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region decoding: use raw image descriptor in Flutter on decoded bytes from Android

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Thibault Deckers 2025-03-02 13:06:58 +01:00
parent 5805bb2b5b
commit f850178afd
13 changed files with 205 additions and 70 deletions
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4
android/app/src/main/kotlin/deckers/thibault/aves/channel/calls/AppAdapterHandler.kt
View file

@ -38,7 +38,7 @@ import deckers.thibault.aves.channel.calls.Coresult.Companion.safe
import deckers.thibault.aves.channel.calls.Coresult.Companion.safeSuspend
import deckers.thibault.aves.model.FieldMap
import deckers.thibault.aves.utils.BitmapUtils
import deckers.thibault.aves.utils.BitmapUtils.getBytes
import deckers.thibault.aves.utils.BitmapUtils.getEncodedBytes
import deckers.thibault.aves.utils.LogUtils
import deckers.thibault.aves.utils.anyCauseIs
import deckers.thibault.aves.utils.getApplicationInfoCompat
@ -175,7 +175,7 @@ class AppAdapterHandler(private val context: Context) : MethodCallHandler {
try {
val bitmap = withContext(Dispatchers.IO) { target.get() }
data = bitmap?.getBytes(canHaveAlpha = true, recycle = false)
data = bitmap?.getEncodedBytes(canHaveAlpha = true, recycle = false)
} catch (e: Exception) {
Log.w(LOG_TAG, "failed to decode app icon for packageName=$packageName", e)
}

4
android/app/src/main/kotlin/deckers/thibault/aves/channel/calls/EmbeddedDataHandler.kt
View file

@ -23,7 +23,7 @@ import deckers.thibault.aves.model.FieldMap
import deckers.thibault.aves.model.provider.ImageProvider
import deckers.thibault.aves.model.provider.ImageProviderFactory.getProvider
import deckers.thibault.aves.utils.BitmapUtils
import deckers.thibault.aves.utils.BitmapUtils.getBytes
import deckers.thibault.aves.utils.BitmapUtils.getEncodedBytes
import deckers.thibault.aves.utils.FileUtils.transferFrom
import deckers.thibault.aves.utils.LogUtils
import deckers.thibault.aves.utils.MimeTypes
@ -75,7 +75,7 @@ class EmbeddedDataHandler(private val context: Context) : MethodCallHandler {
val orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL)
exif.thumbnailBitmap?.let { bitmap ->
TransformationUtils.rotateImageExif(BitmapUtils.getBitmapPool(context), bitmap, orientation)?.let {
it.getBytes(canHaveAlpha = false, recycle = false)?.let { bytes -> thumbnails.add(bytes) }
it.getEncodedBytes(canHaveAlpha = false, recycle = false)?.let { bytes -> thumbnails.add(bytes) }
}
}
}

7
android/app/src/main/kotlin/deckers/thibault/aves/channel/calls/MediaFetchBytesHandler.kt
View file

