fix: iOS/watchOS scale not work

[akring]

No description provided.

[swhitty]

Hi, thanks for attempting to address this issue. I've double checked and SwiftDraw's code is working correctly — I've added a new unit test to prove it;

When we rasterize an image we provide the size in points (not pixels) and a scale that would typically correlate to the screen scale. The underlying UIImage is created with the right number of pixels, but this is not really visible until you save it to disk and open in an editor.

let svg = SVG(named: "gradient-apple.svg", in: .test)!
let image = svg.rasterize(with: CGSize(width: 100, height: 100), scale: 3)
XCTAssertEqual(image.size, CGSize(width: 100, height: 100))
XCTAssertEqual(image.scale, 3)

You can also load the PNG Data back into a new UIImage and it will show the size in raw pixels.

let data = image.pngData()!
let reloaded = UIImage(data: data)!
XCTAssertEqual(reloaded.size, CGSize(width: 300, height: 300))
XCTAssertEqual(reloaded.scale, 1)

I appreciate this may not be clear from the API and possibly you are looking to instead increase/decrease the size of an SVG? I could offer a "transform" API on SVG to allow this, after applying all transformations you can then rasterize using the existing API. I'm thinking something like this;

let svg = SVG(named: "chart.svg", in: .test)!
let scaled = svg.scale(2.0)

// svg.size == CGSize(width: 160, height: 160)
// scaled.size == CGSize(width: 320, height: 320)

let image = scaled.rasterize()

[swhitty]

FYI I have made these changes on the main branch allowing the SVG object to be transformed with scale / translate / expand before calling rasterize()

let svg = SVG(name: "fish.svg")!  // 100x100 
    .expand(left: 10, right: 10)  // 120x100
    .scale(2)                     // 240x200

let image = svg.rasterize()       // 240x200