我正在开发一个跟踪系统，用于绘制用户在房间或其他地方的移动轨迹。
现在，我已经成功将我的地图导入应用程序中，并且可以自由缩放和移动地图。下一步是在地图上放置标记来指示用户位置，并在地图上移动标记（就像漂浮在地图上一样）。
我在某个地方读到过，认为这可以使用MyLocationOverlay来实现，但是大多数在线示例都是应用于google map。然而，在我的情况下，我的地图不是google map，它是我自己的地图。（地图可以是我的房间的地图，甚至是我自己绘制的地图！）
我已经完成了跟踪算法，即我知道在哪里放置我的标记图像。
因此，唯一的问题是如何在地图图像的顶部呈现标记图像。
具体来说，我有一个自定义视图MapView，如下所示：
package com.example.drsystem;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
public class MapView extends View {
private static final int INVALID_POINTER_ID = -1;
private Drawable mImage;
private float mPosX;
private float mPosY;
private float mLastTouchX;
private float mLastTouchY;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
public MapView(Context context) {
this(context, null, 0);
mImage = getResources().getDrawable(R.drawable.lv12n);
mImage.setBounds(0, 0, mImage.getIntrinsicWidth(), mImage.getIntrinsicHeight());
}
// called when XML tries to inflate this View
public MapView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
mImage = getResources().getDrawable(R.drawable.lv12n);
mImage.setBounds(0, 0, mImage.getIntrinsicWidth(), mImage.getIntrinsicHeight());
}
public MapView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
// Let the ScaleGestureDetector inspect all events.
mScaleDetector.onTouchEvent(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
// Only move if the ScaleGestureDetector isn't processing a gesture.
if (!mScaleDetector.isInProgress()) {
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
invalidate();
}
mLastTouchX = x;
mLastTouchY = y;
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
Log.d("MapView", "X: " + mPosX + " Y: " + mPosY);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
mImage.draw(canvas);
canvas.restore();
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 10.0f));
invalidate();
return true;
}
}
}
到目前为止，地图已成功输入到应用程序中，并且可以移动和缩放。
然后，我将此自定义视图插入到布局XML文件中，如下所示：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MapView" >
<com.example.drsystem.MapView
android:id="@+id/mapView1"
android:layout_width="fill_parent"
android:layout_height="400dp"
android:layout_above="@+id/button2"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true" />
...
</RelativeLayout>
基于所有这些信息，我该如何在我的地图上绘制一个点并不断更新其位置？
更新：
问题就是关于将另一幅小图片放置在自定义视图之上并移动它。
我还附上了此处的屏幕截图供您参考：
上面按钮和文本视图的区域是我的MapView。