[BUG] Markers without symmetrical anchors disappear before they are out of bounds

[aytunch]

I believe the fix below handles the markers which have anchors in the center or edges.

#313

I have printed the marker width and height values and they are all as they are supposed to be.
If I increase the marker width artificially then the disappearing stops but the anchors are getting corrupted of course. So I think it might be a bug in the package. I might be wrong though.

RPReplay_Final1622477362.mov

[aytunch]

@lpongetti sorry to bother you but do you think this might be a bug? Or am I doing something wrong?

[rorystephenson]

@aytunch can you provide a minimal code example?

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[aytunch]

@JaffaKetchup @ibrierley Hi:)
I am still having this issue with anchors not in the horizontal middle. Have you encountered something similar?
I checked my code multiple times and the anchor position and marker width/height are right.
When I zoom in/out the notch below the marker always stays on the center latLng as expected. But For some reason, the markers disappear while leaving the map bounds. I am thinking maybe there is something wrong with the optimization calculations done to not display out of bound markers. It might assume that anchors are always in the middle horizontally.

This calculation in lib/src/layer/marker_layer.dart assumes that the marker is symmetric around pixelPoint which is the center latLng (anchor)
As seen in my video, some markers have different space on the left and right side of the anchor points.
So when calculating, sw and ne we need to add different widths which are calculated using non existent anchor.right and anchor.bottom (we can deduce them though)

  bool _boundsContainsMarker(Marker marker) {
    var pixelPoint = map.project(marker.point);

    final width = marker.width - marker.anchor.left;
    final height = marker.height - marker.anchor.top;

    var sw = CustomPoint(pixelPoint.x + width, pixelPoint.y - height);
    var ne = CustomPoint(pixelPoint.x - width, pixelPoint.y + height);
    return map.pixelBounds.containsPartialBounds(Bounds(sw, ne));
  }

[ibrierley]

Out of interest, what are your marker and anchor details ?

[aytunch]

@ibrierley This is what I have. Nothing special. Just some arithmetic to calculate the width and anchorX positions according to how many icons will be inside the marker. Now that I tried putting the anchor in width/2, and saw no disappearing, I am very positive the NE and SW calculations are assuming symmetry.

[aytunch]

@ibrierley You can see what double and triple icon markers look like and please see where the notch (anchor) is. It is unsymmetrical according to the width.

I am positive that my markers fall in to this condition when they are half way off screen's left edge and they don't get displayed. The for loop continues from the next marker.

if (!_boundsContainsMarker(markerOpt)) {
   continue;
}