CODEWITHSUNDEEP
iosiphoneobjective-cios7
user1831389
user1831389

Reputation: 201

iPhone CGContext: drawing line with two different colors

I want to draw a line with different colors using CGContext.

This is my code

   CGSize size = CGSizeMake(200, 200);
    UIGraphicsBeginImageContextWithOptions(size, NO, 0);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetLineWidth(context, 2.0);
    CGContextMoveToPoint(context, 1, 1);

    CGContextBeginPath(context);
    CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
    CGContextAddLineToPoint(context, 50, 50);
    CGContextAddLineToPoint(context, 100, 50);
    CGContextStrokePath(context);

    CGContextBeginPath(context);
    CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
    CGContextAddLineToPoint(context, 200, 100);
    CGContextStrokePath(context);

I am trying this code, its returns error:

<Error>: CGContextAddLineToPoint: no current point.

Upvotes: 0

Views: 1304

Answers (2)

simalone
simalone

Reputation: 2768

Following code maybe help you:

CGSize size = CGSizeMake(200, 200);
//UIGraphicsBeginImageContextWithOptions(size, NO, 0); //comment this line,  if you want a image, see bottom two line.
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);

CGContextBeginPath(context);
CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
CGContextMoveToPoint(context, 1, 1);   //MoveToPoint First
CGContextAddLineToPoint(context, 50, 50);
CGContextAddLineToPoint(context, 100, 50);
CGContextStrokePath(context);

CGContextBeginPath(context);
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
CGContextMoveToPoint(context, 100, 50);   //MoveToPoint First
CGContextAddLineToPoint(context, 200, 100);
CGContextStrokePath(context);

//UIImage* resultImage = UIGraphicsGetImageFromCurrentImageContext(); //if you just need a image
//UIGraphicsEndImageContext(); //match UIGraphicsBeginImageContextWithOptions, if need a image

Upvotes: 0

ChenSmile
ChenSmile

Reputation: 3441

CGContextRef context = UIGraphicsGetCurrentContext();
CGContextClearRect(context, rect);
CGContextSetLineWidth(context, 2.0);

CGContextBeginPath(context);
CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
CGContextMoveToPoint(context, 1, 1);
CGContextAddLineToPoint(context, 100, 100);
CGContextStrokePath(context); // and draw blue line

CGContextBeginPath(context);
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
CGContextMoveToPoint(context, 100, 100);
CGContextAddLineToPoint(context, 200, 100);     
CGContextStrokePath(context); // draw red line

Upvotes: 2

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