core, ui: resize images in the core for sharper previews and images (#7941)

* WIP: Haskell impl of resizeImageToStrSize * WIP: add FFI export wrapper * WIP: switch ios resizeImageToStrSizeSync to backend * WIP: fix resizeImageToStrSizeSync * WIP: add JNI wrappers * Add non-base64 resize and cWriteImage * WIP: add chat_write_image * fix resizeToStr * fixes * fix syntax, raise jpeg quality back * add chatWriteImage * Fix cfArgs in tests * Use jpeg-turbo encoder * add nix pins * bump jpeg-turbo * add CI deps * add encoding funs to android lib * bump jpeg-turbo for 20.04 fix * jpeg-turbo fix for 8.10 * android fixes * Bump jpeg-turbo * set static flag for jpeg-turbo * Fix nix for aarch64/android * Fix android C api * Fix resize in android * Bump hs-libjpeg-turbo * target correct override * override android lib from android pkgs * add macos build tweaks * bump hs-jpeg-turbo for 8.10 fixes * more build fixes * make ios compile * Always use pkgconfig for libjpeg-turbo * WIP: debug libjpeg in ubuntu pkg-config CI * Add pkg-config to dockerfiles * Add libturbojpeg to dockerfiles * Use -dev version of libturbojpeg in dockerfiles * Install pkg-config in windows CI * Disable flag for custom libturbojpeg linking options Workarounds relocation error on x86_64-linux with gcc: /usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/13/../../../x86_64-linux-gnu/libturbojpeg.a(turbojpeg.c.o): relocation R_X86_64_TPOFF32 against `errStr' can not be used when making a shared object; recompile with -fPIC /usr/bin/ld: failed to set dynamic section sizes: bad value * WIP: debug libjpeg in windows pkg-config CI * WIP: debug libjpeg package in windows CI * core: image resize module and buffer FFI * ci: link libjpeg-turbo statically on all platforms * ui: resize images in the core * core: rename image resize functions to chat_resize_image and chat_resize_image_uri * ci: restore whitespace in build.yml * ci: build libjpeg-turbo 3.1.4.1 from a submodule * core: hs-jpeg-turbo from github.com/simplex-chat * nodejs: resize images * python: resize images * core: hs-jpeg-turbo from gitlab.com, the GitHub import lacks LFS objects * core: generate /img previews * ci: link libjpeg-turbo on Windows without pkg-config * ci: build libjpeg-turbo on Windows with the GHC toolchain * docs: plan for image resizing in the core * docs: update image resizing plan * ios: prevent crash when wallpaper image cannot be resized * android, desktop: raise an error when an image cannot be resized * docs: update spec references for image resizing * docker: build the CLI image from a clone without submodules * docs: apply review fixes to image resizing plan * docker: build the CLI from a git worktree with the submodule present * docs: apply second review to image resizing plan * docs: point image resizing plan at the rewritten commit * core: choose image format by transparency in chat_resize_image * nodejs: resize images to the app sizes * python: resize images to the app sizes * nodejs, python: describe the core modules as used for image resizing * docs: add license notices of the image libraries * ci: describe the avatar method without attributing it to the apps * ci, ios, nix: remove the libjpeg-turbo build outside cabal * python: name resize_image in the core module text * nodejs, python: describe resizing to the app image sizes * core: refuse images larger than the supported size * core: resize to JPEG images with a side above 65500 pixels * docs: record image resizing decisions for the bundled libjpeg-turbo * core, docs: build libjpeg-turbo and stb from the fork submodules * docs: record the fork pins in the image resizing plan * core: resize images to at most 4320 pixels per side, refuse above 16384 * docs: record the image side limits in the image resizing plan * core: pin the rebased hs-jpeg-turbo fork * core: pin the hs-jpeg-turbo fork without package.yaml * docs: plan scaled JPEG decoding and EXIF orientation of images * docs: copy the JuicyPixels-stbir licence of the pinned fork * core: pin the hs-jpeg-turbo fork with scaled JPEG decoding * core: decode JPEG at the display size, up to 65500 pixels per side * core: rotate JPEG images by their EXIF orientation * docs: refer the image plan to the JPEG decoding code * docs: record the approved image processing decisions * core: limit JPEG decoding memory to 1024 MB outside iOS and Android * docs: name JPEG decoding in the libjpeg-turbo notice * docs: plan image resizing from files and the decisions of 26 Oct * core: scale images in one Catmull-Rom pass with sharpening * docs: plan image sizes at a fixed quality * core: resize images at a fixed quality to fill the size limit * core: resize images from a file path or a file descriptor * ios, android, desktop: resize picked images from their files * core: encode resized images with mozjpeg * tests: check descriptor closing by the file it refers to * core: raise JPEG quality only for a full-size image below 97% of the limit * ci: name the mozjpeg submodule in the Windows cleanup comments * docs: refer the image plan to the current code * docs: refer the image plan to the code merged with master * core: export every image resizing function from each library * core: close the file descriptor when its handle cannot be created * docs: count the C sources of mozjpeg with the arithmetic decoder * core: use the reviewed hs-jpeg-turbo and JuicyPixels-stbir forks * ci: build the armv7a Android core library on request * core: round image heights half up in the size search * ios: describe the file image resizing functions in SimpleX.h * ci: pick, preview and send images in the Claude app tests * core: decode PNG images with libspng and refuse other formats * core: encode PNG with libspng, keeping the smaller filter choice * ci: pick, preview and send images in the scripted app smoke tests * flake: build the PNG decoder package in nix builds * ios: remove the copy of a picked image after sending it * core: refuse image files larger than the decode memory limit * core: scale a JPEG image to its largest size once per resize * core: bisect JPEG quality without a step function * core: reduce the memory used to sharpen and to decode PNG images * android, desktop: pass the image format to the core as an integer * android, desktop: fuse the preview conditions of picked media * android, desktop, ci: check that the core resized the smoke test images * python: remove the docstrings of the explicit image resizing functions * docs: add the second review fixes to the image plan * ci: tap the iOS attachment button by its accessibility label * core: keep the colour profiles of resized images * docs: add the colour profiles to the image plan * ci: wait up to 30 s for the new group screens in the iOS smoke test * ci: pick the Android smoke test images from their own photo folders * ci: tap the iOS photo picker by position, as its tree is not shown * ci: pick the test card and the logo by their iOS picker positions * core: update JuicyPixels-stbir with the stb_image_resize licence terms * core: write a fixed Display P3 profile for Display P3 images only * core: do not keep the input image in memory for its colour profile * core: read the JPEG segments once for the orientation and the profile * core: read an image file into one buffer of its size * docs: add the third review fixes to the image plan * core: resize images with Display P3 or no profile, not profile bytes * ci: check the pixel sizes of the images sent in the iOS smoke test * core: update hs-jpeg-turbo with PNG chunk limits and encoder fixes * docs: list Compact ICC Profiles, libspng and miniz in the dependencies * android, desktop: reword the picked media preview comment * docs: refer the image plan to the code merged with master * ci: render the iOS snapshots before the images case * ci: dismiss the snapshot tests' camera alert before the iOS images case * core: update hs-jpeg-turbo with tests and the JuicyPixels-spng synopsis * core: pin hs-jpeg-turbo and JuicyPixels-stbir in simplex-chat repositories * update ios core library * core, ui: accept only JPEG and PNG image data * core: update JuicyPixels-stbir * docs: plan for the iOS copy of picked images --------- Co-authored-by: IC Rainbow <aenor.realm@gmail.com> Co-authored-by: Evgeny Poberezkin <evgeny@poberezkin.com> Co-authored-by: Alexandre Esteves <alexfmpe@proton.me>
2026-11-04 08:37:30 +00:00 · 2026-10-30 12:14:51 +00:00
1 parent 1491d0cff8
commit fbca2cae81
@@ -13,6 +13,7 @@ import androidx.core.graphics.scale
 import boofcv.android.ConvertBitmap
 import boofcv.struct.image.GrayU8
 import chat.simplex.common.R
+import chat.simplex.common.helpers.toUri
 import chat.simplex.common.views.helpers.decodeSampledBitmapFromByteArray
 import chat.simplex.common.views.helpers.errorBitmap
 import chat.simplex.common.views.helpers.getFileName
@@ -20,7 +21,6 @@ import java.io.ByteArrayOutputStream
 import java.io.InputStream
 import java.net.URI
 import kotlin.math.min
-import kotlin.math.sqrt

