如何正确处理SDL2中的控制键组合 [英] How to correctly handle control-key combinations in SDL2

问题描述

在基于 SDL 2.0 的应用程序中，我想同时处理Control +和Control =.

In my SDL 2.0 based application, I would like to handle both Control + and Control =.

我知道我可以处理SDL_KEYDOWN事件，并结合KEYMODE_CTRL查找SDLK_EQUALS密钥代码.甚至检查KEYMOD_SHIFT' to distinguish between + and =`.但是，这不是便携式的，并且在将这些符号映射到不同键的键盘上会损坏.

I understand that I could handle the SDL_KEYDOWN event and look for the SDLK_EQUALS keycode in combination with KEYMODE_CTRL. And even check for KEYMOD_SHIFT' to distinguish between+and=`. However, this is not portable and breaks on keyboards where those symbols are mapped to different keys.

我尝试过的另一件事是启用SDL_StartTextInput()，然后侦听SDL_TEXTINPUT事件.但是，这仅适用于可打印字符.它完全忽略了控制序列.

Another thing I have tried is to enable SDL_StartTextInput() and then listen to SDL_TEXTINPUT events. However that only works for printable characters. It ignores control sequences completely.

正确的方法是什么?我看到 SDL 1.2 实际上在SDL_Keysym结构中有一个unicode字段.那绝对会让我容易得多.有谁知道为什么要删除它，以及 SDL 2.0 中的等效内容是什么?

What is the correct the way to do this? I see SDL 1.2 actually had a unicode field in the SDL_Keysym structure. That would definitely make this a lot easier for me. Does anyone know why that was removed and what the equivalent in SDL 2.0 would be?

推荐答案

下面是一个示例，您如何将unicode输入作为SDL_TEXTINPUT获得，而将其余部分作为SDL_KEYDOWN获得:

Here is an example how you can get unicode input as SDL_TEXTINPUT but the rest as SDL_KEYDOWN:

#include "SDL.h"

int main(int argc, char *argv[]) {
    int done = 0;
    SDL_Init(SDL_INIT_VIDEO);
    SDL_Window *w = SDL_CreateWindow("foo", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
            640, 480, 0);

    int lctrl = 0, rctrl = 0;

    SDL_StartTextInput();
    while (!done) {
        SDL_Event event;
        while(SDL_PollEvent(&event)) {
            switch (event.type) {
            case SDL_QUIT:
                done = 1;
                break;
            case SDL_TEXTINPUT: {
                int ctrl_state = lctrl || rctrl;
                printf("%s, ctrl %s\n", event.text.text, (ctrl_state) ? "pressed" : "released");
            } break;
            case SDL_KEYDOWN:
                if(event.key.keysym.sym == SDLK_RCTRL) { rctrl = 1; }
                else if(event.key.keysym.sym == SDLK_LCTRL) { lctrl = 1; }
                break;
            case SDL_KEYUP:
                if(event.key.keysym.sym == SDLK_RCTRL) { rctrl = 0; }
                else if(event.key.keysym.sym == SDLK_LCTRL) { lctrl = 0; }
                break;
            }
        }
        SDL_UpdateWindowSurface(w);
    }

    SDL_Quit();

    return 0;
}

为简化起见，它忽略了SDL_TEXTEDITING，它可能是(也可能不是)您想要的.也可以使用SDL_GetKeyboardState代替手动处理事件和累积修饰键标志，从而得到相同的结果.

To simplify things, it ignores SDL_TEXTEDITING, which may (or not) be what you want. Also SDL_GetKeyboardState can be used instead of manually processing events and accumulating modifier keys flags, with the same result.

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