Add --render-driver command-line option

Add an option to set a render driver hint (SDL_HINT_RENDER_DRIVER).

app/scrcpy.1

@@ -106,6 +106,14 @@ option if set, or by the file extension (.mp4 or .mkv).
 .BI "\-\-record\-format " format
 Force recording format (either mp4 or mkv).
 
+.TP
+.BI "\-\-render\-driver " name
+Request SDL to use the given render driver (this is just a hint).
+
+Supported names are currently "direct3d", "opengl", "opengles2", "opengles", "metal" and "software".
+.UR https://wiki.libsdl.org/SDL_HINT_RENDER_DRIVER
+.UE
+
 .TP
 .B \-\-render\-expired\-frames
 By default, to minimize latency, scrcpy always renders the last available decoded frame, and drops any previous ones. This flag forces to render all frames, at a cost of a possible increased latency.

app/src/cli.c

@@ -99,6 +99,13 @@ scrcpy_print_usage(const char *arg0) {
         "    --record-format format\n"
         "        Force recording format (either mp4 or mkv).\n"
         "\n"
+        "    --render-driver name\n"
+        "        Request SDL to use the given render driver (this is just a\n"
+        "        hint).\n"
+        "        Supported names are currently \"direct3d\", \"opengl\",\n"
+        "        \"opengles2\", \"opengles\", \"metal\" and \"software\".\n"
+        "        <https://wiki.libsdl.org/SDL_HINT_RENDER_DRIVER>\n"
+        "\n"
         "    --render-expired-frames\n"
         "        By default, to minimize latency, scrcpy always renders the\n"
         "        last available decoded frame, and drops any previous ones.\n"
@@ -454,6 +461,7 @@ guess_record_format(const char *filename) {
 #define OPT_LOCK_VIDEO_ORIENTATION 1013
 #define OPT_DISPLAY_ID             1014
 #define OPT_ROTATION               1015
+#define OPT_RENDER_DRIVER          1016
 
 bool
 scrcpy_parse_args(struct scrcpy_cli_args *args, int argc, char *argv[]) {
@@ -474,6 +482,7 @@ scrcpy_parse_args(struct scrcpy_cli_args *args, int argc, char *argv[]) {
         {"push-target",            required_argument, NULL, OPT_PUSH_TARGET},
         {"record",                 required_argument, NULL, 'r'},
         {"record-format",          required_argument, NULL, OPT_RECORD_FORMAT},
+        {"render-driver",          required_argument, NULL, OPT_RENDER_DRIVER},
         {"render-expired-frames",  no_argument,       NULL,
                                                   OPT_RENDER_EXPIRED_FRAMES},
         {"rotation",               required_argument, NULL, OPT_ROTATION},
@@ -617,6 +626,9 @@ scrcpy_parse_args(struct scrcpy_cli_args *args, int argc, char *argv[]) {
                     return false;
                 }
                 break;
+            case OPT_RENDER_DRIVER:
+                opts->render_driver = optarg;
+                break;
             default:
                 // getopt prints the error message on stderr
                 return false;

app/src/scrcpy.c

@@ -47,7 +47,7 @@ static struct input_manager input_manager = {
 
 // init SDL and set appropriate hints
 static bool
-sdl_init_and_configure(bool display) {
+sdl_init_and_configure(bool display, const char *render_driver) {
     uint32_t flags = display ? SDL_INIT_VIDEO : SDL_INIT_EVENTS;
     if (SDL_Init(flags)) {
         LOGC("Could not initialize SDL: %s", SDL_GetError());
@@ -60,6 +60,10 @@ sdl_init_and_configure(bool display) {
         return true;
     }
 
+    if (render_driver && !SDL_SetHint(SDL_HINT_RENDER_DRIVER, render_driver)) {
+        LOGW("Could not set render driver");
+    }
+
     // Linear filtering
     if (!SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "1")) {
         LOGW("Could not enable linear filtering");
@@ -310,7 +314,7 @@ scrcpy(const struct scrcpy_options *options) {
     bool controller_initialized = false;
     bool controller_started = false;
 
-    if (!sdl_init_and_configure(options->display)) {
+    if (!sdl_init_and_configure(options->display, options->render_driver)) {
         goto end;
     }
 

app/src/scrcpy.h

@@ -15,6 +15,7 @@ struct scrcpy_options {
     const char *record_filename;
     const char *window_title;
     const char *push_target;
+    const char *render_driver;
     enum recorder_format record_format;
     struct port_range port_range;
     uint16_t max_size;
@@ -44,6 +45,7 @@ struct scrcpy_options {
     .record_filename = NULL, \
     .window_title = NULL, \
     .push_target = NULL, \
+    .render_driver = NULL, \
     .record_format = RECORDER_FORMAT_AUTO, \
     .port_range = { \
         .first = DEFAULT_LOCAL_PORT_RANGE_FIRST, \

app/src/screen.c

@@ -226,6 +226,11 @@ screen_init_rendering(struct screen *screen, const char *window_title,
         return false;
     }
 
+    SDL_RendererInfo renderer_info;
+    int r = SDL_GetRendererInfo(screen->renderer, &renderer_info);
+    const char *renderer_name = r ? NULL : renderer_info.name;
+    LOGI("Renderer: %s", renderer_name ? renderer_name : "(unknown)");
+
     if (SDL_RenderSetLogicalSize(screen->renderer, content_size.width,
                                  content_size.height)) {
         LOGE("Could not set renderer logical size: %s", SDL_GetError());