Draw squares with Core Graphics or include pngs? - iphone

Question

I'm making a legend for a graph that will basically look like this:
[ ] Line 1
[ ] Line 2
[ ] Line 3
The boxes on the left need to be the same color as the lines on the graph.
Anyhow, all I need to know, is whether it's faster to draw the boxes with Core Graphics or just make some pngs with GIMP for the squares and include them.

Answer 1

Use UIView for each legend and set their background color to the color you want.

Answer 2

Both approaches are fast enough that it shouldn't make a difference. However, using Core Graphics has the advantage that you're a lot more flexible, e.g. when you later decide that you need additional colors. Plus, your app will be smaller, because you don't have to include the PNG files.

Answer 3

Drawing boxes is a snap! I would go with Core Graphics everyday, especially since you get retina support for free.
As can be seen in this example you can do it using UIKit only classes:
// Setup colors
[myBoxColor setFill];
[myBoxBorderColor set];
// Setup a path for the box
UIBezierPath* path = [UIBezierBath bezierPathWithRect:rectOfTheBox];
path.lineWidth = 2;
// Draw!
[path fill];
[path stroke];
One warning; stroke fills using the edges of the path as the center of the line. So you will get a blurry line if you stroke a path with integral rect with a 1 point line width.
You can remedy this is you want a 1 point line for the border by doing something like this:
CGRect strokeRect = UIEdgeInsetsInsetRect(rectOfTheBox,
UIEdgeInsetsMake(0.5f,0.5f,0.5f,0.5f));
UIBezierPath* path = [UIBezierPath bezierPathWithRect:strokeRect];
[path stroke];

Answer 4

On iOS, Core Graphics is quite simple to use. In your view's drawRect: method, just do this to draw a square:
- (void)drawRect:(CGRect)frame {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(context, 0.5, 0.5, 0.5, 1); // gray
CGContextFillRect(context, CGRectMake(10, 10, 20, 20)); // our rect is {10,10,20,20)
// draw a line
CGContextSetRGBStrokeColor(context, 1, 0, 0, 1);
CGContextBeginPath(context);
CGContextMoveToPoint(context, startX, startY);
CGContextAddLineToPoint(context, endX, endY);
CGContextStrokePath(context);
}
Hope this helps!