Android画画板

main.xml布局

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main"    android:layout_width="match_parent" android:layout_height="match_parent"    tools:context="com.example.demo.MainActivity">    <ImageView        android:id="@+id/iv"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:src="@drawable/bg"        />    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal"        android:layout_alignParentBottom="true"        >        <Button            android:id="@+id/red"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="红色"            android:onClick="onplay"            />        <Button            android:id="@+id/green"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="绿色"            android:onClick="onplay"            />        <Button            android:id="@+id/root"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="刷子"            android:onClick="onplay"            />        <Button            android:id="@+id/save"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="保存"            android:onClick="onplay"            />        <Button            android:id="@+id/finish"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="涂漆"            android:onClick="onplay"            />    </LinearLayout></RelativeLayout>

main布局

/*画板canvas    画板paint  手势识别器整体思路:因为我是图片是作画,实际是对图片进行修改,起到画图的效果1.原图,白纸,画笔,画板2.根据手势识别进行作画 */public class MainActivity extends AppCompatActivity {private Bitmap bitmap;    private Canvas canvas;private ImageView iv;    private int startx;    private int starty;    private Paint paint;    private Bitmap bmSrc;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //加载原图        bmSrc = BitmapFactory.decodeResource(getResources(), R.drawable.bg);        //创建白纸,宽,高,图片的参数         bitmap = Bitmap.createBitmap(bmSrc.getWidth(), bmSrc.getHeight(), bmSrc.getConfig());        //创建画板,参数是白纸对象        canvas = new Canvas(bitmap);        //创建画笔        paint = new Paint();        //在纸上作画        iv=(ImageView)findViewById(R.id.iv);        canvas.drawBitmap(bmSrc,new Matrix(), paint);        //-----------------手势识别器和画笔结合的知识-------------------   //给控件设置手势适配器,可以得到用户在这个控件上所做的手势        iv.setOnTouchListener(new View.OnTouchListener() {            //当用户手在这个控件时,指的就是用户的手对控件滑动,按下,松开的三种场景,自动回调            @Override            public boolean onTouch(View view, MotionEvent motionEvent) {                switch (motionEvent.getAction()){                    case MotionEvent.ACTION_DOWN://按下时回调一次                        //获取用户手指按下时的坐标                        startx = (int) motionEvent.getX();                        starty = (int) motionEvent.getY();                        break;                    case MotionEvent.ACTION_MOVE://手指滑动时,不停地调用                        int newx = (int) motionEvent.getX();                        int newy = (int) motionEvent.getY();                        //在背景图画线                        canvas.drawLine(startx,starty,newx,newy, paint);                        startx=newx;                        starty=newy;                        iv.setImageBitmap(bitmap);                        break;                    case MotionEvent.ACTION_UP://松开时回调一次                        break;                }                //事情分发机制                //true:iv处理该触摸事件                //false:iv不处理该触摸事件,事件传递给上一级                return true;            }        });    }    public void onplay(View view){      switch (view.getId()){          case R.id.red:              paint.setColor(Color.RED);              break;          case R.id.green:              paint.setColor(Color.GREEN);              break;          case R.id.root:              paint.setStrokeWidth(5);              break;          case R.id.save:              if(SaveViewUtil.saveScreen(iv)){                  Toast.makeText(this, "截图成功", Toast.LENGTH_SHORT).show();              }else{                  Toast.makeText(this, "截图失败，请检查sdcard是否可用", Toast.LENGTH_SHORT).show();              }              break;          //涂漆          case R.id.finish:              canvas.drawRect(new Rect(0,0,width,height), paint);              break;          }     }    }
这是一个把画的图存储SD卡的工具类

public class SaveViewUtil {      private static final File rootDir = new File(Environment.getExternalStorageDirectory()+File.separator);   /**保存截图的方法*/   public static boolean saveScreen(View view){      //判断sdcard是否可用      if(!Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())){         return false;      }      if(!rootDir.exists()){         rootDir.mkdir();      }      view.setDrawingCacheEnabled(true);      view.buildDrawingCache();      Bitmap bitmap = view.getDrawingCache();      try {         bitmap.compress(CompressFormat.JPEG, 100, new FileOutputStream(new File(rootDir,System.currentTimeMillis()+".jpg")));         return true;      } catch (FileNotFoundException e) {         e.printStackTrace();         return false;      }finally{         view.setDrawingCacheEnabled(false);         bitmap = null;      }   }}
<!-- 往SDCard写入数据权限 --><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>