stack: force nonfactor generation

If the number of images in the stack hadn't been a divisor of the number
of input images, the last images would have been dropped. This makes
sure all images are processed and fills the last positions of the stack
(when the total number of stacked images starts to exceed the number of
input images) with arbitrary previous images. Fixes #210.

2 files changed, 26 insertions, 4 deletions

diff --git a/docs/filters.rst b/docs/filters.rst
index 5227f3b..f2b32ec 100644
--- a/docs/filters.rst
+++ b/docs/filters.rst
@@ -751,7 +751,9 @@ Stacking
 .. gobj:class:: stack
 
     Symmetrical to the slice filter, the stack filter stacks two-dimensional
-    input.
+    input. If ``number`` is not a divisor of the number of input images, the
+    last produced stack at index which starts to exceed the number of input
+    images will contain arbitrary images from the previous iterations.
 
     .. gobj:prop:: number:uint
 
diff --git a/src/ufo-stack-task.c b/src/ufo-stack-task.c
index b8a5446..0d35dad 100644
--- a/src/ufo-stack-task.c
+++ b/src/ufo-stack-task.c
@@ -25,6 +25,8 @@
 struct _UfoStackTaskPrivate {
     guint n_items;
     guint current;
+    gboolean inputs_stopped;
+    gboolean finished;
     gboolean generated;
 };
 
@@ -113,12 +115,11 @@ ufo_stack_task_process (UfoTask *task,
     size = ufo_buffer_get_size (inputs[0]);
     in_mem = (guint8 *) ufo_buffer_get_host_array (inputs[0], NULL);
     out_mem = (guint8 *) ufo_buffer_get_host_array (output, NULL);
-    memcpy (out_mem + priv->current * size, in_mem, size);
+    memcpy (out_mem + (priv->current % priv->n_items) * size, in_mem, size);
     priv->current++;
 
-    if (priv->current == priv->n_items) {
+    if (priv->current % priv->n_items == 0) {
         // g_warning ("StackTask: stack full, ready for generating. [current %d]", priv->current);
-        priv->current = 0;
         priv->generated = FALSE;
         return FALSE;
     }
@@ -135,6 +136,15 @@ ufo_stack_task_generate (UfoTask *task,
 
     priv = UFO_STACK_TASK_GET_PRIVATE (task);
 
+    if (priv->inputs_stopped && !priv->finished) {
+        /* If the inputs stopped and n_items is not a divisor of the length of
+         * the input stream, force generation to make sure the last chunk of
+         * data is produced, even though with invalid last elements (leftovers
+         * from previous stack filling) */
+        priv->generated = FALSE;
+        priv->finished = TRUE;
+    }
+
     if (!priv->generated) {
         priv->generated = TRUE;
         return TRUE;
@@ -144,6 +154,13 @@ ufo_stack_task_generate (UfoTask *task,
     }
 }
 
+static void inputs_stopped_callback (UfoTask *task)
+{
+    UfoStackTaskPrivate *priv = UFO_STACK_TASK_GET_PRIVATE (task);
+
+    priv->inputs_stopped = TRUE;
+}
+
 static void
 ufo_stack_task_set_property (GObject *object,
                              guint property_id,
@@ -225,4 +242,7 @@ ufo_stack_task_init(UfoStackTask *self)
 {
     self->priv = UFO_STACK_TASK_GET_PRIVATE(self);
     self->priv->n_items = 1;
+    self->priv->inputs_stopped = FALSE;
+    self->priv->finished = FALSE;
+    g_signal_connect (self, "inputs_stopped", (GCallback) inputs_stopped_callback, NULL);
 }