CODEWITHSUNDEEP
c++windowswinapiconsole
user8087992
user8087992

Reputation:

Set the console window size to match screen buffer on Windows

Playing around with the console functions to control the layout of a console program, and I cannot change its size.

Currently, what I can do is disable resizing, remove buttons and change the buffer size, but if I try to resize the window itself, all attempts fail; albeit, some functions do resize the window, but in pixels, so scale is drastically off.

What I've done so far (not a C++ person, just fiddling around, go easy on syntax-isms):

#include <iostream>
#include <Windows.h>

using namespace std;

COORD conBufferSize = { 150, 40 };
SMALL_RECT conScreen = { 0, 0, 150, 40 };

CONSOLE_SCREEN_BUFFER_INFOEX csbie;

int main()
{   
    // console opened for application
    HWND hwConsole = GetConsoleWindow();

    // hide it
    ShowWindow(hwConsole, SW_HIDE);
    
    // get the style for it
    DWORD style = GetWindowLong(hwConsole, GWL_STYLE);

    // disable maximizing and minimizing and resizing
    style &= ~(WS_MAXIMIZEBOX | WS_MINIMIZEBOX | WS_SIZEBOX);
    SetWindowLong(hwConsole, GWL_STYLE, style);

    HANDLE hConsole = CreateConsoleScreenBuffer(GENERIC_READ | GENERIC_WRITE, 0, NULL, CONSOLE_TEXTMODE_BUFFER, NULL);

    SetConsoleScreenBufferSize(hConsole, conBufferSize);

    // this does nothing to the window itself as best I can tell
    // if by "window" it means what portion of the display window you view "into"
    // commented out here for functionality
    // SetConsoleWindowInfo(hConsole, TRUE, &conScreen);

    SetConsoleActiveScreenBuffer(hConsole);
    
    // this sequence works, but seems by accident
    // surely there is another method?
    csbie.cbSize = sizeof(csbie);
    GetConsoleScreenBufferInfoEx(hConsole, &csbie);
    csbie.srWindow = conScreen;
    SetConsoleScreenBufferInfoEx(hConsole, &csbie);

    // required to update styles
    // using the cx/cy parameters sets size in pixels
    // that is much smaller than buffer size which accounts for font size
    // therefore this "doesn't" work
    SetWindowPos(hwConsole, HWND_TOP, 0, 0, 0, 0, SWP_FRAMECHANGED | SWP_NOMOVE | SWP_NOSIZE| SWP_SHOWWINDOW);
    
    // to look at the console until close
    while (1) {

    }

    return 0;
}

Now from what I can reason, if I have a screen buffer that is 100 columns by 40 rows, that doesn't translate directly to the size of the window housing the buffer. So my next thought is that I need to determine how many pixels the current console font is using, then multiply the buffer dimensions by that to determine the pixel size and use SetWindowPos or the SetConsoleScreenBufferInfoEx methods.

One thing I am unsure about is why the srWindow attribute is able to modify the display window with a similar description to that of SetConsoleWindowInfo and yet that produces no discernable change.

Upvotes: 0

Views: 1821

Answers (1)

Strive Sun
Strive Sun

Reputation: 6289

One thing I am unsure about is why the srWindow attribute is able to modify the display window with a similar description to that of SetConsoleWindowInfo and yet that produces no discernable change.

According to the doc,

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).

Use GetConsoleScreenBufferInfoEx to get the size of the screen buffer (e.p: 120,30). As long as the SMALL_RECT set is less than 120, 30, you will see the screen buffer size change after calling SetConsoleActiveScreenBuffer.

SMALL_RECT conScreen = { 0, 0, 50, 20 };
...
SetConsoleWindowInfo(hConsole, TRUE, &conScreen);
SetConsoleActiveScreenBuffer(hConsole);

Please always check the return value of each api when debugging.

Upvotes: 1

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