我正试图在放置为res / drawable / schoolboard.png的图像上绘制一个圆圈.图像填充活动背景.以下不起作用：
Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.schoolboard);
Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(Color.BLUE);
Canvas canvas = new Canvas(bitmap);
canvas.drawCircle(60,50,25,paint);
ImageView imageView = (ImageView)findViewById(R.drawable.schoolboard);
imageView.setAdjustViewBounds(true);
imageView.setImageBitmap(bitmap);
任何帮助将受到高度赞赏.谢谢.
解决方法
您的代码中存在一些错误：
首先,你不能在findViewById中为drawable提供参考ID
所以我觉得你的意思是那样的
首先,你不能在findViewById中为drawable提供参考ID
所以我觉得你的意思是那样的
ImageView imageView = (ImageView)findViewById(R.id.schoolboard_image_view);
schoolboard_image_view是xml布局中的图像ID(检查你的布局是否有正确的id)
BitmapFactory.Options myOptions = new BitmapFactory.Options();
myOptions.inDither = true;
myOptions.inScaled = false;
myOptions.inPreferredConfig = Bitmap.Config.ARGB_8888;// important
myOptions.inPurgeable = true;
Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.schoolboard,myOptions);
Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(Color.BLUE);
Bitmap workingBitmap = Bitmap.createBitmap(bitmap);
Bitmap mutableBitmap = workingBitmap.copy(Bitmap.Config.ARGB_8888,true);
Canvas canvas = new Canvas(mutableBitmap);
canvas.drawCircle(60,paint);
ImageView imageView = (ImageView)findViewById(R.id.schoolboard_image_view);
imageView.setAdjustViewBounds(true);
imageView.setImageBitmap(mutableBitmap);
请确保使用正确的图片ID：
ImageView imageView =(ImageView)findViewById(R.id.schoolboard_image_view);
