hmicontroller: Pass INVALID_ID to auto-generate layer ID

A layer ID of zero is not correct.  I am guessing that the previous
intention was to use zero to generate an automatic ID, and the ILM
documentation incorrectly said that it would (upstream bug [LM-6]).
INVALID_ID should be passed instead, to get a generated ID.

The parameter to helper function createLayer() must now be passed by
reference so that the member variable m_backgroundSurfaceId can be
assigned the right value. The layer ID used to be constant (zero) and
therefore this was not the case before.

[GDP-778] wayland-ivi-extension layer id integration issues from P-0.1
          and P-1.0 upgrade

[LM-6] Documentation for ilm_layerCreateWithDimension() is wrong
       regarding creating new ID automatically?

Signed-off-by: Gunnar Andersson <gandersson@genivi.org>

plugins/hmi-controller/hmicontroller.cpp

@@ -1,4 +1,5 @@
 #include "hmicontroller.h"
+#include <ilm/ilm_types.h>
 
 #include <QProcess>
 
@@ -15,7 +16,8 @@ HMIController::HMIController(QObject *parent) :
     m_lucFile("lastUserContext")
 {
     m_layerController.setLauncherPid(getpid());
-    m_layerController.setBackgroundSurfaceId(0); //TODO test more
+    // NOTE: INVALID_ID will be changed by ILM to a auto-generated ID
+    m_layerController.setBackgroundSurfaceId(INVALID_ID);
 
     connect(&m_layerController, &LayerController::currentAppIDChanged,
             this, &HMIController::appIsDisplayedChanged);

plugins/hmi-controller/layercontroller.cpp

@@ -74,7 +74,12 @@ LayerController::LayerController(AppManager &appManager) :
     m_appWidth(0),
     m_appHeight(0),
     m_launcherPid(0),
-    m_backgroundSurfaceId(0),
+    // INVALID_ID can be passed to automatically generate layer ID, but
+    // this member is also redefined by the main program through a call to
+    // setBackgroundSurfaceId().  This might still need some cleanup. 
+    // Since any other number is valid, it should likely be initialized to
+    // INVALID_ID regardless.
+    m_backgroundSurfaceId(INVALID_ID),
     m_currentLayer(0),
     m_launcherOnTop(true)
 {
@@ -359,7 +364,7 @@ void LayerController::setLayerVisible(unsigned int layerId)
     ilm_commitChanges();
 }
 
-bool LayerController::createLayer(unsigned int layerId)
+bool LayerController::createLayer(unsigned int &layerId)
 {
     ilmErrorTypes callResult = ILM_FAILED;
     callResult = ilm_layerCreateWithDimension(&layerId, m_screenWidth, m_screenHeight);
@@ -615,7 +620,18 @@ void LayerController::addAppProcess(const AppManager::AppInfo app, const pid_t p
     pinfo.surfaceList = {};
 
     // Create layer for new app
-    createLayer(pid);
+
+    // We need a new variable because gcc is picky with having a true lvalue
+    // for the non-const pass by reference, and not pid which is an rvalue.
+    // (createLayer will modify the input variable to the layer ID that was
+    // actually chosen.  In this case it should be always what we asked
+    // for, but it can be dynamic in other cases)
+    unsigned int layerId = pid;
+    createLayer(layerId /*by reference*/);
+
+    // FIXME: This could use an assert(layerId == pid) and also error 
+    // checking (createLayer should return true).
+    // but this is a quick fix - changing as little as possible.
 
     m_processMap[pid]= pinfo;
 }

plugins/hmi-controller/layercontroller.h

@@ -60,7 +60,7 @@ class LayerController : public QObject
     void setSurfaceVisible(unsigned int surfaceId);
     void setLayerVisible(unsigned int layerId);
 
-    bool createLayer(unsigned int layerId);
+    bool createLayer(unsigned int &layerId);
     bool destroyLayer(unsigned int layerId);
     void focusOnLayer(unsigned int layerId);