Touch Event Support for Simple2D

patch.diff

diff --git a/README.md b/README.md
index 2f09eed..f5412d7 100644
--- a/README.md
+++ b/README.md
@@ -596,6 +596,43 @@ S2D_ShowCursor(true);
 S2D_ShowCursor(false);
 ```
 
+### Touch Displays
+
+There are three types of touch event captured by the window: touch start, finger movement, and touch end.
+When a touch event is detected, the window calls its `on_touch` function.
+
+To capture game touch input, first define the `on_touch` function and read the 
+event details from the S2D_Event structure, for example:
+
+void on_touch(S2D_Event e) {
+  // Check `e.touch_id` for the device being interacted with 
+  // Check `e.x` and `e.y` for the coordinates of a touch event 
+  switch (e.type) {
+    case S2D_FINGER_DOWN:
+      // A touch sensitive device was touched
+      // Use `e.finger_id` to trace which finger is touching 
+      break;
+
+    case S2D_FINGER_UP:
+      // A finger has been lifted from a touch sensitive device
+      // Use `e.finger_id` to see what finger was lifted
+      break;
+
+    case S2D_FINGER_MOTION:
+      // A finger has moved on a touch device
+      // Check `e.delta_x` and `e.delta_y` for the difference in x and y position
+      break;
+
+  }
+}
+```
+
+Then, attach the callback to the window:
+
+```c
+window->on_touch = on_touch;
+```
+
 ### Game controllers and joysticks
 
 There are two types of controller or joystick events captured by the window: axis motion and button presses. When a button is pressed or a joystick moved, the window calls its `on_controller` function.
diff --git a/include/simple2d.h b/include/simple2d.h
index 69c7806..b8f810b 100644
--- a/include/simple2d.h
+++ b/include/simple2d.h
@@ -7,7 +7,7 @@ extern "C" {
 #include <stdio.h>
 #include <stdbool.h>
 #include <math.h>
-
+#include <inttypes.h>
 // Set Platform Constants //////////////////////////////////////////////////////
 
 // If ARM, assume GLES
@@ -109,6 +109,11 @@ extern "C" {
 #define S2D_BUTTON_DOWN 2
 #define S2D_BUTTON_UP   3
 
+// Touch events
+#define S2D_FINGER_DOWN   1
+#define S2D_FINGER_UP     2
+#define S2D_FINGER_MOTION 3
+
 // Internal Shared Data ////////////////////////////////////////////////////////
 
 extern char S2D_msg[1024];    // for S2D_Log messages
@@ -130,6 +135,8 @@ typedef struct {
   int direction;
   int axis;
   int value;
+  int64_t finger_id;
+  int64_t touch_id;
 } S2D_Event;
 
 typedef void (*S2D_Update)();
@@ -137,6 +144,7 @@ typedef void (*S2D_Render)();
 typedef void (*S2D_On_Key)(S2D_Event e);
 typedef void (*S2D_On_Mouse)(S2D_Event e);
 typedef void (*S2D_On_Controller)(S2D_Event e);
+typedef void (*S2D_On_Touch)(S2D_Event e);
 
 // S2D_Color
 typedef struct {
@@ -183,6 +191,7 @@ typedef struct {
   S2D_On_Key on_key;
   S2D_On_Mouse on_mouse;
   S2D_On_Controller on_controller;
+  S2D_On_Touch on_touch;
   bool vsync;
   int fps_cap;
   S2D_Color background;
diff --git a/src/window.c b/src/window.c
index 90b3641..e242b06 100644
--- a/src/window.c
+++ b/src/window.c
@@ -29,6 +29,7 @@ S2D_Window *S2D_CreateWindow(const char *title, int width, int height,
   window->on_key          = NULL;
   window->on_mouse        = NULL;
   window->on_controller   = NULL;
+  window->on_touch        = NULL;
   window->vsync           = true;
   window->fps_cap         = 60;
   window->background.r    = 0.0;
