Simple issue -

What's wrong with this code!? -

#include <windows.h>
#include "Resource.h"

const char *ClsName = "BasicApp";
const char *WndName = "A Simple Window";

LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg,
WPARAM wParam, LPARAM lParam);

HINSTANCE hInstance;

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
MSG Msg;
HWND hWnd;
WNDCLASSEX WndClsEx;

// Create the application window
WndClsEx.cbSize = sizeof(WNDCLASSEX);
WndClsEx.style = CS_HREDRAW | CS_VREDRAW;
WndClsEx.lpfnWndProc = WndProc;
WndClsEx.cbClsExtra = 0;
WndClsEx.cbWndExtra = 0;
WndClsEx.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(WindowIcon));
WndClsEx.hCursor = LoadCursor(hInstance, MAKEINTRESOURCE(WindowCursor));
WndClsEx.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
WndClsEx.lpszMenuName = NULL;
WndClsEx.lpszClassName = ClsName;
WndClsEx.hInstance = hInstance;
WndClsEx.hIconSm = LoadIcon(hInstance, MAKEINTRESOURCE(TaskbarIcon));

// Register the application
RegisterClassEx(&WndClsEx);

// Create the window object
hWnd = CreateWindow(ClsName,
WndName,
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hInstance,
NULL);

// Find out if the window was created
if( !hWnd ) // If the window was not created,
return 0; // stop the application

// Display the window to the user
ShowWindow(hWnd, SW_SHOWNORMAL);
UpdateWindow(hWnd);

// Decode and treat the messages
// as long as the application is running
while( GetMessage(&Msg, NULL, 0, 0) )
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}

return Msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{

static int Draw = 0;
static POINT CursorPosition, CursorPosition2;
static HICON Icon;

switch (Msg)
{

case WM_DESTROY :

PostQuitMessage(WM_QUIT);

break;

case WM_CLOSE :

DestroyWindow(hWnd);

break;

case WM_LBUTTONDOWN :

Draw = 1;
GetCursorPos(&CursorPosition);
ScreenToClient(hWnd, &CursorPosition);

break;

case WM_MOUSEMOVE :

if (Draw != 0)
{

GetCursorPos(&CursorPosition2);
ScreenToClient(hWnd, &CursorPosition2);
InvalidateRect(hWnd, NULL, true);

}

break;

case WM_LBUTTONUP :

HDC DC2;
Icon = LoadIcon(hInstance, MAKEINTRESOURCE(WindowIcon));

DC2 = GetDC(hWnd);

if (Draw == 1)
{

MoveToEx(DC2, CursorPosition.x, CursorPosition.y, NULL);
LineTo(DC2, CursorPosition2.x, CursorPosition2.y);
DrawIcon(DC2, 0, 0, Icon);

}

ReleaseDC(hWnd, DC2);

Draw = 0;

break;

case WM_PAINT :

if (Draw != 0)
{

HDC DC;
PAINTSTRUCT PS;

DC = BeginPaint(hWnd, &PS);

if (Draw == 1)
{

MoveToEx(DC, CursorPosition.x, CursorPosition.y, NULL);
LineTo(DC, CursorPosition2.x, CursorPosition2.y);

}

EndPaint(hWnd, &PS);

}

break;

}

return DefWindowProc(hWnd, Msg, wParam, lParam);

}

Why does it just display a question mark at the top left?

Thanks.

If you want any help, please describe the problem.
Do you have a compilation error?
Do you have a runtime error?
What's the exact error message?
...

This doesn't draw while you are dragging. Although it does keep track of all segments.

#include <windows.h>
#include <vector>

struct LineSegment
{
POINT pt1;
POINT pt2;
};

/* Declare Windows procedure */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

/* Make the class name into a global variable */
char szClassName[ ] = "CodeBlocksWindowsApp";

int WINAPI WinMain (HINSTANCE hThisInstance,
HINSTANCE hPrevInstance,
LPSTR lpszArgument,
int nFunsterStil)
{
HWND hwnd; /* This is the handle for our window */
MSG messages; /* Here messages to the application are saved */
WNDCLASSEX wincl; /* Data structure for the windowclass */

/* The Window structure */
wincl.hInstance = hThisInstance;
wincl.lpszClassName = szClassName;
wincl.lpfnWndProc = WindowProcedure; /* This function is called by windows */
wincl.style = CS_DBLCLKS; /* Catch double-clicks */
wincl.cbSize = sizeof (WNDCLASSEX);

/* Use default icon and mouse-pointer */
wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
wincl.lpszMenuName = NULL; /* No menu */
wincl.cbClsExtra = 0; /* No extra bytes after the window class */
wincl.cbWndExtra = 0; /* structure or the window instance */
/* Use Windows's default color as the background of the window */
wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

/* Register the window class, and if it fails quit the program */
if (!RegisterClassEx (&wincl))
return 0;

/* The class is registered, let's create the program*/
hwnd = CreateWindowEx (
0, /* Extended possibilites for variation */
szClassName, /* Classname */
"Code::Blocks Template Windows App", /* Title Text */
WS_OVERLAPPEDWINDOW, /* default window */
CW_USEDEFAULT, /* Windows decides the position */
CW_USEDEFAULT, /* where the window ends up on the screen */
544, /* The programs width */
375, /* and height in pixels */
HWND_DESKTOP, /* The window is a child-window to desktop */
NULL, /* No menu */
hThisInstance, /* Program Instance handler */
NULL /* No Window Creation data */
);

/* Make the window visible on the screen */
ShowWindow (hwnd, nFunsterStil);