 private const val MAX_IMAGE_DIMENSION = 4320

@@ -50,20 +50,6 @@ actual fun decodeBase64Image(base64: String, width: Int): ImageBitmap? =
    null
  }

-actual fun resizeImageToStrSize(image: ImageBitmap, maxDataSize: Long): String {
-  var img = image
-  var str = compressImageStr(img)
-  while (str.length > maxDataSize) {
-    val ratio = sqrt(str.length.toDouble() / maxDataSize.toDouble())
-    val clippedRatio = min(ratio, 2.0)
-    val width = (img.width.toDouble() / clippedRatio).toInt()
-    val height = img.height * width / img.width
-    img = Bitmap.createScaledBitmap(img.asAndroidBitmap(), width, height, true).asImageBitmap()
-    str = compressImageStr(img)
-  }
-  return str
-}
-
 // Inspired by https://github.com/MakeItEasyDev/Jetpack-Compose-Capture-Image-Or-Choose-from-Gallery
 actual fun cropToSquare(image: ImageBitmap): ImageBitmap {
  var xOffset = 0
@@ -87,32 +73,12 @@ fun Bitmap.clipToCircle(): Bitmap {
  return circle
 }

-actual fun compressImageStr(bitmap: ImageBitmap): String {
-  val usePng = bitmap.hasAlpha()
-  val ext = if (usePng) "png" else "jpg"
-  return "data:image/$ext;base64," + Base64.encodeToString(compressImageData(bitmap, usePng).toByteArray(), Base64.NO_WRAP)
-}
-
 actual fun compressImageData(bitmap: ImageBitmap, usePng: Boolean): ByteArrayOutputStream {
  val stream = ByteArrayOutputStream()
  bitmap.asAndroidBitmap().compress(if (!usePng) Bitmap.CompressFormat.JPEG else Bitmap.CompressFormat.PNG, 85, stream)
  return stream
 }

-actual fun resizeImageToDataSize(image: ImageBitmap, usePng: Boolean, maxDataSize: Long): ByteArrayOutputStream {
-  var img = image
-  var stream = compressImageData(img, usePng)
-  while (stream.size() > maxDataSize) {
-    val ratio = sqrt(stream.size().toDouble() / maxDataSize.toDouble())
-    val clippedRatio = min(ratio, 2.0)
-    val width = (img.width.toDouble() / clippedRatio).toInt()
-    val height = img.height * width / img.width
-    img = Bitmap.createScaledBitmap(img.asAndroidBitmap(), width, height, true).asImageBitmap()
-    stream = compressImageData(img, usePng)
-  }
-  return stream
-}
-
 actual fun GrayU8.toImageBitmap(): ImageBitmap = ConvertBitmap.grayToBitmap(this, Bitmap.Config.RGB_565).asImageBitmap()

 actual fun ImageBitmap.hasAlpha(): Boolean = hasAlpha
@@ -142,3 +108,17 @@ actual fun isAnimImage(uri: URI, drawable: Any?): Boolean {

