modified CvMat#snake_image to check sizes of alpha, beta, gamma when coeff_usage == CV_ARRAY

Author: ser1zw

ext/cvmat.cpp

@@ -4826,14 +4826,19 @@ rb_snake_image(int argc, VALUE *argv, VALUE self)
   IplImage stub;
   int i;
   if (coeff == CV_VALUE) {
-    a = ALLOCA_N(float, 1);
-    a[0] = (float)NUM2DBL(alpha);
-    b = ALLOCA_N(float, 1);
-    b[0] = (float)NUM2DBL(beta);
-    c = ALLOCA_N(float, 1);
-    c[0] = (float)NUM2DBL(gamma);
+    float buff_a, buff_b, buff_c;
+    buff_a = (float)NUM2DBL(alpha);
+    buff_b = (float)NUM2DBL(beta);
+    buff_c = (float)NUM2DBL(gamma);
+    a = &buff_a;
+    b = &buff_b;
+    c = &buff_c;
   }
   else { // CV_ARRAY
+    if ((RARRAY_LEN(alpha) != length) ||
+	(RARRAY_LEN(beta) != length) ||
+	(RARRAY_LEN(gamma) != length))
+      rb_raise(rb_eArgError, "alpha, beta, gamma should be same size of points");
     a = ALLOCA_N(float, length);
     b = ALLOCA_N(float, length);
     c = ALLOCA_N(float, length);

test/test_cvmat_imageprocessing.rb

@@ -1630,6 +1630,10 @@ def test_snake_image
     assert_raise(TypeError) {
       mat.snake_image(points, alpha, arr_beta, gamma, size, term_criteria)
     }
+
+    assert_raise(ArgumentError) {
+      mat.snake_image(points, arr_alpha[0 .. num_points / 2], arr_beta, arr_gamma, size, term_criteria)
+    }
   end
 end