sdk: update cpp sample for DDR, fix DDR MDXF polling when api/sdk is providing input (#679)

## Link to GitHub Issue or related Pull Request, if one exists
#676 
#452 

## Description of change

When spice SDK or API sets or clears button and analog override, we
don't tell MDXF about it, so it may fall behind. This is a special case
for DDR MDXF I/O emulation. For Naive/Xinput I think we are getting
lucky because they usually also generate WM_INPUT events.

Update the C++ SDK sample to provide more interesting example of
emulating DDR arrows with the keyboard.

## Testing

src/spice2x/api/modules/analogs.cpp

@@ -6,6 +6,7 @@
 #include "launcher/launcher.h"
 #include "games/io.h"
 #include "util/utils.h"
+#include "acio/mdxf/mdxf_poll.h"
 
 using namespace std::placeholders;
 using namespace rapidjson;
@@ -104,6 +105,7 @@ namespace api::modules {
                 for (auto &analog : *this->analogs) {
                     analog.override_enabled = false;
                 }
+                mdxf_poll(true);
             }
             return;
         }
@@ -148,6 +150,7 @@ namespace api::modules {
             if (analog.getName() == name) {
                 analog.override_state = CLAMP(state, 0.f, 1.f);
                 analog.override_enabled = true;
+                mdxf_poll(true);
                 return true;
             }
         }
@@ -167,6 +170,7 @@ namespace api::modules {
         for (auto &analog : *this->analogs) {
             if (analog.getName() == name) {
                 analog.override_enabled = false;
+                mdxf_poll(true);
                 return true;
             }
         }

src/spice2x/api/modules/buttons.cpp

@@ -6,6 +6,7 @@
 #include "launcher/launcher.h"
 #include "games/io.h"
 #include "util/utils.h"
+#include "acio/mdxf/mdxf_poll.h"
 
 using namespace std::placeholders;
 using namespace rapidjson;
@@ -107,6 +108,7 @@ namespace api::modules {
                 for (auto &button : *this->buttons) {
                     button.override_enabled = false;
                 }
+                mdxf_poll(true);
             }
             return;
         }
@@ -153,6 +155,7 @@ namespace api::modules {
                         GameAPI::Buttons::BUTTON_PRESSED : GameAPI::Buttons::BUTTON_NOT_PRESSED;
                 button.override_velocity = CLAMP(state, 0.f, 1.f);
                 button.override_enabled = true;
+                mdxf_poll(true);
                 return true;
             }
         }
@@ -172,6 +175,7 @@ namespace api::modules {
         for (auto &button : *this->buttons) {
             if (button.getName() == name) {
                 button.override_enabled = false;
+                mdxf_poll(true);
                 return true;
             }
         }

src/spice2x/sdk/sample/v0/cpp/v0_cpp.cpp

@@ -1,30 +1,25 @@
+#include <format>
 #include <chrono>
 #include <thread>
+#include <windows.h>
 
 #include "sdk/include/spicesdk.h"
 #include "sdk/include/spicesdk_io.h"
 
+// this sample assumes that the game is DDR
+
+// convenience wrapper for logging; feel free to add other levels
 #define LOG_INFO(message) spice.log(SPICE_SDK_LOG_LEVEL_INFO, "sample_v0_cpp", message)
 
 static SPICE_SDK_V0 spice = {};
+
 static spice_sdk_destroy_callback_func destroy_callback;
 static std::jthread worker_thread;
+static void worker_thread_main(std::stop_token stop_token);
 
-static void worker_thread_main(std::stop_token stop_token) {
-    while (!stop_token.stop_requested()) {
-
-        static bool state = false;
-        bool new_state;
-        spice.get_button(IIDX_Button_P1_Start, &new_state, nullptr);
-        if (!state && new_state) {
-            LOG_INFO("user pressed P1 Start button!");
-        }
-        state = new_state;
-
-        std::this_thread::sleep_for(std::chrono::milliseconds(1));
-    }
-}
-
+// main entry point into the DLL
+// spice executable will call into this shortly after the game is partially 
+// initialized (but not quite fully booted just yet)
 SPICE_SDK_ENTRY_POINT
 spice_sdk_entry_point(
     spice_sdk_init_func *init
@@ -32,13 +27,22 @@ spice_sdk_entry_point(
 {
     SPICE_SDK_STATUS_CODE status;
 
+    // SPICE_SDK_V0 must be zeroed AND the size field must be set
     spice.size = sizeof(spice);
+
+    // initialize the SDK - can be called any time, but we'll do it here
     status = init(0, destroy_callback, &spice);
+
+    // always check for return value; failure could be usage error,
+    // or the spice executable doesn't support this SDK version
+    // check the log messages from sdk:
     if (status != SPICE_SDK_STATUS_SUCCESS) {
         return 0;
     }
 
     LOG_INFO("plugin loaded");
+
+    // spin up a worker thread
     worker_thread = std::jthread(worker_thread_main);
     return 1;
 }
@@ -55,3 +59,40 @@ destroy_callback(
         worker_thread.join();
     }
 }
+
+struct ArrowButton {
+    int key;
+    SPICE_SDK_DDR_BUTTONS button;
+    const char* name;
+    bool previous_state;
+};
+
+static ArrowButton arrow_buttons[] = {
+    { VK_UP, DDR_Button_P1_PANEL_UP, "UP", false },
+    { VK_DOWN, DDR_Button_P1_PANEL_DOWN, "DOWN", false },
+    { VK_LEFT, DDR_Button_P1_PANEL_LEFT, "LEFT", false },
+    { VK_RIGHT, DDR_Button_P1_PANEL_RIGHT, "RIGHT", false },
+};
+
+// worker thread for I/O
+static void worker_thread_main(std::stop_token stop_token) {
+    while (!stop_token.stop_requested()) {
+        for (auto& arrow : arrow_buttons) {
+            // check for ctrl + arrow keys and trigger p1 pad arrows
+            if (((GetAsyncKeyState(VK_CONTROL) & 0x8000) != 0) &&
+                ((GetAsyncKeyState(arrow.key) & 0x8000) != 0)) {
+                spice.set_button(arrow.button, true, 1.f);
+
+                if (!arrow.previous_state) {
+                    LOG_INFO(std::format("let me hear you say: {}", arrow.name).c_str());
+                    arrow.previous_state = true;
+                }
+            } else {
+                spice.set_button(arrow.button, false, 0.f);
+                arrow.previous_state = false;
+            }
+        }
+
+        std::this_thread::sleep_for(std::chrono::milliseconds(1));
+    }
+}

src/spice2x/sdk/sdk.cpp

@@ -11,6 +11,7 @@
 #include "touch/touch.h"
 #include "util/logging.h"
 #include "util/utils.h"
+#include "acio/mdxf/mdxf_poll.h"
 
 namespace sdk {
 
@@ -323,6 +324,7 @@ sdk_set_button (
         button.override_velocity = velocity;
     }
     button.override_enabled = pressed;
+    mdxf_poll(true);
     return SPICE_SDK_STATUS_SUCCESS;
 }
 
@@ -381,6 +383,7 @@ sdk_set_analog (
         analog.override_state = value;
     }
     analog.override_enabled = override_active;
+    mdxf_poll(true);
     return SPICE_SDK_STATUS_SUCCESS;
 }