/* Run the message loop. It will run until GetMessage() returns 0 */
while (GetMessage (&messages, NULL, 0, 0))
{
/* Translate virtual-key messages into character messages */
TranslateMessage(&messages);
/* Send message to WindowProcedure */
DispatchMessage(&messages);
}

/* The program return-value is 0 - The value that PostQuitMessage() gave */
return messages.wParam;
}

/* This function is called by the Windows function DispatchMessage() */

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static int Draw = 0;
static LineSegment LineObj;
static std::vector<LineSegment> Segments;
PAINTSTRUCT ps;
HDC hPaintDC;
std::vector<LineSegment>::iterator it;

switch (message) /* handle the messages */
{
case WM_LBUTTONDOWN:
::GetCursorPos(&LineObj.pt1);
::ScreenToClient(hwnd,&LineObj.pt1);
Draw = 1;
return 0;
case WM_LBUTTONUP:
if (Draw == 1)
{
::GetCursorPos(&LineObj.pt2);
::ScreenToClient(hwnd,&LineObj.pt2);
Segments.push_back(LineObj);
::RedrawWindow(hwnd,0,0,RDW_INVALIDATE | RDW_ERASE);
Draw = 0;
}
return 0;
case WM_PAINT:
hPaintDC = ::BeginPaint(hwnd,&ps);

it = Segments.begin();

while (it != Segments.end())
{
::MoveToEx(hPaintDC,it->pt1.x,it->pt1.y,0);
::LineTo(hPaintDC,it->pt2.x,it->pt2.y);
++it;
}

::EndPaint(hwnd,&ps);

return 0;
case WM_DESTROY:
PostQuitMessage (0); /* send a WM_QUIT to the message queue */
break;
default: /* for messages that we don't deal with */
return DefWindowProc (hwnd, message, wParam, lParam);
}

return 0;
}

James : Isn't there any other method? I don't even understand what just happened!

Marc G : Mind WinSpy++ :p -

Thanks.

In the second problem I am drawing an image but the wrong one comes up - check it out(Borland C++ Builder 6) -

Grrr, it still did not work :( - here's the updaed code -

#include <windows.h>
#include "Resource.h"

const char *ClsName = "BasicApp";
const char *WndName = "A Simple Window";

LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg,
WPARAM wParam, LPARAM lParam);

HINSTANCE hInstance;

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
MSG Msg;
HWND hWnd;
WNDCLASSEX WndClsEx;

// Create the application window
WndClsEx.cbSize = sizeof(WNDCLASSEX);
WndClsEx.style = CS_HREDRAW | CS_VREDRAW;
WndClsEx.lpfnWndProc = WndProc;
WndClsEx.cbClsExtra = 0;
WndClsEx.cbWndExtra = 0;
WndClsEx.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(WindowIcon));
WndClsEx.hCursor = LoadCursor(hInstance, MAKEINTRESOURCE(WindowCursor));
WndClsEx.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
WndClsEx.lpszMenuName = NULL;
WndClsEx.lpszClassName = ClsName;
WndClsEx.hInstance = hInstance;
WndClsEx.hIconSm = LoadIcon(hInstance, MAKEINTRESOURCE(TaskbarIcon));

// Register the application
RegisterClassEx(&WndClsEx);

// Create the window object
hWnd = CreateWindow(ClsName,
WndName,
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hInstance,
NULL);

// Find out if the window was created
if( !hWnd ) // If the window was not created,
return 0; // stop the application

// Display the window to the user
ShowWindow(hWnd, SW_SHOWNORMAL);
UpdateWindow(hWnd);

// Decode and treat the messages
// as long as the application is running
while( GetMessage(&Msg, NULL, 0, 0) )
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}

return Msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{

static int Draw = 0;
static POINT CursorPosition, CursorPosition2;
static HANDLE Icon;

switch (Msg)
{

case WM_DESTROY :

PostQuitMessage(WM_QUIT);

break;

case WM_CLOSE :

DestroyWindow(hWnd);

break;

case WM_LBUTTONDOWN :

Draw = 1;
GetCursorPos(&CursorPosition);
ScreenToClient(hWnd, &CursorPosition);

break;

case WM_MOUSEMOVE :

if (Draw != 0)
{

GetCursorPos(&CursorPosition2);
ScreenToClient(hWnd, &CursorPosition2);
InvalidateRect(hWnd, NULL, true);

}

break;

case WM_LBUTTONUP :

HDC DC2;
Icon = LoadImage(hInstance, MAKEINTRESOURCE(WindowIcon), IMAGE_ICON, 300, 300, LR_DEFAULTCOLOR | LR_DEFAULTSIZE);

DC2 = GetDC(hWnd);

if (Draw == 1)
{

MoveToEx(DC2, CursorPosition.x, CursorPosition.y, NULL);
LineTo(DC2, CursorPosition2.x, CursorPosition2.y);
DrawIcon(DC2, 0, 0, Icon);

}

ReleaseDC(hWnd, DC2);

Draw = 0;

break;

case WM_PAINT :

if (Draw != 0)
{

HDC DC;
PAINTSTRUCT PS;

DC = BeginPaint(hWnd, &PS);

if (Draw == 1)
{

MoveToEx(DC, CursorPosition.x, CursorPosition.y, NULL);
LineTo(DC, CursorPosition2.x, CursorPosition2.y);

}

EndPaint(hWnd, &PS);

}

break;

}

return DefWindowProc(hWnd, Msg, wParam, lParam);

}

Thanks.

LoadImage() could be used just once to get a handle to the icon. (you do not have to load the image every time WM_LBUTTONUP is handled.
I know. The reason I do it is because when it works once I like to do it again, sort of like a mini party or hooray :)

As for the rest its the first time I used the function...

Are there any ideas for why that unusual image pops up?

Thanks.

Yip I did :( and it had the same results.