Android图像处理（三）刮刮卡

偏执的太偏执、 2022-08-22 05:56 289阅读 0赞

## 思路： ##

类似前面的画画板  
不过这里是通过将滑动的像素点设置成透明颜色  
`altBitMap.setPixel(x + i, y + j, Color.TRANSPARENT)`  
而且是双层for循环设置以这个点为中心的圆为透明颜色(一个像素一个像素的刮太慢了。。。)  
而且在设置的时候注意边界问题。

## 代码： ##

package cn.zsp.guaguale;
    
    import android.graphics.Bitmap;
    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.support.v7.app.AppCompatActivity;
    import android.view.MotionEvent;
    import android.view.View;
    import android.widget.ImageView;
    import android.widget.Toast;
    
    public class MainActivity extends AppCompatActivity { 
        private ImageView imageView;
        private Bitmap altBitMap;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            imageView = (ImageView) findViewById(R.id.iv);
    
            Bitmap bitMap = BitmapFactory.decodeResource(getResources(), R.drawable.guagua);
            altBitMap = Bitmap.createBitmap(bitMap.getWidth(), bitMap.getHeight(), bitMap.getConfig());
    
            Canvas canvas = new Canvas(altBitMap);
            Paint paint = new Paint();
            canvas.drawBitmap(bitMap, new Matrix(), paint);
            imageView.setImageBitmap(altBitMap);
            imageView.setOnTouchListener(new View.OnTouchListener() {
                @Override
                public boolean onTouch(View v, MotionEvent event) {
                    switch (event.getAction()) {
                        case MotionEvent.ACTION_MOVE:
                            int x = (int) event.getX();
                            int y = (int) event.getY();
                            Toast.makeText(MainActivity.this, "移动" + x + "," + y, Toast.LENGTH_SHORT).show();
                            for (int i = -20; i < 20; i++) {
                                for (int j = -20; j < 20; j++) {
                                    if (Math.sqrt((i * i) + (j * j)) <= 20) {
       //设置成透明 以x，y 为半径的圆 遍历
                                        //宽 高 不能越界
                                        if (x + i >= 0 && x + i < altBitMap.getWidth() && y + j >= 0 && y + j < altBitMap.getHeight()) {
                                            altBitMap.setPixel(x + i, y + j, Color.TRANSPARENT);
                                        }
                                    }
                                }
                            }
                            imageView.setImageBitmap(altBitMap);
                            break;
                    }
                    return true;
                }
            });
        }
    }