23     i: i32,  field
30         if self.i < self.rect.height() {  in next()
31             let start = (self.rect.top() + self.i) * self.w + self.rect.left();  in next()
33             self.i += 1;  in next()
50     i: i32,  field
57         if self.i < self.rect.height() {  in next()
61             if self.i == 0 {  in next()
72             self.i += 1;  in next()
104             i: 0,  in into_iter()
116             i: 0,  in rows()
126             i: 0,  in rows_mut()