painting.s

;
;  painting.s
;  General rendering routines for 80 column text elements
;
;  Created by Quinn Dunki on 8/15/14.
;  Copyright (c) 2014 One Girl, One Laptop Productions. All rights reserved.
;


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; WGDesktop
; Paints the desktop pattern (assumes 80 cols)
;
WGDesktop:
	pha
	lda #'W'
	sta WGClearScreen_charPage1+1
	lda #'V'
	bra WGClearScreen_common

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; WGClearScreen
; Clears the text screen (assumes 80 cols)
;
WGClearScreen:
	pha
	lda #' ' + $80
	sta WGClearScreen_charPage1+1
WGClearScreen_common:
	sta WGClearScreen_charPage2+1
	SAVE_XY
	SETSWITCH PAGE2OFF
	ldx #23
WGClearScreen_lineLoop:
	lda TEXTLINES_L,x	; Compute video memory address of line
	sta WGClearScreen_charLoop1+1
	sta WGClearScreen_charLoop2+1
	lda TEXTLINES_H,x
	sta WGClearScreen_charLoop1+2
	sta WGClearScreen_charLoop2+2
	ldy #39
WGClearScreen_charPage1:
	lda #$FF			; Self-modifying code!
WGClearScreen_charLoop1:
	sta $FFFF,y			; Self-modifying code!
	dey
	bpl WGClearScreen_charLoop1
	SETSWITCH PAGE2ON
	ldy #39
WGClearScreen_charPage2:
	lda #$FF			; Self-modifying code!
WGClearScreen_charLoop2:
	sta $FFFF,y			; Self-modifying code!
	dey
	bpl WGClearScreen_charLoop2
	SETSWITCH PAGE2OFF
	dex
	bpl WGClearScreen_lineLoop
	RESTORE_XY
	pla
	rts


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; WGPlot
; Plots a character at global cursor position (assumes 80 cols)
; A: Character to plot (Apple format)
; Side effects: Clobbers BASL,BASH
;
WGPlot:
	SAVE_XY
	pha

	ldx WG_CURSORY
	lda TEXTLINES_L,x	; Compute video memory address of point
	sta BASL
	lda TEXTLINES_H,x
	sta BASH

	lda WG_CURSORX
	lsr
	clc
	adc BASL
	sta BASL
	bcc WGPlot_SkipInc
	inc BASH
WGPlot_SkipInc:

	lda WG_CURSORX			; X even?
	ror
	bcs WGPlot_xOdd

	SETSWITCH PAGE2ON		; Plot the character
	pla
	sta (BASL)
	jmp WGPlot_done

WGPlot_xOdd:
	SETSWITCH PAGE2OFF	; Plot the character
	pla
	sta (BASL)

WGPlot_done:
	SETSWITCH PAGE2OFF
	RESTORE_XY
	rts


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; WGPrint
; Prints a null-terminated ASCII string at the current view's
; cursor position. Clips to current view.
; PARAM0: String pointer, LSB
; PARAM1: String pointer, MSB
; V: If set, characters are printed raw with no high bit alterations
; Side effects: Clobbers SA,BASL,BASH
;
WGPrint:
	SAVE_AXY
	SAVE_ZPS

	lda #%10000000
	ldx #%00111111
	bvc WGPrint_setupMask
	lda #0
	ldx #$ff
	clv

WGPrint_setupMask:
	sta WGPrint_specialMask
	stx WGPrint_setupMaskInverse

	; Start checking clipping boundaries
	lda WG_LOCALCURSORY
	cmp WG_VIEWCLIP+3
	bcs WGPrint_leapDone	; Entire string is below the clip box

	jsr WGStrLen			; We'll need the length of the string
	sta SCRATCH1

	LDX_ACTIVEVIEW			; Cache view width for later
	lda WG_VIEWRECORDS+7,x
	sta WG_SCRATCHA

	ldy #0

WGPrint_lineLoopFirst:		; Calculating start of first line is slightly different
	lda WG_LOCALCURSORY
	cmp WG_VIEWCLIP+1
	bcc WGPrint_skipToEndFirst	; This line is above the clip box

	lda WG_LOCALCURSORX		; Find start of line within clip box
	cmp WG_VIEWCLIP+0
	bcs WGPrint_visibleChars

	lda WG_VIEWCLIP+0		; Line begins before left clip plane
	sec						; Advance string index and advance cursor into clip box
	sbc WG_LOCALCURSORX
	tay
	lda WG_VIEWCLIP+0
	sta WG_LOCALCURSORX
	bra WGPrint_visibleChars

