I would like to answer your question in two parts. The first addressing how the Muslims were viewed and the second addressing their contributions to Europe.
History is often obscured by the "victors". Opinions are often constructed for an agenda. So to answer your question literally, the various Muslim civilizations were mostly viewed and propagated as barbaric foreigners. The main perpetrators were the Christian Spanish, the Church, and the Byzantines. At that time Europe was devoutly Christian, mostly Catholic although the Byzantines were Eastern Orthodox. Xenophobia served the Spanish and Byzantine agendas because they were under military threat from Muslim powers. Spain had been conquered, and the Byzantines were being conquered. Additionally, the Papacy's legitimacy was being challenged because of Muslim expansion into Christian civilization and holy lands. The Church detested the Muslims to the extent that they sent Crusaders to conquer Jerusalem. So during that time, the Muslims were seen as barbarians and that is probably still ingrained in our culture to some extent. In a similar vein, the Mongols are also remembered for being barbaric because many cultures that exist today had once been subject to or threatened by them. Consider that every independence movement to remove Mongol rule would have left a legacy of hate against the Mongols.
So were the Muslims savages? No, of course not. The Muslim civilizations parted many technological and cultural advancements to Europe, some of which are still unclear and require academic research. Among the most important influences were preserving ancient Greek texts, extensive mapping, mathematics, and coffee. I have very briefly summarized these contributions below:
The preservation of Greek texts were incredibly important to starting the Renaissance. While the Muslim world was experiencing an Islamic Golden Age, Europe had been in the Dark Ages. Many Greek texts had been lost in Europe, and intellectualism had declined. These texts would later be reintroduced to Europe and was one of the factors beginning the Renaissance.
European explorers used and improved upon the techniques of Muslim explorers of the Islamic Golden Age as well as using Muslim maps. These contributions kick started European exploration and trade capacities.
Many works of math came into contact with the West from the Middle East, including algebra. The word "algebra" is actually a loan word from Arabic. The Italian mathematician Fibonacci studied in the Middle East and advocated for the use of Arabic-Hindu numerals, which we use today.
Coffee has origins in Africa, but was transmitted to Europe from Muslim traders.
Although there was extensive intellectual and commercial contact, the Muslim civilizations were often at odds with European civilizations. Therefore, their contributions are often forgotten or overshadowed.