java - Can anyone help me with the code (the use of Android's Canvas and Paint, file saving, and gesture recognition)?

Question

研究了好久 都写不好 。。。

package com.li.zhuoyuan.designmodel;

import android.content.Context;
import android.os.Build;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;

public abstract class GestureDetector {
    private static final String TAG = "VersionedGestureDetector";

    OnGestureListener mListener;

    public static GestureDetector newInstance(Context context,
                                              OnGestureListener listener) {
        final int sdkVersion = Integer.parseInt(Build.VERSION.SDK);
        GestureDetector detector = null;
        if (sdkVersion < Build.VERSION_CODES.ECLAIR) {
            detector = new CupcakeDetector();
        } else if (sdkVersion < Build.VERSION_CODES.FROYO) {
            detector = new EclairDetector();
        } else {
            detector = new FroyoDetector(context);
        }

        Log.d(TAG, "Created new " + detector.getClass());
        detector.mListener = listener;

        return detector;
    }

    public abstract boolean onTouchEvent(MotionEvent ev);

    public interface OnGestureListener {
        public void onDrag(float dx, float dy);

        public void onScale(float scaleFactor);
    }

    private static class CupcakeDetector extends GestureDetector {
        float mLastTouchX;
        float mLastTouchY;

        float getActiveX(MotionEvent ev) {
            return ev.getX();
        }

        float getActiveY(MotionEvent ev) {
            return ev.getY();
        }

        boolean shouldDrag() {
            return true;
        }

        @Override
        public boolean onTouchEvent(MotionEvent ev) {
            switch (ev.getAction()) {
                case MotionEvent.ACTION_DOWN: {
                    mLastTouchX = getActiveX(ev);
                    mLastTouchY = getActiveY(ev);
                    break;
                }
                case MotionEvent.ACTION_MOVE: {
                    final float x = getActiveX(ev);
                    final float y = getActiveY(ev);

                    if (shouldDrag()) {
                        mListener.onDrag(x - mLastTouchX, y - mLastTouchY);
                    }

                    mLastTouchX = x;
                    mLastTouchY = y;
                    break;
                }
            }
            return true;
        }
    }

    private static class EclairDetector extends CupcakeDetector {
        private static final int INVALID_POINTER_ID = -1;
        private int mActivePointerId = INVALID_POINTER_ID;
        private int mActivePointerIndex = 0;

        @Override
        float getActiveX(MotionEvent ev) {
            return ev.getX(mActivePointerIndex);
        }

        @Override
        float getActiveY(MotionEvent ev) {
            return ev.getY(mActivePointerIndex);
        }

        @Override
        public boolean onTouchEvent(MotionEvent ev) {
            final int action = ev.getAction();
            //No.1
            //开始写代码，请结合所有代码在这里实现，计算手指在屏幕上移动的位置。从而方便其他调用这个类的地方更新屏幕上小机器人的位置。小机器人跟随手指移动。
            switch (action & MotionEvent.ACTION_MASK) {
                case MotionEvent.ACTION_DOWN:
                    mLastTouchX = ev.getX();
                    mLastTouchY = ev.getY();
                    break;
                case MotionEvent.ACTION_MOVE:
                    mLastTouchX = ev.getX();
                    mLastTouchY = ev.getY();


            }

            mActivePointerIndex = 0;
            //end_code
            return super.onTouchEvent(ev);
        }
    }

    private static class FroyoDetector extends EclairDetector {
        private ScaleGestureDetector mDetector;

        public FroyoDetector(Context context) {
            mDetector = new ScaleGestureDetector(context,
                    new ScaleGestureDetector.SimpleOnScaleGestureListener() {
                        @Override
                        public boolean onScale(ScaleGestureDetector detector) {
                            mListener.onScale(detector.getScaleFactor());
                            return true;
                        }
                    });
        }

        @Override
        boolean shouldDrag() {
            return !mDetector.isInProgress();
        }

        @Override
        public boolean onTouchEvent(MotionEvent ev) {
            mDetector.onTouchEvent(ev);
            return super.onTouchEvent(ev);
        }
    }
}

package com.li.zhuoyuan.designmodel;

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
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.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;

public class MainActivity extends AppCompatActivity {
    private Button button_save, button_resume;
    private ImageView iv_canvas;
    private Bitmap baseBitmap;
    private Canvas canvas;
    /*声明画笔*/
    private Paint mPaint;
    /*手势监听器*/
    private View.OnTouchListener onTouchListener = new View.OnTouchListener() {
        /*表示手指在屏幕上X轴Y轴的坐标点*/
        float startX;
        float startY;

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    //No.1
                    //开始写代码，请用代码实现初始化Bitmap对象、定义画布颜色（请定义为白色）、记录用户手指在屏幕上的触摸点坐标 将坐标存入到startX和startY变量中。

                    Bitmap bitmap = Bitmap.createBitmap(iv_canvas.getWidth(),
                            iv_canvas.getHeight(), Bitmap.Config.ARGB_8888);
                    mPaint.setColor(Color.WHITE);
                    startX = iv_canvas.getX();
                    startX = iv_canvas.getY();
                    //end_code
                    break;
                case MotionEvent.ACTION_MOVE:
                    //No.2
                    //开始写代码，根据手指在屏幕滑动的轨迹实现绘制轨迹的线条，并更新手指在屏幕上的坐标点（startX和startY变量），将绘制好的图像展示在ImageView中。
                    float stopX = iv_canvas.getX();
                    float stopY = iv_canvas.getY();


                    //end_code
                    break;
                case MotionEvent.ACTION_UP:

                    break;

                default:
                    break;
            }
            return true;
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        /*初始化画笔 设置画笔的宽度和颜色*/
        mPaint = new Paint();
        mPaint.setStrokeWidth(5);
        mPaint.setColor(Color.RED);

        iv_canvas = (ImageView) findViewById(R.id.iv_canvas);
        button_save = (Button) findViewById(R.id.button_save);
        button_resume = (Button) findViewById(R.id.button_resume);
        /*保存按钮的监听器*/
        button_save.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                saveBitmap();
            }
        });
        /*清除按钮的监听器*/
        button_resume.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                resumeCanvas();
            }
        });
        iv_canvas.setOnTouchListener(onTouchListener);
    }

    /*保存图片的方法*/
    protected void saveBitmap() {
        try {
            /*以png的格式保存的手机内存中*/
            //No.3
            //开始写代码，请在这里实现文件存储的方法，将手指在屏幕上涂鸦的图形以PNG图片的形式保存到SD卡中；并发送广播进行扫描SD卡。

            File file


            //end_code
        } catch (Exception e) {
            Toast.makeText(MainActivity.this, "保存图片失败", 0).show();
            e.printStackTrace();
        }
    }

    /*清除画布的方法*/
    protected void resumeCanvas() {
        if (baseBitmap != null) {
            baseBitmap = Bitmap.createBitmap(iv_canvas.getWidth(),
                    iv_canvas.getHeight(), Bitmap.Config.ARGB_8888);
            canvas = new Canvas(baseBitmap);
            canvas.drawColor(Color.WHITE);
            iv_canvas.setImageBitmap(baseBitmap);
            Toast.makeText(MainActivity.this, "清除画板成功，可以重新开始绘图", 0).show();
        }
    }
}

请输入代码

Answer 1

Just tell me directly what function you want to make, so no one will go back and help you fill in the code

Answer 2

Can you share your salary with me?