CODEWITHSUNDEEP
c++windowsgraphics
Mark
Mark

Reputation: 182

How can i make a screen buffer c++

I want to be able to draw all my text, lines , triangles and other stuff to screen and then clear the screen and draw something new, BUT this method makes the screen flicker, and all the drawings dont appear at the same time.

My idea is to draw to some kind of a buffer and then draw that buffer to the screen and clear the buffer, and repeat. This way the screen wont flicker and all will be drawn at the same time.

I am using windows.h , Visual Studio.

#include <Windows.h>
#include <iostream>
using namespace std;

struct vec2d
{
    int x, y;
};

void Line(HDC dc, vec2d a, vec2d b)
{
    MoveToEx(dc, a.x, a.y, NULL);
    LineTo(dc, b.x, b.y);
}

vec2d GetMousePos(HWND console)
{
    vec2d out;
    POINT p;
    GetCursorPos(&p);
    out.x = p.x; out.y = p.y;       
    return out;
}

int main()
{
    HWND console = GetConsoleWindow();
    HDC dc = GetDC(console);
    SelectObject(dc, CreatePen(PS_SOLID, 1, RGB(255, 255, 255)));

    while (1)
    {
        //BitBlt(dc, 0, 0, 1000, 1000, 0, 0, 0, BLACKNESS);        Flickering is much much bigger, because its faster
        system("cls");
        Line(dc, { 0, 0 }, GetMousePos(console));       
    }
}

Thanks in advance, Mark.

Upvotes: 1

Views: 5980

Answers (1)

001
001

Reputation: 13533

I don't think you have as much control over a console window as you would over your own HWND. I was able to eliminate the flicker in your code by replacing system("cls"); with InvalidateRect().

RECT client;
GetClientRect(console, &client);
while (1)
{
    InvalidateRect(console, &client, TRUE);
    Line(dc, console, { 0, 0 }, GetMousePos(console));
}

(You can probably improve this by only invalidating the area where the previous line was drawn.)

Also, one other change you can make (unrelated to flicker) is to add:

ScreenToClient(console, &p);

to GetMousePos() after you call GetCursorPos(&p);. This will map the pointer co-ords to the window instead of the screen.

Further reading on creating your own window: Creating a Window. Not as simple as using a console window, but you have much greater control.

Upvotes: 3

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