Disable scroll when "drawmode" enabled.

[bdero]

This is a port of the change from https://github.com/open-craft/jsinput-vectordraw/pull/31.

Testing instructions (Using an Android or IOS browser):

1. Setup a devstack.

2. Install this xblock on this branch into the edxapp Python virtualenv.

   # In the same directory as your Vagrantfile:
   vagrant ssh -- sudo -u edxapp /edx/bin/pip.edxapp install -e git+https://github.com/open-craft/xblock-vectordraw.git@bdero/disable-scroll-during-draw#egg=vectordraw-xblock

3. Run Studio
4. Navigate to a course, and then "Settings > Advanced Settings".
5. Update the "Advanced Module List" field to contain ["vectordraw"].
6. Click "Save Changes".
7. Navigate to the outline and create a new Section, Subsection, and Unit. You will be redirected to the Unit authoring view.
8. Select "Advanced > Vector Drawing" to create a new Vector Drawing problem.
9. Click "Edit".

10. Set the "Vectors" field with the following block:

    [
    {
        "name": "1",
        "description": "Vector 1",
        "coords": [
            [
                2.6877256317689535,
                1.3971119133574006
            ],
            [
                2.6877256317689535,
                4.397111913357403
            ]
        ],
        "type": "vector",
        "render": false,
        "length_factor": 1,
        "length_units": "",
        "base_angle": 0,
        "style": {
            "pointSize": 1,
            "pointColor": "red",
            "width": 4,
            "color": "blue",
            "label": null,
            "labelColor": "black"
        },
        "tail": [
            2.6877256317689535,
            1.3971119133574006
        ],
        "tip": [
            2.6877256317689535,
            4.397111913357403
        ],
        "length": 3.000000000000002,
        "angle": 90
    },
    {
        "name": "2",
        "description": "Vector 2",
        "coords": [
            [
                -1,
                1
            ],
            [
                -0.9999999999999998,
                4
            ]
        ],
        "type": "vector",
        "render": false,
        "length_factor": 1,
        "length_units": "",
        "base_angle": 0,
        "style": {
            "pointSize": 1,
            "pointColor": "red",
            "width": 4,
            "color": "blue",
            "label": null,
            "labelColor": "black"
        },
        "tail": [
            -1,
            1
        ],
        "tip": [
            -0.9999999999999998,
            4
        ],
        "length": 3,
        "angle": 90
    }
    ]

11. Set the "Expected result" field to the following block:

    {
    "1": {
        "tail": [
            2.69,
            1.4
        ],
        "tail_tolerance": 1,
        "tip": [
            2.69,
            4.4
        ],
        "tip_tolerance": 1
    },
    "2": {
        "tail": [
            -1,
            1
        ],
        "tail_tolerance": 1,
        "tip": [
            -0.9999999999999998,
            4
        ],
        "tip_tolerance": 1
    }
    }

12. Click "Save".
13. Click "Publish".
14. Launch a browser on a mobile device (note that the Chromium device emulator will not work for this test) and navigate to the Vector Drawing problem in the LMS.
15. Tap and drag to create two new vectors. Observe that the browser window does not scroll as you slide your finger to initialize the new vector.

[pomegranited]

@bdero The PR description contains install instructions for the wrong branch. Could you please update it?

[pomegranited]

@bdero Your fix works great! I'll approve once you've fixed these minor issues.

• [x] I tested this by following the instructions in the PR (with a small modification). Tested on:
  • Android: Chrome, Firefox, and the default Internet browser. Noticed that the scroll-disabling on Firefox is slightly delayed, but it's still functional.
  • Mac desktop: Chrome, Firefox, Safari - to ensure mouse and keyboard behaviour are unaffected.
  • I don't have a iOS device though, so am unable to test it there.
• [x] I read through the code - found one nit
• [ ] Includes documentation - requested updated comments

[bdero]

@pomegranited Thanks for the review! I addressed your comments. Do you want to take a second pass or do you think this is good for me to merge?

[pomegranited]

@bdero Thanks for addressing my comments! You're good to squash and merge.

:+1:

• [x] I tested this by following the instructions in the PR. Tested on:
  • Android: Chrome, Firefox, and the default Internet browser. Noticed that the scroll-disabling on Firefox is slightly delayed, but it's still functional.
  • Mac desktop: Chrome, Firefox, Safari - to ensure mouse and keyboard behaviour are unaffected.
  • I don't have a iOS device though, so am unable to test it there.
• [x] I read through the code
• [x] Includes documentation