Android画画板的制作方法

本文实例为大家分享了Android画画板展示的具体代码，供大家参考，具体内容如下

main.xml布局

main布局

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);

  
  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;
   }
  }
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持考高分网。