我正在为DOSBOX编写一个汇编绘画程序,用于学校项目。在我的程序中,用户使用左键以特定颜色绘制像素。我在13号模式下直接写入。用户可以通过右键更改颜色,这将读取鼠标指向的像素的颜色。
这很好地工作,直到用户启动某个旨在清除屏幕并显示可供选择的调色板颜色的子例程(具有相同的右键功能)。然后,用户在调色板上右键单击,并使用int 10h,0dh读取颜色。无论用户在调色板屏幕上右键单击哪里,稍后由用户写入屏幕的颜色始终是白色。
简而言之,右键单击任何位置都会正确更改画笔颜色,但如果在调色板模式下进行,则随后的颜色始终为白色。 以下是我的代码:
GRAPHICS equ 13h
H_HOTSPOT equ 7
V_HOTSPOT equ 7
H_RES equ 320
V_RES equ 200
PIXELCOUNT equ H_RES*V_RES
DISPLAY_SEG equ 0A000h
EXIT_KEY equ 1071h ; q key
COLORPICKER_KEY equ 1177h ; w key
PALETTE_SIZE equ 16
SQUARE_SIZE equ 10
SQUARE_PADDING equ 2
SQUARE_ROW_JUMP equ H_RES - SQUARE_SIZE
PALETTE_ROW_JUMP equ H_RES - (SQUARE_PADDING + SQUARE_SIZE)*PALETTE_SIZE
sseg SEGMENT
db 256 dup(?)
sseg ENDS
dseg SEGMENT
stdBrushMask dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 0000000100000000b
dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 1111111011111111b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
dw 1111111011111111b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
dw 0000000100000000b
stdBrushHotSpots dw 7
dw 7
pickerToolMask dw 1111100001000001b
dw 1111100000000000b
dw 1111100000000000b
dw 1111100000000000b
dw 1111100000000000b
dw 1111000000000000b
dw 1110000000000000b
dw 1100000000000000b
dw 1000000000000000b
dw 1000000000000000b
dw 1000000000000000b
dw 1000000000011111b
dw 0000000000111111b
dw 0000000001111111b
dw 0000000011111111b
dw 0000111111111111b
dw 0000000000000000b
dw 0000001100011100b
dw 0000001111111110b
dw 0000000111111110b
dw 0000000111111110b
dw 0000001111111100b
dw 0000011111111100b
dw 0000111111111100b
dw 0001111111111110b
dw 0011111111100110b
dw 0001111111000000b
dw 0001111110000000b
dw 0011111100000000b
dw 0111001000000000b
dw 0110000000000000b
dw 0000000000000000b
pickerToolHotSpots dw 1
dw 14
foreground_color dw 000fh
background_color dw 0000h
colorpicker_flag db 00
prev_position dw H_RES ; Cache of the last drawn pixel's coordinates, to avoid duplicate writes.
dw V_RES
pos_backup dw H_RES/2
dw V_RES/2 ; Cache of the mouse position before switching to palette mode or back.
video_mode_not_available db "Mode 13h is not supported on this computer. To use this program, get a VGA or MCGA graphics card / monitor.$"
display_backup db PIXELCOUNT dup(?)
dseg ENDS
cseg SEGMENT
assume cs:cseg, ds:dseg, ss:sseg
;---------------Mouse Procs-------------
stdBrush PROC
push bx cx ax dx
mov ax, dseg
mov es, ax
mov bx, stdBrushHotSpots
mov cx, stdBrushHotSpots + 2
mov ax, 9
mov dx, offset stdBrushMask
int 33h
mov ax, DISPLAY_SEG
mov es, ax
pop dx ax cx bx
ret
stdBrush ENDP
pickerTool PROC
push bx cx ax dx
mov ax, dseg
mov es, ax
mov bx, pickerToolHotSpots
mov cx, pickerToolHotSpots + 2
mov ax, 9
mov dx, offset pickerToolMask
int 33h
mov ax, DISPLAY_SEG
mov es, ax
pop dx ax cx bx
ret
pickerTool ENDP
mouseReset PROC
push ax
mov ax, 0
int 33h
pop ax
ret
mouseReset ENDP
showCursor PROC
push ax
mov ax, 1
int 33h
pop ax
ret
showCursor ENDP
hideCursor PROC
push ax
mov ax, 2
int 33h
pop ax
ret
hideCursor ENDP
getCursorStat PROC
push ax
mov ax, 3
int 33h
pop ax
ret
getCursorStat ENDP
initCursor PROC
mov ax, dseg
mov es, ax
call mouseReset
call stdBrush
call showCursor
mov ax, DISPLAY_SEG
mov es, ax
ret
initCursor ENDP
;--------------------Graphics Procs-------------
graphicsCompat PROC
; Checks if mode 13h is supported on this machine.
