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android+ canvas绘图后保存图片

canvas绘图后保存图片,分两种情况,一种:自己new一个canvas对象。 第二种:在onDraw函数作为参数引入Canvas

 

第一种情况:

  建一个空的bitmap对象,然后在初始化画布时,把它作为参数带入,之后canvas所做的绘图操作,都是在该bitmap上,只要保存该bitmap对象即可。如下代码:画一个蓝色的圆环:

            //这边直接用canvas画,然后保存            Bitmap bitmap = Bitmap.createBitmap(700,700, Bitmap.Config.ARGB_8888);            Canvas canvas = new Canvas(bitmap);            canvas.drawColor(Color.WHITE);            Paint paint = new Paint();            paint.setAntiAlias(true);//设置抗锯齿            paint.setStrokeWidth(7);//设置笔触宽度            paint.setStyle(Paint.Style.STROKE);            //画奥运五环            paint.setColor(Color.BLUE);            canvas.drawCircle(150,150,100,paint); //绘制蓝色圆环            canvas.save(Canvas.ALL_SAVE_FLAG); //保存            canvas.restore(); // 存储            File sdRoot = Environment.getExternalStorageDirectory();            String save_path = sdRoot.getAbsolutePath() + "/DCIM/100MEDIA/114.jpg";            try {                bitmap.compress(Bitmap.CompressFormat.JPEG, 100, new FileOutputStream(new File(save_path)));            } catch (FileNotFoundException e) {                e.printStackTrace();            }

 

 

第二种情况:

  重点就是setDrawingCacheEnabled(true); 和 getDrawingCache()这两个函数

        public MyView(Context context) {            super(context);            //这函数是要打开图形缓存,这样才能getDrawingCache            setDrawingCacheEnabled(true);        }

 

        protected void onDraw(Canvas canvas){            canvas.drawColor(Color.WHITE);            Paint paint = new Paint();            paint.setAntiAlias(true);//设置抗锯齿            paint.setStrokeWidth(7);//设置笔触宽度            paint.setStyle(Paint.Style.STROKE);            //画一个环            paint.setColor(Color.BLUE);            canvas.drawCircle(150,150,100,paint); //绘制蓝色圆环            canvas.save(Canvas.ALL_SAVE_FLAG); //保存            canvas.restore(); // 存储            //将canvas里的draw保存下来            File sdRoot = Environment.getExternalStorageDirectory();            String save_path = sdRoot.getAbsolutePath() + "/DCIM/100MEDIA/113.jpg";            try {                getDrawingCache().compress(Bitmap.CompressFormat.JPEG, 100, new FileOutputStream(new File(save_path)));            } catch (Exception e) {                Log.e("Error--------->", e.toString());            }            super.onDraw(canvas);        }    

 

android+ canvas绘图后保存图片