Reputation: 1297

Set console window size on Windows

I know that there is a lot questions about how to set console size. But all found solutions are the same to my and my code doesn't works for me.

Ok, so for setting console window size, I need two functions. They are SetConsoleScreenBufferSize() and SetConsoleWindowInfo(). First version of my function:

bool SetWindowSize(size_t width, size_t height)
{
    HANDLE output_handle = ::GetStdHandle(STD_OUTPUT_HANDLE);
    if(output_handle == INVALID_HANDLE_VALUE)
        return false;

    COORD coord = {};
    coord.X = static_cast<SHORT>(width);
    coord.Y = static_cast<SHORT>(height);
    if(::SetConsoleScreenBufferSize(output_handle, coord) == FALSE)
        return false;

    SMALL_RECT rect = {};
    rect.Bottom = coord.X - 1;
    rect.Right = coord.Y - 1;
    return (::SetConsoleWindowInfo(output_handle, TRUE, &rect) != FALSE);
}

SetConsoleScreenBufferSize() will work not for all values. From documentation:

The specified width and height cannot be less than the width and height of the console screen buffer's window

Lets try to get current window's size and call our function. To get window size, I need GetConsoleScreenBufferInfo() function. main() test code:

HANDLE output_handle = ::GetStdHandle(STD_OUTPUT_HANDLE);
if(output_handle == INVALID_HANDLE_VALUE)
    return 0;
CONSOLE_SCREEN_BUFFER_INFO info = {};
if(::GetConsoleScreenBufferInfo(output_handle, &info) == FALSE)
    return 0;
size_t width = info.srWindow.Right - info.srWindow.Left;
size_t height = info.srWindow.Bottom - info.srWindow.Top;
bool suc = SetWindowSize(width + 1, height + 1);

In this case SetConsoleScreenBufferSize() works fine. Next function is SetConsoleWindowInfo(). This function will work in case:

The function fails if the specified window rectangle extends beyond the boundaries of the console screen buffer. This means that the Top and Left members of the lpConsoleWindow rectangle (or the calculated top and left coordinates, if bAbsolute is FALSE) cannot be less than zero. Similarly, the Bottom and Right members (or the calculated bottom and right coordinates) cannot be greater than (screen buffer height – 1) and (screen buffer width – 1), respectively. The function also fails if the Right member (or calculated right coordinate) is less than or equal to the Left member (or calculated left coordinate) or if the Bottom member (or calculated bottom coordinate) is less than or equal to the Top member (or calculated top coordinate).

In our case, the values of rectangle are the same (because Left and Top are zeroes) as values of info.srWindow rectangle after call of GetConsoleScreenBufferInfo(). But! SetConsoleWindowInfo() fails with next ::GetLastError()

@err,hr ERROR_INVALID_PARAMETER : The parameter is incorrect.   unsigned int

If I swap calls of this two functions:

bool SetWindowSize(size_t width, size_t height)
{
    HANDLE output_handle = ::GetStdHandle(STD_OUTPUT_HANDLE);
    if(output_handle == INVALID_HANDLE_VALUE)
        return false;

    SMALL_RECT rect = {};
    rect.Bottom = static_cast<SHORT>(width);
    rect.Right = static_cast<SHORT>(height);
    if(::SetConsoleWindowInfo(output_handle, TRUE, &rect) == FALSE)
        return false;

    COORD coord = {};
    coord.X = rect.Bottom + 1;
    coord.Y = rect.Right + 1;

    return (::SetConsoleScreenBufferSize(output_handle, coord) != FALSE);
}

then I will have the same error.

So, how can I use SetConsoleScreenBufferSize() and SetConsoleWindowInfo() correctly ?

Upvotes: 3

Answers (3)

anzz1

Reputation: 121

I solved this issue by making these functions which can get/set the console window/buffer sizes in characters taking into account increasing the buffer size if needed, console font size, window borders and all that jazz.

The variables at play here to understand:

Windows have a client area, which is the coordinates (in pixels) excluding the borders
Windows have a window area, which is the coordinates (in pixels) including the borders
Console has a view area, which is the window size in characters
Console has a screen buffer, which is the scrollable buffer size in characters
Console has a font size, which is the character size in coordinates (pixels)
Console's screen buffer cannot be smaller than the view area

You need to correctly mix and match these around to achieve the desired result.

These functions are plug-n-play so you don't need to worry about none of that though.

All functions return TRUE (1) on success and FALSE (0) on error.