slideshow-source: add slideshow source class

The slideshow_source class is an implementation of the video_source
class that streams a set of images as video.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>

3 files changed, 412 insertions, 0 deletions

diff --git a/include/uvcgadget/slideshow-source.h b/include/uvcgadget/slideshow-source.h
new file mode 100644
index 0000000..9b1d9f9
--- /dev/null
+++ b/include/uvcgadget/slideshow-source.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Slideshow video source
+ *
+ * Copyright (C) 2018 Paul Elder
+ *
+ * Contact: Paul Elder <paul.elder@ideasonboard.com>
+ */
+#ifndef __SLIDESHOW_VIDEO_SOURCE_H__
+#define __SLIDESHOW_VIDEO_SOURCE_H__
+
+#include "video-source.h"
+
+struct events;
+struct video_source;
+
+struct video_source *slideshow_video_source_create(const char *img_dir);
+void slideshow_video_source_init(struct video_source *src, struct events *events);
+
+#endif /* __SLIDESHOW_VIDEO_SOURCE_H__ */
diff --git a/lib/meson.build b/lib/meson.build
index a0d67d5..680be1c 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -4,6 +4,7 @@ libuvcgadget_sources = files([
   'configfs.c',
   'events.c',
   'jpg-source.c',
+  'slideshow-source.c',
   'stream.c',
   'test-source.c',
   'timer.c',
diff --git a/lib/slideshow-source.c b/lib/slideshow-source.c
new file mode 100644
index 0000000..42a42a9
--- /dev/null
+++ b/lib/slideshow-source.c
@@ -0,0 +1,391 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Slideshow video source
+ *
+ * Copyright (C) 2018 Paul Elder
+ *
+ * Contact: Paul Elder <paul.elder@ideasonboard.com>
+ */
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <linux/limits.h>
+#include <linux/videodev2.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "events.h"
+#include "list.h"
+#include "slideshow-source.h"
+#include "timer.h"
+#include "tools.h"
+#include "video-buffers.h"
+
+struct slide {
+	struct list_entry list;
+	unsigned int imgsize;
+	void *imgdata;
+};
+
+struct slideshow_source {
+	struct video_source src;
+
+	char img_dir[NAME_MAX];
+
+	struct slide *cur_slide;
+	struct list_entry slides;
+
+	struct timer *timer;
+	bool streaming;
+};
+
+#define to_slideshow_source(s) container_of(s, struct slideshow_source, src)
+
+static void slideshow_source_destroy(struct video_source *s)
+{
+	struct slideshow_source *src = to_slideshow_source(s);
+	struct slide *slide, *next;
+
+	list_for_each_entry_safe(slide, next, &src->slides, list) {
+		list_remove(&slide->list);
+		free(slide->imgdata);
+		free(slide);
+	}
+	timer_destroy(src->timer);
+	free(src);
+}
+
+char *v4l2_fourcc2s(__u32 fourcc, char *buf)
+{
+	buf[0] = fourcc & 0x7f;
+	buf[1] = (fourcc >> 8) & 0x7f;
+	buf[2] = (fourcc >> 16) & 0x7f;
+	buf[3] = (fourcc >> 24) & 0x7f;
+	if (fourcc & (1 << 31)) {
+		buf[4] = '-';
+		buf[5] = 'B';
+		buf[6] = 'E';
+		buf[7] = '\0';
+	} else {
+		buf[4] = '\0';
+	}
+	return buf;
+}
+
+/*
+ * slideshow_source_set_format - set the V4L2 format
+ *
+ * For this source, we require images stored in a directory structure with nodes
+ * for each format and framesize, for example:
+ *
+ * slideshow +
+ *	     |
+ *	     + MJPG +
+ *	     |      |
+ *	     |      + 1280x720  +
+ *	     |      |           |
+ *	     |      |           + 01.jpg
+ *	     |      |           |
+ *	     |      |           + 02.jpg
+ *	     |      |           |
+ *	     |      |           + 03.jpg
+ *	     |      |
+ *	     |      + 1920x1080
+ *	     |
+ *	     + YUYV +
+ *		    |
+ *		    + 1280x720
+ *		    |
+ *		    + 1920x1080
+ *
+ * The root directory will be passed as an argument to slideshow_source_create()
+ * and so is not fixed, but the second level directories must be named with the
+ * fourcc of the format the images within represent, and the third level's node
+ * names must be in the format "<width>x<height>".
