Question

我正在写一个音乐应用程序，我已经获得了专辑艺术。然而，它们出现了各种尺寸。那么，我如何标准化返回的位图的大小？

Answer 1

你会做这样的事情：

// load the origial BitMap (500 x 500 px)
        Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),
               R.drawable.android);

        int width = bitmapOrg.width();
        int height = bitmapOrg.height();
        int newWidth = 200;
        int newHeight = 200;

        // calculate the scale - in this case = 0.4f
        float scaleWidth = ((float) newWidth) / width;
        float scaleHeight = ((float) newHeight) / height;

        // createa matrix for the manipulation
        Matrix matrix = new Matrix();
        // resize the bit map
        matrix.postScale(scaleWidth, scaleHeight);

        // recreate the new Bitmap
        Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0,
                          width, height, matrix, true);

Answer 2

或者，当您在画布上绘制位图时，可以将位图缩放到所需的大小：

来自android文档：

drawBitmap（位图位图，Rect src，Rect dst，Paint paint）绘制指定的位图，自动缩放/平移以填充目标矩形。

使src为null，dst是一个Rect，你想要它在画布上的大小/位置，设置如

Rect rect = new Rect(0, 0, width, height)
canvas.drawBitmap(bitmap, null, rect)

Answer 3

根据我的经验，接受的答案中的代码不起作用，至少在某些平台上是这样。

Bitmap.createBitmap(bitmapOrg, 0, 0, width, height, matrix, true);

会以原始尺寸为您提供缩减采样图像 - 所以只是模糊的图像。

有趣的是，代码

Bitmap resizedBitmap = Bitmap.createScaledBitmap(square, (int) targetWidth, (int) targetHeight, false);

也会产生模糊的图像。在我的情况下，有必要这样做：

// RESIZE THE BIT MAP

// According to a variety of resources, this function should give us pixels from the dp of the screen
// From http://stackoverflow.com/questions/4605527/converting-pixels-to-dp-in-android
float targetHeight = DWUtilities.convertDpToPixel(80, getActivity());
float targetWidth = DWUtilities.convertDpToPixel(80, getActivity());

// However, the above pixel dimension are still too small to show in my 80dp image view
// On the Nexus 4, a factor of 4 seems to get us up to the right size
// No idea why.
targetHeight *= 4;
targetWidth *= 4;

matrix.postScale( (float) targetHeight / square.getWidth(), (float) targetWidth / square.getHeight());


Bitmap resizedBitmap = Bitmap.createBitmap(square, 0, 0, square.getWidth(), square.getHeight(), matrix, false); 

// By the way, the below code also gives a full size, but blurry image
// Bitmap resizedBitmap = Bitmap.createScaledBitmap(square, (int) targetWidth, (int) targetHeight, false

我还没有进一步的解决方案，但希望这对某人有帮助。

调整位图大小

3 个答案: