Expose grab-by-callback via camera and add asynchronous grabbing example

2 files changed, 192 insertions, 91 deletions

diff --git a/src/cameras/dummy.c b/src/cameras/dummy.c
index ba95a67..0177c6a 100644
--- a/src/cameras/dummy.c
+++ b/src/cameras/dummy.c
@@ -1,19 +1,144 @@
-
 #include <stdlib.h>
 #include <string.h>
+#define __USE_BSD
+#include <unistd.h>
+#undef __USE_BSD
+
+#include "config.h"
 #include "uca.h"
 #include "uca-cam.h"
 #include "uca-grabber.h"
 
+#ifdef HAVE_PTHREADS
+#include <pthread.h>
+#endif
+
+/**
+ * User structure for the dummy camera.
+ */
 typedef struct dummy_cam {
     uint32_t bitdepth;
-    uint32_t framerate;
-    char*   buffer;
+    uint32_t frame_rate;
+#ifdef HAVE_PTHREADS
+    pthread_t   grab_thread;
+    bool        thread_running;
+    char        *buffer;
+#endif
 } dummy_cam_t;
 
+
+static const char digits[10][20] = {
+    /* 0 */
+    { 0x00, 0xff, 0xff, 0x00,
+      0xff, 0x00, 0x00, 0xff,
+      0xff, 0x00, 0x00, 0xff,
+      0xff, 0x00, 0x00, 0xff,
+      0x00, 0xff, 0xff, 0x00 },
+    /* 1 */
+    { 0x00, 0x00, 0xff, 0x00,
+      0x00, 0xff, 0xff, 0x00,
+      0x00, 0x00, 0xff, 0x00,
+      0x00, 0x00, 0xff, 0x00,
+      0x00, 0x00, 0xff, 0x00 },
+    /* 2 */
+    { 0x00, 0xff, 0xff, 0x00,
+      0xff, 0x00, 0x00, 0xff,
+      0x00, 0x00, 0xff, 0x00,
+      0x00, 0xff, 0x00, 0x00,
+      0xff, 0xff, 0xff, 0xff },
+    /* 3 */
+    { 0x00, 0xff, 0xff, 0x00,
+      0xff, 0x00, 0x00, 0xff,
+      0x00, 0x00, 0xff, 0x00,
+      0xff, 0x00, 0x00, 0xff,
+      0x00, 0xff, 0xff, 0x00 },
+    /* 4 */
+    { 0xff, 0x00, 0x00, 0x00,
+      0xff, 0x00, 0x00, 0xff,
+      0xff, 0xff, 0xff, 0xff,
+      0x00, 0x00, 0x00, 0xff,
+      0x00, 0x00, 0x00, 0xff },
+    /* 5 */
+    { 0xff, 0xff, 0xff, 0xff,
+      0xff, 0x00, 0x00, 0x00,
+      0x00, 0xff, 0xff, 0x00,
+      0x00, 0x00, 0x00, 0xff,
+      0xff, 0xff, 0xff, 0x00 },
+    /* 6 */
+    { 0x00, 0xff, 0xff, 0xff,
+      0xff, 0x00, 0x00, 0x00,
+      0xff, 0xff, 0xff, 0x00,
+      0xff, 0x00, 0x00, 0xff,
+      0x00, 0xff, 0xff, 0x00 },
+    /* 7 */
+    { 0xff, 0xff, 0xff, 0xff,
+      0x00, 0x00, 0x00, 0xff,
+      0x00, 0x00, 0xff, 0x00,
+      0x00, 0xff, 0x00, 0x00,
+      0xff, 0x00, 0x00, 0x00 },
+    /* 8 */
+    { 0x00, 0xff, 0xff, 0x00,
+      0xff, 0x00, 0x00, 0xff,
+      0x00, 0xff, 0xff, 0x00,
+      0xff, 0x00, 0x00, 0xff,
+      0x00, 0xff, 0xff, 0x00 },
+    /* 9 */
+    { 0x00, 0xff, 0xff, 0x00,
+      0xff, 0x00, 0x00, 0xff,
+      0x00, 0xff, 0xff, 0xff,
+      0x00, 0x00, 0x00, 0xff,
+      0xff, 0xff, 0xff, 0x00 }
+};
+
+const int DIGIT_WIDTH = 4;
+const int DIGIT_HEIGHT = 5;
+
 #define GET_DUMMY(uca) ((struct dummy_cam *)(uca->user))
 #define set_void(p, type, value) { *((type *) p) = value; }
 