@ -3,6 +3,7 @@ package deckers.thibault.aves.channel.calls
import android.content.Context
import android.graphics.Rect
import androidx.core.net.toUri
import deckers.thibault.aves.channel.calls.Coresult.Companion.safe
import deckers.thibault.aves.channel.calls.Coresult.Companion.safeSuspend
import deckers.thibault.aves.channel.calls.fetchers.RegionFetcher
import deckers.thibault.aves.channel.calls.fetchers.SvgRegionFetcher
@ -29,7 +30,7 @@ class MediaFetchBytesHandler(private val context: Context) : MethodCallHandler {
override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
when (call.method) {
"getThumbnail" -> ioScope.launch { safeSuspend(call, result, ::getThumbnail) }
"getRegion" -> ioScope.launch { safeSuspend(call, result, ::getRegion) }
"getRegion" -> ioScope.launch { safe(call, result, ::getRegion) }
else -> result.notImplemented()
}
}
@ -68,7 +69,7 @@ class MediaFetchBytesHandler(private val context: Context) : MethodCallHandler {
).fetch()
}
private suspend fun getRegion(call: MethodCall, result: MethodChannel.Result) {
private fun getRegion(call: MethodCall, result: MethodChannel.Result) {
val uri = call.argument<String>("uri")?.toUri()
val mimeType = call.argument<String>("mimeType")
val pageId = call.argument<Int>("pageId")
@ -97,6 +98,7 @@ class MediaFetchBytesHandler(private val context: Context) : MethodCallHandler {
imageHeight = imageHeight,
result = result,
)
MimeTypes.TIFF -> TiffRegionFetcher(context).fetch(
uri = uri,
page = pageId ?: 0,
@ -104,6 +106,7 @@ class MediaFetchBytesHandler(private val context: Context) : MethodCallHandler {
regionRect = regionRect,
result = result,
)
else -> regionFetcher.fetch(
uri = uri,
mimeType = mimeType,

48
android/app/src/main/kotlin/deckers/thibault/aves/channel/calls/fetchers/RegionFetcher.kt
View file

@ -4,16 +4,17 @@ import android.content.Context
import android.graphics.Bitmap
import android.graphics.BitmapFactory
import android.graphics.BitmapRegionDecoder
import android.graphics.ColorSpace
import android.graphics.Rect
import android.net.Uri
import android.os.Build
import android.util.Log
import com.bumptech.glide.Glide
import deckers.thibault.aves.decoder.AvesAppGlideModule
import deckers.thibault.aves.decoder.MultiPageImage
import deckers.thibault.aves.utils.BitmapRegionDecoderCompat
import deckers.thibault.aves.utils.BitmapUtils
import deckers.thibault.aves.utils.BitmapUtils.ARGB_8888_BYTE_SIZE
import deckers.thibault.aves.utils.BitmapUtils.getBytes
import deckers.thibault.aves.utils.BitmapUtils.getDecodedBytes
import deckers.thibault.aves.utils.LogUtils
import deckers.thibault.aves.utils.MathUtils
import deckers.thibault.aves.utils.MemoryUtils
@ -33,7 +34,10 @@ class RegionFetcher internal constructor(
private val exportUris = HashMap<Pair<Uri, Int?>, Uri>()
suspend fun fetch(
// return decoded bytes in ARGB_8888, with trailer bytes:
// - width (int32)
// - height (int32)
fun fetch(
uri: Uri,
mimeType: String,
pageId: Int?,
@ -99,26 +103,37 @@ class RegionFetcher internal constructor(
}
}
// use `Long` as rect size could be unexpectedly large and go beyond `Int` max
val targetBitmapSizeBytes: Long = ARGB_8888_BYTE_SIZE.toLong() * effectiveRect.width() * effectiveRect.height() / effectiveSampleSize
val options = BitmapFactory.Options().apply {
inSampleSize = effectiveSampleSize
// Specifying preferred config and color space avoids the need for conversion afterwards,
// but may prevent decoding (e.g. from RGBA_1010102 to ARGB_8888 on some devices).
inPreferredConfig = PREFERRED_CONFIG
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
inPreferredColorSpace = ColorSpace.get(ColorSpace.Named.SRGB)
}
}
val pixelCount = effectiveRect.width() * effectiveRect.height() / effectiveSampleSize
val targetBitmapSizeBytes = BitmapUtils.getExpectedImageSize(pixelCount.toLong(), options.inPreferredConfig)
if (!MemoryUtils.canAllocate(targetBitmapSizeBytes)) {
// decoding a region that large would yield an OOM when creating the bitmap
result.error("fetch-large-region", "Region too large for uri=$uri regionRect=$regionRect", null)
return
}
val options = BitmapFactory.Options().apply {
inSampleSize = effectiveSampleSize
}
val bitmap = decoder.decodeRegion(effectiveRect, options)
if (bitmap != null) {
val canHaveAlpha = MimeTypes.canHaveAlpha(mimeType)
val recycle = false
var bytes = bitmap.getBytes(canHaveAlpha, recycle = recycle)
if (bytes != null && bytes.isEmpty()) {
bytes = BitmapUtils.tryPixelFormatConversion(bitmap)?.getBytes(canHaveAlpha, recycle = recycle)
var bitmap = decoder.decodeRegion(effectiveRect, options)
if (bitmap == null) {
// retry without specifying config or color space,
// falling back to custom byte conversion afterwards
options.inPreferredConfig = null
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O && options.inPreferredColorSpace != null) {
options.inPreferredColorSpace = null
}
bitmap.recycle()
bitmap = decoder.decodeRegion(effectiveRect, options)
}
val bytes = bitmap?.getDecodedBytes(recycle = true)
if (bytes != null) {
result.success(bytes)
} else {
result.error("fetch-null", "failed to decode region for uri=$uri regionRect=$regionRect", null)
@ -173,5 +188,6 @@ class RegionFetcher internal constructor(
companion object {
private val LOG_TAG = LogUtils.createTag<RegionFetcher>()
private val PREFERRED_CONFIG = Bitmap.Config.ARGB_8888
}
}

