在運行時更改標記圖標

Question

有沒有辦法在運行時更改 Google Maps Android API v2 標記的圖標，而無需刪除/重新添加我想更改其圖標的標記？ 我可以對其應用轉換（如旋轉）嗎？

謝謝。

Answer 1

現在，我可以在更新到Google Play Services Rev 7后輕松地在運行時更改標記圖標

Marker.setIcon（BitmapDescriptor圖標）

是可用的，以前我刪除並添加標記來改變它的顏色。

Answer 2

目前，您無法在運行時更改標記，也不能對其應用旋轉。

您可以使用變通方法 - 我正在使用BlinkingMarker類，我必須在運行時調整標記圖像的不透明度。

現在唯一的解決方案是創建具有不同旋轉的位圖，然后定期添加/刪除它們。 此解決方案的問題是添加/刪除標記需要大量內存分配，因此會導致不斷的垃圾回收。 更好，更順暢的解決方法是預先創建所有圖像，並立即將所有圖像添加到地圖中。 之后，您可以使用Marker.setVisible(boolean)函數來顯示您當前需要的那個。

注意：在執行此操作之前測量位圖，因為添加大量大位圖會導致應用程序的內存大小增大。

您可以在此處查看我的解決方法： https ： //github.com/balazsbalazs/blinking-marker-mapsv2

這是閃爍的標記（更改位圖的不透明度），但在相同的行上，您可以應用任何類型的轉換。

Answer 3

文件在這個問題上非常明確 -

 Icon A bitmap that's displayed in place of the default marker image. You can't change the icon once you've created the marker. 

如果您想要更改標記，您可以選擇一些選項。 一個是，正如您所注意到的，刪除標記並添加另一個標記。 另一種是在同一位置放置多個標記，並在任何給定時間切換哪一個可見。

我可以對其應用變換（如旋轉）嗎？

在使用圖像創建標記之前，您可以將任何您喜歡的變換應用於圖像。

Answer 4

在2013年9月的Google Maps Android API v2版本中 ，現在有一個新的標記setRotation()方法，以及一個新的setFlat()方法。

這是Google對新功能的描述：

給你的標記一個方向感

我們添加了一個標記旋轉屬性，允許您圍繞它的錨點旋轉標記。 新的平面屬性允許您使標記平放在地圖表面上，而不是彈出以面向相機。 當地圖旋轉或傾斜時，這兩個新屬性對於指示羅盤方向特別有用。

這是一篇描述新功能的文章 。

Answer 5

要在運行時更改選定的標記圖標，只需添加

      @Override
      public boolean onMarkerClick(Marker marker) {

       Marker.setIcon (BitmapDescriptor icon);
       }

Answer 6

僅針對 Android 進行了測試

為了在運行時更改標記的圖標，我通過刪除第 186 行中的“final”鍵將圖標變量從最終更改為非最終：

final BitmapDescriptor icon;

BitmapDescriptor icon;

並將第 136 行中的標記構造函數從“const”更改為“non-const”：

const Marker({

Marker({

要在包中進行更改，您必須按照此說明進行操作。

使用 google_maps_flutter 存儲庫，您將收到類似“找不到 pubspec.yaml”的錯誤消息。 那是因為 google_maps_flutter 包放置在存儲庫的子目錄中。

要獲得正確的依賴項，您必須在 pubspec.yaml 中添加包的特定路徑：

 dependencies:
  # google_maps_flutter: ^2.1.1
  google_maps_flutter:
    git:
      url: https://github.com/[username]/plugins.git
      path: packages/google_maps_flutter/google_maps_flutter/

然后您可以通過直接將其設置在標記上來更改圖標。 我通過使用“OnTap”方法來做到這一點。

Marker marker = Marker(
  icon: firstIcon,
  markerId: MarkerId(id),
  position: position,
  infoWindow: InfoWindow(
    title: name,
    snippet: address,
  ),
  onTap: () {
    setState(() {
      _markers[name]?.icon = secondIcon;
    });
  }
);

整個 Marker 類：

@immutable
class Marker implements MapsObject {
  /// Creates a set of marker configuration options.
  ///
  /// Default marker options.
  ///
  /// Specifies a marker that
  /// * is fully opaque; [alpha] is 1.0
  /// * uses icon bottom center to indicate map position; [anchor] is (0.5, 1.0)
  /// * has default tap handling; [consumeTapEvents] is false
  /// * is stationary; [draggable] is false
  /// * is drawn against the screen, not the map; [flat] is false
  /// * has a default icon; [icon] is `BitmapDescriptor.defaultMarker`
  /// * anchors the info window at top center; [infoWindowAnchor] is (0.5, 0.0)
  /// * has no info window text; [infoWindowText] is `InfoWindowText.noText`
  /// * is positioned at 0, 0; [position] is `LatLng(0.0, 0.0)`
  /// * has an axis-aligned icon; [rotation] is 0.0
  /// * is visible; [visible] is true
  /// * is placed at the base of the drawing order; [zIndex] is 0.0
  /// * reports [onTap] events
  /// * reports [onDragEnd] events
  Marker({
    required this.markerId,
    this.alpha = 1.0,
    this.anchor = const Offset(0.5, 1.0),
    this.consumeTapEvents = false,
    this.draggable = false,
    this.flat = false,
    this.icon = BitmapDescriptor.defaultMarker,
    this.infoWindow = InfoWindow.noText,
    this.position = const LatLng(0.0, 0.0),
    this.rotation = 0.0,
    this.visible = true,
    this.zIndex = 0.0,
    this.onTap,
    this.onDrag,
    this.onDragStart,
    this.onDragEnd,
  }) : assert(alpha == null || (0.0 <= alpha && alpha <= 1.0));

  /// Uniquely identifies a [Marker].
  final MarkerId markerId;

