gistfile1.cpp

#include <gphoto2/gphoto2.h>
#include <iostream>
#include <string.h>
#include <unistd.h>

class CanonTrigger
{
private:
	Camera* m_camera;
	GPContext* m_context;

public:
	CanonTrigger()
	{
		gp_camera_new(&m_camera);
		m_context = createContext();
	}

	~CanonTrigger()
	{
		gp_camera_exit(m_camera, m_context);
		gp_camera_unref(m_camera);
		gp_context_unref(m_context);
	}

	GPContext* createContext()
	{
		GPContext* context;

		// TODO: see context.c for optional parts (LOGGING)
		context = gp_context_new();
		return context;
	}

	// TODO: puts the camera in a busy state (it is not possible to change the oesviewfinder config after this)
	// NOTE: gphoto2 has the same problem (with --set-config autofocusdrive=1)
	/**
	 * \brief Runs autofocus.
	 *
	 * NOTE:  * Only works while in preview mode.
	 * 	  * Breaks the eosviewfinder anyway...
	 */
	bool autofocus()
	{
		// TODO: return false if not in preview mode?
		// => save the mode as a member

		return toggleConfig("autofocusdrive", "1");
	}

	bool setPreviewMode(bool enabled)
	{
		if (enabled)
		{
			return toggleConfig("eosviewfinder", "1");
		}
		else
		{
			return toggleConfig("eosviewfinder", "0");
		}
	}

	bool toggleConfig(const std::string key, const std::string value)
	{
		CameraWidget* widget = NULL;
		CameraWidget* child = NULL;
		CameraWidgetType type;
		int ret;
		int val;

		// "Retrieve a configuration window for the camera" (from API documentation)
		ret = gp_camera_get_config(m_camera, &widget, m_context);
		if (ret < GP_OK)
		{
			std::cout << " - camera_get_config failed (returned " << ret << ")." << std::endl;
			return false;
		}

		if (!lookupWidget(widget, key, &child))
		{
			std::cout << " - could not retrieve widget \"" << key << "\"." << std::endl;
			return false;
		}

		// Check that this is a toggle
		ret = gp_widget_get_type(child, &type);
		if (ret < GP_OK)
		{
			std::cout << " - gp_widget_get_type failed (returned " << ret << ")." << std::endl;
			gp_widget_free(widget);
			return false;
		}

		switch (type)
		{
			case GP_WIDGET_TOGGLE:
				break;
			default:
				std::cout << " - Widget has bad type: " << type << std::endl;
				gp_widget_free(widget);
				return false;
		}

		// Is this really useful?
		ret = gp_widget_get_value(child, &val);
		if (ret < GP_OK)
		{
			std::cout << " - Could not get widget value." << std::endl;
			gp_widget_free(widget);
			return false;
		}
		else
		{
			std::cout << " - key \"" << key << "\" has value \"" << val << "\"" << std::endl;
		}

		std::cout << " - set value of " << key << " to " << value << std::endl;
		ret = gp_widget_set_value(child, value.c_str());
		if (ret < GP_OK)
		{
			std::cout << " Could not set widget value to " << value << "..." << std::endl;
			gp_widget_free(widget);
			return false;
		}

		ret = gp_camera_set_config(m_camera, widget, m_context);
		if (ret < GP_OK)
		{
			std::cout << " - Could not set config tree to autofocus." << std::endl;
			gp_widget_free(widget);
			return false;
		}

		gp_widget_free(widget);
		return true;
	}

	static bool lookupWidget(CameraWidget* widget, const std::string key, CameraWidget** child)
	{
		int ret;
		if (gp_widget_get_child_by_name(widget, key.c_str(), child) < GP_OK
			&& gp_widget_get_child_by_label(widget, key.c_str(), child) < GP_OK)
		{
			return false;
		}
		return true;
	}
};

int main()
{
	CanonTrigger canon_trigger;
	canon_trigger.setPreviewMode(true);
	sleep(2);
	canon_trigger.setPreviewMode(false);

        return 0;
}