Prevent activating an already active size

Changing resolution is costly, as we need first to wait
for pending buffers and stop streaming.

So, optimize resolution switch by not trying to
activate the already activated resolution.

3 files changed, 36 insertions, 16 deletions

diff --git a/src/callbacks.c b/src/callbacks.c
index 0b193c8..3db9ba5 100644
--- a/src/callbacks.c
+++ b/src/callbacks.c
@@ -364,29 +364,32 @@ void on_change_size_activate (GtkWidget * widget, cam * cam)
 {
     gchar const *name;
     gchar       *title;
+    int         width, height;
 
     name = gtk_widget_get_name (widget);
-    printf("name = %s\n",name);
+
     if (strcmp (name, "small") == 0) {
-        cam->width = cam->min_width;
-        cam->height = cam->min_height;
-        if (cam->debug) {
-            printf ("\nsmall\n");
-        }
+        width = cam->min_width;
+        height = cam->min_height;
     } else if (strcmp (name, "medium") == 0) {
-        cam->width = cam->max_width / 2;
-        cam->height = cam->max_height / 2;
-        if (cam->debug) {
-            printf ("\nmed\n");
-        }
+        width = cam->max_width / 2;
+        height = cam->max_height / 2;
     } else {
-        cam->width = cam->max_width;
-        cam->height = cam->max_height;
-        if (cam->debug) {
-            printf ("\nlarge\n");
-        }
+        width = cam->max_width;
+        height = cam->max_height;
     }
 
+    try_set_win_info(cam, &width, &height);
+
+    /* Nothing to do, so just return */
+    if (width == cam->width && height == cam->height)
+        return;
+
+    cam->width = width;
+    cam->height = height;
+
+    printf("name = %s\n",name);
+
     if (cam->read == FALSE)
        stop_streaming(cam);
     set_win_info (cam);
diff --git a/src/v4l.c b/src/v4l.c
index 47c0fe6..f2eff32 100644
--- a/src/v4l.c
+++ b/src/v4l.c
@@ -258,6 +258,22 @@ void get_win_info(cam * cam)
    }
 }
 
+void try_set_win_info(cam * cam, int *x, int *y)
+{
+   gchar *msg;
+   struct v4l2_format fmt;
+
+   memset(&fmt, 0, sizeof(fmt));
+   fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+   fmt.fmt.pix.pixelformat = cam->pixformat;
+   fmt.fmt.pix.width  = *x;
+   fmt.fmt.pix.height = *y;
+   if (!v4l2_ioctl(cam->dev, VIDIOC_TRY_FMT, &fmt)) {
+      *x = fmt.fmt.pix.width;
+      *y = fmt.fmt.pix.height;
+   }
+}
+
 void set_win_info(cam * cam)
 {
    gchar *msg;
diff --git a/src/v4l.h b/src/v4l.h
index 1c07641..b29bb42 100644
--- a/src/v4l.h
+++ b/src/v4l.h
@@ -86,6 +86,7 @@ typedef struct camera {
 } cam;
 
 void camera_cap (cam *);
+void try_set_win_info(cam * cam, int *x, int *y);
 void set_win_info (cam * cam);
 void get_pic_info (cam *);
 void get_win_info (cam *);