image popup: zoom, pan, scroll, pin, scale
当前为
// 01. to use hover over the image(container) to view a popup of the target image
// 02. to zoom in/out use wheel up/down.
// 03. click left mouse to lock popup this will make it move along with the mouse, click again to release (indicated by green border)
// 04. while being locked"Y" the wheel up/down will act as scroll up/down
// 05. double click will lock it on screen preventing it from being hidden
// 06. hover below the image and click blue bar this will make a 3rd mode for wheel bottom, which will scroll next/previous image under an album
// 07. while locked at screen (indicated by red outline) a single click with the blurred background will unblur it, only one popup per time, so the locked popup will prevent other popup to spawn
// 08. double clicking on blurred background will de-spawn popup
// 09. click on the corner to toggle scaling (blue) will retain current aspect ratio, double clicking will turn to 2nd mode for scaling (magenta) will not retain current aspect ratio
// 10. return to original aspect ration via clicking on sides, if it's in an album to reset to aspect ratio on bottom side use double click
// 11. to turn on/off hover at the bottom of the page