+ */
+static int slideshow_source_set_format(struct video_source *s,
+				       struct v4l2_pix_format *fmt)
+{
+	struct slideshow_source *src = to_slideshow_source(s);
+	char dirname[PATH_MAX];
+	struct slide *slide, *next;
+	struct dirent *file;
+	char fourcc_buf[8];
+	int fd = -1;
+	char *cwd;
+	DIR *dir;
+	int ret;
+
+	/*
+	 * If the format is changed, we need to clear the existing list of
+	 * slides before adding new ones.
+	 */
+	list_for_each_entry_safe(slide, next, &src->slides, list) {
+		list_remove(&slide->list);
+		free(slide->imgdata);
+		free(slide);
+	}
+
+	ret = snprintf(dirname, sizeof(dirname), "%s/%s/%ux%u", src->img_dir,
+		       v4l2_fourcc2s(fmt->pixelformat, fourcc_buf),
+		       fmt->width, fmt->height);
+	if (ret < 0) {
+		fprintf(stderr, "failed to store directory name: %s (%d)\n",
+			strerror(ret), ret);
+		ret = errno;
+		goto err_dummy_slide;
+	}
+
+	dir = opendir(dirname);
+	if (!dir) {
+		fprintf(stderr, "unable to find directory %s\n", dirname);
+		ret = -ENOENT;
+		goto err_dummy_slide;
+	}
+
+	cwd = getcwd(NULL, 0);
+	if (!cwd) {
+		fprintf(stderr, "unable to allocate memory for cwd name\n");
+		ret = -ENOMEM;
+		goto err_dummy_slide;
+	}
+
+	ret = chdir(dirname);
+	if (ret) {
+		fprintf(stderr, "unable to cd to directory '%s': %s (%d)\n",
+			dirname, strerror(ret), ret);
+		goto err_close_dir;
+	}
+
+	while ((file = readdir(dir))) {
+		if (!strcmp(file->d_name, ".") ||
+		    !strcmp(file->d_name, ".."))
+			continue;
+
+		fd = open(file->d_name, O_RDONLY);
+		if (fd == -1) {
+			fprintf(stderr, "Unable to open file '%s/%s'\n", dirname,
+				file->d_name);
+			ret = errno;
+			goto err_unwind;
+		}
+
+		slide = malloc(sizeof(*slide));
+		if (!slide) {
+			fprintf(stderr, "failed to allocate memory for slide\n");
+			ret = -ENOMEM;
+			goto err_close_fd;
+		}
+
+		slide->imgsize = lseek(fd, 0, SEEK_END);
+		lseek(fd, 0, SEEK_SET);
+
+		slide->imgdata = malloc(slide->imgsize);
+		if (!slide->imgdata) {
+			fprintf(stderr, "failed to allocate memory for image\n");
+			ret = -ENOMEM;
+			goto err_free_slide;
+		}
+
+		ret = read(fd, slide->imgdata, slide->imgsize);
+		if (ret < 0) {
+			fprintf(stderr, "failed to read from %s/%s: %u\n",
+				dirname, file->d_name, errno);
+			ret = errno;
+			goto err_free_imgdata;
+		}
+
+		list_append(&slide->list, &src->slides);
+		close(fd);
+	}
+
+	if (list_empty(&src->slides)) {
+		fprintf(stderr, "failed to find any images in %s\n", dirname);
+		ret = -ENOENT;
+		goto err_free_cwd;
+	}
+
+	ret = chdir(cwd);
+	if (ret) {
+		fprintf(stderr, "unable to cd to directory '%s': %s (%d)\n",
+			cwd, strerror(ret), ret);
+		goto err_free_cwd;
+	}
+
+	free(cwd);
+	closedir(dir);
+	src->cur_slide = list_first_entry(&src->slides, struct slide, list);
+
+	return 0;
+
+err_free_imgdata:
+	free(slide->imgdata);
+err_free_slide:
+	free(slide);
+err_close_fd:
+	close(fd);
+err_unwind:
+	list_for_each_entry_safe(slide, next, &src->slides, list) {
+		list_remove(&slide->list);
+		free(slide->imgdata);
+		free(slide);
+	}
+err_free_cwd:
+	chdir(cwd);
+	free(cwd);
+err_close_dir:
+	closedir(dir);
+err_dummy_slide:
+
+	/*
+	* At present, there is no means of stalling a USB SET_CUR control from
+	* the host; this means that the format passed here _must_ be accepted
+	* until this issue is resolved. To work around the issue for now simply
+	* use a single dummy slide... as long as we manage to allocate the
+	* memory for it at least.
