CrosshairOverlay.java

package jjil.android;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class CrosshairOverlay extends View {
    private Integer mnHorizStart, mnHorizEnd;
    private Integer mnVertStart, mnVertEnd;
    
    public CrosshairOverlay(Context context) {
        super(context);
    }
    
    public CrosshairOverlay(Context context, AttributeSet attrs)
    {
        super(context, attrs);
    }

    public CrosshairOverlay(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
    }
    
    public void clearLimits() {
        mnHorizStart = mnHorizEnd = mnVertStart = mnVertEnd = null;
    }
    
    @Override
    public void onDraw(Canvas c) {
        super.onDraw(c);
        
        // draw a partially transparent crosshairs on the canvas
        Paint p = new Paint();
        p.setColor(Color.RED);
        p.setAlpha(128);
        c.drawLine(0.0f, getHeight()/2, getWidth(), getHeight()/2, p);
        c.drawLine(getWidth()/2, 0.0f, getWidth()/2, getHeight(), p);
        if (mnHorizStart != null) {
            c.drawLine(mnHorizStart, getHeight()/2-5, mnHorizStart, getHeight()/2+5, p);
            c.drawLine(mnHorizEnd, getHeight()/2-5, mnHorizEnd, getHeight()/2+5, p);
        }
        if (mnVertStart != null) {
            c.drawLine(getWidth()/2-5, mnVertStart, getWidth()/2+5, mnVertStart, p);
            c.drawLine(getWidth()/2-5, mnVertEnd, getWidth()/2+5, mnVertEnd, p);
        }
    }
    
    public void setHorizLimits(int nStart, int nEnd) {
        mnHorizStart = nStart;
        mnHorizEnd = nEnd;
    }

    public void setVertLimits(int nStart, int nEnd) {
        mnVertStart = nStart;
        mnVertEnd = nEnd;
    }
}