 actual fun loadImageBitmap(inputStream: InputStream): ImageBitmap =
  BitmapFactory.decodeStream(inputStream).asImageBitmap()
+
+actual fun resizeImageFileUri(uri: URI, maxSize: Int): String =
+  imageFileDescriptor(uri)?.let { chatResizeImageFdUri(it, maxSize) } ?: ""
+
+actual fun resizeImageFileData(uri: URI, maxSize: Int): String =
+  imageFileDescriptor(uri)?.let { chatResizeImageFd(it, maxSize, -1) } ?: ""
+
+private fun imageFileDescriptor(uri: URI): Int? =
+  try {
+    androidAppContext.contentResolver.openFileDescriptor(uri.toUri(), "r")?.detachFd()
+  } catch (e: Exception) {
+    Log.e(TAG, "imageFileDescriptor error: ${e.stackTraceToString()}")
+    null
+  }
@@ -6,7 +6,6 @@ import android.content.pm.PackageManager
 import android.net.Uri
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.compose.runtime.*
-import androidx.compose.ui.graphics.ImageBitmap
 import androidx.core.content.ContextCompat
 import chat.simplex.common.helpers.toURI
 import chat.simplex.common.platform.*
@@ -23,9 +22,9 @@ actual fun AttachmentSelection(
 ) {
  val cameraLauncher = rememberCameraLauncher { uri: Uri? ->
    if (uri != null) {
-      val bitmap: ImageBitmap? = getBitmapFromUri(uri.toURI())
-      if (bitmap != null) {
-        val imagePreview = resizeImageToStrSize(bitmap, maxDataSize = 14000)
+      val imagePreview = resizeImageFileToStrSize(uri.toURI(), maxDataSize = 14000)
+        ?: getBitmapFromUri(uri.toURI())?.let { resizeImageToStrSize(it, maxDataSize = 14000) }
+      if (imagePreview != null) {
        composeState.value = composeState.value.copy(preview = ComposePreview.MediaPreview(listOf(imagePreview), listOf(UploadContent.SimpleImage(uri.toURI()))))
      }
    }
@@ -83,6 +83,10 @@ extern char *chat_write_file(chat_ctrl ctrl, const char *path, char *ptr, int le
 extern char *chat_read_file(const char *path, const char *key, const char *nonce);
 extern char *chat_encrypt_file(chat_ctrl ctrl, const char *from_path, const char *to_path);
 extern char *chat_decrypt_file(const char *from_path, const char *key, const char *nonce, const char *to_path);
+extern char *chat_resize_image_uri(char *ptr, int length, int max_size);
+extern char *chat_resize_image(char *ptr, int length, int max_size, int png);
+extern char *chat_resize_image_fd_uri(int fd, int max_size);
+extern char *chat_resize_image_fd(int fd, int max_size, int png);

 JNIEXPORT jobjectArray JNICALL
 Java_chat_simplex_common_platform_CoreKt_chatMigrateInit(JNIEnv *env, __unused jclass clazz, jstring dbPath, jstring dbKey, jstring confirm) {
@@ -273,3 +277,27 @@ Java_chat_simplex_common_platform_CoreKt_chatDecryptFile(JNIEnv *env, jclass cla
    (*env)->ReleaseStringUTFChars(env, to_path, _to_path);
    return res;
 }
+
+JNIEXPORT jstring JNICALL
+Java_chat_simplex_common_platform_CoreKt_chatResizeImageUri(JNIEnv *env, jclass clazz, jobject buffer, jint maxSize) {
+    jbyte *buff = (jbyte *) (*env)->GetDirectBufferAddress(env, buffer);
+    jlong capacity = (*env)->GetDirectBufferCapacity(env, buffer);
+    return decode_and_free(env, chat_resize_image_uri(buff, capacity, maxSize));
+}
+
+JNIEXPORT jstring JNICALL
+Java_chat_simplex_common_platform_CoreKt_chatResizeImage(JNIEnv *env, jclass clazz, jobject buffer, jint maxSize, jint png) {
+    jbyte *buff = (jbyte *) (*env)->GetDirectBufferAddress(env, buffer);
+    jlong capacity = (*env)->GetDirectBufferCapacity(env, buffer);
+    return decode_and_free(env, chat_resize_image(buff, capacity, maxSize, png));
+}
+
+JNIEXPORT jstring JNICALL
+Java_chat_simplex_common_platform_CoreKt_chatResizeImageFdUri(JNIEnv *env, jclass clazz, jint fd, jint maxSize) {
+    return decode_and_free(env, chat_resize_image_fd_uri(fd, maxSize));
+}
+
+JNIEXPORT jstring JNICALL
+Java_chat_simplex_common_platform_CoreKt_chatResizeImageFd(JNIEnv *env, jclass clazz, jint fd, jint maxSize, jint png) {
+    return decode_and_free(env, chat_resize_image_fd(fd, maxSize, png));
+}
@@ -46,6 +46,10 @@ extern char *chat_write_file(chat_ctrl ctrl, const char *path, char *ptr, int le
 extern char *chat_read_file(const char *path, const char *key, const char *nonce);
 extern char *chat_encrypt_file(chat_ctrl ctrl, const char *from_path, const char *to_path);
 extern char *chat_decrypt_file(const char *from_path, const char *key, const char *nonce, const char *to_path);
+extern char *chat_resize_image_uri(char *ptr, int length, int max_size);
+extern char *chat_resize_image(char *ptr, int length, int max_size, int png);
+extern char *chat_resize_image_file_uri(const char *path, int max_size);
+extern char *chat_resize_image_file(const char *path, int max_size, int png);

