SearchDrawable.java

package com.marshalchen.common.ui;

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.DashPathEffect;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PathMeasure;
import android.graphics.PixelFormat;
import android.graphics.RectF;
import android.graphics.drawable.Drawable;

public class SearchDrawable extends Drawable{
	
	private final Paint mPaint = new Paint();
	private Path mPath;	
	private PathMeasure pm;
	private Path editorPath;
	private float mPhase;
	private float mRadius = 30;;
	private float distance = 300;
		
	public SearchDrawable() {
		mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(4);
        mPaint.setColor(Color.WHITE);
        mPaint.setAntiAlias(true);
        
   	 	createSearchPath(0);
   	 	pm = new PathMeasure(mPath,false);
    	editorPath = new Path();
	}

	@Override
	public void draw(Canvas canvas) {
        canvas.save();
        canvas.translate(distance*mPhase, 0.0f);
        canvas.drawPath(mPath, mPaint);
        mPaint.setPathEffect(null);
        canvas.drawPath(editorPath, mPaint);
        canvas.restore();
	}

    @Override
    public void setAlpha(int i) {
        mPaint.setAlpha(i);
    }

    @Override
    public void setColorFilter(ColorFilter colorFilter) {
        mPaint.setColorFilter(colorFilter);
    }

	@Override
	public int getOpacity() {		
		return PixelFormat.OPAQUE;
	}

	private void createSearchPath(float phase){
        RectF oval = new RectF(0.0f, 0.0f, mRadius * 2.0f, mRadius * 2.0f);

        float cx = oval.centerX();
        float cy = oval.centerY();
        float rx = oval.width() / 2.0f;
        float ry = oval.height() / 2.0f;

        final float TAN_PI_OVER_8 = 0.414213562f;
        final float ROOT_2_OVER_2 = 0.707106781f;

        float sx = rx * TAN_PI_OVER_8;
        float sy = ry * TAN_PI_OVER_8;
        float mx = rx * ROOT_2_OVER_2;
        float my = ry * ROOT_2_OVER_2;

        float L = oval.left;
        float T = oval.top;
        float R = oval.right;
        float B = oval.bottom;
        
        mPath = new Path();
        mPath.moveTo(cx+mx,cy+my);
        mPath.quadTo(cx+sx,B,cx,B);
        mPath.quadTo(cx-sx,B,cx-mx,cy+my);
        mPath.quadTo(L,cy+sy,L,cy);
        mPath.quadTo(L,cy-sy,cx-mx,cy-my);
        mPath.quadTo(cx - sx,T,cx,T);
        mPath.quadTo(cx + sx,T,cx + mx, cy-my);
        mPath.quadTo(R, cy-sy,R, cy);       
        mPath.quadTo(R, cy + sy,cx+mx,cy+my);       
        mPath.lineTo(1.5f*R,1.5f*B);                         
    }
    
    private void createEditorPath(float phase){
    	editorPath.reset();
    	editorPath.moveTo(3f*mRadius,3f*mRadius);
    	editorPath.lineTo(3f*mRadius-400*phase,3f*mRadius);
    }
    
    public void setPhase(float phase){
    	mPhase = phase;
    	float len = pm.getLength();
    	DashPathEffect effect = new DashPathEffect(new float[] {len,len},-phase*len);
    	mPaint.setPathEffect(effect);                
    	createEditorPath(phase);
    	invalidateSelf();
    }
    
    public float getPhase(){
    	return mPhase;
    }
}