Android/Java - GoogleMaps FragmentActivity 上的自定义视图未显示

问题描述

我正在尝试在自定义视图中绘制一些用于测试的东西，该视图已添加到 GoogleMaps FragmentActivity.但不知何故，当我在模拟器中运行它时，似乎我的 CustomView 不是绘图.我尝试使用新的 RelativeLayout 和 MapLayout.有任何想法吗 ?我做错了什么?

Im trying to draw some Stuff for testing in an Custom View, which is added to the GoogleMaps FragmentActivity. But somehow, when i run it in the emulator, it seems like my CustomView isnt drawing.I tried it with a new RelativeLayout and an MapLayout. Any ideas ? What did i do wrong ?

这是我的主要 GoogleMaps FragmentActivity 代码，从 Android 模板自动生成:

Heres my Main GoogleMaps FragmentActivity code, auto generated from Android templates :

public class GoogleMaps extends FragmentActivity implements OnMapReadyCallback {

private GoogleMap mMap;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.google_maps);
    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);

    //RelativeLayout relativeLayout = new RelativeLayout(this);
    //relativeLayout.addView(new SpriteLayer(this));

    MapView map = new MapView(this);
    map.addView(new SpriteLayer(this));

}

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    // Add a marker in Sydney and move the camera
    LatLng sydney = new LatLng(-34, 151);
    mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
}
}

这是我的自定义视图代码:

Thats my CustomView Code :

public class SpriteLayer extends View {

Paint paint = new Paint();

public SpriteLayer(Context context) {
    super(context);

    setWillNotDraw(false);

}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

    int desiredWidth = 100;
    int desiredHeight = 100;

    int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    int widthSize = MeasureSpec.getSize(widthMeasureSpec);
    int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    int heightSize = MeasureSpec.getSize(heightMeasureSpec);

    int width;
    int height;

    //Measure Width
    if (widthMode == MeasureSpec.EXACTLY) {
        //Must be this size
        width = widthSize;
    } else if (widthMode == MeasureSpec.AT_MOST) {
        //Can't be bigger than...
        width = Math.min(desiredWidth, widthSize);
    } else {
        //Be whatever you want
        width = desiredWidth;
    }

    //Measure Height
    if (heightMode == MeasureSpec.EXACTLY) {
        //Must be this size
        height = heightSize;
    } else if (heightMode == MeasureSpec.AT_MOST) {
        //Can't be bigger than...
        height = Math.min(desiredHeight, heightSize);
    } else {
        //Be whatever you want
        height = desiredHeight;
    }

    //MUST CALL THIS
    setMeasuredDimension(width, height);

}

@Override
public void onDraw(Canvas canvas) {

    paint.setColor(Color.GREEN);
    Rect rect = new Rect(20, 56, 200, 112);
    canvas.drawRect(rect, paint );

    Log.println(Log.ERROR,"Test ","One");
}
}

目前我只看到带有标记的标准地图，仍然没有矩形:(

Currently i only see the standard map with an marker on it, still no Rectangle :(

推荐答案

您需要测量所需的视图大小.你只是传递你收到的东西，可能是 0.

You need to measure the desired size of your view. You are just passing what you are receiving, which probably is 0.

另一种选择是使用 MATCH_PARENT 设置 LayoutParams，但我不确定这是否可行.

Another option is to set a LayoutParams with MATCH_PARENT, but I'm not sure if this will work.

您尝试做的是高级，您应该在尝试之前阅读一些教程.

What you are trying to do is advanced, you should read some tutorials before trying it.

这里有更多信息:https://developer.android.com/training/custom-views/custom-drawing.html

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