Refine snapshot invalidation and modal resize behavior

Control.cpp

@@ -58,7 +58,7 @@ void Control::setIsVisible(bool show)
 	if (!show)
 	{
 		// 隐藏：擦除自己在屏幕上的内容，并释放快照
-		this->updateBackground();
+		discardBackground();
 		return;
 	}
 
@@ -74,7 +74,7 @@ void Control::onWindowResize()
 		<< SX_T(" -> 丢背景快照 + 标脏", " -> discardSnap + dirty");
 
 	// 自己：丢快照 + 标脏
-	discardBackground();
+	invalidateBackgroundSnapshot();
 	setDirty(true);
 }
 void Control::setLayoutMode(StellarX::LayoutMode layoutMode_)
@@ -200,8 +200,16 @@ void Control::discardBackground()
 	hasSnap = false; saveWidth = saveHeight = 0;
 }
 
-void Control::updateBackground()
+void Control::invalidateBackgroundSnapshot()
 {
-	restBackground();
-	discardBackground();
+	if (saveBkImage)
+	{
+		SX_LOGD("Snap") << SX_T("作废背景快照：id=", "invalidateBackgroundSnapshot: id=") << id
+			<< " hasSnap=" << (hasSnap ? 1 : 0);
+		saveBkImage.reset();
+	}
+	hasSnap = false;
+	saveBkX = saveBkY = 0;
+	saveWidth = saveHeight = 0;
 }
+