26
android/app/src/main/kotlin/deckers/thibault/aves/channel/calls/fetchers/SvgRegionFetcher.kt
View file

@ -13,8 +13,8 @@ import com.caverock.androidsvg.SVG
import com.caverock.androidsvg.SVGParseException
import deckers.thibault.aves.metadata.SVGParserBufferedInputStream
import deckers.thibault.aves.metadata.SvgHelper.normalizeSize
import deckers.thibault.aves.utils.BitmapUtils.ARGB_8888_BYTE_SIZE
import deckers.thibault.aves.utils.BitmapUtils.getBytes
import deckers.thibault.aves.utils.BitmapUtils
import deckers.thibault.aves.utils.BitmapUtils.getDecodedBytes
import deckers.thibault.aves.utils.MemoryUtils
import deckers.thibault.aves.utils.StorageUtils
import io.flutter.plugin.common.MethodChannel
@ -25,7 +25,7 @@ class SvgRegionFetcher internal constructor(
) {
private var lastSvgRef: LastSvgRef? = null
suspend fun fetch(
fun fetch(
uri: Uri,
sizeBytes: Long?,
scale: Int,
@ -92,25 +92,25 @@ class SvgRegionFetcher internal constructor(
val targetBitmapWidth = regionRect.width()
val targetBitmapHeight = regionRect.height()
val canvasWidth = targetBitmapWidth + bleedX * 2
val canvasHeight = targetBitmapHeight + bleedY * 2
// use `Long` as rect size could be unexpectedly large and go beyond `Int` max
val targetBitmapSizeBytes: Long = ARGB_8888_BYTE_SIZE.toLong() * targetBitmapWidth * targetBitmapHeight
val config = PREFERRED_CONFIG
val pixelCount = canvasWidth * canvasHeight
val targetBitmapSizeBytes = BitmapUtils.getExpectedImageSize(pixelCount.toLong(), config)
if (!MemoryUtils.canAllocate(targetBitmapSizeBytes)) {
// decoding a region that large would yield an OOM when creating the bitmap
result.error("fetch-read-large-region", "SVG region too large for uri=$uri regionRect=$regionRect", null)
return
}
var bitmap = createBitmap(
targetBitmapWidth + bleedX * 2,
targetBitmapHeight + bleedY * 2,
Bitmap.Config.ARGB_8888
)
var bitmap = createBitmap(canvasWidth, canvasHeight, config)
val canvas = Canvas(bitmap)
svg.renderToCanvas(canvas, renderOptions)
bitmap = Bitmap.createBitmap(bitmap, bleedX, bleedY, targetBitmapWidth, targetBitmapHeight)
result.success(bitmap.getBytes(canHaveAlpha = true, recycle = true))
val bytes = bitmap.getDecodedBytes(recycle = true)
result.success(bytes)
} catch (e: Exception) {
result.error("fetch-read-exception", "failed to initialize region decoder for uri=$uri regionRect=$regionRect", e.message)
}
@ -120,4 +120,8 @@ class SvgRegionFetcher internal constructor(
val uri: Uri,
val svg: SVG,
)
companion object {
private val PREFERRED_CONFIG = Bitmap.Config.ARGB_8888
}
}