mov ax, 1a00h
int 10h ; Get display combination
cmp al, 1ah
je mode_13_supported
mov ah, 9
mov dx, offset video_mode_not_available
int 21h ; Display error message
inc sp ; Discard the return address
inc sp
push offset exit ; Replace return address with exit procedure address
ret ; Return to exit procedure.
mode_13_supported:
;No error, mode 13 is supported
ret
graphicsCompat ENDP
graphicsMode PROC
mov ah, 0
mov al, GRAPHICS
int 10h
ret
graphicsMode ENDP
pixel PROC
push bp
mov bp, sp
push ax bx cx dx
xor bx, bx
mov cx, ss:[bp+6] ; x coord
mov dx, ss:[bp+4] ; y coord
cmp cx, H_RES
jnc pixel_outofbounds
cmp dx, V_RES
jnc pixel_outofbounds
mov ax, H_RES
mul dx
add ax, cx
mov di, ax ; Puts the pixel's offset in di
mov ax, ss:[bp+8] ; read color argument
stosb
pixel_outofbounds:
pop dx cx bx ax bp
ret 6
pixel ENDP
backupScreen PROC
push ax di si
mov ax, DISPLAY_SEG
mov ds, ax
mov ax, dseg
mov es, ax
mov cx, PIXELCOUNT
mov si, 0
mov di, offset display_backup
call hideCursor
rep movsb
call showCursor
mov ds, ax
mov ax, DISPLAY_SEG
mov es, ax
pop si di ax
ret
backupScreen ENDP
restoreScreen PROC
push di si
mov cx, PIXELCOUNT
mov si, offset display_backup
mov di, 0
rep movsb
pop si di
ret
restoreScreen ENDP
;-------------------Colorpicker Procs----------
paletteModeToggle PROC
push ax
call hideCursor
mov pos_backup, cx
mov pos_backup+2, dx
mov al, colorpicker_flag
not al
mov colorpicker_flag, al
test al, al
jz palette_mode_off
palette_mode_on:
call backupScreen
call graphicsMode
call paletteDraw
call showCursor
call pickerTool
pop ax
jmp input_loop
palette_mode_off:
call graphicsMode
call restoreScreen
call showCursor
call stdBrush
pop ax
jmp input_loop
paletteModeToggle ENDP
paletteSquareDraw PROC
push bp
mov bp, sp
push ax cx dx
mov dx, ss:[bp+4] ; retrieves ypos
mov cx, ss:[bp+6] ; retrieves xpos
mov ax, H_RES
mul dx
add ax, cx
mov di, ax ; Puts the real pixel address in di.
