How to make right drawing of rectangele and ellipse on ASM? - windows

Question

Good afternoon. I'm currently building a Paint program in assembler using win32api. The functionality, as in the original Paint program, is as simple as possible: "The ability to draw with a brush, point, straight line, create a rectangle, ellipse, write text"
A problem occurred while creating shapes
Thats how my programm looks like:
Thats how problem looks like:
Code of drawing rectangle and ellipse procedure:
.elseif eax == WM_MOUSEMOVE
.if wParam == MK_LBUTTON
invoke GetCursorPos, addr CurPos
.if flag == 4
mov ecx,lParam
mov eax,lParam
shr ecx,16
and eax,0ffffh
invoke Rectangle,hdc_bitmap, CurPos.x, CurPos.y, eax, ecx
.elseif flag == 5
mov ecx,lParam
mov eax,lParam
shr ecx,16
and eax,0ffffh
invoke Ellipse,hdc_bitmap, CurPos.x, CurPos.y, eax, ecx
.endif
.endif
The rectangle is created using the Rectangle function, where we conditionally pass "canvas" as the first parameter, then the next two parameters are the x, y coordinate of the top left corner, and the last two parameters are the x, y coordinate of the bottom right corner.
As planned, when I left-click on the canvas, I should fix the coordinates of this point (and not change them later), and pass them as the coordinates of the upper left corner. To find the coordinates of the lower right corner, I use the WM_MOUSEMOVE message in which wParam will store MK_LBUTTON, and lParam will contain x, y coordinates (in the code above everything is described in more detail and clearer)
But for some reason, when I click on the canvas with the left mouse button, I create a ready-made rectangle, and when moving the mouse, the entire rectangle moves, and not its lower right corner. And in addition, when moving, the square leaves, let's say, a "trace".
Ellipse is the same story.
If someone knows how to fix this, please tell me.
All program code:
.INC file
include windows.inc
include kernel32.inc
include user32.inc
include Comctl32.inc
include shell32.inc
include gdi32.inc
includelib kernel32.lib
includelib user32.lib
includelib Comctl32.lib
includelib shell32.lib
includelib gdi32.lib
DlgProc PROTO :HWND,:UINT,:WPARAM,:LPARAM
.const
IDD_DIALOG1 equ 101
;#########################################################################
;menu.mnu
IDR_MENU equ 10000
;----------------------------------------
IDM_File equ 10001
IDM_Open equ 10002
IDM_Save equ 10003
IDM_Close equ 10004
;----------------------------------------
IDM_Tools equ 10005
IDM_Brush equ 10006
IDM_Dot equ 10007
IDM_Line equ 10008
;----------------------------------------
IDM_Figures equ 10009
IDM_Rectangle equ 10010
IDM_Ellipse equ 10011
;----------------------------------------
IDM_Text equ 10012
;Res\SixRes.rc
MANIFEST equ 24
Paint equ 200
.data
id dd 200
hdc_bitmap dd 0
hbitmap dd 0
CurPos POINT <?>
.data?
flag dd ?
hInstance dd ?
hdc1 dd ?
;#########################################################################
.ASM file
.386
.model flat, stdcall ;32 bit memory model
option casemap :none ;case sensitive
include Six.inc
;include RADbg.inc
.code
start:
invoke GetModuleHandle,NULL
mov hInstance,eax
invoke InitCommonControls
invoke DialogBoxParam,hInstance,IDD_DIALOG1,NULL,addr DlgProc,NULL
invoke ExitProcess,0
;########################################################################
Draw proc
invoke BitBlt,hdc1, 0, 0, 750, 500, hdc_bitmap, 0, 0, SRCCOPY
ret
Draw endp
DlgProc proc hWin:HWND,uMsg:UINT,wParam:WPARAM,lParam:LPARAM
mov eax,uMsg
.if eax==WM_INITDIALOG
invoke LoadIcon, hInstance, id
invoke SendMessage, hWin, WM_SETICON, ICON_SMALL, eax
invoke GetDC,hWin
mov hdc1,eax
invoke CreateCompatibleDC,hdc1
mov hdc_bitmap, eax
invoke CreateCompatibleBitmap,hdc_bitmap, 750, 500
mov hbitmap, eax
invoke SelectObject, hdc_bitmap, hbitmap
invoke Rectangle, hdc_bitmap, 0, 0, 750, 500
invoke SetTimer, hWin, 12, 10, addr Draw
.elseif eax == WM_COMMAND
.if wParam == IDM_Close ; "Close"
jmp #F
.elseif wParam == IDM_Brush ; "Brush"
mov flag, 1
.elseif wParam == IDM_Dot ; "Dot"
mov flag, 2
.elseif wParam == IDM_Line ; "Line"
mov flag, 3
.elseif wParam == IDM_Rectangle ; "Rectangle"
mov flag, 4
.elseif wParam == IDM_Ellipse ; "Ellipse"
mov flag, 5
.elseif wParam == IDM_Text ; "Text"
mov flag, 6
.endif
.elseif eax == WM_MOUSEMOVE
.if wParam == MK_LBUTTON
invoke GetCursorPos, addr CurPos
.if flag == 1
mov ecx,lParam
mov eax,lParam
shr ecx,16
and eax,0ffffh
mov CurPos.y, ecx
mov CurPos.x, eax
invoke PolylineTo, hdc_bitmap, addr CurPos, 1
.elseif flag == 2
.elseif flag == 3
.elseif flag == 4
mov ecx,lParam
mov eax,lParam
shr ecx,16
and eax,0ffffh
invoke Rectangle,hdc_bitmap, CurPos.x, CurPos.y, eax, ecx
.elseif flag == 5
mov ecx,lParam
mov eax,lParam
shr ecx,16
and eax,0ffffh
invoke Ellipse,hdc_bitmap, CurPos.x, CurPos.y, eax, ecx
.elseif flag == 6
.endif
.endif
.elseif eax==WM_CLOSE
##:
invoke DeleteObject, hbitmap
invoke DeleteDC, hdc_bitmap
invoke ReleaseDC, hWin, hdc1
invoke KillTimer,hWin,12
invoke EndDialog,hWin,0
.else
mov eax,FALSE
ret
.endif
mov eax,TRUE
ret
DlgProc endp
end start
I tried initially to fix the coordinates of the beginning of the rectangle using the GetCursorPos function, when the left mouse button is pressed. But, for some reason, the result was not what I expected (