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Scroll Zoom Speed Logic

See original GitHub issue

Hello, In one of my projects, I had to implement logic to increase zoom speed based on how fast the user is scrolling the mouse wheel. I figured that this might be a useful feature for some, so I decided to post it here. Here’s the core code:

viewer.addHandler("canvas-scroll", function (event) {
        //Create var to count number of consecutive scrolls that have taken place within the specified time limit of each other
        if (typeof this.scrollNum == 'undefined') {
            this.scrollNum = 0;
        }

        //Create var to store the time of the previous scroll that occurred
        if (typeof this.lastScroll == 'undefined') {
            this.lastScroll = new Date();
        }

        this.currentScroll = new Date(); //Time that this scroll occurred at

        //If the last scroll was less than 400 ms ago, increase the scroll count
        if (this.currentScroll - this.lastScroll < 400) {
            this.scrollNum++;
        }
        //Otherwise, reset the count and zoom speed
        else {
            this.scrollNum = 0;
            viewer.zoomPerScroll = 1.2;
        }

        //If user has scrolled more than twice consecutively within 400 ms, increase the scroll speed with each consecutive scroll afterwards
        if (this.scrollNum > 2) {
            //Limit maximum scroll speed to 2.5
            if (viewer.zoomPerScroll <= 2.5) {
                viewer.zoomPerScroll += 0.2;
            }
        }

        this.lastScroll = this.currentScroll; //Set last scroll to now
    });

Currently there are a lot of hard coded values but those could easily be changed to variables.

Enjoy!