java/com/android/dialer/contactphoto/BitmapUtil.java

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.dialer.contactphoto;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;

/** Provides static functions to decode bitmaps at the optimal size */
public class BitmapUtil {

  private BitmapUtil() {}

  /**
   * Returns Width or Height of the picture, depending on which size is smaller. Doesn't actually
   * decode the picture, so it is pretty efficient to run.
   */
  public static int getSmallerExtentFromBytes(byte[] bytes) {
    final BitmapFactory.Options options = new BitmapFactory.Options();

    // don't actually decode the picture, just return its bounds
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options);

    // test what the best sample size is
    return Math.min(options.outWidth, options.outHeight);
  }

  /**
   * Finds the optimal sampleSize for loading the picture
   *
   * @param originalSmallerExtent Width or height of the picture, whichever is smaller
   * @param targetExtent Width or height of the target view, whichever is bigger.
   *     <p>If either one of the parameters is 0 or smaller, no sampling is applied
   */
  public static int findOptimalSampleSize(int originalSmallerExtent, int targetExtent) {
    // If we don't know sizes, we can't do sampling.
    if (targetExtent < 1) {
      return 1;
    }
    if (originalSmallerExtent < 1) {
      return 1;
    }

    // Test what the best sample size is. To do that, we find the sample size that gives us
    // the best trade-off between resulting image size and memory requirement. We allow
    // the down-sampled image to be 20% smaller than the target size. That way we can get around
    // unfortunate cases where e.g. a 720 picture is requested for 362 and not down-sampled at
    // all. Why 20%? Why not. Prove me wrong.
    int extent = originalSmallerExtent;
    int sampleSize = 1;
    while ((extent >> 1) >= targetExtent * 0.8f) {
      sampleSize <<= 1;
      extent >>= 1;
    }

    return sampleSize;
  }

  /** Decodes the bitmap with the given sample size */
  public static Bitmap decodeBitmapFromBytes(byte[] bytes, int sampleSize) {
    final BitmapFactory.Options options;
    if (sampleSize <= 1) {
      options = null;
    } else {
      options = new BitmapFactory.Options();
      options.inSampleSize = sampleSize;
    }
    return BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options);
  }

  /**
   * Given an input bitmap, scales it to the given width/height and makes it round.
   *
   * @param input {@link Bitmap} to scale and crop
   * @param targetWidth desired output width
   * @param targetHeight desired output height
   * @return output bitmap scaled to the target width/height and cropped to an oval. The cropping
   *     algorithm will try to fit as much of the input into the output as possible, while
   *     preserving the target width/height ratio.
   */
  public static Bitmap getRoundedBitmap(Bitmap input, int targetWidth, int targetHeight) {
    if (input == null) {
      return null;
    }
    final Bitmap.Config inputConfig = input.getConfig();
    final Bitmap result =
        Bitmap.createBitmap(
            targetWidth, targetHeight, inputConfig != null ? inputConfig : Bitmap.Config.ARGB_8888);
    final Canvas canvas = new Canvas(result);
    final Paint paint = new Paint();
    canvas.drawARGB(0, 0, 0, 0);
    paint.setAntiAlias(true);
    final RectF dst = new RectF(0, 0, targetWidth, targetHeight);
    canvas.drawOval(dst, paint);

    // Specifies that only pixels present in the destination (i.e. the drawn oval) should
    // be overwritten with pixels from the input bitmap.
    paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));

    final int inputWidth = input.getWidth();
    final int inputHeight = input.getHeight();

    // Choose the largest scale factor that will fit inside the dimensions of the
    // input bitmap.
    final float scaleBy =
        Math.min((float) inputWidth / targetWidth, (float) inputHeight / targetHeight);

    final int xCropAmountHalved = (int) (scaleBy * targetWidth / 2);
    final int yCropAmountHalved = (int) (scaleBy * targetHeight / 2);

    final Rect src =
        new Rect(
            inputWidth / 2 - xCropAmountHalved,
            inputHeight / 2 - yCropAmountHalved,
            inputWidth / 2 + xCropAmountHalved,
            inputHeight / 2 + yCropAmountHalved);

    canvas.drawBitmap(input, src, dst, paint);
    return result;
  }
}