Android 实现简单的画画版一

来源：互联网发布：游戏作弊神器软件编辑：程序博客网时间：2024/04/30 08:14

原理：
1）首先创建一个创建一张空白图片
2）把空白图片设置到imageview控件
3）给imageview设置监听，并返回值true;

代码如下:

/** * @描述         画板 * @项目名称      App_Basic * @包名         com.example.basic.image * @类名         CanvaImage * @author      chenlin * @version     1.0 */public class CanvaImageActivty extends BaseActivity implements OnTouchListener, OnClickListener {    private Button mBtnView;    private ImageView mImageView;    private Bitmap mBlankBitmap;    private Canvas mCanvas;    private Paint mPaint;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_canvas);        mBtnView = (Button) findViewById(R.id.btn_view_image);        mImageView = (ImageView) findViewById(R.id.iv_canvas);        mImageView.setOnTouchListener(this);        mBtnView.setOnClickListener(this);        createBitmap();    }    private void createBitmap() {        WindowManager manager = (WindowManager) getSystemService(WINDOW_SERVICE);        DisplayMetrics outMetrics = new DisplayMetrics();        manager.getDefaultDisplay().getMetrics(outMetrics);        mBtnView.measure(0, 0);        int height = outMetrics.heightPixels - mBtnView.getMeasuredHeight();        // 创建一张空白图片        mBlankBitmap = Bitmap.createBitmap(outMetrics.widthPixels, height, Config.ARGB_8888);        // 创建一张画布        mCanvas = new Canvas(mBlankBitmap);        //画布背景为白色        mCanvas.drawColor(Color.WHITE);        //初始化画笔        mPaint = new Paint();        mPaint.setColor(Color.RED);        mPaint.setStrokeWidth(3);        //绘制白色背景        mCanvas.drawBitmap(mBlankBitmap, new Matrix(), mPaint);        mImageView.setImageBitmap(mBlankBitmap);    }    private int downX;    private int downY;    @Override    public boolean onTouch(View v, MotionEvent event) {        switch (event.getAction()) {        case MotionEvent.ACTION_DOWN:            // 获取手按下时的坐标            downX = (int) event.getX();            downY = (int) event.getY();            break;        case MotionEvent.ACTION_MOVE:            // 获取手移动后的坐标            int moveX = (int) event.getX();            int moveY = (int) event.getY();            // 在开始和结束坐标间画一条线            mCanvas.drawLine(downX, downY, moveX, moveY, mPaint);            // 实时更新开始坐标            downX = (int) event.getX();            downY = (int) event.getY();            mImageView.setImageBitmap(mBlankBitmap);            break;        case MotionEvent.ACTION_UP:        case MotionEvent.ACTION_CANCEL:            //mImageView.setImageBitmap(mBlankBitmap);            //保存图片到sdcard            saveBitmap(mBlankBitmap);            break;        }        return true;    }    private void saveBitmap(Bitmap bitmap) {        try {            String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/image/";            File dir = new File(path);            if (!dir.exists()) {                dir.mkdirs();            }            String filename = System.currentTimeMillis() + ".jpg";            FileOutputStream fos = new FileOutputStream(new File(path, filename));            //把保存图片            bitmap.compress(CompressFormat.JPEG, 100, fos);            fos.close();            notifyHasMount();        } catch (FileNotFoundException e) {            e.printStackTrace();            show("保存失败" + e.getMessage());        } catch (IOException e) {            e.printStackTrace();            show("保存失败" + e.getMessage());        }    }    /**     * 模拟一个广播，通知系统sdcard被挂载     * */    private void notifyHasMount() {        Intent intent = new Intent();        intent.setAction(Intent.ACTION_MEDIA_MOUNTED);        intent.setData(Uri.fromFile(Environment.getExternalStorageDirectory()));        sendBroadcast(intent);    }    /**     * 查看图片     */    @Override    public void onClick(View v) {        if (v == mBtnView) {            Intent intent = new Intent();            intent.setAction(Intent.ACTION_PICK);            intent.setType("image/*");            startActivity(intent);        }    }}

布局文件

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <ImageView        android:id="@+id/iv_canvas"        android:layout_width="match_parent"        android:layout_height="0dp"        android:layout_weight="1"        />    <Button        android:id="@+id/btn_view_image"        android:gravity="center"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="查看图片" /></LinearLayout>

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