6
android/app/src/main/kotlin/deckers/thibault/aves/channel/calls/fetchers/ThumbnailFetcher.kt
View file

@ -17,7 +17,7 @@ import deckers.thibault.aves.decoder.AvesAppGlideModule
import deckers.thibault.aves.decoder.MultiPageImage
import deckers.thibault.aves.utils.BitmapUtils
import deckers.thibault.aves.utils.BitmapUtils.applyExifOrientation
import deckers.thibault.aves.utils.BitmapUtils.getBytes
import deckers.thibault.aves.utils.BitmapUtils.getEncodedBytes
import deckers.thibault.aves.utils.MimeTypes
import deckers.thibault.aves.utils.MimeTypes.SVG
import deckers.thibault.aves.utils.MimeTypes.isVideo
@ -81,9 +81,9 @@ class ThumbnailFetcher internal constructor(
if (bitmap != null) {
val canHaveAlpha = MimeTypes.canHaveAlpha(mimeType)
val recycle = false
var bytes = bitmap.getBytes(canHaveAlpha, quality, recycle)
var bytes = bitmap.getEncodedBytes(canHaveAlpha, quality, recycle)
if (bytes != null && bytes.isEmpty()) {
bytes = BitmapUtils.tryPixelFormatConversion(bitmap)?.getBytes(canHaveAlpha, quality, recycle)
bytes = BitmapUtils.tryPixelFormatConversion(bitmap)?.getEncodedBytes(canHaveAlpha, quality, recycle)
}
result.success(bytes)
} else {

9
android/app/src/main/kotlin/deckers/thibault/aves/channel/calls/fetchers/TiffRegionFetcher.kt
View file

@ -3,7 +3,7 @@ package deckers.thibault.aves.channel.calls.fetchers
import android.content.Context
import android.graphics.Rect
import android.net.Uri
import deckers.thibault.aves.utils.BitmapUtils.getBytes
import deckers.thibault.aves.utils.BitmapUtils.getDecodedBytes
import io.flutter.plugin.common.MethodChannel
import org.beyka.tiffbitmapfactory.DecodeArea
import org.beyka.tiffbitmapfactory.TiffBitmapFactory
@ -11,7 +11,7 @@ import org.beyka.tiffbitmapfactory.TiffBitmapFactory
class TiffRegionFetcher internal constructor(
private val context: Context,
) {
suspend fun fetch(
fun fetch(
uri: Uri,
page: Int,
sampleSize: Int,
@ -32,8 +32,9 @@ class TiffRegionFetcher internal constructor(
inDecodeArea = DecodeArea(regionRect.left, regionRect.top, regionRect.width(), regionRect.height())
}
val bitmap = TiffBitmapFactory.decodeFileDescriptor(fd, options)
if (bitmap != null) {
result.success(bitmap.getBytes(canHaveAlpha = true, recycle = true))
val bytes = bitmap?.getDecodedBytes(recycle = true)
if (bytes != null) {
result.success(bytes)
} else {
result.error("getRegion-tiff-null", "failed to decode region for uri=$uri page=$page regionRect=$regionRect", null)
}

8
android/app/src/main/kotlin/deckers/thibault/aves/channel/streams/ImageByteStreamHandler.kt
View file

