implement osx grabber .... not tested! need testers!

tune usage hints in external grabbers


Former-commit-id: 816821dd773e90b8076e9b50ced9eb052f43c2f4

include/grabber/OsxFrameGrabber.h

@@ -0,0 +1,59 @@
+#pragma once
+
+// OSX includes
+#include <CoreGraphics/CoreGraphics.h>
+
+// Utils includes
+#include <utils/Image.h>
+#include <utils/ColorRgb.h>
+#include <utils/VideoMode.h>
+#include <utils/ImageResampler.h>
+
+///
+/// The OsxFrameGrabber is used for creating snapshots of the display (screenshots) 
+///
+class OsxFrameGrabber
+{
+public:
+	///
+	/// Construct a OsxFrameGrabber that will capture snapshots with specified dimensions.
+	///
+	/// @param[in] display The index of the display to capture
+	/// @param[in] width  The width of the captured screenshot
+	/// @param[in] height The heigth of the captured screenshot
+	///
+	OsxFrameGrabber(const unsigned display, const unsigned width, const unsigned height);
+	~OsxFrameGrabber();
+
+	///
+	/// Set the video mode (2D/3D)
+	/// @param[in] mode The new video mode
+	///
+	void setVideoMode(const VideoMode videoMode);
+
+	///
+	/// Captures a single snapshot of the display and writes the data to the given image. The
+	/// provided image should have the same dimensions as the configured values (_width and
+	/// _height)
+	///
+	/// @param[out] image  The snapped screenshot (should be initialized with correct width and
+	/// height)
+	///
+	void grabFrame(Image<ColorRgb> & image);
+
+private:	
+	/// display
+	const unsigned _screenIndex;
+	
+	/// With of the captured snapshot [pixels]
+	const unsigned _width;
+	
+	/// Height of the captured snapshot [pixels]
+	const unsigned _height;
+	
+	/// Reference to the captured diaplay
+	CGDirectDisplayID _display;
+	
+	/// Image resampler for downscaling the image
+	ImageResampler * _imgResampler;
+};