Added plugin support for drawing messages to screen.

- Either a single string will be drawn to screen, or nothing will be drawn.
 - Intelligently registers and unregisters drawing callback to minimize overhead when no message is being displayed.
 - Currently does not support newline characters (\r or \n). Newlines will cause text to be drawn overlapped.

xpcPlugin/XPCPlugin.cpp

@@ -68,6 +68,7 @@
 //#include "XPLMPlanes.h"
 #include "XPLMProcessing.h"
 #include "XPLMGraphics.h"
+#include "xpcDrawing.h"
 #include "xpcPluginTools.h"
 
 #ifdef _WIN32 /* WIN32 SYSTEM */
@@ -124,6 +125,7 @@ int handleGETD(char *buf);
 int handleDREF(char *buf);
 int handleVIEW();
 int handleDATA(char *buf, int buflen);
+int handleTEXT(char *buf, int len);
 short handleInput(struct XPCMessage * theMessage);
 
 char setPOSI(short aircraft, float pos[3]);
@@ -189,6 +191,8 @@ PLUGIN_API void XPluginDisable(void)
 	closeUDP(recSocket);
 	closeUDP(sendSocket);
 	updateLog(logmsg,strlen(logmsg));
+
+	XPCClearMessage();
 }
 
 PLUGIN_API int XPluginEnable(void)
@@ -369,6 +373,10 @@ short handleInput(struct XPCMessage * theMessage)
 		{
 			handleDATA(theMessage->msg, theMessage->msglen);
 		}
+		else if (strncmp(theMessage->head, "TEXT", 4) == 0) // Header = TEXT (Screen message)
+		{
+			handleTEXT(theMessage->msg, theMessage->msglen);
+		}
 		else if ((strncmp(theMessage->head,"DSEL",4)==0) || (strncmp(theMessage->head,"USEL",4)==0)) // Header = DSEL/USEL (Select UDP Send)
 		{
 			sendBUF(theMessage->msg,theMessage->msglen); // Send to UDP
@@ -409,9 +417,9 @@ short handleInput(struct XPCMessage * theMessage)
 		{
 			sendBUF(theMessage->msg,theMessage->msglen); // Send to UDP
 		}
-		else if (strncmp(theMessage->head,"BOAT",4)==0)
+		else if (strncmp(theMessage->head, "BOAT", 4) == 0)
 		{
-			sendBUF(theMessage->msg,theMessage->msglen); // Send to UDP
+			sendBUF(theMessage->msg, theMessage->msglen); // Send to UDP
 		}
 		else
 		{ //unrecognized header
@@ -491,6 +499,31 @@ int handleSIMU(char buf[])
 	return 0;
 }
 
+int handleTEXT(char *buf, int len)
+{
+	char msg[256] = { 0 };
+	if (len < 14)
+	{
+		updateLog("[TEXT] ERROR: Length less than 14 bytes", 39);
+		return -1;
+	}
+	int msgLen = buf[13];
+	if (msgLen == 0)
+	{
+		updateLog("[TEXT] Text cleared", 19);
+		XPCClearMessage();
+	}
+	else
+	{
+		updateLog("[TEXT] Text set", 15);
+		int x = *((int*)(buf + 5));
+		int y = *((int*)(buf + 9));
+		strncpy(msg, buf + 14, msgLen);
+		XPCSetMessage(x, y, msg);
+	}
+	return 0;
+}
+
 char setDREF(XPLMDataRef theDREF, float floatarray[], short arrayStart, short arraySize)
 {
 	XPLMDataTypeID dataType;

xpcPlugin/xpcDrawing.cpp

@@ -0,0 +1,73 @@
+#include "xpcDrawing.h"
+#include "XPLMDisplay.h"
+#include "XPLMGraphics.h"
+
+//Internal Memory
+static int msgEnabled = 0;
+static int msgX = -1;
+static int msgY = -1;
+static char* msgVal = NULL;
+static float rgb[4] = { 0.5F, 1.0F, 0.5F };
+
+//Internal Functions
+static int MessageDrawCallback(XPLMDrawingPhase inPhase, int inIsBefore, void * inRefcon)
+{
+	if (msgVal)
+	{
+		XPLMDrawString(rgb, msgX, msgY, msgVal, NULL, xplmFont_Basic);
+	}
+	return 1;
+}
+
+//Public Functions
+void XPCClearMessage()
+{
+	if (msgVal != NULL)
+	{
+		free(msgVal);
+	}
+	msgVal = NULL;
+	if (msgEnabled)
+	{
+		XPLMUnregisterDrawCallback(MessageDrawCallback, xplm_Phase_LastCockpit, 0, NULL);
+		msgEnabled = 0;
+	}
+}
+
+void XPCSetMessage(int x, int y, char* msg)
+{
+	//Determine size of message and clear instead if the message string
+	//is empty.
+	size_t len = strlen(msg);
+	if (len == 0)
+	{
+		XPCClearMessage();
+		return;
+	}
+
+	//Try to size msgVal to fit the new message. If we fail for any
+	//reason, clear the message and bail.
+	if (msgVal != NULL)
+	{
+		msgVal = (char*)realloc(msgVal, len);
+	}
+	else
+	{
+		msgVal = (char*)malloc(len);
+	}
+	if (!msgVal)
+	{
+		XPCClearMessage();
+		return;
+	}
+
+	//Set the message, location, and enable drawing if necessary.
+	strcpy(msgVal, msg);
+	msgX = x < 0 ? 10 : x;
+	msgY = y < 0 ? 600 : y;
+	if (!msgEnabled)
+	{
+		XPLMRegisterDrawCallback(MessageDrawCallback, xplm_Phase_LastCockpit, 0, NULL);
+		msgEnabled = 1;
+	}
+}

xpcPlugin/xpcDrawing.h

@@ -0,0 +1,8 @@
+#ifndef xpcDrawing_h
+#define xpcDrawing_h
+
+void XPCClearMessage();
+
+void XPCSetMessage(int x, int y, char* msg);
+
+#endif

xpcPlugin/xpcPlugin/xpcPlugin.vcxproj

@@ -97,10 +97,12 @@
   </ItemDefinitionGroup>
   <ItemGroup>
     <ClInclude Include="..\..\C\src\xplaneConnect.h" />
+    <ClInclude Include="..\xpcDrawing.h" />
     <ClInclude Include="..\xpcPluginTools.h" />
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\..\C\src\xplaneConnect.c" />
+    <ClCompile Include="..\xpcDrawing.cpp" />
     <ClCompile Include="..\XPCPlugin.cpp" />
     <ClCompile Include="..\xpcPluginTools.cpp" />
   </ItemGroup>

xpcPlugin/xpcPlugin/xpcPlugin.vcxproj.filters

@@ -21,6 +21,9 @@
     <ClInclude Include="..\xpcPluginTools.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="..\xpcDrawing.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\..\C\src\xplaneConnect.c">
@@ -32,6 +35,9 @@
     <ClCompile Include="..\xpcPluginTools.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="..\xpcDrawing.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <Library Include="..\SDK\Libraries\Win\XPLM.lib">