[GitHub] [echarts] grigiada commented on issue #16103: zoom / datazoom in touchscreen

[GitBox <gi...@apache.org>]

grigiada commented on issue #16103:
URL: https://github.com/apache/echarts/issues/16103#issuecomment-979724403


   Thank you for your reply.
   No particular device is needed to test the malfunction but any touch
   monitor connected to a windows pc.
   I seem to have solved this problem by rewriting the function that
   recognizes the touch capabilities of the monitor.
   
   In echarts.js I substitute this condition
        env.touchEventsSupported = 'ontouchstart' in window && !browser.ie &&
   !browser.edge;
   with this one:
        env.touchEventsSupported = detectTouchscreen();
   
   where the function detectTouchscreen() is implemented as follows:
   
   function detectTouchscreen() {
           var result = false;
           if (window.PointerEvent && ('maxTouchPoints' in navigator)) {
               // if Pointer Events are supported, just check maxTouchPoints
               if (navigator.maxTouchPoints > 0) {
                   result = true;
               }
    } else {
               // no Pointer Events...
               if (window.matchMedia &&
   window.matchMedia("(any-pointer:coarse)").matches) {
                   // check for any-pointer:coarse which mostly means
   touchscreen
                   result = true;
               } else if (window.TouchEvent || ('ontouchstart' in window)) {
                   // last resort - check for exposed touch events API / event
   handler
                   result = true;
               }
           }
           return result;
       }
   
   I hope it will be useful to improve the functioning of your library.
   
   Reading the forums I am not the only one with this problem and it would be
   very useful if the next release had this function.
   
   Have a good day.
   
   Giada
   
   Il giorno ven 26 nov 2021 alle ore 06:03 Yi Shen ***@***.***>
   ha scritto:
   
   > @grigiada <https://github.com/grigiada> I'm afraid we don't have the
   > specifc device to do the test. Do you mind taking a deep look at it and
   > report us with more detail?
   >
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