qcam: Add Qt-based GUI application

qcam is a sample camera GUI application based on Qt. It demonstrates
integration of the Qt event loop with libcamera.

The application lets the user select a camera through the GUI, and then
captures a single stream from the camera and displays it in a window.
Only streams in YUYV formats are supported for now.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 104 insertions, 0 deletions

diff --git a/src/qcam/format_converter.cpp b/src/qcam/format_converter.cpp
new file mode 100644
index 00000000..6979a054
--- /dev/null
+++ b/src/qcam/format_converter.cpp
@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * format_convert.cpp - qcam - Convert buffer to RGB
+ */
+
+#include <errno.h>
+
+#include <linux/videodev2.h>
+
+#include "format_converter.h"
+
+#define RGBSHIFT		8
+#ifndef MAX
+#define MAX(a,b)		((a)>(b)?(a):(b))
+#endif
+#ifndef MIN
+#define MIN(a,b)		((a)<(b)?(a):(b))
+#endif
+#ifndef CLAMP
+#define CLAMP(a,low,high)	MAX((low),MIN((high),(a)))
+#endif
+#ifndef CLIP
+#define CLIP(x)			CLAMP(x,0,255)
+#endif
+
+int FormatConverter::configure(unsigned int format, unsigned int width,
+			       unsigned int height)
+{
+	switch (format) {
+	case V4L2_PIX_FMT_VYUY:
+		y_pos_ = 1;
+		cb_pos_ = 2;
+		break;
+	case V4L2_PIX_FMT_YVYU:
+		y_pos_ = 0;
+		cb_pos_ = 3;
+		break;
+	case V4L2_PIX_FMT_UYVY:
+		y_pos_ = 1;
+		cb_pos_ = 0;
+		break;
+	case V4L2_PIX_FMT_YUYV:
+		y_pos_ = 0;
+		cb_pos_ = 1;
+		break;
+	default:
+		return -EINVAL;
+	};
+
+	width_ = width;
+	height_ = height;
+
+	return 0;
+}
+
+static void yuv_to_rgb(int y, int u, int v, int *r, int *g, int *b)
+{
+	int c = y - 16;
+	int d = u - 128;
+	int e = v - 128;
+	*r = CLIP(( 298 * c           + 409 * e + 128) >> RGBSHIFT);
+	*g = CLIP(( 298 * c - 100 * d - 208 * e + 128) >> RGBSHIFT);
+	*b = CLIP(( 298 * c + 516 * d           + 128) >> RGBSHIFT);
+}
+
+void FormatConverter::convert(const unsigned char *src, unsigned char *dst)
+{
+	unsigned int src_x, src_y, dst_x, dst_y;
+	unsigned int src_stride;
+	unsigned int dst_stride;
+	unsigned int cr_pos;
+	int r, g, b, y, cr, cb;
+
+	cr_pos = (cb_pos_ + 2) % 4;
+	src_stride = width_ * 2;
+	dst_stride = width_ * 4;
+
+	for (src_y = 0, dst_y = 0; dst_y < height_; src_y++, dst_y++) {
+		for (src_x = 0, dst_x = 0; dst_x < width_; ) {
+			cb = src[src_y * src_stride + src_x * 4 + cb_pos_];
+			cr = src[src_y * src_stride + src_x * 4 + cr_pos];
+
+			y = src[src_y * src_stride + src_x * 4 + y_pos_];
+			yuv_to_rgb(y, cb, cr, &r, &g, &b);
+			dst[dst_y * dst_stride + 4 * dst_x + 0] = b;
+			dst[dst_y * dst_stride + 4 * dst_x + 1] = g;
+			dst[dst_y * dst_stride + 4 * dst_x + 2] = r;
+			dst[dst_y * dst_stride + 4 * dst_x + 3] = 0xff;
+			dst_x++;
+
+			y = src[src_y * src_stride + src_x * 4 + y_pos_ + 2];
+			yuv_to_rgb(y, cb, cr, &r, &g, &b);
+			dst[dst_y * dst_stride + 4 * dst_x + 0] = b;
+			dst[dst_y * dst_stride + 4 * dst_x + 1] = g;
+			dst[dst_y * dst_stride + 4 * dst_x + 2] = r;
+			dst[dst_y * dst_stride + 4 * dst_x + 3] = 0xff;
+			dst_x++;
+
+			src_x++;
+		}
+	}
+}