Image recenters after dragging

[ascoders]

Image recenters after dragging

[marconett]

Same problem as #47, #39, #11.

two workarounds:

1. setting an initial zoomscale larger than 1

    centerOn={{
        x: 0, y: 0, scale: 1.01, duration: 100
    }}

problem with this: if the user manually zooms all the way out, the problem is there again.

2. enabling swipeDown and settings Threshold to -1

          enableSwipeDown={true}
          swipeDownThreshold={-1}

problem with this: there's no bounceback at all and you can scroll indefinitely on the vertical axis (scrolling the image out if view).

i think the problem stems from people (including myself) trying to use this library to display very large images (like a map), where the lib trying to center and show the image as a whole is unwanted behavior.

would be kind of cool to be able to enable a "Map Mode" or something. it's almost there with the second workaround, there just needs to be a fix for the indefinite vertical scroll.

[allthetime]

Seeing this as well. Also, edges are chopped off landscape images and zooming out to show the whole image also leads to this problem.

[ascoders]

Seems like edges would be chopped when load large image? I'll test it.

[allthetime]

@ascoders I made a workaround by changing _this.scale to 0.6 in image-zoom.component.js. I think I can figure out how to fix it properly but I don't have time right now!