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Add allowsEdgeAntialiasing on views with rotations or skew tr… (#32920)
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Summary:
…ansforms

On iOS, if a View is rotated with the a transform (e.g. <View style={{transform: {rotationZ: 5}}} />), the view has aliasing  (see screenshot). Same for a skew transformation. We don't have the issue on Android

This behavior had originally being fixed by this PR #1999

However a new PR was merge ( #19360 ) that broke this. I think it was made to add antialiasing during perspective transforms but seems to have broken the antialiasing when rotationZ transforms

This PR adds back the antialising during rotation transform , while keeping it during perspective transform.

## Changelog

I changed the allowsEdgeAntialiasing condition, making it "true" when the m12 or m21 is not 0. From this article https://medium.com/swlh/understanding-3d-matrix-transforms-with-pixijs-c76da3f8bd8 , I've understood that in all rotation or skew transformations, m12 or m21 is different than 0 . In the other transformation (e.g. scale or translate) it stays at 0.

Although, I'm not a matrix transformation expert so I may be mistaken

Pull Request resolved: #32920

Test Plan:
I've written several views with all rotateX/Y/Z , skewX,Y and perpective transformation. Before the PR some transformation was showing aliasing on iOS (e.g. top-left view in the screenshot, don't hesitate to zoom in the image if you don't see it) and with this PR it does not have anymore

Before

![Simulator Screen Shot - iPhone 13 - 2022-01-19 at 10 09 35](https://user-images.githubusercontent.com/6890533/150100149-5370c0fc-ba4f-499f-8e41-a40a10b466a9.png)

After
![Simulator Screen Shot - iPhone 13 - 2022-01-19 at 10 10 39](https://user-images.githubusercontent.com/6890533/150100229-1bb5077f-d6bb-48a2-b852-acf726fcb59e.png)

Code I used to test

```
const commonStyle = {
  width: 150,
  height: 100,
  backgroundColor: "red",
  margin: 10,
}

const Test = () => (
  <View style={{ flexDirection: "row" }}>
    <View>
      <View
        style={[
          commonStyle,
          {
            transform: [{ rotateZ: "4deg" }],
          },
        ]}
      />

      <View
        style={[
          commonStyle,
          {
            transform: [{ rotateX: "30deg" }],
          },
        ]}
      />

      <View
        style={[
          commonStyle,
          {
            transform: [{ rotateY: "30deg" }],
          },
        ]}
      />
      <View
        style={[
          commonStyle,
          {
            transform: [{ rotateX: "30deg" }, { rotateY: "30deg" }, { rotateZ: "3deg" }],
          },
        ]}
      />
    </View>

    <View>
      <View
        style={[
          commonStyle,
          {
            transform: [{ skewX: "4deg" }],
          },
        ]}
      />

      <View
        style={[
          commonStyle,
          {
            transform: [{ skewY: "4deg" }],
          },
        ]}
      />

      <View
        style={[
          commonStyle,
          {
            transform: [{ skewY: "4deg" }, { rotateZ: "3deg" }],
          },
        ]}
      />

      <View
        style={[
          commonStyle,
          {
            transform: [{ perspective: 1000 }],
          },
        ]}
      />
    </View>
  </View>
)
```

Reviewed By: lunaleaps

Differential Revision: D33665910

Pulled By: sshic

fbshipit-source-id: 91163ec2a0897a73ddf0310d86afacea04b89bc7
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Arkolos authored and facebook-github-bot committed Jan 24, 2022
1 parent 48f6967 commit e6a3410
Showing 1 changed file with 3 additions and 2 deletions.
5 changes: 3 additions & 2 deletions React/Views/RCTViewManager.m
Original file line number Diff line number Diff line change
Expand Up @@ -163,8 +163,9 @@ - (RCTShadowView *)shadowView
RCT_CUSTOM_VIEW_PROPERTY(transform, CATransform3D, RCTView)
{
view.layer.transform = json ? [RCTConvert CATransform3D:json] : defaultView.layer.transform;
// Enable edge antialiasing in perspective transforms
view.layer.allowsEdgeAntialiasing = !(view.layer.transform.m34 == 0.0f);
// Enable edge antialiasing in rotation, skew, or perspective transforms
view.layer.allowsEdgeAntialiasing = view.layer.transform.m12 != 0.0f || view.layer.transform.m21 != 0.0f ||
view.layer.transform.m34 != 0.0f;
}

RCT_CUSTOM_VIEW_PROPERTY(accessibilityRole, UIAccessibilityTraits, RCTView)
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