I'm trying to adapt an example provided by Apple in order to programmatically draw stars in line, the code is the following:
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, aSize);
for (NSUInteger i=0; i<stars; i++)
{
CGContextSetFillColorWithColor(context, aColor);
CGContextSetStrokeColorWithColor(context, aColor);
float w = item.size.width;
double r = w / 2;
double theta = 2 * M_PI * (2.0 / 5.0); // 144 degrees
CGContextMoveToPoint(context, 0, r);
for (NSUInteger k=1; k<5; k++)
{
float x = r * sin(k * theta);
float y = r * cos(k * theta);
CGContextAddLineToPoint(context, x, y);
}
CGContextClosePath(context);
CGContextFillPath(context);
}
The code above draws a perfect star, but is 1. displayed upside down 2. is black and without border. What I want to achive is to draw many stars on the same line and with the given style. I understand that I'm actually drawing the same path 5 times in the same position and that I have somehow to flip the context vertically, but after several tests I gave up! (I lack the necessary math and geometry skills :P)... could you please help me?
UPDATE:
Ok, thanks to CocoaFu, this is my refactored and working draw utility:
- (void)drawStars:(NSUInteger)count inContext:(CGContextRef)context;
{
// constants
const float w = self.itemSize.width;
const float r = w/2;
const double theta = 2 * M_PI * (2.0 / 5.0);
const float flip = -1.0f; // flip vertically (default star representation)
// drawing center for the star
float xCenter = r;
for (NSUInteger i=0; i<count; i++)
{
// get star style based on the index
CGContextSetFillColorWithColor(context, [self fillColorForItemAtIndex:i]);
CGContextSetStrokeColorWithColor(context, [self strokeColorForItemAtIndex:i]);
// update position
CGContextMoveToPoint(context, xCenter, r * flip + r);
// draw the necessary star lines
for (NSUInteger k=1; k<5; k++)
{
float x = r * sin(k * theta);
float y = r * cos(k * theta);
CGContextAddLineToPoint(context, x + xCenter, y * flip + r);
}
// update horizontal center for the next star
xCenter += w + self.itemMargin;
// draw current star
CGContextClosePath(context);
CGContextFillPath(context);
CGContextStrokePath(context);
}
}
Here is code that will draw 3 stars in a horizontal line, it's is not pretty but it may help:
-(void)drawRect:(CGRect)rect
{
int aSize = 100.0;
const CGFloat color[4] = { 0.0, 0.0, 1.0, 1.0 }; // Blue
CGColorRef aColor = CGColorCreate(CGColorSpaceCreateDeviceRGB(), color);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, aSize);
CGFloat xCenter = 100.0;
CGFloat yCenter = 100.0;
float w = 100.0;
double r = w / 2.0;
float flip = -1.0;
for (NSUInteger i=0; i<3; i++)
{
CGContextSetFillColorWithColor(context, aColor);
CGContextSetStrokeColorWithColor(context, aColor);
double theta = 2.0 * M_PI * (2.0 / 5.0); // 144 degrees
CGContextMoveToPoint(context, xCenter, r*flip+yCenter);
for (NSUInteger k=1; k<5; k++)
{
float x = r * sin(k * theta);
float y = r * cos(k * theta);
CGContextAddLineToPoint(context, x+xCenter, y*flip+yCenter);
}
xCenter += 150.0;
}
CGContextClosePath(context);
CGContextFillPath(context);
}