Fix miscellaneous issues and warnings (#652)

- Binding loop warning in WorldStats
- ImageDisplay warning stating that the image source is invalid
  - This happened because the provider is being initialized in
    LoadConfig which runs after the QML has been loaded. The solution
    was to move it to the constructor. However, it depends on a unique
    name obtained from the QML, which causes a chicken and egg problem.
    To fix this, the QML now calls a member function of ImageDisplay to register the image provider with a unique name.


---------

Signed-off-by: Addisu Z. Taddese <[email protected]>

src/plugins/image_display/ImageDisplay.cc

@@ -51,19 +51,33 @@ class ImageDisplay::Implementation
 
   /// \brief To provide images for QML.
   public: ImageProvider *provider{nullptr};
+
+  /// \brief Holds the provider name unique to this plugin instance
+  public: QString providerName;
 };
 
 /////////////////////////////////////////////////
 ImageDisplay::ImageDisplay()
   : dataPtr(gz::utils::MakeUniqueImpl<Implementation>())
 {
+  this->dataPtr->provider = new ImageProvider();
 }
 
 /////////////////////////////////////////////////
 ImageDisplay::~ImageDisplay()
 {
-  App()->Engine()->removeImageProvider(
-      this->CardItem()->objectName() + "imagedisplay");
+  App()->Engine()->removeImageProvider(this->ImageProviderName());
+}
+
+void ImageDisplay::RegisterImageProvider(const QString &_uniqueName)
+{
+  this->dataPtr->providerName = _uniqueName;
+  App()->Engine()->addImageProvider(_uniqueName,
+                                    this->dataPtr->provider);
+}
+
+QString ImageDisplay::ImageProviderName() {
+  return this->dataPtr->providerName;
 }
 
 /////////////////////////////////////////////////
@@ -95,13 +109,11 @@ void ImageDisplay::LoadConfig(const tinyxml2::XMLElement *_pluginElem)
   this->PluginItem()->setProperty("showPicker", topicPicker);
 
   if (!topic.empty())
-    this->OnTopic(QString::fromStdString(topic));
+  {
+    this->SetTopicList({QString::fromStdString(topic)});
+  }
   else
     this->OnRefresh();
-
-  this->dataPtr->provider = new ImageProvider();
-  App()->Engine()->addImageProvider(
-      this->CardItem()->objectName() + "imagedisplay", this->dataPtr->provider);
 }
 
 /////////////////////////////////////////////////

src/plugins/image_display/ImageDisplay.hh

@@ -18,8 +18,9 @@
 #ifndef GZ_GUI_PLUGINS_IMAGEDISPLAY_HH_
 #define GZ_GUI_PLUGINS_IMAGEDISPLAY_HH_
 
-#include <algorithm>
-#include <memory>
+#include <QImage>
+#include <QString>
+#include <QStringList>
 #include <QQuickImageProvider>
 
 #include <gz/msgs/image.pb.h>
@@ -53,8 +54,7 @@ namespace gz::gui::plugins
       if (!this->img.isNull())
       {
         // Must return a copy
-        QImage copy(this->img);
-        return copy;
+        return this->img;
       }
 
       // Placeholder in case we have no image yet
@@ -115,6 +115,13 @@ namespace gz::gui::plugins
     /// \param[in] _topicList Message type
     public: Q_INVOKABLE void SetTopicList(const QStringList &_topicList);
 
+    /// \brief Register the image provider with the given name
+    /// \param[in] _uniqueName Unique name for the provider to be registered
+    public: Q_INVOKABLE void RegisterImageProvider(const QString &_uniqueName);
+
+    /// \brief Get the provider name unique to this plugin instance
+    public: Q_INVOKABLE QString ImageProviderName();
+
     /// \brief Notify that topic list has changed
     signals: void TopicListChanged();
 

src/plugins/image_display/ImageDisplay.qml

@@ -44,6 +44,7 @@ Rectangle {
       return;
 
     uniqueName = parent.card().objectName + "imagedisplay";
+    ImageDisplay.RegisterImageProvider(uniqueName);
     image.reload();
   }
 

src/plugins/world_stats/WorldStats.qml

@@ -93,7 +93,7 @@ Rectangle {
         }
         PropertyChanges {
           target: hideButton
-          x: worldStats.width - hideToolButton.width - compactLabel.width - 10
+          x: worldStats.width - hideToolButton.width - compactLabel.implicitWidth - 10
         }
         PropertyChanges {
           target: compactLabel