Initial pressure-sensitive pen API + XInput2 implementation

- Adds new event types "PenMotion" and "PenButton"
- Adds internal pipeline for reporting pen events, tee-ing
  them into mouse events with mouse ID SDL_PEN_MOUSEID
- XInput2 pen support, incl. pressure, horizontal / vertical tilt
- Test program: test/testpen

bool -> SDL_bool fixes by @sezero

Author: creichen

include/SDL_events.h

@@ -157,6 +157,11 @@ typedef enum
     /* Sensor events */
     SDL_SENSORUPDATE = 0x1200,     /**< A sensor was updated */
 
+    /* Pressure-sensitive pen events */
+    SDL_PENMOTION    = 0x1300,     /**< Pressure-sensitive pen moved, or change in angle/pressure changed */
+    SDL_PENBUTTONDOWN,             /**< Pressure-sensitive pen button pressed */
+    SDL_PENBUTTONUP,               /**< Pressure-sensitive pen button released */
+
     /* Render events */
     SDL_RENDER_TARGETS_RESET = 0x2000, /**< The render targets have been reset and their contents need to be updated */
     SDL_RENDER_DEVICE_RESET, /**< The device has been reset and all textures need to be recreated */
@@ -278,7 +283,7 @@ typedef struct SDL_MouseMotionEvent
     Uint32 type;        /**< ::SDL_MOUSEMOTION */
     Uint32 timestamp;   /**< In milliseconds, populated using SDL_GetTicks() */
     Uint32 windowID;    /**< The window with mouse focus, if any */
-    Uint32 which;       /**< The mouse instance id, or SDL_TOUCH_MOUSEID */
+    Uint32 which;       /**< The mouse instance id, SDL_TOUCH_MOUSEID, or SDL_PEN_MOUSEID */
     Uint32 state;       /**< The current button state */
     Sint32 x;           /**< X coordinate, relative to window */
     Sint32 y;           /**< Y coordinate, relative to window */
@@ -294,7 +299,7 @@ typedef struct SDL_MouseButtonEvent
     Uint32 type;        /**< ::SDL_MOUSEBUTTONDOWN or ::SDL_MOUSEBUTTONUP */
     Uint32 timestamp;   /**< In milliseconds, populated using SDL_GetTicks() */
     Uint32 windowID;    /**< The window with mouse focus, if any */
-    Uint32 which;       /**< The mouse instance id, or SDL_TOUCH_MOUSEID */
+    Uint32 which;       /**< The mouse instance id, SDL_TOUCH_MOUSEID, or SDL_PEN_MOUSEID */
     Uint8 button;       /**< The mouse button index */
     Uint8 state;        /**< ::SDL_PRESSED or ::SDL_RELEASED */
     Uint8 clicks;       /**< 1 for single-click, 2 for double-click, etc. */
@@ -311,7 +316,7 @@ typedef struct SDL_MouseWheelEvent
     Uint32 type;        /**< ::SDL_MOUSEWHEEL */
     Uint32 timestamp;   /**< In milliseconds, populated using SDL_GetTicks() */
     Uint32 windowID;    /**< The window with mouse focus, if any */
-    Uint32 which;       /**< The mouse instance id, or SDL_TOUCH_MOUSEID */
+    Uint32 which;       /**< The mouse instance id, SDL_TOUCH_MOUSEID, or SDL_PEN_MOUSEID */
     Sint32 x;           /**< The amount scrolled horizontally, positive to the right and negative to the left */
     Sint32 y;           /**< The amount scrolled vertically, positive away from the user and negative toward the user */
     Uint32 direction;   /**< Set to one of the SDL_MOUSEWHEEL_* defines. When FLIPPED the values in X and Y will be opposite. Multiply by -1 to change them back */
@@ -530,6 +535,43 @@ typedef struct SDL_DollarGestureEvent
     float y;            /**< Normalized center of gesture */
 } SDL_DollarGestureEvent;
 
+/**
+ *  \brief Pressure-sensitive pen motion / pressure / angle event structure (event.pmotion.*)
+ */
+typedef struct SDL_PenMotionEvent
+{
+    Uint32 type;        /**< ::SDL_PENMOTION */
+    Uint32 timestamp;   /**< In milliseconds, populated using SDL_GetTicks() */
+    Uint32 windowID;    /**< The window with pen focus, if any */
+    Uint32 which;       /**< The pen instance id */
+    Uint16 state;       /**< The current button state */
+    Uint8 eraser;       /**< Nonzero iff this pen is an eraser */
+    float x;            /**< X coordinate, relative to window */
+    float y;            /**< Y coordinate, relative to window */
+    float pressure;     /**< Pen pressure, normalised to the range 0..1.0 */
+    float xtilt;        /**< Pen horizontal tilt, normalised to the range -1.0..1.0 */
+    float ytilt;        /**< Pen vertical tilt, normalised to the range -1.0..1.0 */
+} SDL_PenMotionEvent;
+
+/**
+ *  \brief Pressure-sensitive pen button event structure (event.pbutton.*)
+ */
+typedef struct SDL_PenButtonEvent
+{
+    Uint32 type;        /**< ::SDL_PENBUTTONDOWN or ::SDL_PENBUTTONUP */
+    Uint32 timestamp;   /**< In milliseconds, populated using SDL_GetTicks() */
+    Uint32 windowID;    /**< The window with pen focus, if any */
+    Uint32 which;       /**< The pen instance id */
+    Uint8 button;       /**< The pen button index */
+    Uint8 state;        /**< ::SDL_PRESSED or ::SDL_RELEASED */
+    Uint8 eraser;       /**< Nonzero iff this pen is an eraser */
+    Uint8 padding1;
+    float x;            /**< X coordinate, relative to window */
+    float y;            /**< Y coordinate, relative to window */
+    float pressure;     /**< Pen pressure, normalised to the range 0..1.0 */
+    float xtilt;        /**< Pen horizontal tilt, normalised to the range -1.0..1.0 */
+    float ytilt;        /**< Pen vertical tilt, normalised to the range -1.0..1.0 */
+} SDL_PenButtonEvent;
 