@ -10,7 +10,7 @@ import com.bumptech.glide.Glide
import deckers.thibault.aves.decoder.AvesAppGlideModule
import deckers.thibault.aves.utils.BitmapUtils
import deckers.thibault.aves.utils.BitmapUtils.applyExifOrientation
import deckers.thibault.aves.utils.BitmapUtils.getBytes
import deckers.thibault.aves.utils.BitmapUtils.getEncodedBytes
import deckers.thibault.aves.utils.LogUtils
import deckers.thibault.aves.utils.MemoryUtils
import deckers.thibault.aves.utils.MimeTypes
@ -140,9 +140,9 @@ class ImageByteStreamHandler(private val context: Context, private val arguments
if (bitmap != null) {
val recycle = false
val canHaveAlpha = MimeTypes.canHaveAlpha(mimeType)
var bytes = bitmap.getBytes(canHaveAlpha, recycle = recycle)
var bytes = bitmap.getEncodedBytes(canHaveAlpha, recycle = recycle)
if (bytes != null && bytes.isEmpty()) {
bytes = BitmapUtils.tryPixelFormatConversion(bitmap)?.getBytes(canHaveAlpha, recycle = recycle)
bytes = BitmapUtils.tryPixelFormatConversion(bitmap)?.getEncodedBytes(canHaveAlpha, recycle = recycle)
}
if (MemoryUtils.canAllocate(sizeBytes)) {
success(bytes)
@ -168,7 +168,7 @@ class ImageByteStreamHandler(private val context: Context, private val arguments
try {
val bitmap = withContext(Dispatchers.IO) { target.get() }
if (bitmap != null) {
val bytes = bitmap.getBytes(canHaveAlpha = false, recycle = false)
val bytes = bitmap.getEncodedBytes(canHaveAlpha = false, recycle = false)
if (MemoryUtils.canAllocate(sizeBytes)) {
success(bytes)
} else {

25
android/app/src/main/kotlin/deckers/thibault/aves/decoder/VideoThumbnailGlideModule.kt
View file

@ -20,7 +20,7 @@ import com.bumptech.glide.load.model.MultiModelLoaderFactory
import com.bumptech.glide.module.LibraryGlideModule
import com.bumptech.glide.signature.ObjectKey
import deckers.thibault.aves.utils.BitmapUtils
import deckers.thibault.aves.utils.BitmapUtils.getBytes
import deckers.thibault.aves.utils.BitmapUtils.getEncodedBytes
import deckers.thibault.aves.utils.MemoryUtils
import deckers.thibault.aves.utils.StorageUtils.openMetadataRetriever
import kotlinx.coroutines.CoroutineScope
@ -112,7 +112,8 @@ internal class VideoThumbnailFetcher(private val model: VideoThumbnail, val widt
// the returned frame is already rotated according to the video metadata
val frame = if (dstWidth > 0 && dstHeight > 0 && Build.VERSION.SDK_INT >= Build.VERSION_CODES.O_MR1) {
val targetBitmapSizeBytes: Long = FORMAT_BYTE_SIZE.toLong() * dstWidth * dstHeight
val pixelCount = dstWidth * dstHeight
val targetBitmapSizeBytes = BitmapUtils.getExpectedImageSize(pixelCount.toLong(), getPreferredConfig())
if (!MemoryUtils.canAllocate(targetBitmapSizeBytes)) {
throw Exception("not enough memory to allocate $targetBitmapSizeBytes bytes for the scaled frame at $dstWidth x $dstHeight")
}
@ -122,7 +123,8 @@ internal class VideoThumbnailFetcher(private val model: VideoThumbnail, val widt
retriever.getScaledFrameAtTime(timeMicros, option, dstWidth, dstHeight)
}
} else {
val targetBitmapSizeBytes: Long = (FORMAT_BYTE_SIZE.toLong() * videoWidth * videoHeight).toLong()
val pixelCount = videoWidth * videoHeight
val targetBitmapSizeBytes = BitmapUtils.getExpectedImageSize(pixelCount.toLong(), getPreferredConfig())
if (!MemoryUtils.canAllocate(targetBitmapSizeBytes)) {
throw Exception("not enough memory to allocate $targetBitmapSizeBytes bytes for the full frame at $videoWidth x $videoHeight")
}
@ -132,7 +134,7 @@ internal class VideoThumbnailFetcher(private val model: VideoThumbnail, val widt
retriever.getFrameAtTime(timeMicros, option)
}
}
bytes = frame?.getBytes(canHaveAlpha = false, recycle = false)
bytes = frame?.getEncodedBytes(canHaveAlpha = false, recycle = false)
}
if (bytes != null) {
@ -151,8 +153,14 @@ internal class VideoThumbnailFetcher(private val model: VideoThumbnail, val widt
}
@RequiresApi(Build.VERSION_CODES.P)
private fun getBitmapParams() = MediaMetadataRetriever.BitmapParams().apply {
preferredConfig = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
private fun getBitmapParams(): MediaMetadataRetriever.BitmapParams {
val params = MediaMetadataRetriever.BitmapParams()
params.preferredConfig = this.getPreferredConfig()
return params
}
private fun getPreferredConfig(): Bitmap.Config {
return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
// improved precision with the same memory cost as `ARGB_8888` (4 bytes per pixel)
// for wide-gamut and HDR content which does not require alpha blending
Bitmap.Config.RGBA_1010102
@ -170,9 +178,4 @@ internal class VideoThumbnailFetcher(private val model: VideoThumbnail, val widt
override fun getDataClass(): Class<InputStream> = InputStream::class.java
override fun getDataSource(): DataSource = DataSource.LOCAL
companion object {
// same for either `ARGB_8888` or `RGBA_1010102`
private const val FORMAT_BYTE_SIZE = BitmapUtils.ARGB_8888_BYTE_SIZE
}
}

