Silverlight 2 如何接收滑鼠滾輪訊息 - Application.NET - Site Home

註: 這裡的範例程式碼是針對 Silverlight 2 Beta1, 在 beta2 中, MultiScaleImage 的 Source 的型態有些改變。

在 Deep Zoom 的應用中, 常常會用滑鼠滾輪來作 Zoom In/ Zoom Out 的動作, 但是 Silverlight 2 Beta1 的 .NET 事件裡並沒有滑鼠滑輪的事件, 必需藉用瀏覽器事件來呼叫滾輪訊息。此外, 要特別注意的是, 滑鼠滾輪雖然方便, 但是並不是所有的作業系統都支援滑鼠滾輪, 也要可能有的使用者的滑鼠根本缺少滾輪, 所以我們在設計滾輪應用的同時, 務必要設計無法使用滾輪時的替代方案。(請參考清明上河圖的設計http://learnet.npm.gov.tw/silverlight/)

範例程式如下, 由於 IE, firefox, Safari 的事件模型不同, 所以要特別注意跨瀏覽器支援的部份, 範例程式碼測試過此三種瀏覽器:

Page.xaml

Page.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Windows.Browser;

namespace SilverlightApplication3
{
    [ScriptableType]
    public partial class Page : UserControl
    {
        public Page() {
            InitializeComponent();
            HtmlPage.RegisterScriptableObject("MySilverlightObject", this);
        }

        bool dragging = false;
        Point dragOffset;
        Point currentPosition;

        private void MultiScaleImage_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) {
            dragging = true;
            dragOffset = e.GetPosition(this);
            currentPosition = dz.ViewportOrigin;
        }

        private void MultiScaleImage_MouseMove(object sender, MouseEventArgs e) {
            if (dragging) {
                Point newOrigin = new Point();
                newOrigin.X = currentPosition.X -
                    (((e.GetPosition(dz).X - dragOffset.X)
                    / dz.ActualWidth) * dz.ViewportWidth);
                newOrigin.Y = currentPosition.Y -
                    (((e.GetPosition(dz).Y - dragOffset.Y)
                    / dz.ActualHeight) * dz.ViewportWidth);
                dz.ViewportOrigin = newOrigin;
            }
        }

        private void MultiScaleImage_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) {
            dragging = false;
        }

        [ScriptableMember]
        public void dz_MouseWheel(double x, double y, int delta) {
            double dZoomFactor = 1.25;
            if (delta < 0)
                dZoomFactor = 1 / 1.25;
            Point pz = dz.ElementToLogicalPoint(new Point(x, y));
            dz.ZoomAboutLogicalPoint(dZoomFactor, pz.X, pz.Y);
        }

}
}

TestPage.html

    function handleLoad()
    {
        window.onmousewheel = document.onmousewheel = onMouseWheel;
        if (window.addEventListener) // for firefox
            window.addEventListener('DOMMouseScroll', onMouseWheel, false);
    }

    function onMouseWheel(event)
    {
        if(event === undefined) // for IE
            event = window.event;

        var delta = 0;
        var x = (event.clientX);
        var y = (event.clientY);
        var slPlugin = document.getElementById("slHost");
        if (event.wheelDelta !== undefined) {
            delta = event.wheelDelta;
            slPlugin.content.MySilverlightObject.dz_MouseWheel(x, y ,delta);
        } else if (event.detail) { // for firefox
            delta = -event.detail;
            x /= 15;
            y /= 15;
            slPlugin.content.MySilverlightObject.dz_MouseWheel(x, y ,delta);
        }
    }

</script>
</body>