android radio: add plus and minus to volume PTT icon

tools/chatgui-android/app/src/main/java/com/utun/chat/ui/screens/ChatScreen.kt

@@ -301,7 +301,8 @@ private fun RadioSourceBar(viewModel: ChatViewModel) {
                     }
                 }
                 VerticalDivider(modifier = Modifier.height(32.dp), color = Color(0xFF344550))
-                RadioControlButton(Icons.AutoMirrored.Filled.VolumeUp, stringResource(R.string.volume_ptt), volumePttEnabled) {
+                RadioControlButton(Icons.AutoMirrored.Filled.VolumeUp, stringResource(R.string.volume_ptt),
+                    volumePttEnabled, volumeKeys = true) {
                     viewModel.setRadioVolumePtt(!volumePttEnabled)
                 }
                 RadioControlButton(null, stringResource(if (vadEnabled) R.string.disable_vad else R.string.enable_vad),
@@ -326,7 +327,8 @@ private fun RadioSourceBar(viewModel: ChatViewModel) {
 @Composable
 private fun RadioControlButton(
     icon: ImageVector?, label: String, active: Boolean,
-    centerIcon: ImageVector? = null, bluetooth: Boolean = false, floating: Boolean = false, text: String? = null, onClick: () -> Unit
+    centerIcon: ImageVector? = null, bluetooth: Boolean = false, floating: Boolean = false,
+    volumeKeys: Boolean = false, text: String? = null, onClick: () -> Unit
 ) {
     IconToggleButton(
         checked = active,
@@ -344,6 +346,10 @@ private fun RadioControlButton(
             RadioFloatingIcon(label)
             return@IconToggleButton
         }
+        if (volumeKeys) {
+            RadioVolumeKeysIcon(label)
+            return@IconToggleButton
+        }
         val background = if (active) Color(0xFF1F6FEB) else Color(0xFF24323D)
         Box(modifier = Modifier.size(34.dp), contentAlignment = Alignment.Center) {
             Icon(requireNotNull(icon), contentDescription = label, modifier = Modifier.size(if (centerIcon != null) 32.dp else 28.dp))
@@ -362,6 +368,24 @@ private fun RadioControlButton(
     }
 }
 
+/* Динамик по центру, плюс сверху и минус снизу — аппаратные кнопки громкости. */
+@Composable
+private fun RadioVolumeKeysIcon(label: String) {
+    val color = LocalContentColor.current
+    Box(Modifier.size(34.dp).semantics { contentDescription = label }, contentAlignment = Alignment.Center) {
+        Icon(Icons.AutoMirrored.Filled.VolumeUp, contentDescription = null, modifier = Modifier.size(22.dp))
+        Canvas(Modifier.matchParentSize()) {
+            val half = 2.5.dp.toPx()
+            val top = 3.5.dp.toPx()
+            val bottom = size.height - top
+            val stroke = 1.7.dp.toPx()
+            drawLine(color, Offset(center.x - half, top), Offset(center.x + half, top), stroke, cap = StrokeCap.Round)
+            drawLine(color, Offset(center.x, top - half), Offset(center.x, top + half), stroke, cap = StrokeCap.Round)
+            drawLine(color, Offset(center.x - half, bottom), Offset(center.x + half, bottom), stroke, cap = StrokeCap.Round)
+        }
+    }
+}
+
 /* Кружок и четыре стрелки наружу — плавающая/перемещаемая PTT-кнопка. */
 @Composable
 private fun RadioFloatingIcon(label: String) {