Category: .NET/C#

Just another story happens when developing WordsBaking.

First, the basis. If you don’t have any element in your web page that requires overflow style being auto or scroll, “-ms-touch-action: none;” under “html” selector should work well . Actually it works all the time in Internet Explorer, but in a WebBrowser control, if there’s something like a list for which you may need that style, the solution becomes tricky.

I spent tons of hours and tried tons of ways hoping figure out a solution, and luckily, found one.

That is the good news, but the bad news is, this solution doesn’t seem to be elegant (though it works perfectly so far).

The first thing that I found might be useful is that this bouncing effect happens only when your finger touches the elements that already have their contents at the top/bottom or both. So, the first solution I thought might work was to add a pointerdown (MSPointerDown) event listener on the element, and determine whether its content has reached the top or bottom. Unfortunately, it doesn’t work well.

Later I read about an article shows a solution on suppressing scrolling and zooming in WP7 WebBrowser control, I can’t say that it works (on WP8), but it helps.

Combining these two parts (and this is why I think it’s not elegant enough), here’s the solution:

C# Part

private void mainBrowser_Loaded(object sender, RoutedEventArgs e) {
    // here we are using a library named Linq to Visual Tree.
    // http://www.scottlogic.com/blog/2010/03/04/linq-to-visual-tree.html
    var border = mainBrowser.Descendants().Last() as Border;
    border.ManipulationDelta += border_ManipulationDelta;
    border.ManipulationCompleted += border_ManipulationCompleted;
}

void border_ManipulationCompleted(object sender, ManipulationCompletedEventArgs e) {
    mainBrowser.InvokeScript("onmanipulationcompleted");
}

void border_ManipulationDelta(object sender, ManipulationDeltaEventArgs e) {
    var status = mainBrowser.InvokeScript("onmanipulationdelta") as string;
    if (status == "top" || status == "both") {
        if (e.DeltaManipulation.Translation.Y > 0) {
            e.Handled = true;
        }
    }
    if (status == "bottom" || status == "both") {
        if (e.DeltaManipulation.Translation.Y < 0) {
            e.Handled = true;
        }
    }
}

JavaScript Part

window.manipulationTarget = null;

window.onmanipulationdelta = function () {
    if (!window.manipulationTarget) {
        return '';
    }

    var target = window.manipulationTarget;

    var top = target.scrollTop == 0;
    var bottom = target.scrollTop + target.clientHeight == target.scrollHeight;

    return top ? bottom ? 'both' : 'top': bottom ? 'bottom' : '';
};

window.onmanipulationcompleted = function () {
    window.manipulationTarget = null;
};

// and you'll need to make calls to every elements
// with overflow auto or scroll with this:
function preventBouncing(ele) {
    // using jQuery.
    ele.on('MSPointerDown pointerdown', function (e) {
        window.manipulationTarget = this;
    });
}

And good luck fellows~