+static void uca_dummy_print_number(char *buffer, int number, int x, int y, int width)
+{
+    for (int i = 0; i < DIGIT_WIDTH; i++) {
+        for (int j = 0; j < DIGIT_HEIGHT; j++) {
+            buffer[(y+j)*width + (x+i)] = digits[number][j*DIGIT_WIDTH+i];
+        }
+    }
+}
+
+static void uca_dummy_memcpy(struct uca_camera *cam, char *buffer)
+{
+    /* print current frame number */
+    unsigned int number = cam->current_frame;
+    unsigned int divisor = 100000000;
+    int x = 10;
+    while (divisor > 1) {
+        uca_dummy_print_number(buffer, number / divisor, x, 10, cam->frame_width);
+        number = number % divisor;
+        divisor = divisor / 10;
+        x += 5;
+    }
+}
+
+static void *uca_dummy_grab_thread(void *arg)
+{
+    struct uca_camera *cam = ((struct uca_camera *) arg);
+    struct dummy_cam *dc = GET_DUMMY(cam);
+
+    const __useconds_t sleep_time = (unsigned int) 1000000.0f / dc->frame_rate;
+
+    while (dc->thread_running) {
+        uca_dummy_memcpy(cam, dc->buffer);
+        cam->callback(cam->current_frame, dc->buffer);
+        cam->current_frame++;
+        usleep(sleep_time);
+    }
+    return NULL;
+}
+
+
+/*
+ * --- interface implementations ----------------------------------------------
+ */
 static uint32_t uca_dummy_set_property(struct uca_camera *cam, enum uca_property_ids property, void *data)
 {
     if (cam->state == UCA_CAM_RECORDING)
@@ -28,6 +153,10 @@ static uint32_t uca_dummy_set_property(struct uca_camera *cam, enum uca_property
             cam->frame_height = *((uint32_t *) data);
             break;
 
+        case UCA_PROP_FRAMERATE:
+            GET_DUMMY(cam)->frame_rate = *((uint32_t *) data);
+            break;
+
         default:
             return UCA_ERR_PROP_INVALID;
     }
@@ -78,6 +207,15 @@ static uint32_t uca_dummy_get_property(struct uca_camera *cam, enum uca_property
 
 uint32_t uca_dummy_start_recording(struct uca_camera *cam)
 {
+    if (cam->callback != NULL) {
+#ifdef HAVE_PTHREADS
+        struct dummy_cam *dc = GET_DUMMY(cam);
+        /* FIXME: handle return value */
+        dc->thread_running = true;
+        dc->buffer = (char *) malloc(cam->frame_width * cam->frame_height);
+        pthread_create(&dc->grab_thread, NULL, &uca_dummy_grab_thread, cam);
+#endif
+    }
     cam->current_frame = 0;
     cam->state = UCA_CAM_RECORDING;
     return UCA_NO_ERROR;
@@ -85,106 +223,37 @@ uint32_t uca_dummy_start_recording(struct uca_camera *cam)
 
 uint32_t uca_dummy_stop_recording(struct uca_camera *cam)
 {
+    if (cam->callback != NULL) {
+        GET_DUMMY(cam)->thread_running = false;
+        free(GET_DUMMY(cam)->buffer);
+    }
     cam->state = UCA_CAM_ARMED;
     return UCA_NO_ERROR;
 }
 
