SCI32: Implement basic kMessageBox

This kernel call seems only to be used by KQ7 1.51 (which was
Windows-only) to send warnings to the user.

It was easy enough to do a basic implementation in the ScummVM
GUI rather than just make it an empty call, so now it is a thing.

5 files changed, 61 insertions, 1 deletions

diff --git a/engines/sci/engine/kernel.h b/engines/sci/engine/kernel.h
index 6604387254..b269e9789d 100644
--- a/engines/sci/engine/kernel.h
+++ b/engines/sci/engine/kernel.h
@@ -566,6 +566,7 @@ reg_t kMoveToFront(EngineState *s, int argc, reg_t *argv);
 reg_t kMoveToEnd(EngineState *s, int argc, reg_t *argv);
 reg_t kGetWindowsOption(EngineState *s, int argc, reg_t *argv);
 reg_t kWinHelp(EngineState *s, int argc, reg_t *argv);
+reg_t kMessageBox(EngineState *s, int argc, reg_t *argv);
 reg_t kGetConfig(EngineState *s, int argc, reg_t *argv);
 reg_t kGetSierraProfileInt(EngineState *s, int argc, reg_t *argv);
 reg_t kCelInfo(EngineState *s, int argc, reg_t *argv);
diff --git a/engines/sci/engine/kernel_tables.h b/engines/sci/engine/kernel_tables.h
index 03e56ea559..19bee359c5 100644
--- a/engines/sci/engine/kernel_tables.h
+++ b/engines/sci/engine/kernel_tables.h
@@ -728,6 +728,8 @@ static SciKernelMapEntry s_kernelMap[] = {
 	{ MAP_CALL(ListEachElementDo), SIG_EVERYWHERE,           "li(.*)",                NULL,            NULL },
 	{ MAP_CALL(ListFirstTrue),     SIG_EVERYWHERE,           "li(.*)",                NULL,            NULL },
 	{ MAP_CALL(ListIndexOf),       SIG_EVERYWHERE,           "l[o0]",                 NULL,            NULL },
+	// kMessageBox is used only by KQ7 1.51
+	{ MAP_CALL(MessageBox),        SIG_SCI32, SIGFOR_ALL,    "rri",                   NULL,            NULL },
 	{ "OnMe", kIsOnMe,             SIG_EVERYWHERE,           "iioi",                  NULL,            NULL },
 	// Purge is used by the memory manager in SSCI to ensure that X number of bytes (the so called "unmovable
 	// memory") are available when the current room changes. This is similar to the SCI0-SCI1.1 FlushResources
diff --git a/engines/sci/engine/kgraphics32.cpp b/engines/sci/engine/kgraphics32.cpp
index f8ec96c843..4083414724 100644
--- a/engines/sci/engine/kgraphics32.cpp
+++ b/engines/sci/engine/kgraphics32.cpp
@@ -254,6 +254,10 @@ reg_t kWinHelp(EngineState *s, int argc, reg_t *argv) {
 	return s->r_acc;
 }
 
+reg_t kMessageBox(EngineState *s, int argc, reg_t *argv) {
+	return g_sci->_gfxControls32->kernelMessageBox(s->_segMan->getString(argv[0]), s->_segMan->getString(argv[1]), argv[2].toUint16());
+}
+
 /**
  * Causes an immediate plane transition with an optional transition
  * effect
diff --git a/engines/sci/graphics/controls32.cpp b/engines/sci/graphics/controls32.cpp
index 04014154ae..61dfbedfc5 100644
--- a/engines/sci/graphics/controls32.cpp
+++ b/engines/sci/graphics/controls32.cpp
@@ -21,7 +21,8 @@
  */
 
 #include "common/system.h"
-
+#include "common/translation.h"
+#include "gui/message.h"
 #include "sci/sci.h"
 #include "sci/console.h"
 #include "sci/event.h"
@@ -807,4 +808,37 @@ void GfxControls32::destroyScrollWindow(const reg_t id) {
 	delete scrollWindow;
 }
 
+#pragma mark -
+#pragma mark Message box
+
+int16 GfxControls32::showMessageBox(const Common::String &message, const char *const okLabel, const char *const altLabel, const int16 okValue, const int16 altValue) {
+	GUI::MessageDialog dialog(message, okLabel, altLabel);
+	return (dialog.runModal() == GUI::kMessageOK) ? okValue : altValue;
+}
+
+reg_t GfxControls32::kernelMessageBox(const Common::String &message, const Common::String &title, const uint16 style) {
+	if (g_engine) {
+		g_engine->pauseEngine(true);
+	}
+
+	int16 result;
+
+	switch (style & 0xF) {
+	case kMessageBoxOK:
+		result = showMessageBox(message, _("OK"), NULL, 1, 1);
+	break;
+	case kMessageBoxYesNo:
+		result = showMessageBox(message, _("Yes"), _("No"), 6, 7);
+	break;
+	default:
+		error("Unsupported MessageBox style 0x%x", style & 0xF);
+	}
+
+	if (g_engine) {
+		g_engine->pauseEngine(false);
+	}
+
+	return make_reg(0, result);
+}
+
 } // End of namespace Sci
diff --git a/engines/sci/graphics/controls32.h b/engines/sci/graphics/controls32.h
index 62ab90de1f..460b0b5625 100644
--- a/engines/sci/graphics/controls32.h
+++ b/engines/sci/graphics/controls32.h
@@ -31,6 +31,10 @@ class GfxCache;
 class GfxScreen;
 class GfxText32;
 
+enum MessageBoxStyle {
+	kMessageBoxOK               = 0x0,
+	kMessageBoxYesNo            = 0x4
+};
 
 struct TextEditor {
 	/**
@@ -485,6 +489,21 @@ private:
 	 * A lookup table for registered ScrollWindow instances.
 	 */
 	ScrollWindowMap _scrollWindows;
+
+#pragma mark -
+#pragma mark Message box
+public:
+	/**
+	 * Displays an OS-level message dialog.
+	 */
+	reg_t kernelMessageBox(const Common::String &message, const Common::String &title, const uint16 style);
+
+private:
+	/**
+	 * Convenience function for creating and showing a
+	 * message box.
+	 */
+	int16 showMessageBox(const Common::String &message, const char *const okLabel, const char *const altLabel, const int16 okValue, const int16 altValue);
 };
 
 } // End of namespace Sci