我开发了一个地图应用程序，我想在地图屏幕的右上角显示指南针。指南针也准备好工作和地图，但是当我将两者放在一起时，它不显示指南针（我的意思是当我在自定义 mapview 类的调度绘制中绘制指南针时它会引发问题）
奇怪的是，我制作了两个画布对象 1. 通过绘制路径（箭头） 2. 此处显示的文本“N”显示其显示文本，但它不显示罗盘。
这是为了清楚起见的自定义 Mapview 类..
package com.Espiritos.Home.Map;
import java.util.Timer;
import java.util.TimerTask;
import org.mapsforge.android.maps.MapView;
import org.mapsforge.core.GeoPoint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Shader;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import com.Espiritos.Utility.AppLog;
/**-----------------------------------------------------------------------------
Class Name: MyMapView
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: All Listener and Canvas method are introduce in this class for map operation
-----------------------------------------------------------------------------*/
public class MyMapView extends MapView
{
private float mfDirection = 0;
private float[] mfRotateValue;
private Paint mPntCompass = new Paint(Paint.ANTI_ALIAS_FLAG);
private boolean mIsFirstDraw;
/** ------------------------------------------------------------------------
// LISTENER DEFINITIONS
// ------------------------------------------------------------------------
*/
/** Change listener for mapview*/
public interface OnChangeListener
{
public void onChange(MapView view, GeoPoint newCenter, GeoPoint oldCenter, int newZoom, int oldZoom);
}
/** ------------------------------------------------------------------------
// MEMBERS
// ------------------------------------------------------------------------
*/
private MyMapView mThis;
@Override
protected void onDraw(Canvas amcanvas) {
super.onDraw(amcanvas);
}
private long mlEventsTimeout = 1500;//250L; // Set this variable to your preferred timeout
private boolean mIsTouched = false;
private GeoPoint mLastCenterPosition;
private int miLastZoomLevel;
private Timer mChangeDelayTimer = new Timer();
private MyMapView.OnChangeListener mChangeListener = null;
private int miOldZoomLevel = -1;
private OnClusterMapZoomListener onClusterMapZoomListener;
/**-----------------------------------------------------------------------------
Method Name: MyMapView(CONSTRUCTORS)
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: Get Context from base and use in operation
-----------------------------------------------------------------------------*/
public MyMapView(Context amcontx)
{
super(amcontx);
init();
}
public MyMapView(Context amcontext, AttributeSet amAttrs)
{
super(amcontext, amAttrs);
init();
}
public MyMapView(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs);
init();
}
/**-----------------------------------------------------------------------------
Method Name: init
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: get Mapcenter and Map ZoomLevel
-----------------------------------------------------------------------------*/
private void init()
{
mThis = this;
mLastCenterPosition = this.getMapPosition().getMapCenter();
miLastZoomLevel = this.getMapPosition().getZoomLevel();
mPntCompass.setStyle(Paint.Style.FILL_AND_STROKE);
mPntCompass.setStrokeWidth(4);
mPntCompass.setColor(Color.GRAY);
mPntCompass.setTextSize(30);
mPntCompass.setAntiAlias(true);
mPntCompass.setShader(new LinearGradient(0, 0, 0, getHeight(), Color.BLACK, Color.WHITE, Shader.TileMode.REPEAT));
mIsFirstDraw = true;
}
/**-----------------------------------------------------------------------------
Method Name: setOnChangeListener
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: Mapview change listener implementation
-----------------------------------------------------------------------------*/
public void setOnChangeListener(MyMapView.OnChangeListener l)
{
mChangeListener = l;
}
/**-----------------------------------------------------------------------------
Method Name: onTouchEvent
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: on touch event handling with motionEvent
-----------------------------------------------------------------------------*/
@Override
public boolean onTouchEvent(MotionEvent ev)
{
/** Set touch internal*/
mIsTouched = (ev.getAction() != MotionEvent.ACTION_UP);
return super.onTouchEvent(ev);
}
/**-----------------------------------------------------------------------------
Method Name: computeScroll
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: scroll change counting by this method
-----------------------------------------------------------------------------*/
