添加未添加完的文件

src/main/java/net/micode/notes/PaintView.java

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+package net.micode.notes;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.text.SimpleDateFormat;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.Iterator;
+
+import android.app.Activity;
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.graphics.Path;
+import android.util.AttributeSet;
+import android.util.DisplayMetrics;
+import android.view.MotionEvent;
+import android.view.View;
+
+/**
+ *
+ * @category: View实现涂鸦、撤销以及重做功能
+ * @author: dingruihua
+ * @date: 2022.10.10
+ *
+ */
+
+public class PaintView extends View  {
+
+    private Canvas  mCanvas;
+    private Path    mPath;
+    private Paint   mBitmapPaint;
+    private Bitmap  mBitmap;
+    private Paint mPaint;
+
+    private ArrayList<DrawPath> savePath;
+    private ArrayList<DrawPath> deletePath;
+    private DrawPath dp;
+
+    private float mX, mY;
+    private static final float TOUCH_TOLERANCE = 4;
+
+    private int bitmapWidth;
+    private int bitmapHeight;
+
+    public PaintView(Context c) {
+        super(c);
+        //得到屏幕的分辨率
+        DisplayMetrics dm = new DisplayMetrics();
+        ((Activity) c).getWindowManager().getDefaultDisplay().getMetrics(dm);
+
+        bitmapWidth = dm.widthPixels;
+        bitmapHeight = dm.heightPixels - 2 * 45;
+
+        initCanvas();
+        savePath = new ArrayList<DrawPath>();
+        deletePath = new ArrayList<DrawPath>();
+
+    }
+    public PaintView(Context c, AttributeSet attrs) {
+        super(c,attrs);
+        //得到屏幕的分辨率
+        DisplayMetrics dm = new DisplayMetrics();
+        ((Activity) c).getWindowManager().getDefaultDisplay().getMetrics(dm);
+
+        bitmapWidth = dm.widthPixels;
+        bitmapHeight = dm.heightPixels - 2 * 45;
+
+        initCanvas();
+        savePath = new ArrayList<DrawPath>();
+        deletePath = new ArrayList<DrawPath>();
+    }
+    //初始化画布
+    public void initCanvas(){
+
+        mPaint = new Paint();
+        mPaint.setAntiAlias(true);
+        mPaint.setDither(true);
+        mPaint.setColor(0xFF00FF00);
+        mPaint.setStyle(Paint.Style.STROKE);
+        mPaint.setStrokeJoin(Paint.Join.ROUND);
+        mPaint.setStrokeCap(Paint.Cap.ROUND);
+        mPaint.setStrokeWidth(10);
+
+        mBitmapPaint = new Paint(Paint.DITHER_FLAG);
+
+
+
+        //画布大小
+        mBitmap = Bitmap.createBitmap(bitmapWidth, bitmapHeight,
+                Bitmap.Config.RGB_565);
+        mCanvas = new Canvas(mBitmap);  //所有mCanvas画的东西都被保存在了mBitmap中
+
+        mCanvas.drawColor(Color.WHITE);
+        mPath = new Path();
+        mBitmapPaint = new Paint(Paint.DITHER_FLAG);
+
+    }
+
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+
+        canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);     //显示旧的画布
+        if (mPath != null) {
+            // 实时的显示
+            canvas.drawPath(mPath, mPaint);
+        }
+    }
+    //路径对象
+    class DrawPath{
+        Path path;
+        Paint paint;
+    }
+
+    /**
+     * 撤销的核心思想就是将画布清空，
+     * 将保存下来的Path路径最后一个移除掉，
+     * 重新将路径画在画布上面。
+     */
+    public void undo(){
+
+        System.out.println(savePath.size()+"--------------");
+        if(savePath != null && savePath.size() > 0){
+            //调用初始化画布函数以清空画布
+            initCanvas();
+
+            //将路径保存列表中的最后一个元素删除 ,并将其保存在路径删除列表中
+            DrawPath drawPath = savePath.get(savePath.size() - 1);
+            deletePath.add(drawPath);
+            savePath.remove(savePath.size() - 1);
+
+            //将路径保存列表中的路径重绘在画布上
+            Iterator<DrawPath> iter = savePath.iterator();		//重复保存
+            while (iter.hasNext()) {
+                DrawPath dp = iter.next();
+                mCanvas.drawPath(dp.path, dp.paint);
+
+            }
+            invalidate();// 刷新
+        }
+    }
+    /**
+     * 恢复的核心思想就是将撤销的路径保存到另外一个列表里面(栈)，
+     * 然后从redo的列表里面取出最顶端对象，
+     * 画在画布上面即可
+     */
+    public void redo(){
+        if(deletePath.size() > 0){
+            //将删除的路径列表中的最后一个，也就是最顶端路径取出（栈）,并加入路径保存列表中
+            DrawPath dp = deletePath.get(deletePath.size() - 1);
+            savePath.add(dp);
+            //将取出的路径重绘在画布上
+            mCanvas.drawPath(dp.path, dp.paint);
+            //将该路径从删除的路径列表中去除
+            deletePath.remove(deletePath.size() - 1);
+            invalidate();
+        }
+    }
+    /*
+     * 清空的主要思想就是初始化画布
+     * 将保存路径的两个List清空
+     * */
+    public void removeAllPaint(){
+        //调用初始化画布函数以清空画布
+        initCanvas();
+        invalidate();//刷新
+        savePath.clear();
+        deletePath.clear();
+    }
+
+/*
+     * 保存所绘图形
+     * 返回绘图文件的存储路径
+     *
+    public String saveBitmap(){
+        //获得系统当前时间，并以该时间作为文件名
+        SimpleDateFormat   formatter   =   new   SimpleDateFormat   ("yyyyMMddHHmmss");
+        Date   curDate   =   new   Date(System.currentTimeMillis());//获取当前时间
+        String   str   =   formatter.format(curDate);
+        String paintPath = "";
+        str = str + "paint.png";
+        File dir = new File("/sdcard/notes/");
+        File file = new File("/sdcard/notes/",str);
+        if (!dir.exists()) {
+            dir.mkdir();
+        }
+        else{
+            if(file.exists()){
+                file.delete();
+            }
+        }
+
+        try {
+            FileOutputStream out = new FileOutputStream(file);
+            mBitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
+            out.flush();
+            out.close();
+            //保存绘图文件路径
+            paintPath = "/sdcard/notes/" + str;
+
+
+        } catch (FileNotFoundException e) {
+            // TODO Auto-generated catch block
+            e.printStackTrace();
+        } catch (IOException e) {
+            // TODO Auto-generated catch block
+            e.printStackTrace();
+        }
+
+        return paintPath;
+    }*/
+
+
+    private void touch_start(float x, float y) {
+        mPath.reset();//清空path
+        mPath.moveTo(x, y);
+        mX = x;
+        mY = y;
+    }
+    private void touch_move(float x, float y) {
+        float dx = Math.abs(x - mX);
+        float dy = Math.abs(y - mY);
+        if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
+            //mPath.quadTo(mX, mY, x, y);
+            mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);//源代码是这样写的，可是我没有弄明白，为什么要这样？
+            mX = x;
+            mY = y;
+        }
+    }
+    private void touch_up() {
+        mPath.lineTo(mX, mY);
+        mCanvas.drawPath(mPath, mPaint);
+        savePath.add(dp);
+        mPath = null;
+
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        float x = event.getX();
+        float y = event.getY();
+
+        switch (event.getAction()) {
+            case MotionEvent.ACTION_DOWN:
+
+                mPath = new Path();
+                dp = new DrawPath();
+                dp.path = mPath;
+                dp.paint = mPaint;
+
+                touch_start(x, y);
+                invalidate(); //清屏
+                break;
+            case MotionEvent.ACTION_MOVE:
+                touch_move(x, y);
+                invalidate();
+                break;
+            case MotionEvent.ACTION_UP:
+                touch_up();
+                invalidate();
+                break;
+        }
+        return true;
+    }
+
+}