 // As a reference: https://stackoverflow.com/a/60002045
 jstring decode_to_utf8_string(JNIEnv *env, char *string) {
@@ -274,3 +278,33 @@ Java_chat_simplex_common_platform_CoreKt_chatDecryptFile(JNIEnv *env, jclass cla
    (*env)->ReleaseStringUTFChars(env, to_path, _to_path);
    return res;
 }
+
+JNIEXPORT jstring JNICALL
+Java_chat_simplex_common_platform_CoreKt_chatResizeImageUri(JNIEnv *env, jclass clazz, jobject buffer, jint maxSize) {
+    jbyte *buff = (jbyte *) (*env)->GetDirectBufferAddress(env, buffer);
+    jlong capacity = (*env)->GetDirectBufferCapacity(env, buffer);
+    return decode_to_utf8_string(env, chat_resize_image_uri(buff, capacity, maxSize));
+}
+
+JNIEXPORT jstring JNICALL
+Java_chat_simplex_common_platform_CoreKt_chatResizeImage(JNIEnv *env, jclass clazz, jobject buffer, jint maxSize, jint png) {
+    jbyte *buff = (jbyte *) (*env)->GetDirectBufferAddress(env, buffer);
+    jlong capacity = (*env)->GetDirectBufferCapacity(env, buffer);
+    return decode_to_utf8_string(env, chat_resize_image(buff, capacity, maxSize, png));
+}
+
+JNIEXPORT jstring JNICALL
+Java_chat_simplex_common_platform_CoreKt_chatResizeImageFileUri(JNIEnv *env, jclass clazz, jstring path, jint maxSize) {
+    const char *_path = encode_to_utf8_chars(env, path);
+    jstring res = decode_to_utf8_string(env, chat_resize_image_file_uri(_path, maxSize));
+    (*env)->ReleaseStringUTFChars(env, path, _path);
+    return res;
+}
+
+JNIEXPORT jstring JNICALL
+Java_chat_simplex_common_platform_CoreKt_chatResizeImageFile(JNIEnv *env, jclass clazz, jstring path, jint maxSize, jint png) {
+    const char *_path = encode_to_utf8_chars(env, path);
+    jstring res = decode_to_utf8_string(env, chat_resize_image_file(_path, maxSize, png));
+    (*env)->ReleaseStringUTFChars(env, path, _path);
+    return res;
+}
@@ -2,7 +2,6 @@ package chat.simplex.common.model

 import chat.simplex.common.platform.*
 import kotlinx.serialization.*
-import java.nio.ByteBuffer

@Serializable
 sealed class WriteFileResult {
@@ -23,10 +22,7 @@ sealed class WriteFileResult {
 // Spec: spec/services/files.md#writeCryptoFile
 fun writeCryptoFile(path: String, data: ByteArray): CryptoFileArgs {
  val ctrl = ChatController.getChatCtrl() ?: throw Exception("Controller is not initialized")
-  val buffer = ByteBuffer.allocateDirect(data.size)
-  buffer.put(data)
-  buffer.rewind()
-  val str = chatWriteFile(ctrl, path, buffer)
+  val str = chatWriteFile(ctrl, path, data.toDirectBuffer())
  return when (val d = json.decodeFromString(WriteFileResult.serializer(), str)) {
    is WriteFileResult.Result -> d.cryptoArgs
    is WriteFileResult.Error -> throw Exception(d.writeError)
@@ -39,6 +39,12 @@ external fun chatWriteFile(ctrl: ChatCtrl, path: String, buffer: ByteBuffer): St
 external fun chatReadFile(path: String, key: String, nonce: String): Array<Any>
 external fun chatEncryptFile(ctrl: ChatCtrl, fromPath: String, toPath: String): String
 external fun chatDecryptFile(fromPath: String, key: String, nonce: String, toPath: String): String
+external fun chatResizeImageUri(buffer: ByteBuffer, maxSize: Int): String
+external fun chatResizeImage(buffer: ByteBuffer, maxSize: Int, png: Int): String
+external fun chatResizeImageFileUri(path: String, maxSize: Int): String
+external fun chatResizeImageFile(path: String, maxSize: Int, png: Int): String
+external fun chatResizeImageFdUri(fd: Int, maxSize: Int): String
+external fun chatResizeImageFd(fd: Int, maxSize: Int, png: Int): String

 // the code in core's canonical form (prefix and 20 characters, no separators), or null when core rejects it.
 // The check character is verified by core via FFI, not re-implemented here, so the two cannot disagree.
@@ -47,6 +53,13 @@ fun parseBadgeCode(s: String): String? {
  return if (canonical.isEmpty()) null else canonical
 }

+fun ByteArray.toDirectBuffer(): ByteBuffer {
+  val buffer = ByteBuffer.allocateDirect(size)
+  buffer.put(this)
+  buffer.rewind()
+  return buffer
+}
+
 val chatModel: ChatModel
  get() = chatController.chatModel

@@ -13,13 +13,11 @@ import kotlinx.coroutines.withContext
 import java.io.ByteArrayOutputStream
 import java.io.InputStream
 import java.net.URI
+import java.util.Base64

 expect fun base64ToBitmap(base64ImageString: String): ImageBitmap
 expect fun decodeBase64Image(base64: String, width: Int): ImageBitmap?
-expect fun resizeImageToStrSize(image: ImageBitmap, maxDataSize: Long): String
-expect fun resizeImageToDataSize(image: ImageBitmap, usePng: Boolean, maxDataSize: Long): ByteArrayOutputStream
 expect fun cropToSquare(image: ImageBitmap): ImageBitmap
-expect fun compressImageStr(bitmap: ImageBitmap): String
 expect fun compressImageData(bitmap: ImageBitmap, usePng: Boolean): ByteArrayOutputStream

 expect fun GrayU8.toImageBitmap(): ImageBitmap
@@ -33,6 +31,35 @@ expect fun isAnimImage(uri: URI, drawable: Any?): Boolean