  @override
  MarkerId get mapsId => markerId;

  /// The opacity of the marker, between 0.0 and 1.0 inclusive.
  ///
  /// 0.0 means fully transparent, 1.0 means fully opaque.
  final double alpha;

  /// The icon image point that will be placed at the [position] of the marker.
  ///
  /// The image point is specified in normalized coordinates: An anchor of
  /// (0.0, 0.0) means the top left corner of the image. An anchor
  /// of (1.0, 1.0) means the bottom right corner of the image.
  final Offset anchor;

  /// True if the marker icon consumes tap events. If not, the map will perform
  /// default tap handling by centering the map on the marker and displaying its
  /// info window.
  final bool consumeTapEvents;

  /// True if the marker is draggable by user touch events.
  final bool draggable;

  /// True if the marker is rendered flatly against the surface of the Earth, so
  /// that it will rotate and tilt along with map camera movements.
  final bool flat;

  /// A description of the bitmap used to draw the marker icon.
  BitmapDescriptor icon;

  /// A Google Maps InfoWindow.
  ///
  /// The window is displayed when the marker is tapped.
  final InfoWindow infoWindow;

  /// Geographical location of the marker.
  final LatLng position;

  /// Rotation of the marker image in degrees clockwise from the [anchor] point.
  final double rotation;

  /// True if the marker is visible.
  final bool visible;

  /// The z-index of the marker, used to determine relative drawing order of
  /// map overlays.
  ///
  /// Overlays are drawn in order of z-index, so that lower values means drawn
  /// earlier, and thus appearing to be closer to the surface of the Earth.
  final double zIndex;

  /// Callbacks to receive tap events for markers placed on this map.
  final VoidCallback? onTap;

  /// Signature reporting the new [LatLng] at the start of a drag event.
  final ValueChanged<LatLng>? onDragStart;

  /// Signature reporting the new [LatLng] at the end of a drag event.
  final ValueChanged<LatLng>? onDragEnd;

  /// Signature reporting the new [LatLng] during the drag event.
  final ValueChanged<LatLng>? onDrag;

  /// Creates a new [Marker] object whose values are the same as this instance,
  /// unless overwritten by the specified parameters.
  Marker copyWith({
    double? alphaParam,
    Offset? anchorParam,
    bool? consumeTapEventsParam,
    bool? draggableParam,
    bool? flatParam,
    BitmapDescriptor? iconParam,
    InfoWindow? infoWindowParam,
    LatLng? positionParam,
    double? rotationParam,
    bool? visibleParam,
    double? zIndexParam,
    VoidCallback? onTapParam,
    ValueChanged<LatLng>? onDragStartParam,
    ValueChanged<LatLng>? onDragParam,
    ValueChanged<LatLng>? onDragEndParam,
  }) {
    return Marker(
      markerId: markerId,
      alpha: alphaParam ?? alpha,
      anchor: anchorParam ?? anchor,
      consumeTapEvents: consumeTapEventsParam ?? consumeTapEvents,
      draggable: draggableParam ?? draggable,
      flat: flatParam ?? flat,
      icon: iconParam ?? icon,
      infoWindow: infoWindowParam ?? infoWindow,
      position: positionParam ?? position,
      rotation: rotationParam ?? rotation,
      visible: visibleParam ?? visible,
      zIndex: zIndexParam ?? zIndex,
      onTap: onTapParam ?? onTap,
      onDragStart: onDragStartParam ?? onDragStart,
      onDrag: onDragParam ?? onDrag,
      onDragEnd: onDragEndParam ?? onDragEnd,
    );
  }

  /// Creates a new [Marker] object whose values are the same as this instance.
  Marker clone() => copyWith();

  /// Converts this object to something serializable in JSON.
  Object toJson() {
    final Map<String, Object> json = <String, Object>{};

    void addIfPresent(String fieldName, Object? value) {
      if (value != null) {
        json[fieldName] = value;
      }
    }

    addIfPresent('markerId', markerId.value);
    addIfPresent('alpha', alpha);
    addIfPresent('anchor', _offsetToJson(anchor));
    addIfPresent('consumeTapEvents', consumeTapEvents);
    addIfPresent('draggable', draggable);
    addIfPresent('flat', flat);
    addIfPresent('icon', icon.toJson());
    addIfPresent('infoWindow', infoWindow._toJson());
    addIfPresent('position', position.toJson());
    addIfPresent('rotation', rotation);
    addIfPresent('visible', visible);
    addIfPresent('zIndex', zIndex);
    return json;
  }

  @override
  bool operator ==(Object other) {
    if (identical(this, other)) return true;
    if (other.runtimeType != runtimeType) return false;
    final Marker typedOther = other as Marker;
    return markerId == typedOther.markerId &&
        alpha == typedOther.alpha &&
        anchor == typedOther.anchor &&
        consumeTapEvents == typedOther.consumeTapEvents &&
        draggable == typedOther.draggable &&
        flat == typedOther.flat &&
        icon == typedOther.icon &&
        infoWindow == typedOther.infoWindow &&
        position == typedOther.position &&
        rotation == typedOther.rotation &&
        visible == typedOther.visible &&
        zIndex == typedOther.zIndex;
  }

  @override
  int get hashCode => markerId.hashCode;

  @override
  String toString() {
    return 'Marker{markerId: $markerId, alpha: $alpha, anchor: $anchor, '
        'consumeTapEvents: $consumeTapEvents, draggable: $draggable, flat: $flat, '
        'icon: $icon, infoWindow: $infoWindow, position: $position, rotation: $rotation, '
        'visible: $visible, zIndex: $zIndex, onTap: $onTap, onDragStart: $onDragStart, '
        'onDrag: $onDrag, onDragEnd: $onDragEnd}';
  }
}