Bug - iOS (Safari) runaway memory issue when panning while zoomed on single image

I’m experiencing a major memory issue. It only happens when I’m zoomed in to a certain point though, and only on physical iOS devices.

I’d love to hear if anyone’s having similar issues or have any ideas as to what might be wrong here. Also ideas to workarounds if it’s not feasible to diagnose.

Steps

1. Zoom in on the image (far enough, does not happen when only zoomed in… eh… some)
2. Pan around
3. Crash

Setup

• Runs in within a Cordova app
• iOS 9.3 (same on 3 different test devices)
  • Does not occur on Android
  • Also does not occur when running the same code through the various iOS simulators

Config

OpenSeadragon({
      id: 'seadragon-viewer',
      tileSources: {
        type: 'legacy-image-pyramid',
        levels: [{
          url: 'http://example.com/example.jpeg',
          height: 1938,
          width: 984
        }]
      },
      showNavigationControl: false,
      animationTime: 0.2,
      visibilityRatio: 1.0,
      gestureSettingsTouch: {
        pinchRotate: false,
        flickMomentum: 0,
        dblClickToZoom: false
      },
      maxZoomPixelRatio: 2.0,
      minZoomPixelRatio: 10.0,
      springStiffness: 4.5,
      viewportMargins: {
         left: deviceDimensions.clientWidth * 0.2,
         top: deviceDimensions.clientHeight * 0.1,
         right: deviceDimensions.clientWidth * 0.2,
         bottom: deviceDimensions.clientHeight * 0.1
      }
    })

Measurements

## Profiling

The QuartzCore behaves normally and allocates very little memory each time before suddenly jumping to 11.16MiB several times in the span of a few milliseconds.

[plougsgaard]

@iangilman I found the culprit! - https://github.com/openseadragon/openseadragon/commit/8c4fcc9ca9289b54f3dd77155ff0b3888a3847e7 - after some git bisect action testing with the overlay.html demo page.

This commit turns on when the zoom is greater than smoothTileEdgesMinZoom, so setting it to Infinity simply turns off that commit.

Edit: just like you eluded to in your first comment I suppose!

[iangilman]

Sounds good. Thank you for tracking it down! I look forward to the patch when you can get to it.

@mindfreeze FYI, it appears #764 causes problems on iOS; see above.