Bound video thumbnails and share retriever cleanup ownership

tools/chatgui-android/app/src/main/java/com/utun/chat/data/VideoFileMetadata.kt

@@ -1,6 +1,8 @@
 package com.utun.chat.data
 
 import android.media.MediaMetadataRetriever
+import android.graphics.Bitmap
+import android.os.Build
 import android.os.Handler
 import android.os.Looper
 import java.util.concurrent.ConcurrentHashMap
@@ -11,6 +13,7 @@ internal data class VideoInfo(val width: Int, val height: Int, val rotation: Int
     val displayHeight: Int get() = if (rotation == 90 || rotation == 270) width else height
     val aspect: Float get() = if (displayHeight > 0) displayWidth.toFloat() / displayHeight else 0f
 }
+internal data class VideoFilePreview(val bitmap: Bitmap?, val durationMs: Int)
 
 /** Один IO caller читает metadata внутри use; после завершения чтения допускается только повтор close.
  * Неудавшийся release удерживает retriever до SDK ACK, retry не обращается к UI/native core. */
@@ -35,6 +38,23 @@ internal class VideoFileMetadata : AutoCloseable {
         require(width > 0 && height > 0 && rotation in listOf(0, 90, 180, 270)) { "Invalid video geometry ${width}x$height rotation=$rotation" }
         return VideoInfo(width, height, rotation)
     }
+    /** IO: thumbnail не больше 640 по каждой стороне; Bitmap принадлежит caller, duration в мс.
+     * API 26 сначала извлекает полный кадр и уменьшает до передачи UI; null bitmap не запрещает воспроизведение. */
+    @Synchronized fun preview(path: String): VideoFilePreview {
+        check(!closing) { "Metadata reader closing" }
+        val current = checkNotNull(retriever) { "Metadata reader closed" }
+        current.setDataSource(path)
+        val duration = current.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION)?.toIntOrNull()?.coerceAtLeast(0) ?: 0
+        val raw = if (Build.VERSION.SDK_INT >= 27) current.getScaledFrameAtTime(1_000_000,
+            MediaMetadataRetriever.OPTION_CLOSEST_SYNC, 640, 640) else current.getFrameAtTime(1_000_000)
+        val image = if (raw != null && maxOf(raw.width, raw.height) > 640) {
+            val scale = 640.0 / maxOf(raw.width, raw.height)
+            Bitmap.createScaledBitmap(raw, (raw.width * scale).toInt().coerceAtLeast(1),
+                (raw.height * scale).toInt().coerceAtLeast(1), true).also { if (it !== raw) raw.recycle() }
+        } else raw
+        if (image == null) LogManager.addLog("WARN", "VideoPlayer", "Video preview has no frame owner=${System.identityHashCode(this)}")
+        return VideoFilePreview(image, duration)
+    }
     @Synchronized override fun close() {
         closing = true
         val current = retriever ?: return

tools/chatgui-android/video-tests/src/main/kotlin/android/graphics/Bitmap.kt

@@ -0,0 +1,10 @@
+package android.graphics
+
+/** Только размеры и владение промежуточным кадром, без пикселей/драйвера. */
+class Bitmap(val width: Int, val height: Int) {
+    var recycled = false
+    fun recycle() { recycled = true }
+    companion object {
+        fun createScaledBitmap(source: Bitmap, width: Int, height: Int, filter: Boolean) = Bitmap(width, height)
+    }
+}

tools/chatgui-android/video-tests/src/main/kotlin/android/media/HostFileVideo.kt

@@ -48,6 +48,7 @@ class MediaPlayer {
 class MediaMetadataRetriever {
     companion object {
         const val METADATA_KEY_VIDEO_WIDTH = 18; const val METADATA_KEY_VIDEO_HEIGHT = 19; const val METADATA_KEY_VIDEO_ROTATION = 24
+        const val METADATA_KEY_DURATION = 9; const val OPTION_CLOSEST_SYNC = 2
         val created = mutableListOf<MediaMetadataRetriever>()
         var nextFailures = emptySet<String>()
     }
@@ -55,10 +56,22 @@ class MediaMetadataRetriever {
     var released = false
     var releases = 0
     var width = "1280"; var height = "720"; var rotation = "90"
+    var lastFrame: android.graphics.Bitmap? = null
+    var scaledReads = 0
     init { created.add(this) }
     fun setDataSource(path: String) { check("source" !in failures) { "Metadata source failed" } }
     fun extractMetadata(key: Int): String? = when (key) {
-        METADATA_KEY_VIDEO_WIDTH -> width; METADATA_KEY_VIDEO_HEIGHT -> height; METADATA_KEY_VIDEO_ROTATION -> rotation; else -> null
+        METADATA_KEY_VIDEO_WIDTH -> width; METADATA_KEY_VIDEO_HEIGHT -> height; METADATA_KEY_VIDEO_ROTATION -> rotation
+        METADATA_KEY_DURATION -> "10000"; else -> null
+    }
+    fun getFrameAtTime(time: Long): android.graphics.Bitmap? {
+        check("frame" !in failures)
+        return android.graphics.Bitmap(width.toInt(), height.toInt()).also { lastFrame = it }
+    }
+    fun getScaledFrameAtTime(time: Long, option: Int, maxWidth: Int, maxHeight: Int): android.graphics.Bitmap? {
+        scaledReads++; check("frame" !in failures)
+        val scale = minOf(maxWidth.toDouble() / width.toInt(), maxHeight.toDouble() / height.toInt(), 1.0)
+        return android.graphics.Bitmap((width.toInt() * scale).toInt(), (height.toInt() * scale).toInt()).also { lastFrame = it }
     }
     fun release() {
         releases++; check("release" !in failures) { "Metadata release failed" }; released = true