|00 @System &vector $2 &expansion $2 &wst $1 &rst $1 &metadata $2 &r $2 &g $2 &b $2 &debug $1 &state $1
|10 @Console &vector $2 &read $1 &pad $4 &type $1 &write $1 &error $1
|20 @Screen &vector $2 &width $2 &height $2 &auto $1 &pad $1 &x $2 &y $2 &addr $2 &pixel $1 &sprite $1
|90 @Mouse/vector $2 &x $2 &y $2 &state $5 &scrolly &scrolly-hb $1 &scrolly-lb $1



|58 @canvas-width
|1f @canvas-height

( zero page vars )
|00
@x $2
@y $2

(to run gui: `./run_ui.sh one_line_canvas.tal`)
(to run debugger: `../uxn/bin/uxnasm one_line_canvas.tal one_line_canvas.rom && ../uxn/bin/uxnemu ../beetbug.rom ./one_line_canvas.rom`)
%dbug  { #01 .System/debug DEO }
%PX { #01 .Screen/pixel DEO }

|0100
@on-reset
	setup-gui
	( draw canvas bounds )
	( top line )
	.canvas-width #01 ADD .canvas-width .canvas-height #01 SUB draw-h-line
    ( bot line )
	.canvas-width #01 ADD .canvas-width .canvas-height #02 MUL #01 ADD draw-h-line
	( left line )
	.canvas-height #01 ADD .canvas-width #01 SUB .canvas-height  draw-v-line
	( right line )
	.canvas-height #01 ADD .canvas-width #02 MUL #01 ADD .canvas-height draw-v-line
	;on-mouse .Mouse/vector DEO2
	BRK

@add-px-to-drawing
    ( figure out if px on on canvas )
    ( x too small )
    LIT2 =canvas-width .x LDZ2 GTH2 ?/end
    ( x too big )
    LIT2 =canvas-width #0002 MUL2 .x LDZ2 LTH2 ?/end
    ( y too small )
    LIT2 =canvas-height .y LDZ2 GTH2 ?/end
    ( y too big )
    LIT2 =canvas-height #0002 MUL2 .y LDZ2 LTH2 ?/end
    ( draw px to screen )
    .x LDZ2 .Screen/x DEO2
	.y LDZ2 .Screen/y DEO2
	#01 .Screen/pixel DEO
	&end
	JMP2r

@on-mouse ( -> )
	.Mouse/x DEI2 .x STZ2
	.Mouse/y DEI2 .y STZ2
	draw-cursor
	add-px-to-drawing
	BRK

@draw-cursor
	( clear fg )
	LIT2 0000 .Screen/x DEO2
	LIT2 0000 .Screen/y DEO2
	#c0 .Screen/pixel DEO
	( draw cursor sprite to fg )
	.x LDZ2 .Screen/x DEO2
	.y LDZ2 .Screen/y DEO2
	;cursor-sprite .Screen/addr DEO2
	#41 .Screen/sprite DEO
	JMP2r

@draw-v-line ( l x y )
    SWP ( l y x )
    #00 ( l y x 00 )
    SWP .Screen/x DEO2 ( l y )
    ( store vars )
    !{ &y $1 &l $1 }
    ,/y STR ,/l STR

    &loop
        ( set y )
        ,/y LDR DUP ( y y )
        #00 SWP ( y 00 y )
        .Screen/y DEO2 ( y )
        ( draw pixel )
        PX
        ( incrment y )
        INC ( y+1 )
        ,/y STR ( )
        ( decrement l )
        ,/l LDR #01 ( l 01 )
        SUB ( l-1 )
        ,/l STRk POP ( l )
        #00 NEQ ?&loop
	JMP2r

@draw-h-line ( l x y )
    #00 ( l x y 00 )
    SWP .Screen/y DEO2 ( l x )
    ( store vars )
    !{ &x $1 &l $1 }
    ,/x STR ,/l STR

    &loop
        ( set x )
        ,/x LDR DUP ( x x )
        #00 SWP ( x 00 x )
        .Screen/x DEO2 ( x )
        ( draw pixel )
        PX
        ( incrment x )
        INC ( x+1 )
        ,/x STR ( )
        ( decrement l )
        ,/l LDR #01 ( l 01 )
        SUB ( l-1 )
        ,/l STRk POP ( l )
        #00 NEQ ?&loop
	JMP2r

@setup-gui ( -- )
    (set screen height and width the 3x canvas size)
    LIT2 =canvas-width #0003 MUL2 .Screen/width DEO2
    LIT2 =canvas-height #0003 MUL2 .Screen/height DEO2
    (set basic color scheme)
	#f07f .System/r DEO2
	#f0d6 .System/g DEO2
	#f0b2 .System/b DEO2
	JMP2r


@cursor-sprite
	20 20 d8 20 20 00 00 00
(
. . # . . . . . 20
. . # . . . . . 20
# # . # # . . . d8
. . # . . . . . 20
. . # . . . . . 20
. . . . . . . . 7e
. . . . . . . . 3c
. . . . . . . . 18
)