 expect fun loadImageBitmap(inputStream: InputStream): ImageBitmap

+expect fun resizeImageFileUri(uri: URI, maxSize: Int): String
+expect fun resizeImageFileData(uri: URI, maxSize: Int): String
+
+fun resizeImageFileToStrSize(uri: URI, maxDataSize: Long): String? =
+  resizeImageFileUri(uri, maxDataSize.toInt()).ifEmpty {
+    Log.d(TAG, "resizeImageFileToStrSize: core returned no image")
+    null
+  }
+
+fun resizeImageFileToDataSize(uri: URI, maxDataSize: Long): ByteArray? =
+  resizeImageFileData(uri, maxDataSize.toInt()).ifEmpty {
+    Log.d(TAG, "resizeImageFileToDataSize: core returned no image")
+    null
+  }?.let { Base64.getDecoder().decode(it) }
+
+fun resizeImageToStrSize(image: ImageBitmap, maxDataSize: Long): String {
+  val str = chatResizeImageUri(compressImageData(image, image.hasAlpha()).toByteArray().toDirectBuffer(), maxDataSize.toInt())
+  if (str.isEmpty()) throw Exception("Image resize failed")
+  return str
+}
+
+fun resizeImageToDataSize(image: ImageBitmap, usePng: Boolean, maxDataSize: Long): ByteArrayOutputStream {
+  val str = chatResizeImage(compressImageData(image, usePng).toByteArray().toDirectBuffer(), maxDataSize.toInt(), if (usePng) 1 else 0)
+  if (str.isEmpty()) throw Exception("Image resize failed")
+  val stream = ByteArrayOutputStream()
+  stream.write(Base64.getDecoder().decode(str))
+  return stream
+}
+
@Composable
 fun Base64AsyncImage(
  base64ImageString: String,
@@ -15,7 +15,6 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.focus.FocusRequester
 import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.ImageBitmap
 import androidx.compose.ui.graphics.painter.Painter
 import androidx.compose.ui.text.TextRange
 import androidx.compose.ui.text.TextStyle
@@ -362,43 +361,42 @@ suspend fun MutableState<ComposeState>.processPickedMedia(uris: List<URI>, text:
  val content = ArrayList<UploadContent>()
  val imagesPreview = ArrayList<String>()
  uris.forEach { uri ->
-    var bitmap: ImageBitmap?
+    var preview: String? = null
    val uploadContent: UploadContent? = when {
      isImage(uri) -> {
        // Image
        val drawable = getDrawableFromUri(uri)
        // Do not show alert in case it's already shown from the function above
-        bitmap = getBitmapFromUri(uri, withAlertOnException = !AlertManager.shared.hasAlertsShown())
+        fun bitmapPreview() = getBitmapFromUri(uri, withAlertOnException = !AlertManager.shared.hasAlertsShown())?.let { resizeImageToStrSize(it, maxDataSize = 14000) }
        if (isAnimImage(uri, drawable)) {
          // It's a gif or webp
          val fileSize = getFileSize(uri)
          if (fileSize != null && fileSize <= maxFileSize) {
+            preview = bitmapPreview()
            UploadContent.AnimatedImage(uri)
          } else {
-            bitmap = null
            showLargeFileAlert(fileSize ?: 0, value.sendIncognito, chatModel.currentUser.value?.profile)
            null
          }
-        } else if (bitmap != null) {
-          UploadContent.SimpleImage(uri)
        } else {
-          null
+          preview = resizeImageFileToStrSize(uri, maxDataSize = 14000) ?: bitmapPreview()
+          UploadContent.SimpleImage(uri)
        }
      }
      else -> {
        // Video
        val res = getBitmapFromVideo(uri, withAlertOnException = true)
-        bitmap = res.preview
+        preview = res.preview?.let { resizeImageToStrSize(it, maxDataSize = 14000) }
        val durationMs = res.duration
        UploadContent.Video(uri, durationMs?.div(1000)?.toInt() ?: 0)
      }
    }
    // content and imagesPreview must stay index-aligned and equal-length: both consumers
    // (ComposeImageView and sendMessageAsync) cross-index one list by the other's index.
-    // Only pair them when a preview bitmap exists; otherwise skip the media entirely.
-    if (bitmap != null && uploadContent != null) {
+    // Only pair them when a preview exists; otherwise skip the media entirely.
+    if (preview != null && uploadContent != null) {
      content.add(uploadContent)
-      imagesPreview.add(resizeImageToStrSize(bitmap, maxDataSize = 14000))
+      imagesPreview.add(preview)
    } else if (uploadContent is UploadContent.Video && !AlertManager.shared.hasAlertsShown()) {
      // A corrupted/undecodable video can yield a null preview frame without throwing, so
      // getBitmapFromVideo shows no alert. Skip it (other picked media still send) and tell
@@ -51,8 +51,13 @@ import java.io.File
 import java.net.URI
 import java.nio.ByteBuffer
 import java.nio.charset.CodingErrorAction
+import java.util.Base64

 private const val DATA_IMAGE = "data:image/"
+private val IMAGE_SIGNATURES = listOf(
+  listOf(0xFF, 0xD8, 0xFF),
+  listOf(0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A)
+)
 private const val MAX_MARKDOWN_VIEW_SIZE: Long = 1_048_576
 private const val MAX_MARKDOWN_LINE_LENGTH = 15_000
 private const val MAX_MARKDOWN_DEPTH = 32
@@ -281,7 +286,15 @@ private class DataImageTransformer : ImageTransformer {

  private fun imageWithinBudget(link: String, width: Int): ImageBitmap? =
    link.takeIf { it.startsWith(DATA_IMAGE) }
-      ?.let { decodeBase64Image(it.substringAfter("base64,"), width) }
+      ?.substringAfter("base64,")
+      ?.takeIf(::hasImageSignature)
+      ?.let { decodeBase64Image(it, width) }
      ?.takeIf { it.width.toLong() * it.height <= pixels }
      ?.also { pixels -= it.width.toLong() * it.height }
 }
+
+private fun hasImageSignature(base64: String): Boolean {
+  val header = runCatching { Base64.getDecoder().decode(base64.take(12)) }.getOrNull() ?: return false
+  val bytes = header.map { it.toInt() and 0xFF }
+  return IMAGE_SIGNATURES.any { bytes.take(it.size) == it }
+}
@@ -172,20 +172,14 @@ fun getThemeFromUri(uri: URI, withAlertOnException: Boolean = true): ThemeOverri
 }

