I get the following error(s) on my program that captures the mouse and then draws a line.
Errors:
1>------ Build started: Project: Capture_Mouse_Line, Configuration: Debug Win32 ------
1>
main.cpp
1>main.obj : error LNK2001: unresolved external symbol "public:
static long * Line::yc2" (?yc2@Line@@2PAJA)
1>main.obj : error LNK2001: unresolved external symbol "public:
static long * Line::xc2" (?xc2@Line@@2PAJA)
1>main.obj : error LNK2001: unresolved external symbol "public:
static long * Line::yc1" (?yc1@Line@@2PAJA)
1>main.obj : error LNK2001: unresolved external symbol "public:
static long * Line::xc1" (?xc1@Line@@2PAJA)
1>MSVCRTD.lib(crtexe.obj) : error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup
1>D:\Visual C++ Projects\Capture_Mouse_Line\Debug\Capture_Mouse_Line.exe : fatal error LNK1120: 5 unresolved externals
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
Here is my code:
#include<allegro5\allegro.h>
#include<allegro5\allegro_native_dialog.h>
#include<allegro5\allegro_primitives.h>
#include<Windows.h>
#include<allegro5\allegro_windows.h>
#ifndef WIDTH
#define WIDTH 1440
#endif
#ifndef HEIGHT
#define HEIGHT 900
#endif
class Line
{
public:
static void ErasePreviousLine();
static void DrawLine(long* x, long* y,long* x2,long* y2);
static bool Erasable();
static long* xc1;
static long* yc1;
static long* xc2;
static long* yc2;
};
void Line::ErasePreviousLine()
{
delete xc1;
xc1 = NULL;
delete yc1;
yc1 = NULL;
delete xc2;
xc2 = NULL;
delete yc2;
yc2 = NULL;
}
bool Line::Erasable()
{
if(xc1 && yc1 && xc2 && yc2 == NULL)
{
return false;
}
else
{
return true;
}
}
void Line::DrawLine(long* x,long* y,long* x2,long* y2)
{
if(!al_init_primitives_addon())
{
al_show_native_message_box(NULL,NULL,NULL,"failed to initialize allegro",
NULL,NULL);
}
xc1 = x;
yc1 = y;
xc2 = x2;
yc2 = y2;
al_draw_line((float)*xc1, (float)*yc1, (float)*xc2, (float)*yc2,al_map_rgb(255,0,255), 1);
delete x;
delete y;
delete x2;
delete y2;
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
MSG msg;
ALLEGRO_DISPLAY* display = NULL;
if(!al_init())
{
al_show_native_message_box(NULL,NULL,NULL,"failed to initialize allegro",
NULL,NULL);
return -1;
}
display = al_create_display(WIDTH,HEIGHT);
if(!display)
{
al_show_native_message_box(NULL,NULL,NULL,"failed to initialize display",
NULL,NULL);
return -1;
}
HWND hwnd = al_get_win_window_handle(display);
if(hwnd == NULL)
{
MessageBox(NULL, "Window Creation Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
while(GetMessage(&msg, NULL, 0, 0) > 0)
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
static bool bIsCaptured;
static POINTS ptsBegin;
static POINTS ptsEnd;
switch(msg)
{
case WM_LBUTTONDOWN:
SetCapture(hwnd);
bIsCaptured = true;
ptsBegin = MAKEPOINTS(lParam);
return 0;
case WM_MOUSEMOVE:
if(wParam & MK_LBUTTON)
{
if(!Line::Erasable())
{
return 0;
}
Line::ErasePreviousLine();
ptsEnd = MAKEPOINTS(lParam);
Line::DrawLine(new long(ptsBegin.x),new long(ptsBegin.y),new long(ptsEnd.x),new long(ptsEnd.y));
}
break;
case WM_LBUTTONUP:
bIsCaptured = false;
ReleaseCapture();
break;
case WM_ACTIVATEAPP:
{
if(wParam == TRUE)
{
if(bIsCaptured){
SetCapture(hwnd);}
}
}
break;
}
return 0;
}
