android - 将位图大小调整为更小的位图

Question

我有一个位图列表。我想要的是获取这些位图，并在 Canvas 的帮助下，使用我拥有的位图列表中的按比例缩小的图像(也就是说，使它们非常小)创建一个新的位图。

我已经设法做到了，但是由于缩小比例，图像看起来很糟糕。我已经尝试了很多东西，设置，创建新 Canvas 等。

第一个简单的解决方案看起来像这样(下面的代码)，但是，正如我所说，图像看起来很糟糕。

public static Bitmap folderBitmap(Bitmap bitmap[]) {

    Bitmap b = Bitmap.createBitmap(100, 100, Bitmap.Config.RGB_565);
    Canvas c = new Canvas(b);

    c.drawARGB(255, 255, 255, 255);

    Paint paint = new Paint();
    paint.setAntiAlias(false);
    paint.setFilterBitmap(false);
    paint.setDither(true);

    c.drawBitmap(getBit(bitmap), 4, 4, paint);
    c.drawBitmap(getBit(bitmap), 35, 4, paint);
    c.drawBitmap(getBit(bitmap), 67, 4, paint);

    c.drawBitmap(getBit(bitmap), 4, 35, null);
    c.drawBitmap(getBit(bitmap), 35, 35, null);
    c.drawBitmap(getBit(bitmap), 67, 35, null);

    c.drawBitmap(getBit(bitmap), 4, 67, null);
    c.drawBitmap(getBit(bitmap), 35, 67, null);
    c.drawBitmap(getBit(bitmap), 67, 67, null);

    return b;
}

private static Bitmap getBit(Bitmap[] b) {
    Bitmap newBitmap = Bitmap.createScaledBitmap(b[getR()], 28, 28, false);

    return newBitmap;
}

private static int getR() {
    Random r = new Random();
    int rint = r.nextInt(8);
    return rint;
}

糟糕透顶的意思是，它们看起来像素化且不清晰。

Answer 1

使用inSampleSize 缩放位图。来自文档

If set to a value > 1, requests the decoder to subsample the original image, returning a smaller image to save memory. The sample size is the number of pixels in either dimension that correspond to a single pixel in the decoded bitmap. For example, inSampleSize == 4 returns an image that is 1/4 the width/height of the original, and 1/16 the number of pixels. Any value <= 1 is treated the same as 1. Note: the decoder uses a final value based on powers of 2, any other value will be rounded down to the nearest power of 2.

例如:

 BitmapFactory.Options opts = new BitmapFactory.Options();
 opt.inSampleSize = 4;
 Bitmap newBitmap = BitmapFactory.decodeFile(filePath, opts);