 fun saveImage(uri: URI): CryptoFile? {
-  val bitmap = getBitmapFromUri(uri) ?: return null
-  return saveImage(bitmap)
-}
-
-fun saveImage(image: ImageBitmap): CryptoFile? {
  return try {
    val encrypted = chatController.appPrefs.privacyEncryptLocalFiles.get()
-    val ext = if (image.hasAlpha()) "png" else "jpg"
-    val dataResized = resizeImageToDataSize(image, ext == "png", maxDataSize = MAX_IMAGE_SIZE)
+    val (dataResized, ext) = resizeImageFromUri(uri) ?: return null
    val destFileName = generateNewFileName("IMG", ext, File(getAppFilePath("")))
    val destFile = File(getAppFilePath(destFileName))
    if (encrypted) {
      try {
-        val args = writeCryptoFile(destFile.absolutePath, dataResized.toByteArray())
+        val args = writeCryptoFile(destFile.absolutePath, dataResized)
        CryptoFile(destFileName, args)
      } catch (e: Exception) {
        Log.e(TAG, "Unable to write crypto file: " + e.stackTraceToString())
@@ -194,7 +188,7 @@ fun saveImage(image: ImageBitmap): CryptoFile? {
      }
    } else {
      val output = FileOutputStream(destFile)
-      dataResized.writeTo(output)
+      output.write(dataResized)
      output.flush()
      output.close()
      CryptoFile.plain(destFileName)
@@ -206,14 +200,12 @@ fun saveImage(image: ImageBitmap): CryptoFile? {
 }

 fun desktopSaveImageInTmp(uri: URI): CryptoFile? {
-  val image = getBitmapFromUri(uri) ?: return null
  return try {
-    val ext = if (image.hasAlpha()) "png" else "jpg"
-    val dataResized = resizeImageToDataSize(image, ext == "png", maxDataSize = MAX_IMAGE_SIZE)
+    val (dataResized, ext) = resizeImageFromUri(uri) ?: return null
    val destFileName = generateNewFileName("IMG", ext, tmpDir)
    val destFile = File(tmpDir, destFileName)
    val output = FileOutputStream(destFile)
-    dataResized.writeTo(output)
+    output.write(dataResized)
    output.flush()
    output.close()
    CryptoFile.plain(destFile.absolutePath)
@@ -223,6 +215,17 @@ fun desktopSaveImageInTmp(uri: URI): CryptoFile? {
  }
 }

+private fun resizeImageFromUri(uri: URI): Pair<ByteArray, String>? {
+  val data = resizeImageFileToDataSize(uri, MAX_IMAGE_SIZE)
+  if (data != null) {
+    val ext = if (data.firstOrNull() == 0x89.toByte()) "png" else "jpg"
+    return data to ext
+  }
+  val image = getBitmapFromUri(uri) ?: return null
+  val ext = if (image.hasAlpha()) "png" else "jpg"
+  return resizeImageToDataSize(image, ext == "png", maxDataSize = MAX_IMAGE_SIZE).toByteArray() to ext
+}
+
 fun saveAnimImage(uri: URI): CryptoFile? {
  return try {
    val encrypted = chatController.appPrefs.privacyEncryptLocalFiles.get()
@@ -17,7 +17,6 @@ import java.net.URI
 import java.util.*
 import javax.imageio.*
 import javax.imageio.stream.MemoryCacheImageOutputStream
-import kotlin.math.sqrt

 private fun errorBitmap(): ImageBitmap =
  ImageIO.read(ByteArrayInputStream(Base64.getMimeDecoder().decode("iVBORw0KGgoAAAANSUhEUgAAAEAAAABACAYAAACqaXHeAAAAAXNSR0IArs4c6QAAAKVJREFUeF7t1kENACEUQ0FQhnVQ9lfGO+xggITQdvbMzArPey+8fa3tAfwAEdABZQspQStgBssEcgAIkSAJkiAJljtEgiRIgmUCSZAESZAESZAEyx0iQRIkwTKBJEiCv5fgvTd1wDmn7QAP4AeIgA4oW0gJWgEzWCZwbQ7gAA7ggLKFOIADOKBMIAeAEAmSIAmSYLlDJEiCJFgmkARJkARJ8N8S/ADTZUewBvnTOQAAAABJRU5ErkJggg=="))).toComposeImageBitmap()
@@ -63,33 +62,6 @@ actual fun decodeBase64Image(base64: String, width: Int): ImageBitmap? =
    null
  }

-actual fun resizeImageToStrSize(image: ImageBitmap, maxDataSize: Long): String {
-  var img = image
-  var str = compressImageStr(img)
-  while (str.length > maxDataSize) {
-    val ratio = sqrt(str.length.toDouble() / maxDataSize.toDouble())
-    val clippedRatio = kotlin.math.min(ratio, 2.0)
-    val width = (img.width.toDouble() / clippedRatio).toInt()
-    val height = img.height * width / img.width
-    img = img.scale(width, height)
-    str = compressImageStr(img)
-  }
-  return str
-}
-actual fun resizeImageToDataSize(image: ImageBitmap, usePng: Boolean, maxDataSize: Long): ByteArrayOutputStream {
-  var img = image
-  var stream = compressImageData(img, usePng)
-  while (stream.size() > maxDataSize) {
-    val ratio = sqrt(stream.size().toDouble() / maxDataSize.toDouble())
-    val clippedRatio = kotlin.math.min(ratio, 2.0)
-    val width = (img.width.toDouble() / clippedRatio).toInt()
-    val height = img.height * width / img.width
-    img = img.scale(width, height)
-    stream = compressImageData(img, usePng)
-  }
-  return stream
-}
-
 actual fun cropToSquare(image: ImageBitmap): ImageBitmap {
  var xOffset = 0
  var yOffset = 0
@@ -111,18 +83,6 @@ actual fun cropToSquare(image: ImageBitmap): ImageBitmap {
  return croppedImage
 }

