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From: info-mac@uw-beaver (info-mac)
Newsgroups: fa.info-mac
Subject: QD Text Transfer Modes
Message-ID: <1993@uw-beaver>
Date: Sun, 28-Oct-84 00:49:43 EDT
Article-I.D.: uw-beave.1993
Posted: Sun Oct 28 00:49:43 1984
Date-Received: Tue, 23-Oct-84 00:44:24 EDT
Sender: daemon@uw-beave
Organization: U of Washington Computer Science
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From: Thomas.Newton@cmu-cs-spice.arpa
After looking at the Technical Appendix to the MacPascal Reference Manual,
I am more than a little disturbed.  It claims that the only modes which are
supported for text drawing are srcOr, srcXOr, and srcBic.

I realize that these three modes are the ones that can be implemented most
efficiently (you can do ByteBlt or WordBlt instead of BitBlt by padding the
bit pattern with zeros, which won't have any effect on the screen).  I also
remember some quote in Byte to the effect that "OR mode is used 90 percent
of the time, so it is about twice as fast as the other text modes".

On the other hand, a good graphics package should be *general*.  If I want
to draw text in one of the other modes (I'm especially thinking of srcCopy),
I should be able to do so with no penalty other than a loss of speed because
transfers now must be done at a BitBlt level.

Does anyone know whether the {srcOr, scrXOr, srcBic} restriction is just a
recommendation based on efficiency, or a real limitation of Quickdraw?