add CvMat#decode (wrapper of cvDecodeImageM)

ext/opencv/cvmat.cpp

@@ -386,6 +386,8 @@ void define_ruby_class()
 
   rb_define_method(rb_klass, "encode_image", RUBY_METHOD_FUNC(rb_encode_imageM), -1);
   rb_define_alias(rb_klass, "encode", "encode_image");
+  rb_define_singleton_method(rb_klass, "decode_image", RUBY_METHOD_FUNC(rb_decode_imageM), -1);
+  rb_define_alias(rb_singleton_class(rb_klass), "decode", "decode_image");
 }
 
 
@@ -535,6 +537,66 @@ rb_encode_imageM(int argc, VALUE *argv, VALUE self)
   return array;
 }
 
+/*
+ * call-seq:
+ *   decode_image(buf[, iscolor=CV_LOAD_IMAGE_COLOR]) -> CvMat
+ *
+ * Reads an image from a buffer in memory.
+ *
+ * Parameters:
+ *   buf <CvMat, Array> - Input array
+ *   iscolor <Integer> - Flags specifying the color type of a decoded image (the same flags as CvMat#load)
+ */
+VALUE
+rb_decode_imageM(int argc, VALUE *argv, VALUE self)
+{
+  VALUE _buff, _iscolor;
+  rb_scan_args(argc, argv, "11", &_buff, &_iscolor);
+  int iscolor = NIL_P(_iscolor) ? CV_LOAD_IMAGE_COLOR : NUM2INT(_iscolor);
+
+  CvMat* buff = NULL;
+  int need_release = 0;
+  switch (TYPE(_buff)) {
+  case T_STRING:
+    _buff = rb_funcall(_buff, rb_intern("unpack"), 1, rb_str_new("c*", 2));
+  case T_ARRAY: {
+    int cols = RARRAY_LEN(_buff);
+    need_release = 1;
+    try {
+      buff = rb_cvCreateMat(1, cols, CV_8UC1);
+      for (int i = 0; i < cols; i++) {
+	CV_MAT_ELEM(*buff, char, 0, i) = NUM2CHR(RARRAY_PTR(_buff)[i]);
+      }
+    }
+    catch (cv::Exception& e) {
+      raise_cverror(e);
+    }
+    break;
+  }
+  case T_DATA:
+    if (rb_obj_is_kind_of(_buff, cCvMat::rb_class()) == Qtrue) {
+      buff = CVMAT(_buff);
+      break;
+    }
+  default:
+    raise_typeerror(_buff, "CvMat, Array or String");
+  }
+
+  CvMat* mat_ptr = NULL;
+  try {
+    mat_ptr = cvDecodeImageM(buff, iscolor);
+    // mat = cvDecodeImage();
+    if (need_release) {
+      cvReleaseMat(&buff);
+    }
+  }
+  catch (cv::Exception& e) {
+    raise_cverror(e);
+  }
+
+  return OPENCV_OBJECT(rb_klass, mat_ptr);
+}
+
 /*
  * nodoc
  */

ext/opencv/cvmat.h

@@ -27,6 +27,7 @@ VALUE rb_allocate(VALUE klass);
 VALUE rb_initialize(int argc, VALUE *argv, VALUE self);
 VALUE rb_load_imageM(int argc, VALUE *argv, VALUE self);
 VALUE rb_encode_imageM(int argc, VALUE *argv, VALUE self);
+VALUE rb_decode_imageM(int argc, VALUE *argv, VALUE self);
 
 VALUE rb_method_missing(int argc, VALUE *argv, VALUE self);
 VALUE rb_to_s(VALUE self);

test/test_cvmat.rb

@@ -135,6 +135,56 @@ class TestCvMat < OpenCVTestCase
     # }
   end
 
+  def test_decode
+    data = nil
+    open(FILENAME_CAT, 'rb') { |f|
+      data = f.read
+    }
+    data_ary = data.unpack("c*")
+    data_mat = CvMat.new(1, data_ary.size).set_data(data_ary)
+    expected = CvMat.load(FILENAME_CAT)
+
+    mat1 = CvMat.decode(data)
+    mat2 = CvMat.decode(data_ary)
+    mat3 = CvMat.decode(data_mat)
+    mat4 = CvMat.decode(data, CV_LOAD_IMAGE_COLOR)
+    mat5 = CvMat.decode(data_ary, CV_LOAD_IMAGE_COLOR)
+    mat6 = CvMat.decode(data_mat, CV_LOAD_IMAGE_COLOR)
+    expected_hash = hash_img(expected)
+
+    [mat1, mat2, mat3, mat4, mat5, mat6].each { |mat|
+      assert_equal(CvMat, mat.class)
+      assert_equal(expected.rows, mat.rows)
+      assert_equal(expected.cols, mat.cols)
+      assert_equal(expected.channel, mat.channel)
+      assert_equal(expected_hash, hash_img(mat))
+    }
+
+    expected_c1 = CvMat.load(FILENAME_CAT, CV_LOAD_IMAGE_GRAYSCALE)
+    mat1c1 = CvMat.decode(data, CV_LOAD_IMAGE_GRAYSCALE)
+    mat2c1 = CvMat.decode(data_ary, CV_LOAD_IMAGE_GRAYSCALE)
+    mat3c1 = CvMat.decode(data_mat, CV_LOAD_IMAGE_GRAYSCALE)
+    expected_hash_c1 = hash_img(expected_c1)
+
+    [mat1c1, mat2c1, mat3c1].each { |mat|
+      assert_equal(CvMat, mat.class)
+      assert_equal(expected_c1.rows, mat.rows)
+      assert_equal(expected_c1.cols, mat.cols)
+      assert_equal(expected_c1.channel, mat.channel)
+      assert_equal(expected_hash_c1, hash_img(mat))
+    }
+
+    assert_raise(TypeError) {
+      CvMat.decode(DUMMY_OBJ)
+    }
+    assert_raise(TypeError) {
+      CvMat.decode(data, DUMMY_OBJ)
+    }
+
+    # Uncomment the following line to show the result images
+    # snap mat1, mat2, mat3
+  end
+
   def test_GOOD_FEATURES_TO_TRACK_OPTION
     assert_equal(0xff, CvMat::GOOD_FEATURES_TO_TRACK_OPTION[:max])
     assert_nil(CvMat::GOOD_FEATURES_TO_TRACK_OPTION[:mask])