-actual fun compressImageStr(bitmap: ImageBitmap): String {
-  val usePng = bitmap.hasAlpha()
-  val ext = if (usePng) "png" else "jpg"
-  return try {
-    val encoded  = Base64.getEncoder().encodeToString(compressImageData(bitmap, usePng).toByteArray())
-    "data:image/$ext;base64,$encoded"
-  } catch (e: Exception) {
-    Log.e(TAG, "resizeImageToStrSize error: $e")
-    throw e
-  }
-}
-
 actual fun compressImageData(bitmap: ImageBitmap, usePng: Boolean): ByteArrayOutputStream {
  val writer = ImageIO.getImageWritersByFormatName(if (usePng) "png" else "jpg").next()
  val writeParam = writer.defaultWriteParam
@@ -213,6 +173,10 @@ actual fun isAnimImage(uri: URI, drawable: Any?): Boolean {
 actual fun loadImageBitmap(inputStream: InputStream): ImageBitmap =
  Image.makeFromEncoded(inputStream.readBytes()).toComposeImageBitmap()

+actual fun resizeImageFileUri(uri: URI, maxSize: Int): String = chatResizeImageFileUri(uri.toFile().absolutePath, maxSize)
+
+actual fun resizeImageFileData(uri: URI, maxSize: Int): String = chatResizeImageFile(uri.toFile().absolutePath, maxSize, -1)
+
 // https://stackoverflow.com/a/68926993
 fun BufferedImage.rotate(angle: Double): BufferedImage {
  val sin = Math.abs(Math.sin(Math.toRadians(angle)))
@@ -139,13 +139,20 @@ All JNI declarations reside in [`Core.kt`](../common/src/commonMain/kotlin/chat/
 | 11 | [`chatParseUri()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L33) | `external fun chatParseUri(str: String, safe: Int): String` | 33 | Parse SimpleX connection URI |
 | 12 | [`chatPasswordHash()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L34) | `external fun chatPasswordHash(pwd: String, salt: String): String` | 34 | Hash password with salt |
 | 13 | [`chatValidName()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L35) | `external fun chatValidName(name: String): String` | 35 | Validate/sanitize display name |
-| 14 | [`chatJsonLength()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L36) | `external fun chatJsonLength(str: String): Int` | 36 | Get JSON-encoded string length |
-| 15 | [`chatWriteFile()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L37) | `external fun chatWriteFile(ctrl: ChatCtrl, path: String, buffer: ByteBuffer): String` | 37 | Write encrypted file via core |
-| 16 | [`chatReadFile()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L38) | `external fun chatReadFile(path: String, key: String, nonce: String): Array<Any>` | 38 | Read and decrypt file |
-| 17 | [`chatEncryptFile()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L39) | `external fun chatEncryptFile(ctrl: ChatCtrl, fromPath: String, toPath: String): String` | 39 | Encrypt file on disk |
-| 18 | [`chatDecryptFile()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L40) | `external fun chatDecryptFile(fromPath: String, key: String, nonce: String, toPath: String): String` | 40 | Decrypt file on disk |
+| 14 | [`chatParseBadgeCode()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L36) | `external fun chatParseBadgeCode(code: String): String` | 36 | Canonical form of a badge code, or an empty string |
+| 15 | [`chatJsonLength()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L37) | `external fun chatJsonLength(str: String): Int` | 37 | Get JSON-encoded string length |
+| 16 | [`chatWriteFile()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L38) | `external fun chatWriteFile(ctrl: ChatCtrl, path: String, buffer: ByteBuffer): String` | 38 | Write encrypted file via core |
+| 17 | [`chatReadFile()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L39) | `external fun chatReadFile(path: String, key: String, nonce: String): Array<Any>` | 39 | Read and decrypt file |
+| 18 | [`chatEncryptFile()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L40) | `external fun chatEncryptFile(ctrl: ChatCtrl, fromPath: String, toPath: String): String` | 40 | Encrypt file on disk |
+| 19 | [`chatDecryptFile()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L41) | `external fun chatDecryptFile(fromPath: String, key: String, nonce: String, toPath: String): String` | 41 | Decrypt file on disk |
+| 20 | [`chatResizeImageUri()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L42) | `external fun chatResizeImageUri(buffer: ByteBuffer, maxSize: Int): String` | 42 | Resize encoded image to a data URI of at most `maxSize` characters |
+| 21 | [`chatResizeImage()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L43) | `external fun chatResizeImage(buffer: ByteBuffer, maxSize: Int, png: Int): String` | 43 | Resize encoded image to base64 of PNG or JPEG data of at most `maxSize` bytes |
+| 22 | [`chatResizeImageFileUri()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L44) | `external fun chatResizeImageFileUri(path: String, maxSize: Int): String` | 44 | Desktop: as `chatResizeImageUri`, from the file at `path` |
+| 23 | [`chatResizeImageFile()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L45) | `external fun chatResizeImageFile(path: String, maxSize: Int, png: Int): String` | 45 | Desktop: as `chatResizeImage`, from the file at `path`; `png` −1 selects the format by transparency |
+| 24 | [`chatResizeImageFdUri()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L46) | `external fun chatResizeImageFdUri(fd: Int, maxSize: Int): String` | 46 | Android: as `chatResizeImageUri`, from the file descriptor `fd`, which core closes |
+| 25 | [`chatResizeImageFd()`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L47) | `external fun chatResizeImageFd(fd: Int, maxSize: Int, png: Int): String` | 47 | Android: as `chatResizeImage`, from the file descriptor `fd`, which core closes |

-**Total: 18 external native functions** (the `ChatCtrl` type alias at [line 23](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L23) is `Long`, representing the Haskell-side controller pointer).
+**Total: 25 external native functions** (the `ChatCtrl` type alias at [line 23](../common/src/commonMain/kotlin/chat/simplex/common/platform/Core.kt#L23) is `Long`, representing the Haskell-side controller pointer).

