Java tutorial
/* * Copyright (C) 2009 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 android.media; import android.annotation.UnsupportedAppUsage; import android.content.ContentResolver; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Matrix; import android.graphics.Rect; import android.media.MediaMetadataRetriever; import android.media.MediaFile.MediaFileType; import android.net.Uri; import android.os.Build; import android.os.ParcelFileDescriptor; import android.provider.MediaStore.Images; import android.util.Log; import java.io.FileInputStream; import java.io.FileDescriptor; import java.io.IOException; /** * Thumbnail generation routines for media provider. */ public class ThumbnailUtils { private static final String TAG = "ThumbnailUtils"; /* Maximum pixels size for created bitmap. */ private static final int MAX_NUM_PIXELS_THUMBNAIL = 512 * 384; private static final int MAX_NUM_PIXELS_MICRO_THUMBNAIL = 160 * 120; private static final int UNCONSTRAINED = -1; /* Options used internally. */ private static final int OPTIONS_NONE = 0x0; private static final int OPTIONS_SCALE_UP = 0x1; /** * Constant used to indicate we should recycle the input in * {@link #extractThumbnail(Bitmap, int, int, int)} unless the output is the input. */ public static final int OPTIONS_RECYCLE_INPUT = 0x2; /** * Constant used to indicate the dimension of mini thumbnail. * @hide Only used by media framework and media provider internally. */ public static final int TARGET_SIZE_MINI_THUMBNAIL = 320; /** * Constant used to indicate the dimension of micro thumbnail. * @hide Only used by media framework and media provider internally. */ @UnsupportedAppUsage public static final int TARGET_SIZE_MICRO_THUMBNAIL = 96; /** * This method first examines if the thumbnail embedded in EXIF is bigger than our target * size. If not, then it'll create a thumbnail from original image. Due to efficiency * consideration, we want to let MediaThumbRequest avoid calling this method twice for * both kinds, so it only requests for MICRO_KIND and set saveImage to true. * * This method always returns a "square thumbnail" for MICRO_KIND thumbnail. * * @param filePath the path of image file * @param kind could be MINI_KIND or MICRO_KIND * @return Bitmap, or null on failures * * @hide This method is only used by media framework and media provider internally. */ @UnsupportedAppUsage public static Bitmap createImageThumbnail(String filePath, int kind) { boolean wantMini = (kind == Images.Thumbnails.MINI_KIND); int targetSize = wantMini ? TARGET_SIZE_MINI_THUMBNAIL : TARGET_SIZE_MICRO_THUMBNAIL; int maxPixels = wantMini ? MAX_NUM_PIXELS_THUMBNAIL : MAX_NUM_PIXELS_MICRO_THUMBNAIL; SizedThumbnailBitmap sizedThumbnailBitmap = new SizedThumbnailBitmap(); Bitmap bitmap = null; MediaFileType fileType = MediaFile.getFileType(filePath); if (fileType != null) { if (fileType.fileType == MediaFile.FILE_TYPE_JPEG || MediaFile.isRawImageFileType(fileType.fileType)) { createThumbnailFromEXIF(filePath, targetSize, maxPixels, sizedThumbnailBitmap); bitmap = sizedThumbnailBitmap.mBitmap; } else if (fileType.fileType == MediaFile.FILE_TYPE_HEIF) { bitmap = createThumbnailFromMetadataRetriever(filePath, targetSize, maxPixels); } } if (bitmap == null) { FileInputStream stream = null; try { stream = new FileInputStream(filePath); FileDescriptor fd = stream.getFD(); BitmapFactory.Options options = new BitmapFactory.Options(); options.inSampleSize = 1; options.inJustDecodeBounds = true; BitmapFactory.decodeFileDescriptor(fd, null, options); if (options.mCancel || options.outWidth == -1 || options.outHeight == -1) { return null; } options.inSampleSize = computeSampleSize(options, targetSize, maxPixels); options.inJustDecodeBounds = false; options.inDither = false; options.inPreferredConfig = Bitmap.Config.ARGB_8888; bitmap = BitmapFactory.decodeFileDescriptor(fd, null, options); } catch (IOException ex) { Log.e(TAG, "", ex); } catch (OutOfMemoryError oom) { Log.e(TAG, "Unable to decode file " + filePath + ". OutOfMemoryError.", oom); } finally { try { if (stream != null) { stream.close(); } } catch (IOException ex) { Log.e(TAG, "", ex); } } } if (kind == Images.Thumbnails.MICRO_KIND) { // now we make it a "square thumbnail" for MICRO_KIND thumbnail bitmap = extractThumbnail(bitmap, TARGET_SIZE_MICRO_THUMBNAIL, TARGET_SIZE_MICRO_THUMBNAIL, OPTIONS_RECYCLE_INPUT); } return bitmap; } /** * Create a video thumbnail for a video. May return null if the video is * corrupt or the format is not supported. * * @param filePath the path of video file * @param kind could be MINI_KIND or MICRO_KIND */ public static Bitmap createVideoThumbnail(String filePath, int kind) { Bitmap bitmap = null; MediaMetadataRetriever retriever = new MediaMetadataRetriever(); try { retriever.setDataSource(filePath); bitmap = retriever.getFrameAtTime(-1); } catch (IllegalArgumentException ex) { // Assume this is a corrupt video file } catch (RuntimeException ex) { // Assume this is a corrupt video file. } finally { try { retriever.release(); } catch (RuntimeException ex) { // Ignore failures while cleaning up. } } if (bitmap == null) return null; if (kind == Images.Thumbnails.MINI_KIND) { // Scale down the bitmap if it's too large. int width = bitmap.getWidth(); int height = bitmap.getHeight(); int max = Math.max(width, height); if (max > 512) { float scale = 512f / max; int w = Math.round(scale * width); int h = Math.round(scale * height); bitmap = Bitmap.createScaledBitmap(bitmap, w, h, true); } } else if (kind == Images.Thumbnails.MICRO_KIND) { bitmap = extractThumbnail(bitmap, TARGET_SIZE_MICRO_THUMBNAIL, TARGET_SIZE_MICRO_THUMBNAIL, OPTIONS_RECYCLE_INPUT); } return bitmap; } /** * Creates a centered bitmap of the desired size. * * @param source original bitmap source * @param width targeted width * @param height targeted height */ public static Bitmap extractThumbnail(Bitmap source, int width, int height) { return extractThumbnail(source, width, height, OPTIONS_NONE); } /** * Creates a centered bitmap of the desired size. * * @param source original bitmap source * @param width targeted width * @param height targeted height * @param options options used during thumbnail extraction */ public static Bitmap extractThumbnail(Bitmap source, int width, int height, int options) { if (source == null) { return null; } float scale; if (source.getWidth() < source.getHeight()) { scale = width / (float) source.getWidth(); } else { scale = height / (float) source.getHeight(); } Matrix matrix = new Matrix(); matrix.setScale(scale, scale); Bitmap thumbnail = transform(matrix, source, width, height, OPTIONS_SCALE_UP | options); return thumbnail; } /* * Compute the sample size as a function of minSideLength * and maxNumOfPixels. * minSideLength is used to specify that minimal width or height of a * bitmap. * maxNumOfPixels is used to specify the maximal size in pixels that is * tolerable in terms of memory usage. * * The function returns a sample size based on the constraints. * Both size and minSideLength can be passed in as IImage.UNCONSTRAINED, * which indicates no care of the corresponding constraint. * The functions prefers returning a sample size that * generates a smaller bitmap, unless minSideLength = IImage.UNCONSTRAINED. * * Also, the function rounds up the sample size to a power of 2 or multiple * of 8 because BitmapFactory only honors sample size this way. * For example, BitmapFactory downsamples an image by 2 even though the * request is 3. So we round up the sample size to avoid OOM. */ @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023) private static int computeSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) { int initialSize = computeInitialSampleSize(options, minSideLength, maxNumOfPixels); int roundedSize; if (initialSize <= 8) { roundedSize = 1; while (roundedSize < initialSize) { roundedSize <<= 1; } } else { roundedSize = (initialSize + 7) / 8 * 8; } return roundedSize; } @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023) private static int computeInitialSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) { double w = options.outWidth; double h = options.outHeight; int lowerBound = (maxNumOfPixels == UNCONSTRAINED) ? 