Fix rendering mode in toolbar button by setting it on the UIImage itself

[hartbit]

When displaying a WebImage inside a Button, inside a ToolbarItem, the rendering mode modifier doesn't work. It looks like a SwiftUI bug, although I wasn't able to reproduce it with plain SwiftUI, with images coming from the asset catalog. Instead, I've found a fix which is to set the rendering mode on the UIImage itself.

Here's the code to reproduce the issue:

struct ContentView: View {
    let url = URL(string: "https://png-2.findicons.com/files/icons/2118/nuvola/48/help.png")!

    var body: some View {
        NavigationView {
            WebImage(url: url)
                .renderingMode(.original)
                .toolbar {
                    ToolbarItem(placement: .navigationBarLeading) {
                        WebImage(url: url)
                            .renderingMode(.original)
                    }
                    ToolbarItem(placement: .navigationBarTrailing) {
                        Button(action: {}, label: {
                            WebImage(url: url)
                                .renderingMode(.original)
                        })
                    }
                }
        }
    }
}

Note: If you try to reproduce this, you might encounter another SwiftUI bug which seems unrelated: images render at their native size, even when made resizable and set to a fixed frame.

[codecov[bot]]

Codecov Report

Merging #175 (11c3829) into master (88f2d67) will increase coverage by 0.34%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #175      +/-   ##
==========================================
+ Coverage   73.78%   74.13%   +0.34%     
==========================================
  Files          11       11              
  Lines         965      978      +13     
==========================================
+ Hits          712      725      +13     
  Misses        253      253              

Flag	Coverage Δ
ios	69.55% <85.71%> (+0.21%)	:arrow_up:
macos	75.00% <100.00%> (+0.37%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
SDWebImageSwiftUI/Classes/WebImage.swift	90.30% <100.00%> (+0.68%)	:arrow_up:

---

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[dreampiggy]

This simple fix breaks the Vector image (SVG/PDF) and Animated image (GIF/APNG/WebP) for WebImage struct. So I can not merge.

This is because of [UIImage imageWithRenderingMode:] API recreate a new UIImage instance, which loss the information our framework setup, and does not allows the subclassing SDAnimatedImage.

But I'll try to investigate your demo's issue and provide some solution.

[dreampiggy]

Seems this only works on SwiftUI.Image is because of SwiftUI team do hack type checking to that Image, our WebImage is not considered an actual Image in SwiftUI internal logic.

I'll find some trick way to workaround this.

[dreampiggy]

They override the renderingMode Only if your image is inside an TabbarItem, using UIKit's UIToolBarItem.

How can I get this context as well (That WebImage is now using in Tabbar) ? If I can not get this context, actually, as an framework user, you have to provide .renderingMode modifier when use on Tabbar.

However, SwiftUI.Image does not need you to do this, they provide the renderingMode for you automatically.

[hartbit]

Seems this only works on SwiftUI.Image is because of SwiftUI team do hack type checking to that Image, our WebImage is not considered an actual Image in SwiftUI internal logic.

But WebImage contains a SwiftUI.Image. Why does SwiftUI not notice that? Is it a SwiftUI bug? If yes, is there a simple example we can create a bug report with?

[dreampiggy]

But WebImage contains a SwiftUI.Image. Why does SwiftUI not notice that? Is it a SwiftUI bug? If yes, is there a simple example we can create a bug report with?

You're right. It's Bug. See result:

Demo:

// ContentView.swift
    var body: some View {
        NavigationView {
            WebImage(url: url)
                .renderingMode(.original)
                .toolbar {
                    ToolbarItem(placement: .navigationBarLeading) {
                        Button(action: {}, label: {
                            WebImage()
                        })
                    }
                }
        }
    }
// WebImage.swift
// Helper method, just for testing
   public static func createUIImage() -> UIImage {
        let data = try! Data(contentsOf: URL(string: "https://png-2.findicons.com/files/icons/2118/nuvola/48/help.png")!)
        let source = CGImageSourceCreateWithData(data as CFData, nil)!
        let cgImage = CGImageSourceCreateImageAtIndex(source, 0, nil)!

        let image = UIImage(cgImage: cgImage, scale: 1, orientation: .up)
        return image
    }

Code 1:

    public var body: some View {
        Image(uiImage: WebImage.createUIImage())
    }

Code 2:

    public var body: some View {
        Image(decorative: WebImage.createUIImage().cgImage!, scale: 1)
    }

Screenshot:

[dreampiggy]

@hartbit Effected by #159

Seems Apple does not fix all of the bad case for Image(uiImage:) initializer. I'll decide to revert that MR.

[dreampiggy]

Fix works well. I'll submit PR and release 2.0.2

[hartbit]

Thanks! Do you plan to open a bug report with Apple or do you want me to do it?

[dreampiggy]

@hartbit See #177

[dreampiggy]

Should be fixed in v2.0.2

[hartbit]

@dreampiggy Thanks again for your the support 👍

[dreampiggy]

Thanks! Do you plan to open a bug report with Apple or do you want me to do it?

@hartbit Hi. I think you can submit the bug report to Apple. It's easy to reproduce. https://bugreport.apple.com/web/

Just using this API Image(uiImage:) to create an new Image struct, put it into the Tabbar via Button and see the result.

The demo code is above. The demo is not related to whether use WebImage or your own View type at all.

---

But actually, Apple's team may think this is not a bug ? Because UIImage itself does have a renderingMode property. But Image sturct has another renderingMode modifier. In SwiftUI, the Image is both View and Model. However, in UIKit, UIImage is only the Model but not how it rendered.