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95 lines
3.5 KiB
Lua
95 lines
3.5 KiB
Lua
--[[ Lua Floodfill function
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/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2017 William Wilgus
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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]]
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-- floods an area of targetclr with fillclr x, y specifies the start seed
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-- flood_fill(img, x, y, targetclr, fillclr)
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if not rb.lcd_framebuffer then rb.splash(rb.HZ, "No Support!") return nil end
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do
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local rocklib_image = getmetatable(rb.lcd_framebuffer())
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local _NIL = nil -- nil placeholder
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local _get = rocklib_image.get
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local _line = rocklib_image.line
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local _marshal = rocklib_image.marshal
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return function(img, x, y, targetclr, fillclr)
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-- scanline 4-way flood algorithm
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-- ^
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-- <--------x--->
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-- v
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-- check that target color doesn't = fill and the first point is target color
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if targetclr == fillclr or targetclr ~= _get(img, x, y, true) then return end
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local max_w = img:width()
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local max_h = img:height()
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local qpt = {} -- FIFO queue
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-- rather than moving elements around in our FIFO queue
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-- for each read; increment 'qhead' by 2
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-- set both elements to nil and let the
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-- garbage collector worry about it
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-- for each write; increment 'qtail' by 2
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-- x coordinates are in odd indices while
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-- y coordinates are in even indices
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local qtail = 0
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local function check_ns(val, x, y)
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if targetclr == val then
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y = y - 1
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if targetclr == _get(img, x, y, true) then -- north
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qtail = qtail + 2
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qpt[qtail - 1] = x
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qpt[qtail] = y
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end
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y = y + 2
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if targetclr == _get(img, x, y, true) then -- south
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qtail = qtail + 2
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qpt[qtail - 1] = x
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qpt[qtail] = y
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end
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return fillclr
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end
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return _NIL -- signal marshal to stop
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end
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local function seed_pt(x, y)
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-- should never hit max but make sure not to end early
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for qhead = 2, 0x40000000, 2 do
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if targetclr == _get(img, x, y, true) then
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_marshal(img, x, y, 1, y, _NIL, _NIL, true, check_ns) -- west
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_marshal(img, x + 1, y, max_w, y, _NIL, _NIL, true, check_ns) -- east
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end
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x = qpt[qhead - 1]
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qpt[qhead - 1] = _NIL
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if not x then break end
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y = qpt[qhead]
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qpt[qhead] = _NIL
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end
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end
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seed_pt(x, y) -- Begin
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end -- flood_fill
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end
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