 10.0;
// NOTE: At this point you may want to verify that your radius is no more than half
// the width and height of your rectangle, as this technique degenerates for those cases.
// In order to draw a rounded rectangle, we will take advantage of the fact that
// CGContextAddArcToPoint will draw straight lines past the start and end of the arc
// in order to create the path from the current position and the destination position.
// In order to create the 4 arcs correctly, we need to know the min, mid and max positions
// on the x and y lengths of the given rectangle.
CGFloat minx = CGRectGetMinX(rrect), midx = CGRectGetMidX(rrect), maxx = CGRectGetMaxX(rrect);
CGFloat miny = CGRectGetMinY(rrect), midy = CGRectGetMidY(rrect), maxy = CGRectGetMaxY(rrect);
// Next, we will go around the rectangle in the order given by the figure below.
// minx midx maxx
// miny 2 3 4
// midy 1 9 5
// maxy 8 7 6
// Which gives us a coincident start and end point, which is incidental to this technique, but still doesn't
// form a closed path, so we still need to close the path to connect the ends correctly.
// Thus we start by moving to point 1, then adding arcs through each pair of points that follows.
// You could use a similar tecgnique to create any shape with rounded corners.
// Start at 1
CGContextMoveToPoint(context, minx, midy);
// Add an arc through 2 to 3
CGContextAddArcToPoint(context, minx, miny, midx, miny, radius);
// Add an arc through 4 to 5
CGContextAddArcToPoint(context, maxx, miny, maxx, midy, radius);
// Add an arc through 6 to 7
CGContextAddArcToPoint(context, maxx, maxy, midx, maxy, radius);
// Add an arc through 8 to 9
CGContextAddArcToPoint(context, minx, maxy, minx, midy, radius);
// Close the path
CGContextClosePath(context);
// Fill & stroke the path
CGContextDrawPath(context, kCGPathFillStroke);
Solution 3:
UIBezierPath *bezierPath = [UIBezierPath bezierPathWithRoundedRect:bubbleBounds cornerRadius:15.0];
CGContextSetStrokeColorWithColor(context, [UIColor grayColor].CGColor);
[bezierPath stroke];
Solution 4:
Here is a function I wrote that rounds the input rect using a corner radius.
CGMutablePathRef createRoundedCornerPath(CGRect rect, CGFloat cornerRadius) {
// create a mutable path
CGMutablePathRef path = CGPathCreateMutable();
// get the 4 corners of the rect
CGPoint topLeft = CGPointMake(rect.origin.x, rect.origin.y);
CGPoint topRight = CGPointMake(rect.origin.x + rect.size.width, rect.origin.y);
CGPoint bottomRight = CGPointMake(rect.origin.x + rect.size.width, rect.origin.y + rect.size.height);
CGPoint bottomLeft = CGPointMake(rect.origin.x, rect.origin.y + rect.size.height);
// move to top left
CGPathMoveToPoint(path, NULL, topLeft.x + cornerRadius, topLeft.y);
// add top line
CGPathAddLineToPoint(path, NULL, topRight.x - cornerRadius, topRight.y);
// add top right curve
CGPathAddQuadCurveToPoint(path, NULL, topRight.x, topRight.y, topRight.x, topRight.y + cornerRadius);
// add right line
CGPathAddLineToPoint(path, NULL, bottomRight.x, bottomRight.y - cornerRadius);
// add bottom right curve
CGPathAddQuadCurveToPoint(path, NULL, bottomRight.x, bottomRight.y, bottomRight.x - cornerRadius, bottomRight.y);
// add bottom line
CGPathAddLineToPoint(path, NULL, bottomLeft.x + cornerRadius, bottomLeft.y);
// add bottom left curve
CGPathAddQuadCurveToPoint(path, NULL, bottomLeft.x, bottomLeft.y, bottomLeft.x, bottomLeft.y - cornerRadius);
// add left line
CGPathAddLineToPoint(path, NULL, topLeft.x, topLeft.y + cornerRadius);
// add top left curve
CGPathAddQuadCurveToPoint(path, NULL, topLeft.x, topLeft.y, topLeft.x + cornerRadius, topLeft.y);
// return the path
return path;
}
How to use the function, assuming you subclass UIView and override drawRect:
- (void)drawRect:(CGRect)rect {
// constants
const CGFloat outlineStrokeWidth = 20.0f;
const CGFloat outlineCornerRadius = 15.0f;
const CGColorRef whiteColor = [[UIColor whiteColor] CGColor];
const CGColorRef redColor = [[UIColor redColor] CGColor];
// get the context
CGContextRef context = UIGraphicsGetCurrentContext();
// set the background color to white
CGContextSetFillColorWithColor(context, whiteColor);
CGContextFillRect(context, rect);
// inset the rect because half of the stroke applied to this path will be on the outside
CGRect insetRect = CGRectInset(rect, outlineStrokeWidth/2.0f, outlineStrokeWidth/2.0f);
// get our rounded rect as a path
CGMutablePathRef path = createRoundedCornerPath(insetRect, outlineCornerRadius);
// add the path to the context
CGContextAddPath(context, path);
// set the stroke params
CGContextSetStrokeColorWithColor(context, redColor);
CGContextSetLineWidth(context, outlineStrokeWidth);
// draw the path
CGContextDrawPath(context, kCGPathStroke);
// release the path
CGPathRelease(path);
}
Example output:
Solution 5:
If you want To have rounded corners on any UIView (or subclass) the easy way is to set the cornerRadius property on the view's layer. See Preview rounded image in iphone