bitmap的一些工具

1.100*100圆形头像；当然也可以直接在网上找圆形的imageview；

public static void getCropped2Bitmap(Bitmap bmp, ImageView iv) {
    int radius = 50;
    Bitmap scaledSrcBmp;
    int diameter = radius * 2;
    if (bmp.getWidth() != diameter || bmp.getHeight() != diameter)
        scaledSrcBmp = Bitmap.createScaledBitmap(bmp, diameter, diameter, false);
    else
        scaledSrcBmp = bmp;
    Bitmap output = Bitmap.createBitmap(scaledSrcBmp.getWidth(), scaledSrcBmp.getHeight(), Config.ARGB_4444);
    Canvas canvas = new Canvas(output);

    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, scaledSrcBmp.getWidth(), scaledSrcBmp.getHeight());

    paint.setAntiAlias(true);
    paint.setFilterBitmap(true);
    paint.setDither(true);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(Color.parseColor("#BAB399"));
    canvas.drawCircle(scaledSrcBmp.getWidth() / 2, scaledSrcBmp.getHeight() / 2, scaledSrcBmp.getWidth() / 2,
            paint);
    paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
    canvas.drawBitmap(scaledSrcBmp, rect, rect, paint);
    iv.setImageBitmap(compressImage(output));
}

2.bitmap转字节

public static byte[] Bitmap2Bytes(Bitmap bm) {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
    return baos.toByteArray();
}

3.在使用引导页或者欢迎页的大图的时候，最好是压缩一下；

public static Bitmap readBitMap(Context context, int resId) {
    BitmapFactory.Options opt = new BitmapFactory.Options();
    opt.inPreferredConfig = Config.RGB_565;
    opt.inPurgeable = true;
    opt.inInputShareable = true;
    // 获取资源图片
    InputStream is = context.getResources().openRawResource(resId);
    return BitmapFactory.decodeStream(is, null, opt);
}

质量压缩

public static Bitmap compressImage(Bitmap image) {

    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    image.compress(Bitmap.CompressFormat.JPEG, 30, baos);// 质量压缩方法，这里100表示不压缩，把压缩后的数据存放到baos中
    int options = 100;
    while (baos.toByteArray().length / 1024 > 100) { // 循环判断如果压缩后图片是否大于100kb,大于继续压缩
        baos.reset();// 重置baos即清空baos
        image.compress(Bitmap.CompressFormat.JPEG, options, baos);// 这里压缩options%，把压缩后的数据存放到baos中
        options -= 10;// 每次都减少10
    }
    ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());// 把压缩后的数据baos存放到ByteArrayInputStream中
    Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);// 把ByteArrayInputStream数据生成图片
    return bitmap;
}

以上是最近项目中用到的bitmap工具，在此以作记录