减少BitmapDrawable大小 [英] Reducing BitmapDrawable size

问题描述

我缩小图像大小用此功能：

I am reducing size of images with this function:

Drawable reduceImageSize (String path) 
{
    BitmapDrawable bit1 = (BitmapDrawable) Drawable.createFromPath(path);
    Bitmap bit2 = Bitmap.createScaledBitmap(bit1.getBitmap(), 640, 360, true);
    BitmapDrawable bit3 = new BitmapDrawable(getResources(),bit2);
    return bit3;
}

和它的做工精细，唯一的问题是，当我把这个函数的多个时间的应用越来越慢，有没有什么办法来优化这个功能吗？通过矩阵也许减少大小？
我也是从读取SD卡的图像和需要追溯到绘制对象的动画，而这个功能提供了这一点。

And its working fine, the only problem is when I call this function multiple time the app is getting slow, is there any way to optimize this function? Maybe reducing size via matrix? Also I am reading images from SD Card and need the back as Drawable for animations, and this function provides this.

推荐答案

使用 BitmapFactory.Options 和 inJustDe codeBounds 来规模下来：

位图位= getBitmapFromFile（道路，宽，高）;

public static Bitmap getBitmapFromFile(String path, int width, int height) {
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(path, options);

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, width, height);

    options.inJustDecodeBounds = false;
    Bitmap bitmap = BitmapFactory.decodeFile(path, options);
    return bitmap;
}

public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {
        if (width > height) {
            inSampleSize = Math.round((float)height / (float)reqHeight);
        } else {
            inSampleSize = Math.round((float)width / (float)reqWidth);
        }
    }
    return inSampleSize;
}

了解更多关于在这里：​​装载大位图的高效

另外，我不知道你在哪里调用此方法，但如果你有很多人请确保您使用的缓存位图 LruCache 或类似：< A HREF =htt​​p://developer.android.com/training/displaying-bitmaps/cache-bitmap.html相对=nofollow>缓存位图

Also, I'm not sure where you are calling this method but if you have many of them please make sure you are caching the Bitmaps using LruCache or similar: Caching Bitmaps

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