Android ContentResolver.loadThumbnail转Kotlin

loadThumbnail原先是Java实现的，现在抠出来转Kotlin实现。

    private fun loadThumbnail(uri: Uri, size: Size, signal: CancellationSignal): Bitmap {return myLoadThumbnail(mContext?.contentResolver!!, uri, size, signal, ImageDecoder.ALLOCATOR_SOFTWARE)}private fun myLoadThumbnail(cr: ContentResolver, uri: Uri, size: Size, signal: CancellationSignal, allocator: Int): Bitmap {val opts = Bundle()opts.putParcelable(ContentResolver.EXTRA_SIZE, Point(size.width, size.height))val orientation = Int64Ref(0)var bitmap = ImageDecoder.decodeBitmap(ImageDecoder.createSource {val afd: AssetFileDescriptor = cr.openTypedAssetFile(uri, "image/*", opts,signal)!!val extras = afd.extrasorientation.value = (extras?.getInt(DocumentsContract.EXTRA_ORIENTATION, 0) ?: 0).toLong()afd}) { decoder: ImageDecoder, info: ImageInfo, source: ImageDecoder.Source? ->decoder.allocator = allocator// One last-ditch check to see if we've been canceled.if (signal != null) signal.throwIfCanceled()// We requested a rough thumbnail size, but the remote size may have// returned something giant, so defensively scale down as needed.val widthSample = info.size.width / size.widthval heightSample = info.size.height / size.heightval sample = Math.max(widthSample, heightSample)if (sample > 1) {decoder.setTargetSampleSize(sample)}}// Transform the bitmap if requested. We use a side-channel to// communicate the orientation, since EXIF thumbnails don't contain// the rotation flags of the original image.// Transform the bitmap if requested. We use a side-channel to// communicate the orientation, since EXIF thumbnails don't contain// the rotation flags of the original image.if (orientation.value != 0L) {val width = bitmap.widthval height = bitmap.heightval m = Matrix()m.setRotate(orientation.value.toFloat(), (width / 2).toFloat(), (height / 2).toFloat())bitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, m, false)}return bitmap}

或者：

    private fun loadThumbnail(uri: Uri, size: Size, signal: CancellationSignal): Bitmap {return myLoadThumbnail(mContext?.contentResolver!!, uri, size, signal, ImageDecoder.ALLOCATOR_SOFTWARE)}private fun myLoadThumbnail(cr: ContentResolver, uri: Uri, size: Size, signal: CancellationSignal, allocator: Int): Bitmap {val opts = Bundle()opts.putParcelable(ContentResolver.EXTRA_SIZE, Point(size.width, size.height))val orientation = Int64Ref(0)val afd: AssetFileDescriptor = cr.openTypedAssetFile(uri, "image/*", opts,signal)!!val src = ImageDecoder.createSource {val extras = afd.extrasorientation.value = (extras?.getInt(DocumentsContract.EXTRA_ORIENTATION, 0) ?: 0).toLong()afd}var bmp = ImageDecoder.decodeBitmap(src, ImageDecoder.OnHeaderDecodedListener { decoder, info, source ->decoder.allocator = allocatorval widthSample = info.size.width / size.widthval heightSample = info.size.height / size.heightval sample = Math.max(widthSample, heightSample)if (sample > 1) {decoder.setTargetSampleSize(sample)}})if (orientation.value != 0L) {val width = bmp.widthval height = bmp.heightval m = Matrix()m.setRotate(orientation.value.toFloat(), (width / 2).toFloat(), (height / 2).toFloat())bmp = Bitmap.createBitmap(bmp, 0, 0, width, height, m, false)}return bmp}

Android loadThumbnail ThumbnailUtils.createVideoThumbnail MediaMetadataRetriever time cost, Kotlin_android resolver.loadthumbnail()-CSDN博客文章浏览阅读712次，点赞21次，收藏12次。Android设置头像，手机拍照或从本地相册选取图片作为头像_android 头像拍照_zhangphil的博客-CSDN博客。【代码】Android Paging 3,kotlin（1）在实际的开发中，虽然Glide解决了快速加载图片的问题，但还有一个问题悬而未决：比如用户的头像，往往用户的头像是从服务器端读出的一个普通矩形图片，但是现在的设计一般要求在APP端的用户头像显示成圆形头像，那么此时虽然Glide可以加载，但加载出来的是一个矩形，如果要Glide_android 毛玻璃圆角。_android resolver.loadthumbnail()https://blog.csdn.net/zhangphil/article/details/139985203

Android loadThumbnail ThumbnailUtils.createImageThumbnail BitmapFactory.decodeFile time cost, Kotlin-CSDN博客文章浏览阅读776次，点赞16次，收藏12次。从很小的宽高开始，不断迭代增加setRectToRect的目标RectF的宽高，每次迭代加上一定时延，实现Matrix基础上的动画。【代码】Android Paging 3,kotlin（1）在实际的开发中，虽然Glide解决了快速加载图片的问题，但还有一个问题悬而未决：比如用户的头像，往往用户的头像是从服务器端读出的一个普通矩形图片，但是现在的设计一般要求在APP端的用户头像显示成圆形头像，那么此时虽然Glide可以加载，但加载出来的是一个矩形，如果要Glide_android 毛玻璃圆角。_loadthumbnailhttps://blog.csdn.net/zhangphil/article/details/139962276