Question

我正在尝试使用MapView和ListView创建一个Activity。我使用C＃和MonoDroid。

布局看起来像这样

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">
    <app.MD.UI.PlacesMapView
        android:id="@+id/mapView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:enabled="true"
        android:clickable="true"
        android:layout_weight="1"
        android:apiKey="key" />
    <ListView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_weight="1"
        android:id="@+id/resultsTable" />
</LinearLayout>

我的自定义MapView类实现了长按处理程序

private void HandleLongPress(MotionEvent e)
        {
            if (e.Action == MotionEventActions.Down) {
                // Finger has touched screen.
                longpressTimer = new Timer(LONGPRESS_THRESHOLD);
                longpressTimer.AutoReset = false;
                longpressTimer.Elapsed += delegate(object sender, ElapsedEventArgs e_elapsed) {
                    GeoPoint longpressLocation = Projection.FromPixels((int)e.GetX(), (int)e.GetY());
                    if (OnLongPress != null) {
                        OnMapViewLongPressEventArgs args = new OnMapViewLongPressEventArgs();
                        args.location = longpressLocation;
                        OnLongPress(this, args);
                    }
                };

                longpressTimer.Start();

                lastMapCenter = MapCenter;
            }

            if (e.Action == MotionEventActions.Move) {
                if (!MapCenter.Equals(lastMapCenter)) {
                    longpressTimer.Stop();
                }

                lastMapCenter = MapCenter;
            }

            if (e.Action == MotionEventActions.Up) {
                // User has removed finger from map.
                longpressTimer.Stop();
            }

            if (e.PointerCount > 1) {
                // This is a multitouch event, probably zooming.
                longpressTimer.Stop();
            }
        }

活动方法，它将标记添加到MapView

protected void AddPinToMap(GeoPoint location, string title, bool scrollTo, int zoom)
        {
            var pin = Resources.GetDrawable(Resource.Drawable.maps_pin);
            PinOverlay pinOverlay = new PinOverlay(pin, this);
            OverlayItem item = new OverlayItem(location, title, "");
            pinOverlay.AddOverlay(item);
            mapView.Overlays.Clear();
            mapView.Overlays.Add(pinOverlay);

            if (scrollTo) {
                mapView.Controller.AnimateTo(location);
            }

            mapView.Controller.SetZoom(zoom);
        }

这是我的PinOverlay课程

class PinOverlay : ItemizedOverlay
    {
        private List<OverlayItem> _items = new List<OverlayItem>();
        private Context _context;

        public PinOverlay(Drawable pin, Context context) : base(pin)
        {
            _context = context;
            BoundCenterBottom(pin);
            Populate();
        }

        protected override Java.Lang.Object CreateItem(int i)
        {
            return _items[i];
        }

        public override int Size()
        {
            return _items.Count();
        }

        public void AddOverlay(OverlayItem overlay) {
            _items.Add(overlay);
            Populate();
        }
    }

我的问题是，当我触摸MapView时，我的标记显示低于我触摸的点。我认为这可能是因为我的MapView没有全屏显示。当我删除ListView以便MapView可以占据整个屏幕时，我能够将标记放在我触摸屏幕的确切位置。

如果MapView只占用屏幕的一部分，有关如何处理触摸事件的任何建议或示例吗？

UPD 找到某种解决方法，仍然需要使用不同的屏幕尺寸进行测试

转换触摸坐标

public static Point ConvertCoordinates(Context context, MapView mapView, double x, double y)
        {
            var wm = context.GetSystemService(Context.WindowService).JavaCast<IWindowManager>();
            var display = wm.DefaultDisplay;

            double diffY = (Convert.ToDouble(display.Height) / 2 - Convert.ToDouble(mapView.Height) / 2) / 2 - 20;
            double diffX = Convert.ToDouble(display.Width) / 2 - Convert.ToDouble(mapView.Width) / 2;

            Point size = new Point();
            size.X = (int)(x - diffX);
            size.Y = (int)(y - diffY);

            return size;
        }

像这样使用

var point = MapHelper.ConvertCoordinates(this.Context, this, e.GetX(), e.GetY());

GeoPoint longpressLocation = Projection.FromPixels(point.X, point.Y);

Answer 1

你试过了吗？

public PinOverlay(Drawable pin, Context context) 
    : base(BoundCenterBottom(pin))

这会使你在地图上放置Drawable点，而不是在绘制时将地理坐标作为（x，y）（0,0）坐标。

修改我似乎无法在这里重新创建你的问题，当在构造函数的:base()中使用BoundCenterBottom（pin）时，它使Drawable居中很好。

我还注意到，在AddPinToMap方法中，每次都会创建一个新的PinOverlay。这不是必需的，您只需将新OverlayItem添加到PinOverlay，您只需向地图添加一次。如果要在地图中添加大量引脚，则效率更高，资源消耗更少。

所以看起来应该更像：

protected void AddPinToMap(GeoPoint location, string title, bool scrollTo, int zoom) { var pin = Resources.GetDrawable(Resource.Drawable.maps_pin); OverlayItem item = new OverlayItem(location, title, ""); pinOverlay.AddOverlay(item); // this is instantiated in OnCreate if (scrollTo) { mapView.Controller.AnimateTo(location); } mapView.Controller.SetZoom(zoom); }

如果您希望能够删除Remove，请向PinOverlay添加OverlayItems方法。

同样MapView已经有LongClick个事件，您可以将其挂钩而不是覆盖该类：

var mapView = FindViewById<MapView>(Resource.Id.myMapView); mapView.LongClick += (sender, args) => { //do whatever in here };

或

var mapView = FindViewById<MapView>(Resource.Id.myMapView); mapView.LongClick += OnLongClick; private void OnLongClick(object sender, LongClickEventArgs longClickEventArgs) { // do whatever in here }

Answer 2

最后我找到了问题的原因。

这部分错误，因为在 Elapsed 委托中访问了 Projection 。但到那时Projection已经改变了它的状态，导致坐标错误。

if (e.Action == MotionEventActions.Down) {
    // Finger has touched screen.
    longpressTimer = new Timer(LONGPRESS_THRESHOLD);
    longpressTimer.AutoReset = false;
    longpressTimer.Elapsed += delegate(object sender, ElapsedEventArgs e_elapsed) {
        GeoPoint longpressLocation = Projection.FromPixels((int)e.GetX(), (int)e.GetY());
        if (OnLongPress != null) {
             OnMapViewLongPressEventArgs args = new OnMapViewLongPressEventArgs();
             args.location = longpressLocation;
             OnLongPress(this, args);
        }
    };

    longpressTimer.Start();

    lastMapCenter = MapCenter;
}

因此，解决方案是在 OnTouchEvent 的最开始时获取 GeoPoint 。

if (e.Action == MotionEventActions.Down) {
    capturedProjection = Projection.FromPixels((int)e.GetX(), (int)e.GetY());

    // Finger has touched screen.
    longpressTimer = new Timer(LONGPRESS_THRESHOLD);
    longpressTimer.AutoReset = false;
    longpressTimer.Elapsed += (object sender, ElapsedEventArgs e_timer) => {
        if (OnLongPress != null) {
            OnMapViewLongPressEventArgs args = new OnMapViewLongPressEventArgs();
            args.location = capturedProjection;
            OnLongPress(this, args);
        }
    };

    longpressTimer.Start();

    lastMapCenter = MapCenter;
}

Android MapView中叠加层的位置不准确

2 个答案: