🎨 Palette: 平滑的配对按钮过渡和对比度修复

.Jules/palette.md

@@ -6,3 +6,6 @@
 ## 2024-05-XX - Smooth transitions for state swaps
 **Learning:** Abrupt state swaps in status cards (like VPN or MQTT connection status) can feel jarring. Applying `animateColorAsState` for background colors and `AnimatedContent` for icons/text creates a much smoother, polished micro-interaction. Computing derived state inside the animation lambda is critical so fade-outs display correctly.
 **Action:** Use `animateColorAsState` and `AnimatedContent` for status cards, ensuring target states compute their own icons/text within the lambda.
+## 2024-08-01 - Disabled Button Contrast & Smooth Transition in Compose
+**Learning:** When a Compose button is disabled (e.g. during an async operation), hardcoded text/icon colors like `MaterialTheme.colorScheme.onPrimary` do not automatically dim, resulting in poor contrast and a confusing disabled state. Furthermore, abruptly swapping out button content for a loading spinner can feel jarring.
+**Action:** Use `LocalContentColor.current` for internal elements like `CircularProgressIndicator` so they naturally inherit the button's disabled color styling. Wrap the content in `AnimatedContent` to provide a smooth, delightful transition between default and loading states.

android/app/src/main/java/com/netproxy/gateway/ui/screens/MainScreen.kt

@@ -605,16 +605,26 @@ fun PairingSection(
                 modifier = Modifier.fillMaxWidth(),
                 enabled = pairingCode.length >= 6 && !uiState.isPairingInProgress
             ) {
-                if (uiState.isPairingInProgress) {
-                    CircularProgressIndicator(
-                        modifier = Modifier.size(20.dp),
-                        color = MaterialTheme.colorScheme.onPrimary,
-                        strokeWidth = 2.dp
-                    )
-                    Spacer(modifier = Modifier.width(8.dp))
-                    Text(stringResource(R.string.pairing_in_progress))
-                } else {
-                    Text(stringResource(R.string.pair))
+                AnimatedContent(
+                    targetState = uiState.isPairingInProgress,
+                    label = "PairingButtonAnimated"
+                ) { inProgress ->
+                    if (inProgress) {
+                        Row(
+                            verticalAlignment = Alignment.CenterVertically,
+                            horizontalArrangement = Arrangement.Center
+                        ) {
+                            CircularProgressIndicator(
+                                modifier = Modifier.size(20.dp),
+                                color = LocalContentColor.current,
+                                strokeWidth = 2.dp
+                            )
+                            Spacer(modifier = Modifier.width(8.dp))
+                            Text(stringResource(R.string.pairing_in_progress))
+                        }
+                    } else {
+                        Text(stringResource(R.string.pair))
+                    }
                 }
             }