Add Alt+S keybinding to save screenshot

Not implemented on android or windows (yet). Zenity must be installed
for file picker dialog.

CMakeLists.txt

@@ -67,6 +67,7 @@ target_sources(xsystem4 PRIVATE
   src/resume.c
   src/savedata.c
   src/scene.c
+  src/screenshot.c
   src/sprite.c
   src/swf.c
   src/system4.c

include/xsystem4.h

@@ -81,6 +81,8 @@ char *savedir_path(const char *path);
 void get_date(int *year, int *month, int *mday, int *wday);
 void get_time(int *hour, int *min, int *sec, int *ms);
 
+void screenshot_save(void);
+
 #ifndef XSYS4_DATA_DIR
 #define XSYS4_DATA_DIR "/usr/local/share/xsystem4"
 #endif

src/input.c

@@ -609,12 +609,16 @@ void handle_events(void)
 			handle_window_event(&e);
 			break;
 		case SDL_KEYDOWN:
-			if (e.key.keysym.scancode == SDL_SCANCODE_F9)
+			if (e.key.keysym.scancode == SDL_SCANCODE_F9) {
 				vm_stack_trace();
-			if (e.key.keysym.scancode == SDL_SCANCODE_F11) {
+			} else if (e.key.keysym.scancode == SDL_SCANCODE_F11) {
 				uint32_t flag = SDL_WINDOW_FULLSCREEN_DESKTOP;
 				bool fs = SDL_GetWindowFlags(sdl.window) & flag;
 				SDL_SetWindowFullscreen(sdl.window, fs ? 0 : flag);
+			} else if (e.key.keysym.scancode == SDL_SCANCODE_S) {
+				if (e.key.keysym.mod & (KMOD_LALT | KMOD_RALT)) {
+					screenshot_save();
+				}
 			}
 			// fallthrough
 		case SDL_KEYUP:

src/meson.build

@@ -28,6 +28,7 @@ xsystem4 = [version_h,
             'resume.c',
             'savedata.c',
             'scene.c',
+            'screenshot.c',
             'sprite.c',
             'swf.c',
             'system4.c',

src/screenshot.c

@@ -0,0 +1,140 @@
+/* Copyright (C) 2019 Nunuhara Cabbage <nunuhara@haniwa.technology>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <limits.h>
+#include <time.h>
+#include <SDL.h>
+
+#include "system4.h"
+#include "system4/cg.h"
+#include "system4/file.h"
+#include "gfx/gfx.h"
+#include "xsystem4.h"
+
+static char *default_filename(void)
+{
+	time_t t = time(NULL);
+	struct tm *tm = localtime(&t);
+	char datetime[128];
+	strftime(datetime, sizeof(datetime), "%Y%m%d_%H%M%S", tm);
+
+	// FIXME: Earlier games use "[gamedir]/Snapshot/", but later games save under
+	//        "Documents/AliceSoft/[gamename]/Screenshot/"
+	char name[PATH_MAX];
+	snprintf(name, sizeof(name), "Snapshot/%s_%s.png", config.game_name, datetime);
+	return gamedir_path(name);
+}
+
+#ifdef _WIN32
+
+void screenshot_save(void)
+{
+
+}
+
+#else
+#ifdef __ANDROID__
+
+void screenshot_save(void)
+{
+
+}
+
+#else
+
+static bool have_zenity(void)
+{
+	FILE *fp = popen("zenity --version", "r");
+	if (!fp)
+		return false;
+
+	char line[256];
+	while (fgets(line, sizeof(line), fp))
+		printf("%s", line);
+	if (pclose(fp) != 0)
+		return false;
+	return true;
+}
+
+static char *zenity_get_filename(const char *dflt)
+{
+	char buf[PATH_MAX + 64];
+	snprintf(buf, sizeof(buf), "zenity --file-selection --filename=\"%s\" --save", dflt);
+
+	FILE *fp = popen(buf, "r");
+	if (!fp)
+		return NULL;
+
+	// read filename
+	char *filename = fgets(buf, sizeof(buf), fp);
+	if (filename && *filename) {
+		filename = xstrdup(filename);
+
+		// delete trailing newline
+		size_t len = strlen(filename);
+		if (filename[len-1] == '\n')
+			filename[len-1] = '\0';
+	} else {
+		filename = NULL;
+	}
+
+	// empty pipe and close
+	while (fgets(buf, sizeof(buf), fp))
+		/* nothing */;
+	pclose(fp);
+
+	return filename;
+}
+
+void screenshot_save(void)
+{
+	// get filename
+	char *name = default_filename();
+	if (have_zenity()) {
+		char *tmp = zenity_get_filename(name);
+		free(name);
+		name = tmp;
+		if (!name)
+			return;
+	}
+
+	// create directory
+	char *dir = path_dirname(name);
+	if (mkdir_p(dir)) {
+		WARNING("mkdir_p: %s", strerror(errno));
+		free(name);
+		return;
+	}
+
+	// save screenshot
+	gfx_save_texture(gfx_main_surface(), name, ALCG_PNG);
+
+	// XXX: this uses zenity on wayland, so there is no confirmation
+	//      that anything happened if zenity is not installed
+	char msg[PATH_MAX + 64];
+	snprintf(msg, sizeof(msg), "Screenshot saved to %s", name);
+	SDL_ShowSimpleMessageBox(0, "xsystem4", msg, NULL);
+	NOTICE("%s", msg);
+
+	free(name);
+}
+
+#endif // __ANDROID__
+#endif // _WIN32