Implemented close method for CvCapture

Sometimes it is useful to release a resource BEFORE the garbage collection starts

ext/opencv/cvcapture.cpp

@@ -27,8 +27,12 @@ rb_class()
 void
 cvcapture_free(void *ptr)
 { 
-  if (ptr)
-    cvReleaseCapture((CvCapture**)&ptr);
+  if (ptr) {
+    sCvCapture* scap = (sCvCapture*)ptr;
+    if (scap->opened)
+      cvReleaseCapture(&scap->ptr);
+    delete scap;
+  }
 }
 
 /*
@@ -49,6 +53,7 @@ rb_open(int argc, VALUE *argv, VALUE self)
   VALUE device;
   rb_scan_args(argc, argv, "01", &device);
   CvCapture *capture = 0;
+  sCvCapture *scap = new sCvCapture();
   try {
     switch (TYPE(device)) {
     case T_STRING:
@@ -74,7 +79,27 @@ rb_open(int argc, VALUE *argv, VALUE self)
   }
   if (!capture)
     rb_raise(rb_eStandardError, "Invalid capture format.");
-  return Data_Wrap_Struct(rb_klass, 0, cvcapture_free, capture);
+  scap->ptr = capture;
+  scap->opened = true;
+  return Data_Wrap_Struct(rb_klass, 0, cvcapture_free, scap);
+}
+
+/*
+ * Releases an opened video file or a capturing device
+ * @return [boolean] False if the device was already closed
+ */
+
+VALUE
+rb_close(VALUE self)
+{
+  sCvCapture *scap;
+  Data_Get_Struct(self, sCvCapture, scap);
+  if (scap->opened) {
+    scap->opened = false;
+    cvReleaseCapture(&scap->ptr);
+    return true;
+  } else
+    return false;
 }
 
 /*
@@ -570,6 +595,7 @@ init_ruby_class()
   rb_hash_aset(video_interface, ID2SYM(rb_intern("quicktime")), INT2FIX(CV_CAP_QT));
   
   rb_define_singleton_method(rb_klass, "open", RUBY_METHOD_FUNC(rb_open), -1);
+  rb_define_method(rb_klass, "close", RUBY_METHOD_FUNC(rb_close), 0);
   
   rb_define_method(rb_klass, "grab", RUBY_METHOD_FUNC(rb_grab), 0);
   rb_define_method(rb_klass, "retrieve", RUBY_METHOD_FUNC(rb_retrieve), 0);

ext/opencv/cvcapture.h

@@ -16,6 +16,12 @@
 #define __NAMESPACE_END_CVCAPTURE }
 
 __NAMESPACE_BEGIN_OPENCV
+
+typedef struct {
+  CvCapture* ptr;
+  bool opened;
+} sCvCapture;
+
 __NAMESPACE_BEGIN_CVCAPTURE
 
 
@@ -26,6 +32,8 @@ void init_ruby_class();
 void cvcapture_free(void *ptr);
 VALUE rb_open(int argc, VALUE *argv, VALUE klass);
 
+VALUE rb_close(VALUE self);
+
 VALUE rb_grab(VALUE self);
 VALUE rb_retrieve(VALUE self);
 VALUE rb_query(VALUE self);
@@ -62,9 +70,11 @@ __NAMESPACE_END_CVCAPTURE
 
 inline CvCapture*
 CVCAPTURE(VALUE object) {
-  CvCapture *ptr;
-  Data_Get_Struct(object, CvCapture, ptr);
-  return ptr;
+  sCvCapture *scap;
+  Data_Get_Struct(object, sCvCapture, scap);
+  if (!scap->opened)
+    rb_raise(rb_eIOError, "Resource is not available!");
+  return scap->ptr;
 }
 
 __NAMESPACE_END_OPENCV

test/test_cvcapture.rb

@@ -50,6 +50,14 @@ class TestCvCapture < OpenCVTestCase
     # }
   end
 
+  def test_close
+    cap1 = CvCapture.open(AVI_SAMPLE)
+    cap1.close
+    assert_raise(IOError) do
+      cap1.query
+    end
+  end
+
   def test_grab
     assert(@cap.grab)
   end