鼠標中鍵縮放地圖要用到js,它的實現可以分爲三步。
第一步，在頁面的</form>之前添加如下JavaScript代碼，（切忌一定要在</form>之前）
代碼
<!--
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--><script type="text/javascript">
var Img = document.getElementById("MapControl1_Image");
if(Img != null)
{
Img.attachEvent('onmousewheel', GetMouseWheelEvent);
}
function GetMouseWheelEvent()
{
var mapImage = document.getElementById("MapControl1_Image");
var url = "MapController.ashx?Command=WheelZoom&Width=" + mapImage.width +"&Height=" + mapImage.height
+ "&ExportFormat=" + mapImage.exportFormat + "&Ran=" + Math.random() + "&wheelvalue=" + event.wheelDelta;
if (mapImage.mapAlias)
url += "&MapAlias=" + mapImage.mapAlias;
try
{
mapImage.src = url;
}
catch(e)
{
alert("Error!");
}
}
</script>
第二步，在後臺代碼中，如自定義命令的文件CustomCommands.cs中的添加如下類：
代碼
<!--
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--> [Serializable]
public class WheelZoom : MapBaseCommand
{
public WheelZoom()
{
Name = "WheelZoom";
}
public override void Process()
{
int wheelvalue = int.Parse(System.Convert.ToString(HttpContext.Current.Request["wheelvalue"]));
MapControlModel model = MapControlModel.GetModelFromSession();
model.SetMapSize(MapAlias, MapWidth, MapHeight);
try
{
MapInfo.Mapping.Map map = model.GetMapObj(MapAlias);
MapInfo.Geometry.Distance d;
if (wheelvalue > 0)
{
d = new MapInfo.Geometry.Distance(map.Zoom.Value * 0.5, map.Zoom.Unit);
}
else
{
d = new MapInfo.Geometry.Distance(map.Zoom.Value * 2, map.Zoom.Unit);
}
map.Zoom = d;
}
finally
{
System.IO.MemoryStream ms = model.GetMap(MapAlias, MapWidth, MapHeight, ExportFormat);
StreamImageToClient(ms);
}
}
}
第三步,在頁面註冊WheelZoom
<!--
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-->if(Session.IsNewSession)
{
MapControlModel model = MapControlModel.SetDefaultModelInSession();
model.Commands.Add(new WheelZoom());
}