Terminal: handle color queries

this allows apps like vim to select a color scheme based on a dark or light background.

Change-Id: Ia9f98d2373523a8b5fa379225a1c906ae075edf7
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4693
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

src/apps/terminal/TermConst.h

@@ -87,6 +87,7 @@ static const uint32 MSG_MOVE_TAB_LEFT					= 'mvtl';
 static const uint32 MSG_MOVE_TAB_RIGHT					= 'mvtr';
 static const uint32 MSG_ACTIVATE_TERM					= 'msat';
 static const uint32 MSG_SET_CURSOR_STYLE				= 'mscs';
+static const uint32 MSG_GET_TERMINAL_COLOR				= 'getc';
 
 
 // Preference Read/Write Keys

src/apps/terminal/TermParse.cpp

@@ -1571,6 +1571,10 @@ TermParse::_ProcessOperatingSystemControls(uchar* params)
 			{
 				int32 offset = mode - 10;
 				int32 count = 0;
+				if (strcmp((char*)params, "?") == 0) {
+					fBuffer->GetColor(mode);
+					break;
+				}
 				char* p = strtok((char*)params, ";");
 				do {
 					if (gXColorsTable.LookUpColor(p, &colors[count]) != B_OK) {

src/apps/terminal/TermView.cpp

@@ -720,6 +720,30 @@ TermView::SetTermColor(uint index, rgb_color color, bool dynamic)
 }
 
 
+status_t
+TermView::GetTermColor(uint index, rgb_color* color)
+{
+	if (color == NULL)
+		return B_BAD_VALUE;
+
+	switch (index) {
+		case 10:
+			*color = fTextForeColor;
+			break;
+		case 11:
+			*color = fTextBackColor;
+			break;
+		case 12:
+			*color = fCursorBackColor;
+			break;
+		default:
+			return B_BAD_VALUE;
+			break;
+	}
+	return B_OK;
+}
+
+
 int
 TermView::Encoding() const
 {
@@ -1833,6 +1857,21 @@ TermView::MessageReceived(BMessage *message)
 			}
 			break;
 		}
+		case MSG_GET_TERMINAL_COLOR:
+		{
+			uint8 index = 0;
+			if (message->FindUInt8("index", &index) != B_OK)
+				break;
+			rgb_color color;
+			status_t status = GetTermColor(index, &color);
+			if (status == B_OK) {
+				BString reply;
+				reply.SetToFormat("\033]%u;rgb:%02x/%02x/%02x\033\\",
+					index, color.red, color.green, color.blue);
+				fShell->Write(reply.String(), reply.Length());
+			}
+			break;
+		}
 		case MSG_SET_CURSOR_STYLE:
 		{
 			int32 style = BLOCK_CURSOR;

src/apps/terminal/TermView.h

@@ -94,6 +94,7 @@ public:
 			void				SetSelectColor(rgb_color fore, rgb_color back);
 			void				SetTermColor(uint index, rgb_color color,
 									bool dynamic = false);
+			status_t			GetTermColor(uint index, rgb_color* color);
 
 			int					Encoding() const;
 			void				SetEncoding(int encoding);

src/apps/terminal/TerminalBuffer.cpp

@@ -228,6 +228,17 @@ TerminalBuffer::ResetColors(uint8* indexes, int32 count, bool dynamic)
 }
 
 
+void
+TerminalBuffer::GetColor(uint8 index)
+{
+	if (fListenerValid) {
+		BMessage message(MSG_GET_TERMINAL_COLOR);
+		message.AddUInt8("index", index);
+		fListener.SendMessage(&message);
+	}
+}
+
+
 void
 TerminalBuffer::SetCursorStyle(int32 style, bool blinking)
 {

src/apps/terminal/TerminalBuffer.h

@@ -37,6 +37,7 @@ public:
 									int32 count = 1, bool dynamic = false);
 			void				ResetColors(uint8* indexes,
 									int32 count = 1, bool dynamic = false);
+			void				GetColor(uint8 index);
 			void				SetCursorStyle(int32 style, bool blinking);
 			void				SetCursorBlinking(bool blinking);
 			void				SetCursorHidden(bool hidden);