 /**
  *  \brief An event used to request a file open by the system (event.drop.*)
@@ -638,6 +680,8 @@ typedef union SDL_Event
     SDL_TouchFingerEvent tfinger;           /**< Touch finger event data */
     SDL_MultiGestureEvent mgesture;         /**< Gesture event data */
     SDL_DollarGestureEvent dgesture;        /**< Gesture event data */
+    SDL_PenMotionEvent pmotion;             /**< Pen change in position, pressure, or angle */
+    SDL_PenButtonEvent pbutton;             /**< Pen button press */
     SDL_DropEvent drop;                     /**< Drag and drop event data */
 
     /* This is necessary for ABI compatibility between Visual C++ and GCC.

include/SDL_mouse.h

@@ -69,6 +69,10 @@ typedef enum
     SDL_MOUSEWHEEL_FLIPPED    /**< The scroll direction is flipped / natural */
 } SDL_MouseWheelDirection;
 
+/* Used as the device ID for mouse events triggered by pen events */
+#define SDL_PEN_MOUSEID ((Uint32)-2)
+
+
 /* Function prototypes */
 
 /**

src/events/SDL_mouse.c

@@ -279,20 +279,29 @@ SDL_SetMouseFocus(SDL_Window * window)
     SDL_SetCursor(NULL);
 }
 
-/* Check to see if we need to synthesize focus events */
-static SDL_bool
-SDL_UpdateMouseFocus(SDL_Window * window, int x, int y, Uint32 buttonstate, SDL_bool send_mouse_motion)
+SDL_bool
+SDL_IsMousePositionInWindow(SDL_Window * window, SDL_MouseID mouseID, int x, int y)
 {
-    SDL_Mouse *mouse = SDL_GetMouse();
-    SDL_bool inWindow = SDL_TRUE;
+    if (!window) {
+        return SDL_FALSE;
+    }
 
-    if (window && ((window->flags & SDL_WINDOW_MOUSE_CAPTURE) == 0)) {
+    if (0 == (window->flags & SDL_WINDOW_MOUSE_CAPTURE)) {
         int w, h;
         SDL_GetWindowSize(window, &w, &h);
         if (x < 0 || y < 0 || x >= w || y >= h) {
-            inWindow = SDL_FALSE;
+            return SDL_FALSE;
         }
     }
+    return SDL_TRUE;
+}
+
+/* Check to see if we need to synthesize focus events */
+static SDL_bool
+SDL_UpdateMouseFocus(SDL_Window * window, int x, int y, Uint32 buttonstate, SDL_bool send_mouse_motion)
+{
+    SDL_Mouse *mouse = SDL_GetMouse();
+    SDL_bool inWindow = SDL_IsMousePositionInWindow(window, mouse->mouseID, x, y);
 
     if (!inWindow) {
         if (window == mouse->focus) {

src/events/SDL_mouse_c.h

@@ -147,6 +147,9 @@ extern int SDL_SendMouseButtonClicks(SDL_Window * window, SDL_MouseID mouseID, U
 /* Send a mouse wheel event */
 extern int SDL_SendMouseWheel(SDL_Window * window, SDL_MouseID mouseID, float x, float y, SDL_MouseWheelDirection direction);
 
+/* Check if mouse position is within window or captured by window */
+extern SDL_bool SDL_IsMousePositionInWindow(SDL_Window * window, SDL_MouseID mouseID, int x, int y);
+
 /* Shutdown the mouse subsystem */
 extern void SDL_MouseQuit(void);
 

src/video/x11/SDL_x11events.c

@@ -605,7 +605,7 @@ X11_HandleClipboardEvent(_THIS, const XEvent *xevent)
             int seln_format, mime_formats;
             unsigned long nbytes;
             unsigned long overflow;
-            unsigned char *seln_data;            
+            unsigned char *seln_data;
             Atom supportedFormats[SDL_X11_CLIPBOARD_MIME_TYPE_MAX+1];
             Atom XA_TARGETS = X11_XInternAtom(display, "TARGETS", 0);
 
