Q68574: Performance Differences Between LineTo() and Polyline()

Article: Q68574
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.0,3.1
Operating System(s): 
Keyword(s): 
Last Modified: 06-NOV-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1 
-------------------------------------------------------------------------------

SUMMARY
=======

When an application must draw a large number of lines, the Polyline() function
will execute 1.1 to 1.5 times faster than the equivalent calls to the LineTo()
function on video hardware that does not have a graphics coprocessor (such as
EGA and VGA). On hardware with a graphics coprocessor (such as an 8514/A),
Polyline() can execute up to 12 times faster than LineTo().

In general, Polyline() is faster than LineTo(). This is magnified by drawing a
very large number of lines. With a small number of lines, the difference in
duration of the calls is negligible compared to the time required to draw the
lines.

MORE INFORMATION
================

LineTo() and Polyline() both use the same internal code to draw lines, but with
slightly different setup procedures.

Polyline() calls GlobalAlloc() and copies all points into that memory; as a
result, there is some overhead. A pointer to the memory is passed to an internal
function that draws all the lines.

LineTo() essentially builds one point and calls the same internal function as
Polyline(). LineTo() does not allocate additional memory.

Polyline() is much more efficient for a large number of lines, since an
application makes a single call to Windows and setup is only performed once. A
large number of calls to LineTo() introduces significant overhead to make each
call and repeatedly execute the setup code in LineTo().

Additional query words: 3.00 3.10

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Version           : WINDOWS:3.0,3.1

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.