Android 自定义控件的画画扳的简单实现

核心思路
运用的是图片作画,实际上是对图片进行修改,起到画图的效果


public class MainActivity extends AppCompatActivity implements View.OnClickListener {
 private ImageView mImage; 
   /**     * 修改颜色     */  
  private Button mButColor;  
  /**     * 修改线宽     */   
 private Button mButLine;   
 private Bitmap bitmapCopy;  
  private Canvas canvas;    
private Paint paint;  
  /**     * 画布Canvas  画笔paint 手势识别器    
 * 整体思路,因为我是图片作画,实际上是对图片进行修改,起到画图的效果  
   * 1.原图,白纸,画布,画笔    
 * 2.根据手势识别进行作画     
*     
* @param savedInstanceState    
 */    @Override    
protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 initView();
 //加载原图 
       Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.aaa); 
       //做一个图片的复制 
       bitmapCopy = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
 //创建画布  
      canvas = new Canvas(bitmapCopy);
 //创建画笔        
paint = new Paint();
 //开始画画 
       canvas.drawBitmap(bitmap,new Matrix(),paint);
 //设置手势识别 
       mImage.setOnTouchListener(new View.OnTouchListener() { 
           private float starty;
 private float startx;
 @Override 
           public boolean onTouch(View view, MotionEvent motionEvent) {
 switch(motionEvent.getAction()){
 case MotionEvent.ACTION_DOWN:
 startx = motionEvent.getX();
 starty = motionEvent.getY();
 break;
 case MotionEvent.ACTION_MOVE:
 float x = motionEvent.getX();
 float y = motionEvent.getY();
 canvas.drawLine(startx,starty,x,y,paint);
 startx=x;   
                 
    starty=y;    
                 
   mImage.setImageBitmap(bitmapCopy);      
                  break;              
      default:                 
       break;  
              }   
             return true; 
           } 
       });  
  }   
 private void initView() { 
       mImage = (ImageView) findViewById(R.id.image); 
       mButColor = (Button) findViewById(R.id.butColor);  
      mButColor.setOnClickListener(this); 
       mButLine = (Button) findViewById(R.id.butLine);  
      mButLine.setOnClickListener(this); 
   }  
  //这里指示简单的修改了颜色和线宽 
   @Override 
   public void onClick(View v) { 
       switch (v.getId()) {  
          case R.id.butColor:
 paint.setColor(Color.RED);  
              break;         
   case R.id.butLine:        
        paint.setStrokeWidth(10);
//                paint.setTextSize(1500);  
              break; 
       }    }}

       //保存文件

       File file=new File(path,"名字");try {file.createNewFile();FileOutputStream fos=new FileOutputStream(file);bitmapCopy.compress(Bitmap.CompressFormat.JPEG,50,fos);} catch (IOException e) {                                             e.printStackTrace();}