First draft of an automatic discoverer for gst device source caps

(framerate, resolution and image format) to enable auto creation of
DeviceSource.

DeviceSource.h

@@ -2,6 +2,7 @@
 #define DEVICESOURCE_H
 
 #include <vector>
+#include <set>
 
 #include "GstToolkit.h"
 #include "StreamSource.h"
@@ -23,9 +24,9 @@ public:
 
     int numDevices () const;
     std::string name (int index) const;
-    bool exists (const std::string &device) const;
-
     std::string pipeline (int index) const;
+
+    bool exists (const std::string &device) const;
     std::string pipeline (const std::string &device) const;
 
     static gboolean callback_device_monitor (GstBus *, GstMessage *, gpointer);
@@ -39,6 +40,49 @@ private:
 };
 
 
+struct DeviceInfo {
+    gint width;
+    gint height;
+    gint fps_numerator;
+    gint fps_denominator;
+    std::string format;
+
+    DeviceInfo() {
+        width = 0;
+        height = 0;
+        fps_numerator = 1;
+        fps_denominator = 1;
+        format = "";
+    }
+
+    inline DeviceInfo& operator = (const DeviceInfo& b)
+    {
+        if (this != &b) {
+            this->width = b.width;
+            this->height = b.height;
+            this->fps_numerator = b.fps_numerator;
+            this->fps_denominator = b.fps_denominator;
+            this->format = b.format;
+        }
+        return *this;
+    }
+
+    inline bool operator < (const DeviceInfo b) const
+    {
+        return ( this->fps_numerator * this->height < b.fps_numerator * b.height );
+    }
+};
+
+struct better_device_comparator
+{
+    inline bool operator () (const DeviceInfo a, const DeviceInfo b) const
+    {
+        return (a < b);
+    }
+};
+
+typedef std::set<DeviceInfo, better_device_comparator> DeviceInfoSet;
+
 class DeviceSource : public StreamSource
 {
 public:
@@ -58,6 +102,8 @@ public:
 private:
     std::string device_;
 
+    DeviceInfoSet getDeviceConfigs(const std::string &pipeline);
+
 };
 
 #endif // DEVICESOURCE_H