1 : (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels)); int upperBound = (minSideLength == UNCONSTRAINED) ? 128 : (int) Math.min(Math.floor(w / minSideLength), Math.floor(h / minSideLength)); if (upperBound < lowerBound) { // return the larger one when there is no overlapping zone. return lowerBound; } if ((maxNumOfPixels == UNCONSTRAINED) && (minSideLength == UNCONSTRAINED)) { return 1; } else if (minSideLength == UNCONSTRAINED) { return lowerBound; } else { return upperBound; } } /** * Make a bitmap from a given Uri, minimal side length, and maximum number of pixels. * The image data will be read from specified pfd if it's not null, otherwise * a new input stream will be created using specified ContentResolver. * * Clients are allowed to pass their own BitmapFactory.Options used for bitmap decoding. A * new BitmapFactory.Options will be created if options is null. */ private static Bitmap makeBitmap(int minSideLength, int maxNumOfPixels, Uri uri, ContentResolver cr, ParcelFileDescriptor pfd, BitmapFactory.Options options) { Bitmap b = null; try { if (pfd == null) pfd = makeInputStream(uri, cr); if (pfd == null) return null; if (options == null) options = new BitmapFactory.Options(); FileDescriptor fd = pfd.getFileDescriptor(); options.inSampleSize = 1; options.inJustDecodeBounds = true; BitmapFactory.decodeFileDescriptor(fd, null, options); if (options.mCancel || options.outWidth == -1 || options.outHeight == -1) { return null; } options.inSampleSize = computeSampleSize(options, minSideLength, maxNumOfPixels); options.inJustDecodeBounds = false; options.inDither = false; options.inPreferredConfig = Bitmap.Config.ARGB_8888; b = BitmapFactory.decodeFileDescriptor(fd, null, options); } catch (OutOfMemoryError ex) { Log.e(TAG, "Got oom exception ", ex); return null; } finally { closeSilently(pfd); } return b; } @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023) private static void closeSilently(ParcelFileDescriptor c) { if (c == null) return; try { c.close(); } catch (Throwable t) { // do nothing } } @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023) private static ParcelFileDescriptor makeInputStream(Uri uri, ContentResolver cr) { try { return cr.openFileDescriptor(uri, "r"); } catch (IOException ex) { return null; } } /** * Transform source Bitmap to targeted width and height. */ @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023) private static Bitmap transform(Matrix scaler, Bitmap source, int targetWidth, int targetHeight, int options) { boolean scaleUp = (options & OPTIONS_SCALE_UP) != 0; boolean recycle = (options & OPTIONS_RECYCLE_INPUT) != 0; int deltaX = source.getWidth() - targetWidth; int deltaY = source.getHeight() - targetHeight; if (!scaleUp && (deltaX < 0 || deltaY < 0)) { /* * In this case the bitmap is smaller, at least in one dimension, * than the target. Transform it by placing as much of the image * as possible into the target and leaving the top/bottom or * left/right (or both) black. */ Bitmap b2 = Bitmap.createBitmap(targetWidth, targetHeight, Bitmap.Config.ARGB_8888); Canvas c = new Canvas(b2); int deltaXHalf = Math.max(0, deltaX / 2); int deltaYHalf = Math.max(0, deltaY / 2); Rect src = new Rect(deltaXHalf, deltaYHalf, deltaXHalf + Math.min(targetWidth, source.getWidth()), deltaYHalf + Math.min(targetHeight, source.getHeight())); int dstX = (targetWidth - src.width()) / 2; int dstY = (targetHeight - src.height()) / 2; Rect dst = new Rect(dstX, dstY, targetWidth - dstX, targetHeight - dstY); c.drawBitmap(source, src, dst, null); if (recycle) { source.recycle(); } c.setBitmap(null); return b2; } float bitmapWidthF = source.getWidth(); float bitmapHeightF = source.getHeight(); float bitmapAspect = bitmapWidthF / bitmapHeightF; float viewAspect = (float) targetWidth / targetHeight; if (bitmapAspect > viewAspect) { float scale = targetHeight / bitmapHeightF; if (scale < .9F || scale > 1F) { scaler.setScale(scale, scale); } else { scaler = null; } } else { float scale = targetWidth / bitmapWidthF; if (scale < .9F || scale > 1F) { scaler.setScale(scale, scale); } else { scaler = null; } } Bitmap b1; if (scaler != null) { // this is used for minithumb and crop, so we want to filter here. b1 = Bitmap.createBitmap(source, 0, 0, source.getWidth(), source.getHeight(), scaler, true); } else { b1 = source; } if (recycle && b1 != source) { source.recycle(); } int dx1 = Math.max(0, b1.getWidth() - targetWidth); int dy1 = Math.max(0, b1.getHeight() - targetHeight); Bitmap b2 = Bitmap.createBitmap(b1, dx1 / 2, dy1 / 2, targetWidth, targetHeight); if (b2 != b1) { if (recycle || b1 != source) { b1.recycle(); } } return b2; } /** * SizedThumbnailBitmap contains the bitmap, which is downsampled either from * the thumbnail in exif or the full image. * mThumbnailData, mThumbnailWidth and mThumbnailHeight are set together only if mThumbnail * is not null. * * The width/height of the sized bitmap may be different from mThumbnailWidth/mThumbnailHeight. */ private static class SizedThumbnailBitmap { public byte[] mThumbnailData; public Bitmap mBitmap; public int mThumbnailWidth; public int mThumbnailHeight; } /** * Creates a bitmap by either downsampling from the thumbnail in EXIF or the full image. * The functions returns a SizedThumbnailBitmap, * which contains a downsampled bitmap and the thumbnail data in EXIF if exists. */ @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023) private static void createThumbnailFromEXIF(String filePath, int targetSize, int maxPixels, SizedThumbnailBitmap sizedThumbBitmap) { if (filePath == null) return; ExifInterface exif = null; byte[] thumbData = null; try { exif = new ExifInterface(filePath); thumbData = exif.getThumbnail(); } catch (IOException ex) { Log.w(TAG, ex); } BitmapFactory.Options fullOptions = new BitmapFactory.Options(); BitmapFactory.Options exifOptions = new BitmapFactory.Options(); int exifThumbWidth = 0; int fullThumbWidth = 0; // Compute exifThumbWidth. if (thumbData != null) { exifOptions.inJustDecodeBounds = true; BitmapFactory.decodeByteArray(thumbData, 0, thumbData.length, exifOptions); exifOptions.inSampleSize = computeSampleSize(exifOptions, targetSize, maxPixels); exifThumbWidth = exifOptions.outWidth / exifOptions.inSampleSize; } // Compute fullThumbWidth. fullOptions.inJustDecodeBounds = true; BitmapFactory.decodeFile(filePath, fullOptions); fullOptions.inSampleSize = computeSampleSize(fullOptions, targetSize, maxPixels); fullThumbWidth = fullOptions.outWidth / fullOptions.inSampleSize; // Choose the larger thumbnail as the returning sizedThumbBitmap. if (thumbData != null && exifThumbWidth >= fullThumbWidth) { int width = exifOptions.outWidth; int height = exifOptions.outHeight; exifOptions.inJustDecodeBounds = false; sizedThumbBitmap.mBitmap = BitmapFactory.decodeByteArray(thumbData, 0, thumbData.length, exifOptions); if (sizedThumbBitmap.mBitmap != null) { sizedThumbBitmap.mThumbnailData = thumbData; sizedThumbBitmap.mThumbnailWidth = width; sizedThumbBitmap.mThumbnailHeight = height; } } else { fullOptions.inJustDecodeBounds = false; sizedThumbBitmap.mBitmap = BitmapFactory.decodeFile(filePath, fullOptions); } } private static Bitmap createThumbnailFromMetadataRetriever(String filePath, int targetSize, int maxPixels) { if (filePath == null) { return null; } Bitmap thumbnail = null; MediaMetadataRetriever retriever = new MediaMetadataRetriever(); try { retriever.setDataSource(filePath); MediaMetadataRetriever.BitmapParams params = new MediaMetadataRetriever.BitmapParams(); params.setPreferredConfig(Bitmap.Config.ARGB_8888); thumbnail = retriever.getThumbnailImageAtIndex(-1, params, targetSize, maxPixels); } catch (RuntimeException ex) { // Assume this is a corrupt video file. } finally { if (retriever != null) { retriever.release(); } } return thumbnail; } }