mov ax, ss:[bp+8] ;retrieves color
xor ch, ch
square_loop:
xor cl, cl
square_row_loop:
stosb
inc cl ; increment horizontal counter
cmp cl, SQUARE_SIZE
jb square_row_loop
inc ch ; increment the vertical counter
add di, SQUARE_ROW_JUMP ; move di to the start of the next row
cmp ch, SQUARE_SIZE
jb square_loop
pop dx cx ax bp
ret 6
paletteSquareDraw ENDP
paletteDraw PROC
xor cx, cx ; xpos = 0
xor dx, dx ; ypos = 0
xor ax, ax ; color = 0
xor bx, bx ; squarecounter = 0
palette_loop: ; for i in paletterows:
xor bl, bl
add dx, SQUARE_PADDING
palette_row_loop: ; for j in palettecols:
add cx, SQUARE_PADDING ; xpos += padding
push ax
push cx
push dx
call paletteSquareDraw ; DrawSquare()
add cx, SQUARE_SIZE
inc ax ; next color
inc bl ; squarecounter++
cmp bl, PALETTE_SIZE
jb palette_row_loop
; prep for new row
xor bl, bl
xor cx, cx
add dx, SQUARE_SIZE
inc bh
cmp bh, PALETTE_SIZE
jb palette_loop
ret
paletteDraw ENDP
pickColor PROC
push bp
mov bp, sp
push ax dx si
mov dx, ss:[bp+4]
mov cx, ss:[bp+6]
xor bh, bh
mov ah, 0dh
int 10h
mov foreground_color, ax
pop si dx ax bp
ret 4
pickColor ENDP
;--------------------------Program Entry-------------------------
main:
mov ax, dseg
mov ds, ax
mov ax, sseg
mov ss, ax
mov ax, DISPLAY_SEG
mov es, ax
call graphicsCompat
call graphicsMode
call mouseReset
call stdBrush
call showCursor
mov ax, DISPLAY_SEG
mov es, ax
input_loop:
;------------Mouse Input Detection------------------------------------
call getCursorStat
shr bx, 1
jnc no_left_click
; Left click detected
mov al, colorpicker_flag
test al, al
jnz no_left_click ; no left clicks in palette mode.
shr cx, 1
cmp cx, prev_position
jnz draw_pixel
cmp dx, prev_position + 2
jz no_left_click
draw_pixel:
call hideCursor
mov ax, foreground_color
mov prev_position, cx
mov prev_position + 2, dx
push ax cx dx
call pixel
call showCursor
no_left_click:
mov bx, 1
mov ax, 6
int 33h
test bx, bx
jz keyboard_detection
; Right click detected
shr cx, 1
push cx dx
call pickColor
keyboard_detection:
;------------Keyboard Input Detection----------------------------------
mov ah, 1
int 16h
jz no_keystroke
xor ah, ah
int 16h
cmp ax, EXIT_KEY
je exit
cmp ax, COLORPICKER_KEY
jne no_palette_toggle
jmp paletteModeToggle
no_palette_toggle:
no_keystroke:
jmp input_loop
exit:
mov al, 3
mov ah, 0
int 10h
mov ax, 4c00h
int 21h
cseg ENDS
end main
清晰的截图: 在绘图模式下使用蓝色画笔。 切换到调色板模式后,我右键单击了亮绿色的正方形。 切换回绘图模式后,画笔开始绘制白色像素。 在绘图模式下右键单击蓝色像素。 画笔颜色正确地转换为蓝色。
在此版本中,我使用int 10h,0dh来读取像素,但是当我尝试直接从A000段读取时(在调试期间,当屏幕明显不为空时,该段似乎完全填充为零),出现了相同的问题。我切换到使用int 10h,以查看直接读取是否存在问题。
我确实进行了直接写入操作。
最重要的问题是:我在读取这些像素时做错了什么?为什么我的程序最初能够正确读取像素颜色,但在基本清除屏幕、更改光标并绘制大量彩色正方形后,它只能读取白色?为什么在清除这些正方形并将屏幕恢复到先前状态之后它又可以工作了?
ret #n
在过程中释放堆栈... 嗯...还在寻找任何东西。(抱歉) - Ped7gxchg
操作数中没有段寄存器,即使在单边也是如此,但为什么不直接写出来让TASM告诉你呢?我记得在256B intros中经常使用push 0A000h
pop es
,所以这可能是初始化es
的最短(只是稍微慢一点)方法(除非你已经意外地将0xA000存储在某个寄存器中,那么mov es,reg
当然更好)。我认为VGA VRAM应该在调试期间完全可读,没有任何问题,所以这很令人不安。你使用什么调试器,以及如何使用?也许它会引起其他人的共鸣(我不再使用DOS工具)。 - Ped7g