Under the hood KF 4.6 has moved from using ZDBase for its backing store, instead using a tuplebase. This makes it possible to split HTML page generation into separate processes, potentially running on multiple front end machines. It also restores support for a rich client application, now written in Java, using ZTSoup to efficiently communicate changes in the tuplebase, whether made by other clients or by the web interface.
ZDCPixmapBlit uses templates to generate the code for source/destination and source/matte/destination blitting, matte/destination filling, and destination-only munging, using the four Porter/Duff composition operators Copy, Over, In and Plus.
It was thus relatively straightforward to implement ZFakeWindow_NSPlugin, which translates between the Netscape browser plugin and the ZFakeWindow APIs. What was actually more difficult was finding a decent implementation of the plugin glue code and header files. In 2002 there wasn't anything that would work with current compilers and with current browsers, so most of the effort was in putting together ZNSPlugin, which is a usable implementation of the glue.
ZooLib defines and implements a graphics API that produces identical results across all supported platforms. It is geared towards creating user interface elements and so is pixel-based rather than geometric so that a programmer can know precisely which pixels will be touched by a drawing operation. It supports pixel-plotting, lines of any thickness, text, rectangles, rounded rectangles, ovals, arbitrary regions and the drawing of masked-pixmaps. ZDC_ZooLib is an implementation of this API using no OS facilities at all, and thus can be used in server applications without the difficulties that normally poses (gaining access to a window or graphics server from a low-privilege process).
The implementation uses operations on ZBigRegion instances to decide which pixels to touch, decomposes the regions into rectangles and then calls ZDCPixmapBlit to actually do the work.
NPainter is a suite of classes that provides a MacPaint-like interface, but supporting indexed and true color, across all platforms supported by ZooLib.
Measurement in Motion 1.0 had an interesting interface. A document contained a set of measurements, and various objects that could display and modify those measurements. The objects were represented as 'windoids', windows within the document window. MiM 1.0 was a Mac application, so the windoids could depend only on ZooLib's graphics API, with no help from the OS. When demand for a Windows version became overwhelming I implemented a full windowing system that conformed to ZooLib's ZOSWindow API, so that any code that worked within a regular OS window could instead be hosted in a windoid. QuickTime by this point was writing to the screen buffer asynchronously, so any change in the visible region of a windoid is notified before it happens and after its completed, somewhat like the BeOS BDirectWindow mechanism.
In porting ZooLib to BeOS I found that BeOS's region API was missing key features. Exclusive or and equivalence testing could be handled by composing more primitive operations, but insetting was trickier. So I dug through the X source and found that their implementation of insetting was totally generic, basically shifting the source region for each set bit in the inset distance and accumulating a union (for expanding) or intersection (for contracting).
But BRegion was also quite slow. The internal representation was pretty close to that used by the X code, being a list of non-overlapping rectangles organized into bands. BRegion did not always maintain the same tight constraints as the X code, but it still proved possible to significantly improve performance by manipulating BRegion's internal data using the X code.
By this point I was intimately familiar with X regions and it was a small step to take the X source and rework it, the result being ZBigRegion - a portable region implementation using 32 bit coordinates. Combined with ZDCPixmapBlit it forms the basis of ZDC_ZooLib.
Marrakech took the hypermedia concepts I explored in WorkSpace and applied them to the problem of managing workflow and assets for multimedia development.
