libcamera: v4l2_subdevice: Implement ENUM_FRAME_SIZES

Implement format and size enumeration methods to list all the available
subdevice image resolutions and formats.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/include/geometry.h

@@ -17,6 +17,18 @@ struct Rectangle {
 	unsigned int h;
 };
 
+struct SizeRange {
+	SizeRange(unsigned int minW, unsigned int minH,
+		  unsigned int maxW, unsigned int maxH)
+		: minWidth(minW), minHeight(minH), maxWidth(maxW),
+		  maxHeight(maxH) {}
+
+	unsigned int minWidth;
+	unsigned int minHeight;
+	unsigned int maxWidth;
+	unsigned int maxHeight;
+};
+
 } /* namespace libcamera */
 
 #endif /* __LIBCAMERA_GEOMETRY_H__ */

src/libcamera/include/v4l2_subdevice.h

@@ -7,15 +7,16 @@
 #ifndef __LIBCAMERA_V4L2_SUBDEVICE_H__
 #define __LIBCAMERA_V4L2_SUBDEVICE_H__
 
+#include <map>
 #include <string>
+#include <vector>
 
+#include "geometry.h"
 #include "log.h"
 #include "media_object.h"
 
 namespace libcamera {
 
-struct Rectangle;
-
 struct V4L2SubdeviceFormat {
 	uint32_t mbus_code;
 	uint32_t width;
@@ -39,6 +40,9 @@ public:
 	int setCrop(unsigned int pad, Rectangle *rect);
 	int setCompose(unsigned int pad, Rectangle *rect);
 
+	const std::map<unsigned int, std::vector<SizeRange>>
+						formats(unsigned int pad);
+
 	int getFormat(unsigned int pad, V4L2SubdeviceFormat *format);
 	int setFormat(unsigned int pad, V4L2SubdeviceFormat *format);
 
@@ -46,6 +50,9 @@ protected:
 	std::string logPrefix() const;
 
 private:
+	int enumPadSizes(unsigned int pad, unsigned int code,
+			 std::vector<SizeRange> *size);
+
 	int setSelection(unsigned int pad, unsigned int target,
 			 Rectangle *rect);