119
android/app/src/main/kotlin/deckers/thibault/aves/utils/BitmapUtils.kt
View file

@ -25,10 +25,81 @@ object BitmapUtils {
private val freeBaos = ArrayList<ByteArrayOutputStream>()
private val mutex = Mutex()
const val ARGB_8888_BYTE_SIZE = 4
private const val RGBA_1010102_BYTE_SIZE = 4
private const val INT_BYTE_SIZE = 4
private const val MAX_2_BITS_FLOAT = 0x3.toFloat()
private const val MAX_8_BITS_FLOAT = 0xff.toFloat()
private const val MAX_10_BITS_FLOAT = 0x3ff.toFloat()
suspend fun Bitmap.getBytes(canHaveAlpha: Boolean = false, quality: Int = 100, recycle: Boolean): ByteArray? {
// bytes per pixel with different bitmap config
private const val BPP_ALPHA_8 = 1
private const val BPP_RGB_565 = 2
private const val BPP_ARGB_8888 = 4
private const val BPP_RGBA_1010102 = 4
private const val BPP_RGBA_F16 = 8
private fun getBytePerPixel(config: Bitmap.Config?): Int {
return when (config) {
Bitmap.Config.ALPHA_8 -> BPP_ALPHA_8
Bitmap.Config.RGB_565 -> BPP_RGB_565
Bitmap.Config.ARGB_8888 -> BPP_ARGB_8888
else -> {
return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O && config == Bitmap.Config.RGBA_F16) {
BPP_RGBA_F16
} else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU && config == Bitmap.Config.RGBA_1010102) {
BPP_RGBA_1010102
} else {
// default
BPP_ARGB_8888
}
}
}
}
fun getExpectedImageSize(pixelCount: Long, config: Bitmap.Config?): Long {
return pixelCount * getBytePerPixel(config)
}
fun Bitmap.getDecodedBytes(recycle: Boolean): ByteArray? {
if (!MemoryUtils.canAllocate(byteCount)) {
throw Exception("bitmap buffer is $byteCount bytes, which cannot be allocated to a new byte array")
}
try {
val bytes = ByteBuffer.allocate(byteCount + INT_BYTE_SIZE * 2).apply {
copyPixelsToBuffer(this)
// append bitmap size for use by the caller
putInt(width)
putInt(height)
rewind()
}.array()
// convert pixel format and color space, if necessary
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
colorSpace?.let { srcColorSpace ->
val dstColorSpace = ColorSpace.get(ColorSpace.Named.SRGB)
val connector = ColorSpace.connect(srcColorSpace, dstColorSpace)
if (config == Bitmap.Config.ARGB_8888) {
if (srcColorSpace != dstColorSpace) {
argb8888toArgb8888(bytes, connector, end = byteCount)
}
} else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU && config == Bitmap.Config.RGBA_1010102) {
rgba1010102toArgb8888(bytes, connector, end = byteCount)
}
}
}
// should not be called before accessing color space or other properties
if (recycle) this.recycle()
return bytes
} catch (e: Exception) {
Log.e(LOG_TAG, "failed to get bytes from bitmap", e)
}
return null
}
suspend fun Bitmap.getEncodedBytes(canHaveAlpha: Boolean = false, quality: Int = 100, recycle: Boolean): ByteArray? {
val stream: ByteArrayOutputStream
mutex.withLock {
// this method is called a lot, so we try and reuse output streams