@@ -190,6 +191,58 @@ int S2D_Show(S2D_Window *window) {
             window->on_mouse(event);
           }
           break;
+        case SDL_FINGERMOTION:
+         {
+            if (window->on_touch) {
+           float fx,dx, fy, dy; 
+           fx = e.tfinger.x * window->width; // TODO: Viewport in scaling
+           fy = e.tfinger.y * window->height;
+           dx = e.tfinger.dx * window->width;
+           dy = e.tfinger.dy * window->height;
+           S2D_GetMouseOnViewport(window, (int)fx, (int)fy, &mx, &my);
+            S2D_Event event = {
+              .x = mx, .y = my, .delta_x = dx, .delta_y = dy, .finger_id = e.tfinger.fingerId,
+              .touch_id = e.tfinger.touchId
+            };
+            event.type = S2D_FINGER_MOTION;
+            window->on_touch(event);
+          }
+
+        }break;
+	case SDL_FINGERDOWN:
+        {
+          if (window->on_touch) {
+           float fx, fy; 
+           fx = e.tfinger.x * window->width; // TODO: Viewport in scaling
+           fy = e.tfinger.y * window->height;
+           S2D_GetMouseOnViewport(window, (int)fx, (int)fy, &mx, &my);
+            S2D_Event event = {
+              .x = mx, .y = my, .finger_id = e.tfinger.fingerId,
+              .touch_id = e.tfinger.touchId
+
+            };
+            event.type = S2D_FINGER_DOWN;;
+            window->on_touch(event);
+          }
+        }break;
+	case SDL_FINGERUP:
+        {
+          if (window->on_touch) {
+           float fx, fy; 
+           // TODO: Finger ID tracking
+           fx = e.tfinger.x * window->width; // TODO: Viewport in scaling
+           fy = e.tfinger.y * window->height;
+           S2D_GetMouseOnViewport(window, (int)fx, (int)fy, &mx, &my);
+            S2D_Event event = {
+              .x = mx, .y = my, .finger_id = e.tfinger.fingerId,
+              .touch_id = e.tfinger.touchId
+
+            };
+            event.type = S2D_FINGER_UP;
+            window->on_touch(event);
+          }
+
+        }break;
 
         case SDL_JOYAXISMOTION:
           if (window->on_controller) {
diff --git a/test/testcard.c b/test/testcard.c
index 335310a..7be67cc 100644
--- a/test/testcard.c
+++ b/test/testcard.c
@@ -108,6 +108,27 @@ void on_mouse(S2D_Event e) {
   if (e.type != S2D_MOUSE_SCROLL) printf("x: %i, y: %i\n", e.x, e.y);
 }
 
+void on_touch(S2D_Event e) {
+  puts("=== Touch Event ===");
+  printf("finger: %" PRId64 ", device:%" PRId64 " ",e.finger_id,e.touch_id);
+  switch (e.type) {
+    case S2D_FINGER_DOWN:
+      puts("Finger down");
+      break;
+
+    case S2D_FINGER_UP:
+      puts("Finger up");
+      break;
+
+    case S2D_FINGER_MOTION:
+      puts("Finger motion");
+      printf("delta x: %i\ndelta y: %i\n", e.delta_x, e.delta_y);
+      break;
+
+  }
+
+  printf("x: %i, y: %i\n", e.x, e.y);
+}
 
 void on_controller(S2D_Event e) {
   puts("=== Controller Event ===");
@@ -334,12 +355,12 @@ int main() {
 
   S2D_Diagnostics(true);
 
-  window = S2D_CreateWindow("Simple 2D — Test Card", 600, 500, update, render, S2D_RESIZABLE);
+  window = S2D_CreateWindow("Simple 2D — Test Card", 800, 480, update, render, S2D_RESIZABLE);
 
   window->on_key        = on_key;
   window->on_mouse      = on_mouse;
   window->on_controller = on_controller;
-
+  window->on_touch      = on_touch;
   img_png = S2D_CreateImage("media/image.png");
   img_png->x = 300;
   img_png->y = 0;