src/main/java/net/micode/notes/ui/BoardActivity.java

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+package net.micode.notes.ui;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.view.View;
+import android.widget.ImageButton;
+
+import net.micode.notes.PaintView;
+import net.micode.notes.R;
+
+public class BoardActivity extends Activity {
+    private PaintView paintView;
+
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState); //调用父类的功能
+        this.setContentView(R.layout.activity_paint);
+        //根据id获取添加图片按钮
+        final ImageButton undo = (ImageButton) findViewById(R.id.undo);
+        //为点击图片按钮设置监听器
+        undo.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                paintView.undo();
+            }
+        });
+
+        final ImageButton paint_reset = (ImageButton) findViewById(R.id.paint_reset);
+        //为点击图片按钮设置监听器
+        paint_reset.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                paintView.redo();
+            }
+        });
+
+        final ImageButton paint_delete = (ImageButton) findViewById(R.id.paint_delete);
+        //为点击图片按钮设置监听器
+        paint_delete.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                paintView.removeAllPaint();
+            }
+        });
+        paintView = (PaintView)findViewById(R.id.paint_layout);
+    }
+}

src/main/res/layout/activity_paint.xml

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+
+    >
+
+    <net.micode.notes.PaintView
+        android:id="@+id/paint_layout"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"></net.micode.notes.PaintView>
+
+    <ImageButton
+            android:id="@+id/paint_reset"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginLeft="240dp"
+            android:layout_marginTop="0dp"
+            android:layout_marginBottom="0dp"
+            android:src="@drawable/paint_reset" />
+
+    <ImageButton
+        android:id="@+id/paint_clor"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginLeft="80dp"
+        android:layout_marginTop="0dp"
+        android:layout_marginBottom="0dp"
+        android:src="@drawable/paint_clor" />
+
+    <ImageButton
+        android:id="@+id/paint"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginLeft="0dp"
+        android:layout_marginTop="0dp"
+        android:layout_marginBottom="0dp"
+        android:src="@drawable/paint" />
+
+    <ImageButton
+        android:id="@+id/paint_delete"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginLeft="320dp"
+        android:layout_marginTop="0dp"
+        android:layout_marginBottom="0dp"
+        android:src="@drawable/paint_delete" />
+
+    <ImageButton
+        android:id="@+id/undo"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginLeft="160dp"
+        android:layout_marginTop="0dp"
+        android:layout_marginBottom="0dp"
+        android:src="@drawable/undo" />
+
+</RelativeLayout>