The Shulhan Arukh (OH 47:3) writes that one must make the blessing even upon writing. He does not specify that this be the writing of new ideas. In the Beit Yosef (3) to the Tur there, he quotes this from Abudirham.
This is also the implication of the Pri Megadim (MZ 2) and the conclusion of the Arokh HaShulhan (47:10).
However, the Mishna Berura there (4) states that one should be stringent and not recite the blessing on mere writing, but only on speech. Accordingly one should say some of the words he is writing, or other words of Torah after the blessing.
Regarding the question of whether typing is considered writing, see here.