CODEWITHSUNDEEP
ioscocoa-touchcore-graphicspixelpoint
Siddharth
Siddharth

Reputation:

How do I draw a point using Core Graphics?

I see APIs in Quartz for drawing lines and circles. But all I want to do is to specify the (x,y) cartesian coordinate to color a pixel a particular value. How do I do that?

Upvotes: 18

Views: 23059

Answers (7)

Antoine Weber
Antoine Weber

Reputation: 1904

Swift 3 :

 UIRectFill(CGRect(x: x, y: y, width: 1, height: 1))

UIRectFill()

Upvotes: 0

Doug Ahmann
Doug Ahmann

Reputation: 

CGContextFillRect(context, CGRectMake(x,y,1,1));

Upvotes: 22

Paulo
Paulo

Reputation: 1245

Draw a very small ellipse/circle and fill it!

CGContextAddEllipseInRect(Context,(CGRectMake (x_dot, y_dot, 3.0, 3.0));
CGContextDrawPath(Context, kCGPathFill);
CGContextStrokePath(Context);

I am using this code to create a small dot (3x3 pixels) in a dotted music note.

Upvotes: 8

Chad
Chad

Reputation: 71

I got a point (zero length line) to draw after setting the line-caps to kCGLineCapRound. The default line-cap has no length so can't be drawn.

The argument that a point has no size is silly. The lines have no width but we can draw those (by using the "line width" from the draw state). A point should draw in exactly the same way, and with different line caps I believe it does.

Maybe this behavior is new?

Upvotes: 7

Reputation:

I'm having the same issue - i find the best solution is similar to the last, but at least it doesn't leave something that looks like a "dash"... of course, should ensure x/y are both > 0.

CGContextFillRect(context, CGRectMake(x - 0.5, y - 0.5, 1.0 , 1.0));

Upvotes: 0

Jens Ayton
Jens Ayton

Reputation: 14558

Quartz is not a pixel-oriented API, and its contexts aren’t necessarily pixel buffers. If you want to draw pixmaps, create a bitmap context with CGBitmapContextCreate(). You provide a buffer, which you can manipulate directly, and can copy to another context by creating a CGImage from the same buffer using CGImageCreate() and drawing that.

Upvotes: 16

Ben Gottlieb
Ben Gottlieb

Reputation: 85522

You can draw a 1-pixel-length line at the coordinate in question; that should accomplish what you want.

Upvotes: 4

Related Questions