+	*/
+
+	printf("using dummy slideshow data\n");
+
+	slide = malloc(sizeof(*slide));
+	if (!slide) {
+		fprintf(stderr, "failed to allocate memory for slide\n");
+		return ret;
+	}
+
+	slide->imgsize = fmt->width * fmt->height * 2;
+
+	slide->imgdata = malloc(slide->imgsize);
+	if (!slide->imgdata) {
+		fprintf(stderr, "failed to allocate memory for image\n");
+		free(slide);
+		return -ENOMEM;
+	}
+
+	memset(slide->imgdata, 0, slide->imgsize);
+	list_append(&slide->list, &src->slides);
+	src->cur_slide = slide;
+
+	return ret;
+}
+
+static int slideshow_source_set_frame_rate(struct video_source *s,
+					   unsigned int fps)
+{
+	struct slideshow_source *src = to_slideshow_source(s);
+
+	timer_set_fps(src->timer, fps);
+
+	return 0;
+}
+
+static int slideshow_source_free_buffers(struct video_source *s __attribute__((unused)))
+{
+	return 0;
+}
+
+static int slideshow_source_stream_on(struct video_source *s)
+{
+	struct slideshow_source *src = to_slideshow_source(s);
+	int ret;
+
+	ret = timer_arm(src->timer);
+	if (ret)
+		return ret;
+
+	src->streaming = true;
+	return 0;
+}
+
+static int slideshow_source_stream_off(struct video_source *s)
+{
+	struct slideshow_source *src = to_slideshow_source(s);
+
+	/*
+	 * No error check here, because we want to flag that streaming is over
+	 * even if the timer is still running due to the failure.
+	 */
+	timer_disarm(src->timer);
+	src->streaming = false;
+
+	return 0;
+}
+
+static void slideshow_source_fill_buffer(struct video_source *s,
+					 struct video_buffer *buf)
+{
+	struct slideshow_source *src = to_slideshow_source(s);
+
+	memcpy(buf->mem, src->cur_slide->imgdata, src->cur_slide->imgsize);
+	buf->bytesused = src->cur_slide->imgsize;
+
+	if (src->cur_slide == list_last_entry(&src->slides, struct slide, list))
+		src->cur_slide = list_first_entry(&src->slides, struct slide, list);
+	else
+		src->cur_slide = list_next_entry(&src->cur_slide->list, struct slide, list);
+
+	/*
+	 * Wait for the timer to elapse to ensure that our configured frame rate
+	 * is adhered to.
+	 */
+	if (src->streaming)
+		timer_wait(src->timer);
+}
+
+static const struct video_source_ops slideshow_source_ops = {
+	.destroy = slideshow_source_destroy,
+	.set_format = slideshow_source_set_format,
+	.set_frame_rate = slideshow_source_set_frame_rate,
+	.free_buffers = slideshow_source_free_buffers,
+	.stream_on = slideshow_source_stream_on,
+	.stream_off = slideshow_source_stream_off,
+	.queue_buffer = NULL,
+	.fill_buffer = slideshow_source_fill_buffer,
+};
+
+struct video_source *slideshow_video_source_create(const char *img_dir)
+{
+	struct slideshow_source *src;
+
+	if (img_dir == NULL)
+		return NULL;
+
+	if (strlen(img_dir) > 31)
+		return NULL;
+
+	src = malloc(sizeof *src);
+	if (!src)
+		return NULL;
+
+	memset(src, 0, sizeof *src);
+	src->src.ops = &slideshow_source_ops;
+
+	strncpy(src->img_dir, img_dir, sizeof(src->img_dir));
+
+	src->timer = timer_new();
+	if (!src->timer)
+		goto err_free_src;
+
+	list_init(&src->slides);
+
+	return &src->src;
+
+err_free_src:
+	free(src);
+	return NULL;
+}
+
+void slideshow_video_source_init(struct video_source *s, struct events *events)
+{
+	struct slideshow_source *src = to_slideshow_source(s);
+
+	src->src.events = events;
+}