Browse Prior Art Database

Pixel Protection for Copy/ Zoom in Arbitrarily Shaped Windows

IP.com Disclosure Number: IPCOM000122551D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Vanover, MT: AUTHOR

Abstract

Herein is a method for copying/zooming pixel data both screen to screen and external to screen. This works for both full screen and in arbitrarily shaped windows which are either exposed or obscured. If the copy/zoom source is partially obscured the copy/zoom omits the pixels which are from another window. Since the method is protected per pixel, it supports copying/zooming in NON-RECTANGULAR windows.

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This is the abbreviated version, containing approximately 52% of the total text.

Pixel Protection for Copy/ Zoom in Arbitrarily Shaped Windows

      Herein is a method for copying/zooming pixel data both
screen to screen and external to screen.  This works for both full
screen and in arbitrarily shaped windows which are either exposed or
obscured.  If the copy/zoom source is partially obscured the
copy/zoom omits the pixels which are from another window.  Since the
method is protected per pixel, it supports copying/zooming in
NON-RECTANGULAR windows.

      This is significant since without pixel theft protection, pixel
values from one window are displayed in another without regard to the
color mode in which they were generated and the differences in the
palettes of the source and destination (monochrome, 24-bit, 332-
dithered 044-rgb truncated, etc).  Thus, data from a 24-bit image
generated for a 888 RGB palette could have been copy/zoomed into a
window with an 8-bit indexed palette if pixel theft is not
prohibited.

      Zoom/Pan are functions which have thus far been done on
rectangular regions within a single full screen "window". There is a
need to provide these functions in such a way that the ill effects
possible when copying/zooming/panning in a windowed environment are
protected against on a graphics adapter.  With the advent of X11.4
comes the need to support non-rectangular shaped windows for all
possible functions including copy/zoom/pan.

      This method assumes availability of the following resources:
      1)   Window ID planes which encode a unique ID for each window
present on the adapter.  These are generally used to prohibit writes
of one process into another process's frame buffer pixels. These IDs
per pixel allow arbitrarily shaped overlapping win...