# iPhone Core Quartz 一- Round Rectangle

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iPhone Core Quartz 1- Round Rectangle

- (void)drawRoundRect : (CGContextRef)context {

```	// Drawing with a white stroke color
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
// And draw with a blue fill color
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1.0);
// Draw them with a 2.0 stroke width so they are a bit more visible.
CGContextSetLineWidth(context, 2.0);

CGRect rrect = CGRectMake(210.0, 90.0, 60.0, 60.0);
// 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
// Add an arc through 4 to 5
// Add an arc through 6 to 7