Print centerprint messages to the console (#159)

Add new function `Con_CenterPrint` which can be used to print messages
to the console, without showing onscreen, and with a "horizontal rule"
above and below. Use `Con_CenterPrint` to log centerprint messages to
the console.


![image](https://github.com/DarkPlacesEngine/darkplaces/assets/424218/8ef0bdc4-7481-4f11-b0a3-d46e4d451c74)

Fixes #98

---------

Signed-off-by: bones_was_here <[email protected]>
Co-authored-by: bones_was_here <[email protected]>

cl_screen.c

@@ -143,7 +143,14 @@ for a few moments
 */
 void SCR_CenterPrint(const char *str)
 {
-	dp_strlcpy (scr_centerstring, str, sizeof (scr_centerstring));
+	if (str[0] == '\0') // happens when stepping out of a centreprint trigger on alk1.2 start.bsp
+		return;
+
+	// Print the message to the console, but only if it's different to the previous message
+	if (strcmp(str, scr_centerstring))
+		Con_CenterPrint(str);
+	dp_strlcpy(scr_centerstring, str, sizeof(scr_centerstring));
+
 	scr_centertime_off = scr_centertime.value;
 	scr_centertime_start = cl.time;
 
@@ -168,15 +175,18 @@ static void SCR_Centerprint_f (cmd_state_t *cmd)
 {
 	char msg[MAX_INPUTLINE];
 	unsigned int i, c, p;
+
 	c = Cmd_Argc(cmd);
 	if(c >= 2)
 	{
+		// Merge all the cprint arguments into one string
 		dp_strlcpy(msg, Cmd_Argv(cmd,1), sizeof(msg));
 		for(i = 2; i < c; ++i)
 		{
 			dp_strlcat(msg, " ", sizeof(msg));
 			dp_strlcat(msg, Cmd_Argv(cmd, i), sizeof(msg));
 		}
+
 		c = (unsigned int)strlen(msg);
 		for(p = 0, i = 0; i < c; ++i)
 		{

console.c

@@ -1503,6 +1503,109 @@ void Con_DPrintf(const char *fmt, ...)
 }
 
 
+/**
+ * @brief      Returns a horizontal line
+ * @details    Returns a graphical horizontal line of length len, but never wider than the
+ *             console. Includes a newline, unless len is >= to the console width
+ * @note       Authored by johnfitz
+ *
+ * @param[in]  len   Length of the horizontal line
+ *
+ * @return     A string of the line
+ */
+const char *Con_Quakebar(int len, char *bar, size_t barsize)
+{
+	assert(barsize >= 5);
+
+	len = min(len, (int)barsize - 2);
+	len = min(len, con_linewidth);
+
+	bar[0] = '\35';
+	memset(&bar[1], '\36', len - 2);
+	bar[len - 1] = '\37';
+
+	if (len < con_linewidth)
+	{
+		bar[len] = '\n';
+		bar[len + 1] = 0;
+	}
+	else
+		bar[len] = 0;
+
+	return bar;
+}
+
+/**
+ * @brief      Left-pad a string with spaces to make it appear centered
+ * @note       Authored by johnfitz
+ *
+ * @param[in]  maxLineLength  Center-align
+ * @param[in]  fmt        A printf format string
+ * @param[in]  <unnamed>  Zero or more values used by fmt
+ */
+void Con_CenterPrintf(int maxLineLength, const char *fmt, ...)
+{
+	va_list argptr;
+	char    msg[MAX_INPUTLINE];  // the original message
+	char    line[MAX_INPUTLINE]; // one line from the message
+	char    spaces[21];		     // buffer for spaces
+	char   *msgCursor, *lineCursor;
+	int     lineLength, indentSize, msgLength;
+
+	va_start(argptr, fmt);
+	msgLength = dpvsnprintf(msg, sizeof (msg), fmt, argptr);
+	va_end(argptr);
+
+	if (msgLength == -1)
+	{
+		Con_Printf(CON_WARN "The message given to Con_CenterPrintf was too long\n");
+		return;
+	}
+
+	maxLineLength = min(maxLineLength, con_linewidth);
+
+	for (msgCursor = msg; *msgCursor;)
+	{
+		lineCursor = line;  // Start a the beginning of the line buffer
+
+		// Walk msg, copying characters into the line buffer until a newline or the end of msg
+		while (*msgCursor && *msgCursor != '\n')
+			*lineCursor++ = *msgCursor++;
+		*lineCursor = 0;
+
+		if (*msgCursor == '\n')
+			msgCursor++;
+
+		lineLength = strlen(line);
+		if (lineLength < maxLineLength)
+		{
+			indentSize = (maxLineLength - lineLength) / 2;
+			memset(spaces, ' ', indentSize);
+			spaces[indentSize] = 0;
+			Con_MaskPrintf(CON_MASK_HIDENOTIFY, "%s%s\n", spaces, line);
+		}
+		else
+			Con_MaskPrintf(CON_MASK_HIDENOTIFY, "%s\n", line);
+	}
+}
+
+/**
+ * @brief      Prints a center-aligned message to the console
+ * @note       Authored by johnfitz
+ *
+ * @param[in]  str   A multiline string to print
+ */
+void Con_CenterPrint(const char *str)
+{
+	char bar[42];
+
+	Con_MaskPrintf(CON_MASK_HIDENOTIFY, "%s", Con_Quakebar(40, bar, sizeof(bar)));
+	Con_CenterPrintf(40, "%s\n", str);
+	Con_MaskPrintf(CON_MASK_HIDENOTIFY, "%s", bar);
+}
+
+
+
 /*
 ==============================================================================
 

console.h

@@ -62,6 +62,11 @@ void Con_DPrint(const char *msg);
 
 /// A Con_Printf that only shows up if the "developer" cvar is set
 void Con_DPrintf(const char *fmt, ...) DP_FUNC_PRINTF(1);
+
+const char *Con_Quakebar(int len, char *bar, size_t bufsize);
+void Con_CenterPrintf(int maxLineLength, const char *fmt, ...) DP_FUNC_PRINTF(2);
+void Con_CenterPrint(const char *str);
+
 void Con_Clear_f(cmd_state_t *cmd);
 void Con_DrawNotify (void);