Class: HGR

Inherits:
Object
  • Object
show all
Defined in:
lib/HGR.rb

Constant Summary collapse

PALLETE_MODES = 
[:white,:green,:amber,:colour]
PALLETE = 
{
	:white=>PNG::Color::White,
	:green=>PNG::Color.new(0x00, 0x99, 0x00, 0xFF),
	:amber=>PNG::Color::Orange
}
HGR_BLACK =

colours cribbed from groups.google.com.au/group/comp.sys.apple2/browse_thread/thread/b9aa36ead6935c42/faa0f4df3e89060f

PNG::Color::Black
HGR_GREEN =

color=0,4

PNG::Color.new(0x2F,0xB8,0x1F,0xFF)
HGR_VIOLET =

color=2

PNG::Color.new(0xC8,0x47,0xE4,0xFF)
HGR_WHITE =

color=3,7

PNG::Color::White
HGR_ORANGE =

color=5

PNG::Color.new(0xC7,0x70,0x28,0xFF)
HGR_BLUE =

color=6

PNG::Color.new(0x30,0x8F,0xE3,0xFF)
HGR_COLS = 
40*7
HGR_ROWS = 
8*8*3
SCALE = 
2
@@scanline_offsets =

per Apple // Reference Manual for //e chapter 2, pages 22-35 also TechNote - Apple IIe #3 Double High-Resolution Graphics - web.pdx.edu/~heiss/technotes/aiie/tn.aiie.03.html HGR screen consists of 3 bands of 8 rows of 8 scanlines for each absolute scanline, what is the offset into screen ram that the 40 bytes for this scanline is stored?

Array.new(HGR_ROWS)

Class Method Summary collapse

Class Method Details

.buffer_to_png(buffer, pallete_mode = :amber) ⇒ Object 



94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
 
# File 'lib/HGR.rb', line 94

def HGR.buffer_to_png(buffer,pallete_mode=:amber)
	canvas = PNG::Canvas.new HGR_COLS*SCALE, HGR_ROWS*SCALE, PNG::Color::Black
	0.upto(HGR_ROWS-1) do |y|
		last_bit_set=false
		0.upto(39) do |x_byte|
			offset=@@scanline_offsets[y]+x_byte
			current_byte=buffer[offset]				
			current_byte=0 if current_byte.nil? #if we overrun the buffer then assume it's black
			0.upto(6) do |x_bit|
				x=x_byte*7+x_bit
				bit_set=((current_byte & (2**x_bit))>0)
				if (bit_set) then
					if pallete_mode==:colour then
						if (last_bit_set) then 
							#adjacent pixels should both be white
							set_pixel(canvas,x-1,y,HGR_WHITE) 
							set_pixel(canvas,x,y,HGR_WHITE)
						else
							if current_byte>=0x80 then
								pallete=[HGR_BLUE,HGR_ORANGE]
							else
								pallete=[HGR_VIOLET,HGR_GREEN]
							end
							this_pixel_colour=pallete[x%2]
							set_pixel(canvas,x,y,this_pixel_colour)
							set_pixel(canvas,x+1,y,this_pixel_colour)

						end
					else
						this_pixel_colour=PALLETE[pallete_mode]
						this_pixel_colour=PALLETE.values[0] if this_pixel_colour.nil?
						set_pixel(canvas,x,y,this_pixel_colour)
					end
				end
				last_bit_set=bit_set
			end
		end
	end
	png = PNG.new canvas
	png.raw_bytes
end

.can_be_hgr_screen?(buffer, memory_location = nil) ⇒ Boolean

HGR screen is 8192 bytes stored at either $2000 (page 1) or $4000 (page 2)

Returns:

  • (Boolean) 


69
70
71
72
73
74
75
76
77
78
79
80
81
82
 
# File 'lib/HGR.rb', line 69

def HGR.can_be_hgr_screen?(buffer,memory_location=nil)

#because only 120 out of every 128 bytes are shown, the last 8 bytes are not needed
	#in order to save a sector under dos 3.3 it was common to only store 8192=8184 (0x1FF8) bytes
	#sometimes an extra sector was included by mistake
		if (buffer.length>=8184 && buffer.length<=8192) && ((memory_location.nil?) || (memory_location==0))
			return true
		end
     
     if (buffer.length>=8184) && ((memory_location==0x2000) || (memory_location==0x4000))
			return true
		end
	false
end