add clickable overlay to title screen

plugins/CMakeLists.txt

@@ -144,6 +144,7 @@ if(BUILD_SUPPORTED)
     dfhack_plugin(mousequery mousequery.cpp)
     dfhack_plugin(nestboxes nestboxes.cpp)
     dfhack_plugin(orders orders.cpp LINK_LIBRARIES jsoncpp_static)
+    dfhack_plugin(overlay overlay.cpp)
     dfhack_plugin(pathable pathable.cpp LINK_LIBRARIES lua)
     dfhack_plugin(petcapRemover petcapRemover.cpp)
     dfhack_plugin(plants plants.cpp)

plugins/overlay.cpp

@@ -0,0 +1,80 @@
+#include "df/viewscreen_titlest.h"
+
+#include "modules/Gui.h"
+
+#include "PluginManager.h"
+#include "VTableInterpose.h"
+#include "uicommon.h"
+
+using namespace DFHack;
+
+DFHACK_PLUGIN("overlay");
+DFHACK_PLUGIN_IS_ENABLED(is_enabled);
+REQUIRE_GLOBAL(enabler);
+REQUIRE_GLOBAL(gps);
+
+static const std::string button_text = "[ DFHack Launcher ]";
+static bool clicked = false;
+
+static bool handle_click() {
+    int32_t x, y;
+    if (!enabler->tracking_on || !enabler->mouse_lbut || clicked ||
+            !Gui::getMousePos(x, y))
+        return false;
+    if (y == gps->dimy - 1 && x >= 1 && (size_t)x <= button_text.size()) {
+        clicked = true;
+        Core::getInstance().setHotkeyCmd("gui/launcher");
+        return true;
+    }
+    return false;
+}
+
+static void draw_widgets() {
+    int x = 1;
+    int y = gps->dimy - 1;
+    OutputString(COLOR_GREEN, x, y, button_text);
+}
+
+struct title_hook : df::viewscreen_titlest {
+    typedef df::viewscreen_titlest interpose_base;
+
+    DEFINE_VMETHOD_INTERPOSE(void, feed, (set<df::interface_key> *input)) {
+        if (!handle_click())
+            INTERPOSE_NEXT(feed)(input);
+    }
+    DEFINE_VMETHOD_INTERPOSE(void, render, ()) {
+        INTERPOSE_NEXT(render)();
+        draw_widgets();
+    }
+};
+IMPLEMENT_VMETHOD_INTERPOSE(title_hook, feed);
+IMPLEMENT_VMETHOD_INTERPOSE(title_hook, render);
+
+DFhackCExport command_result plugin_onstatechange(color_ostream &,
+                                                  state_change_event evt) {
+    if (evt == SC_VIEWSCREEN_CHANGED) {
+        clicked = false;
+    }
+    return CR_OK;
+}
+
+DFhackCExport command_result plugin_enable(color_ostream &, bool enable) {
+    if (is_enabled == enable)
+        return CR_OK;
+    if (enable != is_enabled) {
+        if (!INTERPOSE_HOOK(title_hook, feed).apply(enable) ||
+            !INTERPOSE_HOOK(title_hook, render).apply(enable))
+            return CR_FAILURE;
+
+        is_enabled = enable;
+    }
+    return CR_OK;
+}
+
+DFhackCExport command_result plugin_init(color_ostream &out, std::vector <PluginCommand> &) {
+    return plugin_enable(out, true);
+}
+
+DFhackCExport command_result plugin_shutdown(color_ostream &out) {
+    return plugin_enable(out, false);
+}