-static const char digits[10][20] = {
-    /* 0 */
-    { 0x00, 0xff, 0xff, 0x00,
-      0xff, 0x00, 0x00, 0xff,
-      0xff, 0x00, 0x00, 0xff,
-      0xff, 0x00, 0x00, 0xff,
-      0x00, 0xff, 0xff, 0x00 },
-    /* 1 */
-    { 0x00, 0x00, 0xff, 0x00,
-      0x00, 0xff, 0xff, 0x00,
-      0x00, 0x00, 0xff, 0x00,
-      0x00, 0x00, 0xff, 0x00,
-      0x00, 0x00, 0xff, 0x00 },
-    /* 2 */
-    { 0x00, 0xff, 0xff, 0x00,
-      0xff, 0x00, 0x00, 0xff,
-      0x00, 0x00, 0xff, 0x00,
-      0x00, 0xff, 0x00, 0x00,
-      0xff, 0xff, 0xff, 0xff },
-    /* 3 */
-    { 0x00, 0xff, 0xff, 0x00,
-      0xff, 0x00, 0x00, 0xff,
-      0x00, 0x00, 0xff, 0x00,
-      0xff, 0x00, 0x00, 0xff,
-      0x00, 0xff, 0xff, 0x00 },
-    /* 4 */
-    { 0xff, 0x00, 0x00, 0x00,
-      0xff, 0x00, 0x00, 0xff,
-      0xff, 0xff, 0xff, 0xff,
-      0x00, 0x00, 0x00, 0xff,
-      0x00, 0x00, 0x00, 0xff },
-    /* 5 */
-    { 0xff, 0xff, 0xff, 0xff,
-      0xff, 0x00, 0x00, 0x00,
-      0x00, 0xff, 0xff, 0x00,
-      0x00, 0x00, 0x00, 0xff,
-      0xff, 0xff, 0xff, 0x00 },
-    /* 6 */
-    { 0x00, 0xff, 0xff, 0xff,
-      0xff, 0x00, 0x00, 0x00,
-      0xff, 0xff, 0xff, 0x00,
-      0xff, 0x00, 0x00, 0xff,
-      0x00, 0xff, 0xff, 0x00 },
-    /* 7 */
-    { 0xff, 0xff, 0xff, 0xff,
-      0x00, 0x00, 0x00, 0xff,
-      0x00, 0x00, 0xff, 0x00,
-      0x00, 0xff, 0x00, 0x00,
-      0xff, 0x00, 0x00, 0x00 },
-    /* 8 */
-    { 0x00, 0xff, 0xff, 0x00,
-      0xff, 0x00, 0x00, 0xff,
-      0x00, 0xff, 0xff, 0x00,
-      0xff, 0x00, 0x00, 0xff,
-      0x00, 0xff, 0xff, 0x00 },
-    /* 9 */
-    { 0x00, 0xff, 0xff, 0x00,
-      0xff, 0x00, 0x00, 0xff,
-      0x00, 0xff, 0xff, 0xff,
-      0x00, 0x00, 0x00, 0xff,
-      0xff, 0xff, 0xff, 0x00 }
-};
-
-static void uca_dummy_print_number(struct dummy_cam *dummy, int number, int x, int y, int width)
+uint32_t uca_dummy_register_callback(struct uca_camera *cam, uca_cam_grab_callback cb)
 {
-    const int digit_width = 4;
-    const int digit_height = 5;
-    char *buffer = dummy->buffer;
-    for (int i = 0; i < digit_width; i++) {
-        for (int j = 0; j < digit_height; j++) {
-            buffer[(y+j)*width + (x+i)] = digits[number][j*digit_width+i];
-        }
-    }
+    if (cam->callback == NULL)
+        cam->callback = cb;
+    else
+        return UCA_ERR_GRABBER_CALLBACK_ALREADY_REGISTERED;
+
+    return UCA_NO_ERROR;
 }
 
 uint32_t uca_dummy_grab(struct uca_camera *cam, char *buffer)
 {
-    struct dummy_cam *dummy = GET_DUMMY(cam);
-    dummy->buffer = buffer;
+    if (cam->callback != NULL)
+        return UCA_ERR_GRABBER_CALLBACK_ALREADY_REGISTERED;
 
