fxlink: add video capture with frames displayed in an SDL2 window

CMakeLists.txt

@@ -4,6 +4,7 @@ cmake_minimum_required(VERSION 3.15)
 project(fxSDK VERSION 2.5.2 LANGUAGES C)
 
 option(FXLINK_DISABLE_UDISKS2 "Do not build the UDisks2-based features of fxlink")
+option(FXLINK_DISABLE_SDL2 "Do not build the SDL2-based features of fxlink")
 
 find_package(PkgConfig REQUIRED)
 pkg_check_modules(libpng REQUIRED libpng16 IMPORTED_TARGET)
@@ -12,6 +13,9 @@ pkg_check_modules(libusb REQUIRED libusb-1.0 IMPORTED_TARGET)
 if(NOT FXLINK_DISABLE_UDISKS2)
   pkg_check_modules(udisks2 REQUIRED udisks2 IMPORTED_TARGET)
 endif()
+if(NOT FXLINK_DISABLE_SDL2)
+  pkg_check_modules(sdl2 REQUIRED sdl2 IMPORTED_TARGET)
+endif()
 
 set(CMAKE_INSTALL_MESSAGE LAZY)
 set(SRC "${CMAKE_CURRENT_SOURCE_DIR}")
@@ -36,12 +40,15 @@ add_custom_target(fxsdk ALL DEPENDS "${BIN}/fxsdk.sh")
 configure_file(fxlink/config.h.in "${BIN}/include/fxlink/config.h")
 add_executable(fxlink fxlink/usb.c fxlink/filter.c fxlink/interactive.c
   fxlink/main.c fxlink/png.c fxlink/properties.c fxlink/ud2.c fxlink/util.c
-  fxlink/protocol.c)
+  fxlink/protocol.c fxlink/sdl2.c)
 target_link_libraries(fxlink PkgConfig::libpng PkgConfig::libusb) # PkgConfig::libudev
 target_include_directories(fxlink PRIVATE "${BIN}/include/fxlink")
 if(NOT FXLINK_DISABLE_UDISKS2)
   target_link_libraries(fxlink PkgConfig::udisks2)
 endif()
+if(NOT FXLINK_DISABLE_SDL2)
+  target_link_libraries(fxlink PkgConfig::sdl2)
+endif()
 
 # Install rules
 

fxlink/config.h.in

@@ -8,4 +8,7 @@
 /* Disables UDisks2 interfaces for systems that don't use it. */
 #cmakedefine FXLINK_DISABLE_UDISKS2
 
+/* Disable SDL2 interfaces. */
+#cmakedefine FXLINK_DISABLE_SDL2
+
 #endif /* FXLINK_CONFIG_H */

fxlink/interactive.c

@@ -6,6 +6,7 @@
 #include "protocol.h"
 #include "usb.h"
 #include "png.h"
+#include "sdl2.h"
 
 #include <libusb.h>
 #include <string.h>
@@ -88,6 +89,18 @@ static void message_finish(message_t *msg)
 			printf("------------------\n");
 			return;
 		}
+
+		if(!strncmp(msg->header.type, "video", 16)) {
+			usb_fxlink_image_t *img = (void *)msg->output;
+			uint8_t **row_pointers = fxlink_protocol_decode_image(msg);
+
+#ifndef FXLINK_DISABLE_SDL2
+			sdl2_stream(row_pointers, img->width, img->height);
+#else
+			warn("SDL2 support disabled, skipping video frame!");
+#endif
+			return;
+		}
 	}
 
 	/* Default to saving to a blob */
@@ -170,9 +183,13 @@ int main_interactive(filter_t *filter, delay_t *delay, libusb_context *context)
 
 	while(1)
 	{
+#ifndef FXLINK_DISABLE_SDL2
+		sdl2_tick();
+#endif
+
 		int transferred = -1;
 		rc = libusb_bulk_transfer(dh, 0x81, buffer + buffer_size, 2048,
-			&transferred, 2000);
+			&transferred, 500);
 
 		if(rc == LIBUSB_ERROR_NO_DEVICE) {
 			printf("Disconnected, leaving.\n");

fxlink/sdl2.c

@@ -0,0 +1,82 @@
+#include "config.h"
+#ifndef FXLINK_DISABLE_SDL2
+
+#include "sdl2.h"
+#include "util.h"
+
+static SDL_Window *window = NULL;
+
+static int init(size_t width, size_t height)
+{
+	if(!SDL_WasInit(SDL_INIT_VIDEO)) {
+		int rc = SDL_Init(SDL_INIT_VIDEO);
+		if(rc < 0)
+			return err("Cannot initialize SDL: %s\n", SDL_GetError());
+	}
+
+	window = SDL_CreateWindow("fxlink", SDL_WINDOWPOS_CENTERED,
+		SDL_WINDOWPOS_CENTERED, width, height, 0);
+	return 0;
+}
+
+__attribute__((destructor))
+static void quit(void)
+{
+	if(!window)
+		return;
+	SDL_DestroyWindow(window);
+	window = NULL;
+}
+
+/* Generate an RGB888 surface from image data. */
+static SDL_Surface *surface_for_image(uint8_t **RGB888_rows, int width,
+	int height)
+{
+	/* Little endian setup for RGB */
+	SDL_Surface *s = SDL_CreateRGBSurface(0, width, height, 24,
+		0x000000ff, 0x0000ff00, 0x0000ff00, 0);
+	if(!s) {
+		err("Cannot create surface for image");
+		return NULL;
+	}
+
+	for(int i = 0; i < height; i++)
+		memcpy(s->pixels + i * s->pitch, RGB888_rows[i], width * 3);
+
+	return s;
+}
+
+void sdl2_stream(uint8_t **RGB888_rows, int width, int height)
+{
+	if(!window && init(width, height))
+		return;
+
+	int current_w, current_h;
+	SDL_GetWindowSize(window, &current_w, &current_h);
+	if(current_w != width || current_h != height)
+		SDL_SetWindowSize(window, width, height);
+
+	SDL_Surface *src = surface_for_image(RGB888_rows, width, height);
+	if(!src)
+		return;
+
+	SDL_Surface *dst = SDL_GetWindowSurface(window);
+	SDL_BlitSurface(src, NULL, dst, NULL);
+	SDL_FreeSurface(src);
+
+	SDL_UpdateWindowSurface(window);
+}
+
+void sdl2_tick(void)
+{
+	if(!window)
+		return;
+
+	SDL_Event e;
+	while(SDL_PollEvent(&e)) {
+		if(e.type == SDL_QUIT)
+			quit();
+	}
+}
+
+#endif /* FXLINK_DISABLE_SDL2 */

fxlink/sdl2.h

@@ -0,0 +1,23 @@
+//---
+// fxlink:sdl2 - SDL2 functions
+//---
+
+#ifndef FXLINK_SDL2_H
+#define FXLINK_SDL2_H
+
+#ifndef FXLINK_DISABLE_SDL2
+
+#include <SDL2/SDL.h>
+
+/* sdl2_stream(): Display a streaming image on the window
+   This function opens or reuses an SDL2 window to display an image. */
+void sdl2_stream(uint8_t **RGB888_rows, int width, int height);
+
+/* sdl2_tick(): Handle SDL events
+   This just needs to be called regularly from the main thread, to respond to
+   events on the window. */
+void sdl2_tick(void);
+
+#endif /* FXLINK_DISABLE_SDL2 */
+
+#endif /* FXLINK_SDL2_H */