!7

cmodule WebCamDemo > DynPrintLog {
  !include #1029545 // API for Eleu
  
  O html(IWebRequest request) {
    //ret "URI: " + request.uri();
    ret hsansserif() + hfullcenter(p("WebCam Preview")
      + hfulltag video("", autoplay := true, id := "webcamPreview",
          style := "width: 600px; height: 400px; border: 5px solid red;")
      + p("Snapshot " + hbutton("Grab", onclick := "snapshot()"))
      + hfulltag canvas("", id := "snapshotCanvas", width := 300, height := 200, style := "border: 3px solid green;")
    ) + hscript([[
        var video = document.querySelector("#webcamPreview");

        if (navigator.mediaDevices.getUserMedia) {
          navigator.mediaDevices.getUserMedia({ video: true })
            .then(function (stream) {
              video.srcObject = stream;
              getVideoSize();
            })
            .catch(function (err0r) {
              console.log("Something went wrong: " + err0r);
            });
        };

        async function getVideoSize() {
          await new Promise(resolve => video.onloadedmetadata = resolve);
          console.log(`video size: ${video.videoWidth}x${video.videoHeight}`);
        }

        var snapshotW, snapshotH;

        function snapshot() {
          var canvas = document.getElementById("snapshotCanvas");
          var w = video.videoWidth, h = video.videoHeight;
          var w2 = canvas.width, h2 = canvas.height;
          if (w/h > w2/h2)
            h2 = h*w2/w;
          else
            w2 = w*h2/h;
          snapshotW = w2; snapshotH = h2;
          canvas.getContext("2d").drawImage(video, 0, 0, w2, h2);

          avgBrightness();
        }

        function avgBrightness() {
          var imageData = canvas.getContext("2d").getImageData(0, 0, snapshotW, snapshotH);
          var pixels = imageData.data;

          for (var i = 0, il = 10/*pixels.length*/; i < il; i++) {
            console.log(pixels[i]);
          }
        }
      ]]);
  }
}