QLogo: A C++ repository from proteanthread

This is README for version 0.9 of QLogo

QLogo is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.

QLogo is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with QLogo.  If not, see <http://www.gnu.org/licenses/>.


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


QLogo is an interpreter for the Logo language written in C++ using
Qt and OpenGL. Specifically, it mimics (as reasonably as possible)
the UCBLogo interpreter developed at U.C. Berkeley. In fact, the
UCBLogo manual describes about 99.9% of the functionality. You can
find the UCBLogo Manual here:

http://people.eecs.berkeley.edu/~bh/usermanual


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


Compiling

QLogo is being developed and tested to work with C++11 and Qt 5.6.3. Qt 5.6 is the
last version to support Windows XP. However, QLogo is also being developed and tested
against the newest version of Qt (5.10) so it can be assumed that any version in
between should work just fine.


QLogo is currently being developed and tested on the following platforms:

* Windows 10 using Visual Studio 2017 and MinGW GCC 6.3.0.
* Linux Fedora 26 using GCC 7.2.1
* Mac OS X 10.13 using Clang/LLVM


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


There are a few nuances:


* Colors can be specified in one of three ways:

1) as a palette index (0 to 100)

2) as a list of 3 percentages, one for each of red, green, blue
[0 0 0] is black, [100 100 100] is white

3) as a named color from the X Color Database, e.g. "floralwhite or "lemonchiffon.
The X Color database can be found here:
https://en.wikipedia.org/wiki/X11_color_names


* Changes in font properties (size, color, family) do not affect characters already printed.


* The entire Logo standard library is loaded internally and buried. There is no
  library directory at this time.


* QLogo does not look for nor automatically load STARTUP.LG.


* Lists are maintained using QList which is not a linked list. As such, the possible "bug"
  of two lists being joined at some element is not possible in QLogo.


* If ERRACT is set and its size is greater than zero, then any errors execute PAUSE.


* Garbage collection is on-the-fly, meaning that memory is freed the moment a word/list/array
  is no longer needed. GC and .SETSEGMENTSIZE are no-ops.


* SAVEPICT saves a copy of the canvas in the format given by the filename's extension. For
  example: SAVEPICT "MY_PICTURE.PNG will save in PNG format. QLogo can save an image in the
  following formats: BMP, JPG/JPEG, PNG, PPM, XBM, and XPM


* HELP is functional, but the text is a copy of the UCBLogo help text. As such, it should
  be 99.9% correct. This will be fixed.


* There is no facility yet for translation/internationalization. Yet.


* The following commands are not implemented:

SETMARGINS:        No plans.
FILL:              No plans.
LOADPICT:    	   This will be fixed soon.
EPSPICT:    	   This will be replaced by SVG.
CSLSLOAD:   	   This will be fixed soon.
SETEDITOR:  	   QLogo uses a built-in editor.
SETLIBLOC:         The QLogo library is stored internally.
SETHELPLOC:        No plans.
SETCSLSLOC:        This may be fixed soon.
SETTEMPLOC:        QLogo doesn't create temporary files at this time.


* The following variables have no special meaning:

COMMANDLINE:       QLogo is a GUI application.
REDEFP:            There will be another mechanism for internationalization.
USEALTERNATENAMES: ditto


* The following commands are NEW:

ALLFONTS

returns a list of all the fonts available on your system.

CURSORINSERT

sets cursor to insert mode, this is the default.

CURSOROVERWRITE

sets cursor to overwrite mode.

CURSORMODE

outputs either INSERT or OVERWRITE

BOUNDS

outputs a list of two numbers giving the maximum bounds (x,y) of the canvas.
e.g. bounds of [350 150] means that the turtle is visible if its X coordinate is
between -350 and 350 and its Y coordinate is between -150 and 150. The coordinate
[0, 0] is always in the center.

SETBOUNDS xmax ymax

sets the maximum bounds of the canvas.
proteanthread/QLogo