@Override
public void computeScroll()
{
super.computeScroll();
/**Check for change*/
if (isSpanChange() || isZoomChange())
{
/**
* If computeScroll called before timer counts down
we should drop it and
start counter over again
*/
resetMapChangeTimer();
}
}
/**-----------------------------------------------------------------------------
Method Name: resetMapChangeTimer
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: after scroll it get change the position, it getting new position update
-----------------------------------------------------------------------------*/
private void resetMapChangeTimer()
{
mChangeDelayTimer.cancel();
mChangeDelayTimer = new Timer();
mChangeDelayTimer.schedule(new TimerTask()
{
@Override
public void run()
{
if (mChangeListener != null) mChangeListener.onChange(mThis, getMapPosition().getMapCenter(), mLastCenterPosition, getMapPosition().getZoomLevel(), miLastZoomLevel);
mLastCenterPosition = getMapPosition().getMapCenter();
miLastZoomLevel = getMapPosition().getZoomLevel();
}
}, mlEventsTimeout);
}
/**-----------------------------------------------------------------------------
Method Name: isSpanChange
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: after scroll it get change the position, it getting new position update
-----------------------------------------------------------------------------*/
private boolean isSpanChange()
{
return !mIsTouched && !getMapPosition().getMapCenter().equals(mLastCenterPosition);
}
/**-----------------------------------------------------------------------------
Method Name: isZoomChange
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: Get current zoom level
-----------------------------------------------------------------------------*/
private boolean isZoomChange()
{
return (getMapPosition().getZoomLevel() != miLastZoomLevel);
}
/**-----------------------------------------------------------------------------
Method Name: dispatchDraw
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: This method is used to Draw Polygon in map
-----------------------------------------------------------------------------*/
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
// Notify listener, if not null, that the zoom level changed
if (getMapPosition().getZoomLevel() != miOldZoomLevel) {
miOldZoomLevel = getMapPosition().getZoomLevel();
if (onClusterMapZoomListener != null) {
onClusterMapZoomListener.onZoomLevelChanged(miOldZoomLevel);
}
}
if (!mIsFirstDraw)
{
Path mPathArrow = new Path();
mPathArrow.moveTo(0, -50);
mPathArrow.lineTo(-20, 40);
mPathArrow.lineTo(0, 30);
mPathArrow.lineTo(20, 40);
mPathArrow.close();
Paint mPntText = new Paint(Paint.ANTI_ALIAS_FLAG);
mPntText.setAntiAlias(true);
mPntText.setTextSize(30);
mPntText.setColor(Color.BLACK);
mPntText.setStyle(Paint.Style.FILL);
int miCanvasWidth = canvas.getWidth();
int miCanvasHeight = canvas.getHeight();
int miCenterX = miCanvasWidth / 2;
int miCenterY = miCanvasHeight / 2;
canvas.translate(miCanvasWidth-miCanvasWidth/10, miCanvasHeight/10);
if (mfRotateValue != null) {
canvas.rotate(-mfRotateValue[0]);
}
canvas.drawPath(mPathArrow, mPntCompass);
canvas.drawText("N", miCanvasWidth-miCanvasWidth/10, miCanvasHeight/10, mPntText);
}
}
public void updateDirection(float dir,float[] mevent)
{
mIsFirstDraw = false;
mfDirection = dir;
this.mfRotateValue = mevent;
Log.e(VIEW_LOG_TAG, "direction"+mfDirection);
invalidate();
}
/**-----------------------------------------------------------------------------
Method Name: getOnClusterMapZoomListener
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: get Map Zoomlistner implemented
-----------------------------------------------------------------------------*/
public OnClusterMapZoomListener getOnClusterMapZoomListener()
{
return onClusterMapZoomListener;
}
/**-----------------------------------------------------------------------------
Method Name: setOnClusterMapZoomListener
Created By: 704
Created Date:
Modified By:
Modified Date:
Purpose: set Map Zoomlistner implemented
-----------------------------------------------------------------------------*/
public void setOnClusterMapZoomListener(
OnClusterMapZoomListener onClusterMapZoomListener)
{
this.onClusterMapZoomListener = onClusterMapZoomListener;
}
}
注意：我已经为此制作了演示应用程序，它的显示效果很好....
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