[Gzz-commits] manuscripts/xupdf article.rst

[Tuomas J. Lukka]

CVSROOT:        /cvsroot/gzz
Module name:    manuscripts
Changes by:     Tuomas J. Lukka <address@hidden>        03/02/14 11:57:00

Modified files:
        xupdf          : article.rst 

Log message:
        Buoy talk

CVSWeb URLs:
http://savannah.gnu.org/cgi-bin/viewcvs/gzz/manuscripts/xupdf/article.rst.diff?tr1=1.104&tr2=1.105&r1=text&r2=text

Patches:
Index: manuscripts/xupdf/article.rst
diff -u manuscripts/xupdf/article.rst:1.104 manuscripts/xupdf/article.rst:1.105
--- manuscripts/xupdf/article.rst:1.104 Fri Feb 14 11:35:17 2003
+++ manuscripts/xupdf/article.rst       Fri Feb 14 11:56:59 2003
@@ -261,34 +261,37 @@
 Buoy placement
 --------------
 
-Usually everything is either in the coordinate system of the
+In most current systems,
+all graphical objects are placed
+in either the coordinate system of the
 virtual paper (e.g., the margins of the web page being scrolled)
-or in the outside coordinate system, independent of the page.
+or the external coordinate system, independent of the page.
 This is originally because of performance: it is most efficient to update
 a single, rectangular (or rectangular, rectangularly obscured) area 
 of screen.
-With fast hardware, there is no need to be limited to rectangular sections
-because the whole screen can always be drawn.
-Thus, it is possible to place objects in different, interconnected
-coordinate systems.
+For the same reason, smooth scaling is only seldom used.
 
-What we call *buoy* is a common idea from technical diagrams: 
-draw a line to the relevant point and place the label in the margin
-(see Fig. [ref-fignasa]_).
-The scale and location of the buoy and the document can be
-smoothly adjusted, independent of each other, with the connection
-line cross-cutting the view.
+With modern graphics hardware, there is no need to be limited to rectangular 
sections
+and discrete scales
+because the whole screen can be redrawn at interactive frame rates.
+Thus, it is possible to place objects in different
+coordinate systems whose motion depends on the others in complex ways.
 
 We use buoys as link targets floating around the focus.
-For the layout of the buoys, several desirable layout constraints 
-can be enumerated:
+What we call *buoy* is a commonly used tool in technical diagrams: 
+placing a label at the edge of the image and connecting the label
+to the relevant location (anchor) by a line
+(see Fig. [ref-fignasa]_).
 
-- buoys should not be placed directly on the focus 
-- buoys should be placed close to their anchors
-- buoys anchored closer to the focus should be larger
+For the layout of the buoys we give the following criteria
+(in order of importance):
+
+- buoys should not be placed directly on the focus (center of screen)
+- buoys whose anchors are close to the focus should be large
 - the view should animate continuously when the focus moves
 - the user should be able to understand and predict the motion
   of the buoys.
+- buoys should be placed close to their anchors
 
 Furthermore,
 it is important to maintain orientation locally,