@@ -625,7 +625,7 @@ X11_HandleClipboardEvent(_THIS, const XEvent *xevent)
             /* !!! FIXME: We were probably storing this on the root window
                because an SDL window might go away...? but we don't have to do
                this now (or ever, really). */
-            
+
             if (req->target == XA_TARGETS) {
                 supportedFormats[0] = XA_TARGETS;
                 mime_formats = 1;
@@ -908,7 +908,7 @@ X11_DispatchEvent(_THIS, XEvent *xevent)
             if (xevent->xcrossing.mode != NotifyGrab &&
                 xevent->xcrossing.mode != NotifyUngrab &&
                 xevent->xcrossing.detail != NotifyInferior) {
-                
+
                 /* In order for interaction with the window decorations and menu to work properly
                    on Mutter, we need to ungrab the keyboard when the the mouse leaves. */
                 if (!(data->window->flags & SDL_WINDOW_FULLSCREEN)) {
@@ -1124,7 +1124,7 @@ X11_DispatchEvent(_THIS, XEvent *xevent)
                                         &xevent->xconfigure.x, &xevent->xconfigure.y,
                                         &ChildReturn);
             }
-                
+
             if (xevent->xconfigure.x != data->last_xconfigure.x ||
                 xevent->xconfigure.y != data->last_xconfigure.y) {
                 SDL_SendWindowEvent(data->window, SDL_WINDOWEVENT_MOVED,

src/video/x11/SDL_x11video.c

@@ -471,6 +471,8 @@ X11_VideoInit(_THIS)
 
     X11_InitTouch(_this);
 
+    X11_InitPen(_this);
+
     return 0;
 }
 

src/video/x11/SDL_x11video.h

@@ -67,6 +67,7 @@
 #include "SDL_x11modes.h"
 #include "SDL_x11mouse.h"
 #include "SDL_x11opengl.h"
+#include "SDL_x11pen.h"
 #include "SDL_x11window.h"
 #include "SDL_x11vulkan.h"
 
@@ -154,6 +155,11 @@ typedef struct SDL_VideoData
     PFN_XGetXCBConnection vulkan_XGetXCBConnection;
 #endif
 
+#if SDL_VIDEO_DRIVER_X11_XINPUT2
+    Uint32 num_pens;
+    SDL_X11Pen pens[SDL_MAX_PEN_DEVICES];
+#endif /* SDL_VIDEO_DRIVER_X11_XINPUT2 */
+
 } SDL_VideoData;
 
 extern SDL_bool X11_UseDirectColorVisuals(void);

src/video/x11/SDL_x11window.c

@@ -422,7 +422,7 @@ X11_CreateWindow(_THIS, SDL_Window * window)
 #if SDL_VIDEO_OPENGL_EGL
         if (((_this->gl_config.profile_mask == SDL_GL_CONTEXT_PROFILE_ES) ||
              SDL_GetHintBoolean(SDL_HINT_VIDEO_X11_FORCE_EGL, SDL_FALSE))
-#if SDL_VIDEO_OPENGL_GLX            
+#if SDL_VIDEO_OPENGL_GLX
             && ( !_this->gl_data || X11_GL_UseEGL(_this) )
 #endif
         ) {
@@ -635,14 +635,14 @@ X11_CreateWindow(_THIS, SDL_Window * window)
     windowdata = (SDL_WindowData *) window->driverdata;
 
 #if SDL_VIDEO_OPENGL_ES || SDL_VIDEO_OPENGL_ES2 || SDL_VIDEO_OPENGL_EGL
-    if ((window->flags & SDL_WINDOW_OPENGL) && 
+    if ((window->flags & SDL_WINDOW_OPENGL) &&
         ((_this->gl_config.profile_mask == SDL_GL_CONTEXT_PROFILE_ES) ||
          SDL_GetHintBoolean(SDL_HINT_VIDEO_X11_FORCE_EGL, SDL_FALSE))
-#if SDL_VIDEO_OPENGL_GLX            
+#if SDL_VIDEO_OPENGL_GLX
         && ( !_this->gl_data || X11_GL_UseEGL(_this) )
-#endif  
+#endif
     ) {
-#if SDL_VIDEO_OPENGL_EGL  
+#if SDL_VIDEO_OPENGL_EGL
         if (!_this->egl_data) {
             return -1;
         }
@@ -658,7 +658,7 @@ X11_CreateWindow(_THIS, SDL_Window * window)
 #endif /* SDL_VIDEO_OPENGL_EGL */
     }
 #endif
-    
+
 
 #ifdef X_HAVE_UTF8_STRING
     if (SDL_X11_HAVE_UTF8 && windowdata->ic) {
@@ -675,6 +675,8 @@ X11_CreateWindow(_THIS, SDL_Window * window)
                  PropertyChangeMask | StructureNotifyMask |
                  KeymapStateMask | fevent));
 
+    X11_PenXinput2SelectEvents(_this);
+
     /* For _ICC_PROFILE. */
     X11_XSelectInput(display, RootWindow(display, screen), PropertyChangeMask);