@ -101,37 +172,59 @@ object BitmapUtils {
return null
}
@RequiresApi(Build.VERSION_CODES.O)
private fun argb8888toArgb8888(bytes: ByteArray, connector: ColorSpace.Connector, start: Int = 0, end: Int = bytes.size) {
// unpacking from ARGB_8888 and packing to ARGB_8888
// stored as [3,2,1,0] -> [AAAAAAAA BBBBBBBB GGGGGGGG RRRRRRRR]
for (i in start..<end step BPP_ARGB_8888) {
// mask with `0xff` to yield values in [0, 255], instead of [-128, 127]
val iB = bytes[i + 2].toInt() and 0xff
val iG = bytes[i + 1].toInt() and 0xff
val iR = bytes[i].toInt() and 0xff
// components as floats in sRGB
val srgbFloats = connector.transform(iR / MAX_8_BITS_FLOAT, iG / MAX_8_BITS_FLOAT, iB / MAX_8_BITS_FLOAT)
val srgbR = (srgbFloats[0] * 255.0f + 0.5f).toInt()
val srgbG = (srgbFloats[1] * 255.0f + 0.5f).toInt()
val srgbB = (srgbFloats[2] * 255.0f + 0.5f).toInt()
// keep alpha as it is, in `bytes[i + 3]`
bytes[i + 2] = srgbB.toByte()
bytes[i + 1] = srgbG.toByte()
bytes[i] = srgbR.toByte()
}
}
// convert bytes, without reallocation:
// - from config RGBA_1010102 to ARGB_8888,
// - from original color space to sRGB.
@RequiresApi(Build.VERSION_CODES.O)
private fun rgba1010102toArgb8888(bytes: ByteArray, connector: ColorSpace.Connector) {
val max10Bits = 0x3ff.toFloat()
val dstAlpha = 0xff.toByte()
private fun rgba1010102toArgb8888(bytes: ByteArray, connector: ColorSpace.Connector, start: Int = 0, end: Int = bytes.size) {
val alphaFactor = 255.0f / MAX_2_BITS_FLOAT
val byteCount = bytes.size
for (i in 0..<byteCount step RGBA_1010102_BYTE_SIZE) {
for (i in start..<end step BPP_RGBA_1010102) {
// unpacking from RGBA_1010102
// stored as [3,2,1,0] -> [AABBBBBB BBBBGGGG GGGGGGRR RRRRRRRR]
val i3 = bytes[i + 3].toInt()
val i2 = bytes[i + 2].toInt()
val i1 = bytes[i + 1].toInt()
val i0 = bytes[i].toInt()
// unpacking from RGBA_1010102
// stored as [3,2,1,0] -> [AABBBBBB BBBBGGGG GGGGGGRR RRRRRRRR]
// val iA = ((i3 and 0xc0) shr 6)
val iA = ((i3 and 0xc0) shr 6)
val iB = ((i3 and 0x3f) shl 4) or ((i2 and 0xf0) shr 4)
val iG = ((i2 and 0x0f) shl 6) or ((i1 and 0xfc) shr 2)
val iR = ((i1 and 0x03) shl 8) or ((i0 and 0xff) shr 0)
// components as floats in sRGB
val srgbFloats = connector.transform(iR / max10Bits, iG / max10Bits, iB / max10Bits)
val srgbFloats = connector.transform(iR / MAX_10_BITS_FLOAT, iG / MAX_10_BITS_FLOAT, iB / MAX_10_BITS_FLOAT)
val srgbR = (srgbFloats[0] * 255.0f + 0.5f).toInt()
val srgbG = (srgbFloats[1] * 255.0f + 0.5f).toInt()
val srgbB = (srgbFloats[2] * 255.0f + 0.5f).toInt()
val alpha = (iA * alphaFactor + 0.5f).toInt()
// packing to ARGB_8888
// stored as [3,2,1,0] -> [AAAAAAAA BBBBBBBB GGGGGGGG RRRRRRRR]
bytes[i + 3] = dstAlpha
bytes[i + 3] = alpha.toByte()
bytes[i + 2] = srgbB.toByte()
bytes[i + 1] = srgbG.toByte()
bytes[i] = srgbR.toByte()

