resource/bitmap/TransformationUtils.java

package com.bumptech.glide.load.resource.bitmap;

import android.annotation.TargetApi;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RectF;
import android.media.ExifInterface;
import android.os.Build;
import android.util.Log;
import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;

/**
 * A class with methods to efficiently resize Bitmaps.
 */
public final class TransformationUtils {
    private static final String TAG = "TransformationUtils";
    public static final int PAINT_FLAGS = Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG | Paint.FILTER_BITMAP_FLAG;

    private TransformationUtils() {
        // Utility class.
    }

    /**
     * A potentially expensive operation to crop the given Bitmap so that it fills the given dimensions. This operation
     * is significantly less expensive in terms of memory if a mutable Bitmap with the given dimensions is passed in
     * as well.
     *
     * @param recycled A mutable Bitmap with dimensions width and height that we can load the cropped portion of toCrop
     *                 into.
     * @param toCrop The Bitmap to resize.
     * @param width The width of the final Bitmap.
     * @param height The height of the final Bitmap.
     * @return The resized Bitmap (will be recycled if recycled is not null).
     */
    public static Bitmap centerCrop(Bitmap recycled, Bitmap toCrop, int width, int height) {
        if (toCrop == null) {
            return null;
        } else if (toCrop.getWidth() == width && toCrop.getHeight() == height) {
            return toCrop;
        }
        // From ImageView/Bitmap.createScaledBitmap.
        final float scale;
        float dx = 0, dy = 0;
        Matrix m = new Matrix();
        if (toCrop.getWidth() * height > width * toCrop.getHeight()) {
            scale = (float) height / (float) toCrop.getHeight();
            dx = (width - toCrop.getWidth() * scale) * 0.5f;
        } else {
            scale = (float) width / (float) toCrop.getWidth();
            dy = (height - toCrop.getHeight() * scale) * 0.5f;
        }

        m.setScale(scale, scale);
        m.postTranslate((int) (dx + 0.5f), (int) (dy + 0.5f));
        final Bitmap result;
        if (recycled != null) {
            result = recycled;
        } else {
            result = Bitmap.createBitmap(width, height, toCrop.getConfig() == null
                        ? Bitmap.Config.ARGB_8888 : toCrop.getConfig());
        }

        // We don't add or remove alpha, so keep the alpha setting of the Bitmap we were given.
        TransformationUtils.setAlpha(toCrop, result);

        Canvas canvas = new Canvas(result);
        Paint paint = new Paint(PAINT_FLAGS);
        canvas.drawBitmap(toCrop, m, paint);
        return result;
    }

    /**
     * An expensive operation to resize the given Bitmap down so that it fits within the given dimensions maintain
     * the original proportions.
     *
     * @param toFit The Bitmap to shrink.
     * @param pool The BitmapPool to try to reuse a bitmap from.
     * @param width The width the final image will fit within.
     * @param height The height the final image will fit within.
     * @return A new Bitmap shrunk to fit within the given dimensions, or toFit if toFit's width or height matches the
     * given dimensions and toFit fits within the given dimensions
     */
    public static Bitmap fitCenter(Bitmap toFit, BitmapPool pool, int width, int height) {
        if (toFit.getWidth() == width && toFit.getHeight() == height) {
            return toFit;
        }
        final float widthPercentage = width / (float) toFit.getWidth();
        final float heightPercentage = height / (float) toFit.getHeight();
        final float minPercentage = Math.min(widthPercentage, heightPercentage);

        final int targetWidth = Math.round(minPercentage * toFit.getWidth());
        final int targetHeight = Math.round(minPercentage * toFit.getHeight());

        Bitmap.Config config = toFit.getConfig() != null ? toFit.getConfig() : Bitmap.Config.ARGB_8888;
        Bitmap toReuse = pool.get(targetWidth, targetHeight, config);
        if (toReuse == null) {
            toReuse = Bitmap.createBitmap(targetWidth, targetHeight, config);
        }

        // We don't add or remove alpha, so keep the alpha setting of the Bitmap we were given.
        TransformationUtils.setAlpha(toFit, toReuse);

        Canvas canvas = new Canvas(toReuse);
        Matrix matrix = new Matrix();
        matrix.setScale(minPercentage, minPercentage);
        Paint paint = new Paint(PAINT_FLAGS);
        canvas.drawBitmap(toFit, matrix, paint);

        return toReuse;
    }

    /**
     * Sets the alpha of the Bitmap we're going to re-use to the alpha of the Bitmap we're going to transform. This
     * keeps {@link android.graphics.Bitmap#hasAlpha()}} consistent before and after the transformation for
     * transformations that don't add or remove transparent pixels.
     *
     * @param toTransform The {@link android.graphics.Bitmap} that will be transformed.
     * @param outBitmap The {@link android.graphics.Bitmap} that will be returned from the transformation.
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
    public static void setAlpha(Bitmap toTransform, Bitmap outBitmap) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR1 && outBitmap != null) {
            outBitmap.setHasAlpha(toTransform.hasAlpha());
        }
    }

