The new protocol adds support for more native communication of
fractional scaling.
Everything in the wayland backend already existed only our fractional
scale was calculated implicitly through a combination of output size
guesswork for fullscreen windows.
This new protocol makes that explicit, providing a more robust solution
and a solution for non-fullscreen surfaces. The fallback code is still
left in place for now whilst compositors gain support.
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>`
Update the Wayland core protocol spec file and add support for the new axis_value120 event to handle high resolution scroll wheels.
The axis_value120 replaces the axis_discrete event, which is no longer sent as of version 8 of the protocol. Note that unlike the axis_discrete event, no mention in the spec is made regarding how many axis_value120 events may occur per-axis per-frame, so the values are accumulated and committed when the pointer frame event occurs.
Wayland doesn't support mode switching, however Wayland compositors can support the wp_viewporter protocol, which allows for the mapping of arbitrarily sized buffer regions to output surfaces. Use this functionality, when available, for fullscreen output when using non-native display modes and/or when dealing with scaled desktops, which can incur significant overdraw without this extension.
This also allows for the exposure of arbitrarily sized, emulated display modes, which can be useful for legacy compatability.
Using wl-output to get the desktop display dimensions and dividing by the integer scale factor will not return the correct result when using a desktop with fractional scaling (e.g. a 3840x2160 display at 150% will incorrectly report the scaled desktop area as 1920x1080 instead of 2560x1440). Use the xdg-output protocol, if available, to retrieve the correct desktop dimensions and offset.
Versions 1 through 3 of the protocol are supported.
KWin has supported the shared and formalised zxdg_decoration since
Plasma 5.16 which came out mid 2019.
Whilst it made sense to support them both for a while, it should not be
needed for future SDL releases.
We support both the org.freedesktop.ScreenSaver D-Bus API (same as the X11
backend) and the Wayland idle_inhibit_unstable_v1 protocol.
Some Wayland compositors only support one or the other, so we need both to
for broad compatibility.
Use zwp_keyboard_shortcuts_inhibit_manager_v1 to allow SDL applications
to capture system keyboard shortcuts like Alt+Tab when keyboard grab is
enabled via SDL_HINT_GRAB_KEYBOARD.
Now you don't need the latest Wayland installed to build with
newer protocols supported, as they'll build correctly; even if
your system can't use them, we can make intelligent decisions
at runtime about what's available on the current machine anyhow.
This also simplifies some logic and possible failure cases in
the configure and CMake scripts.
Fixes Bugzilla #4207.
