Android图像颜色处理

来自黑马：


///< 脱衣服

package com.errorvenus.undress;

import android.support.v7.app.ActionBarActivity;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;

public class MainActivity extends ActionBarActivity {

    private ImageView img = null;
    private Bitmap bitmapAlert = null;
    private Canvas canvas = null;
    private Paint paint = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        img = (ImageView) findViewById(R.id.undressImg);
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.g3_up);

        ///< 必须设置图片格式，否则会全黑
        bitmapAlert = Bitmap.createBitmap(
                bitmap.getWidth(),
                bitmap.getHeight(),
                Config.ARGB_4444);
        canvas = new Canvas(bitmapAlert);
        paint = new Paint();
        paint.setColor(Color.BLACK);
        canvas.drawBitmap(bitmap, new Matrix(), paint);
        img.setImageBitmap(bitmapAlert);

        img.setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                // TODO Auto-generated method stub
                switch (event.getAction())
                {
                case MotionEvent.ACTION_MOVE: ///< 崩溃是需要处理边界问题
                    int x = (int) event.getX();
                    int y = (int) event.getY();
                    for (int i = -4; i < 5; i++)
                    {
                        for (int j = -4; j < 5; j++)
                        {
                            bitmapAlert.setPixel(x + i, y + j, Color.TRANSPARENT);
                        }
                    }
                    img.setImageBitmap(bitmapAlert);
                    //bitmapAlert.setPixel(x, y, Color.TRANSPARENT);
                    //img.setImageBitmap(bitmapAlert);
                    //                        canvas.drawCircle(event.getX(), event.getY(), 2f, paint);
                    //                        img.setImageBitmap(bitmapAlert);
                    break;
                }

                return true;
            }
        });
    }
}