    /**
     * Returns a matrix with rotation set based on Exif orientation tag.
     * If the orientation is undefined or 0 null is returned.
     *
     * @param pathToOriginal Path to original image file that may have exif data.
     * @return  A rotation in degrees based on exif orientation
     */
    @TargetApi(Build.VERSION_CODES.ECLAIR)
    public static int getOrientation(String pathToOriginal) {
        int degreesToRotate = 0;
        try {
            ExifInterface exif = new ExifInterface(pathToOriginal);
            int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_UNDEFINED);
            if (orientation == ExifInterface.ORIENTATION_ROTATE_90) {
                degreesToRotate = 90;
            } else if (orientation == ExifInterface.ORIENTATION_ROTATE_180) {
                degreesToRotate = 180;
            } else if (orientation == ExifInterface.ORIENTATION_ROTATE_270) {
                degreesToRotate = 270;
            }
        } catch (Exception e) {
            if (Log.isLoggable(TAG, Log.ERROR)) {
                Log.e(TAG, "Unable to get orientation for image with path=" + pathToOriginal, e);
            }
        }
        return degreesToRotate;
    }

    /**
     * This is an expensive operation that copies the image in place with the pixels rotated.
     * If possible rather use getOrientationMatrix, and set that as the imageMatrix on an ImageView.
     *
     * @param pathToOriginal Path to original image file that may have exif data.
     * @param imageToOrient Image Bitmap to orient.
     * @return The oriented bitmap. May be the imageToOrient without modification, or a new Bitmap.
     */
    public static Bitmap orientImage(String pathToOriginal, Bitmap imageToOrient) {
        int degreesToRotate = getOrientation(pathToOriginal);
        return rotateImage(imageToOrient, degreesToRotate);
    }

    /**
     * This is an expensive operation that copies the image in place with the pixels rotated.
     * If possible rather use getOrientationMatrix, and set that as the imageMatrix on an ImageView.
     *
     * @param imageToOrient Image Bitmap to orient.
     * @param degreesToRotate number of degrees to rotate the image by. If zero the original image is returned
     *                        unmodified.
     * @return The oriented bitmap. May be the imageToOrient without modification, or a new Bitmap.
     */
    public static Bitmap rotateImage(Bitmap imageToOrient, int degreesToRotate) {
        Bitmap result = imageToOrient;
        try {
            if (degreesToRotate != 0) {
                Matrix matrix = new Matrix();
                matrix.setRotate(degreesToRotate);
                result = Bitmap.createBitmap(
                        imageToOrient,
                        0,
                        0,
                        imageToOrient.getWidth(),
                        imageToOrient.getHeight(),
                        matrix,
                        true);
            }
        } catch (Exception e) {
            if (Log.isLoggable(TAG, Log.ERROR)) {
                Log.e(TAG, "Exception when trying to orient image", e);
            }
        }
        return result;
    }

    /**
     * Get the # of degrees an image must be rotated to match the given exif orientation.
     *
     * @param exifOrientation The exif orientation [1-8]
     * @return the number of degrees to rotate
     */
    public static int getExifOrientationDegrees(int exifOrientation) {
        final int degreesToRotate;
        switch (exifOrientation) {
            case ExifInterface.ORIENTATION_TRANSPOSE:
            case ExifInterface.ORIENTATION_ROTATE_90:
                degreesToRotate = 90;
                break;
            case ExifInterface.ORIENTATION_ROTATE_180:
            case ExifInterface.ORIENTATION_FLIP_VERTICAL:
                degreesToRotate = 180;
                break;
            case ExifInterface.ORIENTATION_TRANSVERSE:
            case ExifInterface.ORIENTATION_ROTATE_270:
                degreesToRotate = 270;
                break;
            default:
                degreesToRotate = 0;

        }
        return degreesToRotate;
    }

    /**
     * Rotate and/or flip the image to match the given exif orientation.
     *
     * @param toOrient The bitmap to rotate/flip.
     * @param pool A pool that may or may not contain an image of the necessary dimensions.
     * @param exifOrientation the exif orientation [1-8].
     * @return The rotated and/or flipped image or toOrient if no rotation or flip was necessary.
     */
    public static Bitmap rotateImageExif(Bitmap toOrient, BitmapPool pool, int exifOrientation) {
        final Matrix matrix = new Matrix();
        switch (exifOrientation) {
            case ExifInterface.ORIENTATION_FLIP_HORIZONTAL:
                matrix.setScale(-1, 1);
                break;
            case ExifInterface.ORIENTATION_ROTATE_180:
                matrix.setRotate(180);
                break;
            case ExifInterface.ORIENTATION_FLIP_VERTICAL:
                matrix.setRotate(180);
                matrix.postScale(-1, 1);
                break;
            case ExifInterface.ORIENTATION_TRANSPOSE:
                matrix.setRotate(90);
                matrix.postScale(-1, 1);
                break;
            case ExifInterface.ORIENTATION_ROTATE_90:
                matrix.setRotate(90);
                break;
            case ExifInterface.ORIENTATION_TRANSVERSE:
                matrix.setRotate(-90);
                matrix.postScale(-1, 1);
                break;
            case ExifInterface.ORIENTATION_ROTATE_270:
                matrix.setRotate(-90);
                break;
            // case ExifInterface.ORIENTATION_NORMAL
            default:
                return toOrient;
        }

        // From Bitmap.createBitmap.
        final RectF newRect = new RectF(0, 0, toOrient.getWidth(), toOrient.getHeight());
        matrix.mapRect(newRect);

        final int newWidth = Math.round(newRect.width());
        final int newHeight = Math.round(newRect.height());

        Bitmap result = pool.get(newWidth, newHeight, toOrient.getConfig());
        if (result == null) {
            result = Bitmap.createBitmap(newWidth, newHeight, toOrient.getConfig());
        }

        matrix.postTranslate(-newRect.left, -newRect.top);

        final Canvas canvas = new Canvas(result);
        final Paint paint = new Paint(PAINT_FLAGS);
        canvas.drawBitmap(toOrient, matrix, paint);

        return result;
    }
}