WGPrint_leapDone:
	bra WGPrint_done

WGPrint_skipToEndFirst:
	lda WG_SCRATCHA			; Skip string index ahead by distance to EOL
	sec
	sbc WG_LOCALCURSORX
	cmp SCRATCH1
	bcs WGPrint_done		; EOL is past the end of the string, so we're done
	tay

	lda WG_SCRATCHA			; Skip cursor ahead to EOL
	sta WG_LOCALCURSORX
	bra WGPrint_nextLine

WGPrint_skipToEnd:
	tya						; Skip string index ahead by distance to EOL
	clc
	adc WG_SCRATCHA
	cmp SCRATCH1
	bcs WGPrint_done		; EOL is past the end of the string, so we're done
	tay

	lda WG_SCRATCHA			; Skip cursor ahead to EOL
	sta WG_LOCALCURSORX
	bra WGPrint_nextLine

WGPrint_lineLoop:
	lda WG_LOCALCURSORY
	cmp WG_VIEWCLIP+1
	bcc WGPrint_skipToEnd	; This line is above the clip box

	lda WG_LOCALCURSORX		; Find start of line within clip box
	cmp WG_VIEWCLIP+0
	bcs WGPrint_visibleChars

	tya
	clc
	adc WG_VIEWCLIP+0		; Jump ahead by left span
	tay

	lda WG_VIEWCLIP+0		; Set cursor to left edge of visible area
	sta WG_LOCALCURSORX

WGPrint_visibleChars:
	jsr WGSyncGlobalCursor

	lda INVERSE
	cmp #CHAR_INVERSE
	beq WGPrint_charLoopInverse
	
WGPrint_charLoopNormal:
	lda (PARAM0),y			; Draw current character
	beq WGPrint_done
	ora WGPrint_specialMask
	jsr WGPlot
	iny

	inc WG_CURSORX			; Advance cursors
	inc WG_LOCALCURSORX

	lda WG_LOCALCURSORX
	cmp WG_SCRATCHA			; Check for wrap boundary
	beq WGPrint_nextLine
	cmp WG_VIEWCLIP+2		; Check for right clip plane
	beq WGPrint_endVisible
	bra WGPrint_charLoopNormal

WGPrint_done:				; This is in the middle here to keep local branches in range
	RESTORE_ZPS
	RESTORE_AXY
	rts

WGPrint_endVisible:
	tya
	clc
	adc WG_VIEWCLIP+4		; Advance string index by right span
	cmp SCRATCH1
	bcs WGPrint_done
	tay

WGPrint_nextLine:
	inc WG_LOCALCURSORY			; Advance cursor
	lda WG_LOCALCURSORY
	cmp WG_VIEWCLIP+3			; Check for bottom clip plane
	beq WGPrint_done
	cmp WG_VIEWRECORDS+8,x		; Check for bottom of view
	beq WGPrint_done
	lda (PARAM0),y				; Check for end string landing exactly at line end
	beq WGPrint_done
	
	stz WG_LOCALCURSORX
	bra WGPrint_lineLoop

WGPrint_charLoopInverse:
	lda (PARAM0),y			; Draw current character
	beq WGPrint_done
	cmp #$60
	bcc WGPrint_charLoopInverseLow
	and #%01111111			; Inverse lowercase is in alternate character set
	bra WGPrint_charLoopInversePlot

WGPrint_charLoopInverseLow:
	and WGPrint_setupMaskInverse	; Normal inverse

WGPrint_charLoopInversePlot:
	jsr WGPlot
	iny

	inc WG_CURSORX			; Advance cursors
	inc WG_LOCALCURSORX

	lda WG_LOCALCURSORX
	cmp WG_SCRATCHA			; Check for wrap boundary
	beq WGPrint_nextLine
	cmp WG_VIEWCLIP+2		; Check for right clip plane
	beq WGPrint_endVisible
	bra WGPrint_charLoopInverse

WGPrint_specialMask:
	.byte 0
WGPrint_setupMaskInverse:
	.byte 0