X11 has a so-called primary selection, which you can use by marking text and middle-clicking elsewhere to copy the marked text.
There are 3 new API functions in `SDL_clipboard.h`, which work exactly like their clipboard equivalents.
## Test Instructions
* Run the tests (just a copy of the clipboard tests): `$ ./test/testautomation --filter Clipboard`
* Build and run this small application:
<details>
```C
#include <SDL.h>
#include <unistd.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
void print_error(const char *where)
{
const char *errstr = SDL_GetError();
if (errstr == NULL || errstr[0] == '\0')
return;
fprintf(stderr, "SDL Error after '%s': %s\n", where, errstr);
SDL_ClearError();
}
int main()
{
char text_buf[256];
srand(time(NULL));
SDL_Init(SDL_INIT_VIDEO);
print_error("SDL_INIT()");
SDL_Window *window = SDL_CreateWindow("Primary Selection Test", SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED, 400, 400, SDL_WINDOW_SHOWN);
print_error("SDL_CreateWindow()");
SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
print_error("SDL_CreateRenderer()");
bool quit = false;
unsigned int do_render = 0;
while (!quit) {
SDL_Event event;
while (SDL_PollEvent(&event)) {
print_error("SDL_PollEvent()");
switch (event.type) {
case SDL_QUIT: {
quit = true;
break;
} case SDL_KEYDOWN: {
switch (event.key.keysym.sym) {
case SDLK_ESCAPE:
case SDLK_q:
quit = true;
break;
case SDLK_c:
snprintf(text_buf, sizeof(text_buf), "foo%d", rand());
SDL_SetClipboardText(text_buf);
print_error("SDL_SetClipboardText()");
printf("clipboard: set_to=\"%s\"\n", text_buf);
break;
case SDLK_v: {
printf("clipboard: has=%d, ", SDL_HasClipboardText());
print_error("SDL_HasClipboardText()");
char *text = SDL_GetClipboardText();
print_error("SDL_GetClipboardText()");
printf("text=\"%s\"\n", text);
SDL_free(text);
break;
} case SDLK_d:
snprintf(text_buf, sizeof(text_buf), "bar%d", rand());
SDL_SetPrimarySelectionText(text_buf);
print_error("SDL_SetPrimarySelectionText()");
printf("primselec: set_to=\"%s\"\n", text_buf);
break;
case SDLK_f: {
printf("primselec: has=%d, ", SDL_HasPrimarySelectionText());
print_error("SDL_HasPrimarySelectionText()");
char *text = SDL_GetPrimarySelectionText();
print_error("SDL_GetPrimarySelectionText()");
printf("text=\"%s\"\n", text);
SDL_free(text);
break;
} default:
break;
}
break;
} default: {
break;
}}
}
// create less noise with WAYLAND_DEBUG=1
if (do_render == 0) {
SDL_RenderPresent(renderer);
print_error("SDL_RenderPresent()");
}
do_render += 1;
usleep(12000);
}
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
print_error("quit");
return 0;
}
```
</details>
* Use c,v,d,f to get and set the clipboard and primary selection.
* Mark text and middle-click also in other applications.
* For wayland under x:
* `$ mutter --wayland --no-x11 --nested`
* `$ XDG_SESSION_TYPE=wayland SDL_VIDEODRIVER=wayland ./<path_to_test_appl_binary>`
