Tooltip.java

package hk.hku.cs.srli.widget;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.PixelFormat;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.widget.FrameLayout;
import android.widget.TextView;

import hk.hku.cs.srli.widget.util.HoverHandler;

import java.lang.ref.WeakReference;

public class Tooltip extends FrameLayout {
    
    private static final int[] ATTRS = new int[] { android.R.attr.text };
    private static final int INDEX_OF_TEXT_ATTR = 0;
    
    private static final WindowManager.LayoutParams PARAMS = new WindowManager.LayoutParams();
    
    static {
        PARAMS.gravity = Gravity.CENTER;
        PARAMS.height = WindowManager.LayoutParams.WRAP_CONTENT;
        PARAMS.width = WindowManager.LayoutParams.WRAP_CONTENT;
        PARAMS.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                    | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
        PARAMS.format = PixelFormat.TRANSLUCENT;
        PARAMS.windowAnimations = android.R.style.Animation_Dialog;
        PARAMS.type = WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG;
        PARAMS.verticalMargin = 0;
        PARAMS.horizontalMargin = 0; 
        PARAMS.setTitle("Tooltip");
    }
    
    private WeakReference<HoverHandler> hover;
    
    private TextView textView;

    public Tooltip(Context context) {
        super(context);
        init(context, null, 0);
    }

    public Tooltip(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context, attrs, 0);
    }

    public Tooltip(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context, attrs, defStyle);
    }
        
    public void init(Context context, AttributeSet attrs, int defStyle) {
        // Load attributes
        final TypedArray a = getContext().obtainStyledAttributes(
                attrs, ATTRS, defStyle, 0);
        String text = a.getString(INDEX_OF_TEXT_ATTR);
        a.recycle();
        build(context, text);
    }
    
    private void build(Context context, String text) {
        View rootView = LayoutInflater.from(context).inflate(R.layout.tooltip_text, this, true);
        textView = (TextView) rootView.findViewById(R.id.message);
        textView.setText(text);
    }
    
    public static WindowManager.LayoutParams getDefaultLayoutParams() {
        WindowManager.LayoutParams ret = new WindowManager.LayoutParams();        
        ret.copyFrom(PARAMS);
        return ret;
    }
    
    public CharSequence getText() {
        return textView.getText();
    }

    public void setText(CharSequence text) {
        textView.setText(text);
    }
    
    public void setText(int resid) {
        textView.setText(resid);
    }
    
    public void setHoverHandler(HoverHandler hover) {
        this.hover = new WeakReference<HoverHandler>(hover);
    }
    
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return false;
    }
    
    @Override
    public boolean onHoverEvent(MotionEvent event) {
        if (hover != null && hover.get() != null) {
            hover.get().onTooltipHoverEvent(event);
            return true; // Stop event from propaganda.
        } else {
            return false;
        }
    }
}