Fixed clipboard (text copy & paste) implementation (#380)

- fixed "SDL_GetClipboardText" memory leak
- forcing unicode clipboard data format on Windows (UTF-16LE system, UTF-8 in-game)
- all "get_clipboard_text" functions return a zero-width string in case of failure, instead of NULL

src/pc/gfx/gfx_dummy.c

@@ -113,7 +113,7 @@ static void gfx_dummy_wm_start_text_input(void) {
 static void gfx_dummy_wm_stop_text_input(void) {
 }
 
-static void gfx_dummy_wm_set_clipboard_text(UNUSED char* text) {
+static void gfx_dummy_wm_set_clipboard_text(UNUSED const char* text) {
 }
 
 static void gfx_dummy_wm_set_cursor_visible(UNUSED bool visible) {

src/pc/gfx/gfx_dxgi.cpp

@@ -719,26 +719,40 @@ void gfx_dxgi_start_text_input(void) { inTextInput = TRUE; }
 void gfx_dxgi_stop_text_input(void) { inTextInput = FALSE; }
 
 static char* gfx_dxgi_get_clipboard_text(void) {
+    static char clipboard_buf[WAPI_CLIPBOARD_BUFSIZ];
+    clipboard_buf[0] = '\0';
+
     if (OpenClipboard(NULL)) {
-        HANDLE clip = GetClipboardData(CF_TEXT);
-        CloseClipboard();
-        return (char*)clip;
+        LPCWSTR text = (LPCWSTR)GetClipboardData(CF_UNICODETEXT);
+        if (text != NULL) {
+            WideCharToMultiByte(CP_UTF8, 0, text, (-1), clipboard_buf, WAPI_CLIPBOARD_BUFSIZ, NULL, NULL);
         }
-    return NULL;
+        CloseClipboard();
+    }
+
+    clipboard_buf[WAPI_CLIPBOARD_BUFSIZ - 1] = '\0';
+    return clipboard_buf;
 }
 
-void gfx_dxgi_set_clipboard_text(char* text) {
-    if (OpenClipboard(NULL)) {
-        HGLOBAL clipbuffer;
-        char *buffer;
+void gfx_dxgi_set_clipboard_text(const char* text) {
+    if (!OpenClipboard(NULL)) { return; }
     EmptyClipboard();
-        clipbuffer = GlobalAlloc(GMEM_DDESHARE, strlen(text) + 1);
-        buffer = (char *) GlobalLock(clipbuffer);
-        strcpy(buffer, LPCSTR(text));
-        GlobalUnlock(clipbuffer);
-        SetClipboardData(CF_TEXT, clipbuffer);
-        CloseClipboard();
+
+    int cch = MultiByteToWideChar(CP_UTF8, 0, text, (-1), NULL, 0);
+    if (cch > 0) {
+        HGLOBAL hMem = GlobalAlloc(GMEM_MOVEABLE, cch * sizeof(WCHAR));
+        if (hMem != NULL) {
+            LPWSTR wcsBuffer = (LPWSTR)GlobalLock(hMem);
+            if (wcsBuffer != NULL) {
+                MultiByteToWideChar(CP_UTF8, 0, text, (-1), wcsBuffer, cch);
+                GlobalUnlock(hMem);
+                SetClipboardData(CF_UNICODETEXT, hMem);
+            } else {
+                GlobalFree(hMem);
             }
+        }
+    }
+    CloseClipboard();
 }
 
 void gfx_dxgi_set_cursor_visible(bool visible) { ShowCursor(visible); }

src/pc/gfx/gfx_sdl1.c

@@ -211,8 +211,8 @@ static bool gfx_sdl_has_focus(void) {
 
 static void gfx_sdl_start_text_input(void) { return; }
 static void gfx_sdl_stop_text_input(void) { return; }
-static char* gfx_sdl_get_clipboard_text(void) { return NULL; }
-static void gfx_sdl_set_clipboard_text(char* text) { return; }
+static char* gfx_sdl_get_clipboard_text(void) { return ""; }
+static void gfx_sdl_set_clipboard_text(UNUSED const char* text) { return; }
 static void gfx_sdl_set_cursor_visible(bool visible) { SDL_ShowCursor(visible ? SDL_ENABLE : SDL_DISABLE); }
 
 struct GfxWindowManagerAPI gfx_sdl = {

src/pc/gfx/gfx_sdl2.c

@@ -304,8 +304,19 @@ static bool gfx_sdl_has_focus(void) {
 
 static void gfx_sdl_start_text_input(void) { SDL_StartTextInput(); }
 static void gfx_sdl_stop_text_input(void) { SDL_StopTextInput(); }
-static char* gfx_sdl_get_clipboard_text(void) { return SDL_GetClipboardText(); }
-static void gfx_sdl_set_clipboard_text(char* text) { SDL_SetClipboardText(text); }
+
+static char* gfx_sdl_get_clipboard_text(void) {
+    static char clipboard_buf[WAPI_CLIPBOARD_BUFSIZ];
+
+    char* text = SDL_GetClipboardText();
+    strncpy(clipboard_buf, text, WAPI_CLIPBOARD_BUFSIZ - 1);
+    SDL_free(text);
+
+    clipboard_buf[WAPI_CLIPBOARD_BUFSIZ - 1] = '\0';
+    return clipboard_buf;
+}
+
+static void gfx_sdl_set_clipboard_text(const char* text) { SDL_SetClipboardText(text); }
 static void gfx_sdl_set_cursor_visible(bool visible) { SDL_ShowCursor(visible ? SDL_ENABLE : SDL_DISABLE); }
 
 struct GfxWindowManagerAPI gfx_sdl = {

src/pc/gfx/gfx_window_manager_api.h

@@ -7,6 +7,8 @@
 // special value for window position that signifies centered position
 #define WAPI_WIN_CENTERPOS 0xFFFFFFFF
 
+#define WAPI_CLIPBOARD_BUFSIZ 1024
+
 typedef bool (*kb_callback_t)(int code);
 
 struct GfxWindowManagerAPI {
@@ -23,7 +25,7 @@ struct GfxWindowManagerAPI {
     void (*start_text_input)(void);
     void (*stop_text_input)(void);
     char* (*get_clipboard_text)(void);
-    void (*set_clipboard_text)(char*);
+    void (*set_clipboard_text)(const char*);
     void (*set_cursor_visible)(bool);
     void (*delay)(unsigned int ms);
     int  (*get_max_msaa)(void);