By the mid-19th century, European intellectual attitudes towards China had mostly shifted to contempt, to a large extent because the Opium War seemed to 'prove' that China was stagnant and weak, and no match for European civilization.
I believe intellectual attitudes branched more than they shifted. After 1850, there really are two positions. In politics, China, or, more precisely, its government, is despised as decadent and corrupt. On the other hand, the admiration for chinese art, and culture in general was expanding, and getting to larger and larger audiences.
Many intellectuals collected chinese objects (I visited Victor Hugo's house in paris today, I was amazed at the number of Chinese things he had, and he was no more a sinophile than any other, just typical of his time). This is also the time when chinese (Tang, generally) poetry was translated and put into western songs (Mahler, and then Berg and Webern), or made into collection, which enjoyed some publishing success. The second half of the 19th century was also the moment when major classics (Confucius and Laozi) were translated an popularised, and when quite a number of stories taking place in China (from Anderssen's Nightingale, to Puccini's Turandot) were written.
Again, I think a difference must be made between the opinion educated europeans had of chinese art and culture, which was quite positive through all the 19th century, and the judgment passed by europeans on the government and the state of China in their time, which was not very flattering.