-    /* print current frame number */
-    unsigned int number = cam->current_frame;
-    unsigned int divisor = 100000000;
-    int x = 10;
-    while (divisor > 1) {
-        uca_dummy_print_number(dummy, number / divisor, x, 10, cam->frame_width);
-        number = number % divisor;
-        divisor = divisor / 10;
-        x += 5;
-    }
+    uca_dummy_memcpy(cam, buffer);
     cam->current_frame++;
     return UCA_NO_ERROR;
 }
 
 static uint32_t uca_dummy_destroy(struct uca_camera *cam)
 {
+    free(GET_DUMMY(cam));
     return UCA_NO_ERROR;
 }
 
@@ -198,6 +267,8 @@ uint32_t uca_dummy_init(struct uca_camera **cam, struct uca_grabber *grabber)
     uca->start_recording = &uca_dummy_start_recording;
     uca->stop_recording = &uca_dummy_stop_recording;
     uca->grab = &uca_dummy_grab;
+    uca->register_callback = &uca_dummy_register_callback;
+
     uca->state = UCA_CAM_CONFIGURABLE;
     uca->frame_width = 320;
     uca->frame_height = 240;
@@ -205,8 +276,7 @@ uint32_t uca_dummy_init(struct uca_camera **cam, struct uca_grabber *grabber)
 
     struct dummy_cam *dummy_cam = (struct dummy_cam *) malloc(sizeof(struct dummy_cam));
     dummy_cam->bitdepth = 8;
-    dummy_cam->framerate = 100;
-    dummy_cam->buffer = NULL;
+    dummy_cam->frame_rate = 100;
     uca->user = dummy_cam;
 
     *cam = uca;
diff --git a/src/uca-cam.h b/src/uca-cam.h
index 822f011..ca80ec9 100644
--- a/src/uca-cam.h
+++ b/src/uca-cam.h
@@ -129,6 +129,28 @@ typedef uint32_t (*uca_cam_start_recording) (struct uca_camera *cam);
 typedef uint32_t (*uca_cam_stop_recording) (struct uca_camera *cam);
 
 /**
+ * Function pointer to a grab callback.
+ * 
+ * Register such a callback function with uca_cam_register_callback() to
+ * receive data as soon as it is delivered.
+ *
+ * \param[in] image_number Current frame number
+ *
+ * \param[in] buffer Image data
+ */
+typedef void (*uca_cam_grab_callback) (uint32_t image_number, void *buffer);
+
+/**
+ * Register callback for given frame grabber. To actually start receiving
+ * frames, call uca_grabber_acquire().
+ *
+ * \param[in] grabber The grabber for which the callback should be installed
+ *
+ * \param[in] cb Callback function for when a frame arrived
+ */
+typedef uint32_t (*uca_cam_register_callback) (struct uca_camera *cam, uca_cam_grab_callback cb);
+
+/**
  * \brief Grab one image from the camera
  * 
  * The grabbing involves a memory copy because we might have to decode the image
@@ -182,6 +204,13 @@ typedef struct uca_camera {
      */
     uca_cam_grab            grab;
 
+    /**
+     * Method to register an frame acquisition callback.
+     *
+     * \see uca_cam_register_callback
+     */
+    uca_cam_register_callback   register_callback;
+
     /* Private */
     /**
      * Method to close the camera.
@@ -189,11 +218,13 @@ typedef struct uca_camera {
      */
     uca_cam_destroy         destroy;
 
-    struct uca_grabber      *grabber;   /**< grabber associated with this camera */
-    enum uca_cam_state      state;      /**< camera state */
+    /* private */
+    struct uca_grabber      *grabber;       /**< grabber associated with this camera */
+    enum uca_cam_state      state;          /**< camera state */
     uint32_t                frame_width;    /**< current frame width */
     uint32_t                frame_height;   /**< current frame height */
     uint32_t                current_frame;  /**< last grabbed frame number */
+    uca_cam_grab_callback   callback;
 
     void *user; /**< private user data to be used by the camera driver */
 } uca_camera_t;