15
lib/image_providers/region_provider.dart
View file

@ -48,8 +48,21 @@ class RegionProvider extends ImageProvider<RegionProviderKey> {
if (bytes.isEmpty) {
throw StateError('$uri ($mimeType) region loading failed');
}
final trailerOffset = bytes.length - 4 * 2;
final trailer = ByteData.sublistView(bytes, trailerOffset);
final bitmapWidth = trailer.getUint32(0);
final bitmapHeight = trailer.getUint32(4);
final buffer = await ui.ImmutableBuffer.fromUint8List(bytes);
return await decode(buffer);
final descriptor = ui.ImageDescriptor.raw(
buffer,
width: bitmapWidth,
height: bitmapHeight,
pixelFormat: ui.PixelFormat.rgba8888,
);
return descriptor.instantiateCodec();
} catch (error) {
// loading may fail if the provided MIME type is incorrect (e.g. the Media Store may report a JPEG as a TIFF)
debugPrint('$runtimeType _loadAsync failed with mimeType=$mimeType, uri=$uri, error=$error');

3
lib/utils/math_utils.dart
View file

@ -4,7 +4,8 @@ import 'dart:ui';
int highestPowerOf2(num x) => x < 1 ? 0 : pow(2, (log(x) / ln2).floor()).toInt();
num smallestPowerOf2(num x, {bool allowNegativePower = false}) {
return x < 1 && !allowNegativePower ? 1 : pow(2, (log(x) / ln2).ceil());
if ((x < 1 && !allowNegativePower) || x <= 0) return 1;
return pow(2, (log(x) / ln2).ceil());
}
double roundToPrecision(final double value, {required final int decimals}) => (value * pow(10, decimals)).round() / pow(10, decimals);

1
test/utils/math_utils_test.dart
View file

@ -22,6 +22,7 @@ void main() {
expect(smallestPowerOf2(1.5), 2);
expect(smallestPowerOf2(0.5, allowNegativePower: true), 0.5);
expect(smallestPowerOf2(0.1, allowNegativePower: true), 0.125);
expect(smallestPowerOf2(0, allowNegativePower: true), 1);
});
test('rounding to a given precision after the decimal', () {