implement new API: ServerGetCurrentCompositor

include/minigui.h

@@ -1851,7 +1851,7 @@ MG_EXPORT BOOL GUIAPI ServerUnregisterCompositor (const char* name);
  * \brief Select a compositor as the current compositor.
  *
  * This function selects a compositor as the current compositor
- * and returns the compositor object.
+ * and returns the compositor operations.
  * It also destroies the old compositor object if there is old one.
  *
  * \param name The name of the compositor. If the argument is NULL,
@@ -1869,7 +1869,25 @@ MG_EXPORT BOOL GUIAPI ServerUnregisterCompositor (const char* name);
 MG_EXPORT const CompositorOps* GUIAPI ServerSelectCompositor (
             const char* name, CompositorCtxt** ctxt);
 
-#define COMPSOR_OPS_VERSION  1
+/**
+ * \brief Get the name and the context of the current compositor.
+ *
+ * This function gets the name and the context of the current
+ * compositor.
+ *
+ * \param ops The buffer used to return the compositor operations.
+ * \param ctxt The buffer used to return the compositor context.
+ *
+ * \return The name of the current compositor; NULL for error.
+ *
+ * \note Only called by the server.
+ *
+ * Since 5.0.6.
+ */
+MG_EXPORT const char* GUIAPI ServerGetCurrentCompositor (
+        const CompositorOps** ops, CompositorCtxt** ctxt);
+
+#define COMPSOR_OPS_VERSION  2
 
 /**
   * Implement this stub to return the compositor operations

src/kernel/compsor-manager.c

@@ -15,7 +15,7 @@
  *   and Graphics User Interface (GUI) support system for embedded systems
  *   and smart IoT devices.
  *
- *   Copyright (C) 2002~2020, Beijing FMSoft Technologies Co., Ltd.
+ *   Copyright (C) 2002~2021, Beijing FMSoft Technologies Co., Ltd.
  *   Copyright (C) 1998~2002, WEI Yongming
  *
  *   This program is free software: you can redistribute it and/or modify
@@ -489,7 +489,7 @@ const CompositorOps* GUIAPI ServerGetCompositorOps (const char* name)
         return NULL;
 
     for (i = 0; i < MAX_NR_COMPOSITORS; i++) {
-        if (strcmp (compositors [i].name, name) == 0) {
+        if (compositors [i].name && strcmp (compositors [i].name, name) == 0) {
             return compositors [i].ops;
         }
     }
@@ -583,5 +583,24 @@ const CompositorOps* GUIAPI ServerSelectCompositor (const char* name,
     return NULL;
 }
 
+const char* GUIAPI ServerGetCurrentCompositor (
+        const CompositorOps** ops, CompositorCtxt** ctxt)
+{
+    int i;
+    const CompositorOps* the_ops;
+
+    the_ops = ServerSelectCompositor (NULL, ctxt);
+    if (ops) {
+        *ops = the_ops;
+    }
+
+    for (i = 0; i < MAX_NR_COMPOSITORS; i++) {
+        if (compositors [i].ops == the_ops)
+            return compositors [i].name;
+    }
+
+    return NULL;
+}
+
 #endif /* defined(_MGRM_PROCESSES) && defined(_MGSCHEMA_COMPOSITING) */