 <a id="initChatControllerOnStart"></a>
 <a id="chatInitTemporaryDatabase"></a>
@@ -338,7 +345,7 @@ Examples from platform files:
 | `expect class VideoPlayer` | [`VideoPlayer.kt`](../common/src/commonMain/kotlin/chat/simplex/common/platform/VideoPlayer.kt#L25) | 25 |
 | `expect class RecorderNative` | [`RecAndPlay.kt`](../common/src/commonMain/kotlin/chat/simplex/common/platform/RecAndPlay.kt#L17) | 17 |
 | `expect val cryptor: CryptorInterface` | [`Cryptor.kt`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Cryptor.kt#L9) | 9 |
-| `expect fun base64ToBitmap(base64ImageString: String): ImageBitmap` | [`Images.kt`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Images.kt#L17) | 17 |
+| `expect fun base64ToBitmap(base64ImageString: String): ImageBitmap` | [`Images.kt`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Images.kt#L18) | 18 |
 | `expect fun getWakeLock(timeout: Long): (() -> Unit)` | [`SimplexService.kt`](../common/src/commonMain/kotlin/chat/simplex/common/platform/SimplexService.kt#L3) | 3 |
 | `expect class GlobalExceptionsHandler` | [`UI.kt`](../common/src/commonMain/kotlin/chat/simplex/common/platform/UI.kt#L24) | 24 |
 | `expect fun UriHandler.sendEmail(subject: String, body: CharSequence)` | [`Share.kt`](../common/src/commonMain/kotlin/chat/simplex/common/platform/Share.kt#L7) | 7 |
@@ -315,7 +315,7 @@ Bottom sheet (`ModalBottomSheetLayout`) presenting attachment type options:

 **`processPickedMedia`** (line ~300):
 1. For each URI, determines type (image, animated image, video).
-2. Images: Gets bitmap, creates `SimpleImage` or `AnimatedImage` upload content.
+2. Images: the preview of a non-animated image is made by core from the file (`resizeImageFileToStrSize`); otherwise, or when core returns no preview, from the bitmap; creates `SimpleImage` or `AnimatedImage` upload content.
 3. Videos: Extracts thumbnail and duration, creates `Video` upload content.
 4. Generates base64 preview thumbnails (max 14KB).
 5. Sets `ComposePreview.MediaPreview` with thumbnails and content list.
@@ -56,7 +56,7 @@ FileProtocol.LOCAL -> MAX_FILE_SIZE_LOCAL

 ## 3. CryptoFile

-[`CryptoFile.kt`](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt) (62 lines)
+[`CryptoFile.kt`](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt) (58 lines)

 Provides encrypted file I/O backed by the chat core's native cryptography (via JNI/JNA calls to `chatWriteFile`, `chatReadFile`, `chatEncryptFile`, `chatDecryptFile`).

@@ -78,10 +78,10 @@ sealed class WriteFileResult {

 | Function | Line | Signature | Description |
 |---|---|---|---|
-| `writeCryptoFile` | [L24](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt#L24) | `(path: String, data: ByteArray): CryptoFileArgs` | Writes data to an encrypted file via a direct `ByteBuffer`. Returns the generated key and nonce. Requires initialized `ChatController`. |
-| `readCryptoFile` | [L36](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt#L36) | `(path: String, cryptoArgs: CryptoFileArgs): ByteArray` | Reads and decrypts a file given its key and nonce. Returns the plaintext bytes. Throws on error (status != 0). |
-| `encryptCryptoFile` | [L47](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt#L47) | `(fromPath: String, toPath: String): CryptoFileArgs` | Encrypts an existing plaintext file to a new encrypted file. Returns the generated key and nonce. |
-| `decryptCryptoFile` | [L57](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt#L57) | `(fromPath: String, cryptoArgs: CryptoFileArgs, toPath: String)` | Decrypts an encrypted file to a plaintext output file. Throws on non-empty error string. |
+| `writeCryptoFile` | [L23](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt#L23) | `(path: String, data: ByteArray): CryptoFileArgs` | Writes data to an encrypted file via a direct `ByteBuffer`. Returns the generated key and nonce. Requires initialized `ChatController`. |
+| `readCryptoFile` | [L32](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt#L32) | `(path: String, cryptoArgs: CryptoFileArgs): ByteArray` | Reads and decrypts a file given its key and nonce. Returns the plaintext bytes. Throws on error (status != 0). |
+| `encryptCryptoFile` | [L43](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt#L43) | `(fromPath: String, toPath: String): CryptoFileArgs` | Encrypts an existing plaintext file to a new encrypted file. Returns the generated key and nonce. |
+| `decryptCryptoFile` | [L53](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt#L53) | `(fromPath: String, cryptoArgs: CryptoFileArgs, toPath: String)` | Decrypts an encrypted file to a plaintext output file. Throws on non-empty error string. |

 All functions delegate to native C library functions through the chat core JNI bridge.

@@ -205,7 +205,7 @@ When `auto = true`, relay approval alerts are suppressed (the file is silently r

 | File | Path | Lines | Description |
 |---|---|---|---|
-| `CryptoFile.kt` | [`common/src/commonMain/.../model/CryptoFile.kt`](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt) | 62 | Encrypted file read/write via native crypto |
+| `CryptoFile.kt` | [`common/src/commonMain/.../model/CryptoFile.kt`](../../common/src/commonMain/kotlin/chat/simplex/common/model/CryptoFile.kt) | 58 | Encrypted file read/write via native crypto |
 | `Files.kt` | [`common/src/commonMain/.../platform/Files.kt`](../../common/src/commonMain/kotlin/chat/simplex/common/platform/Files.kt) | 191 | Common file path declarations, theme I/O, file helpers |
 | `Files.android.kt` | [`common/src/androidMain/.../platform/Files.android.kt`](../../common/src/androidMain/kotlin/chat/simplex/common/platform/Files.android.kt) | 79 | Android file path implementations |
 | `Files.desktop.kt` | [`common/src/desktopMain/.../platform/Files.desktop.kt`](../../common/src/desktopMain/kotlin/chat/simplex/common/platform/Files.desktop.kt) | 116 | Desktop file path implementations |