From 4473f6d8b7bda3ecb6acaf16e8609a219f7ef6fc Mon Sep 17 00:00:00 2001
From: Harry Jeffery <harry@exec64.co.uk>
Date: Sat, 13 Jul 2019 00:35:19 +0100
Subject: Implement scroll input

---
 src/imv.c    | 17 ++++++++---------
 src/window.c | 39 ++++++++++++++++++++++++++++++++++++---
 src/window.h |  6 ++++++
 3 files changed, 50 insertions(+), 12 deletions(-)

diff --git a/src/imv.c b/src/imv.c
index c6fe9f6..aa99a72 100644
--- a/src/imv.c
+++ b/src/imv.c
@@ -455,6 +455,14 @@ static void event_handler(void *data, const struct imv_event *e)
             e->data.mouse_motion.dy, imv->current_image);
       }
       break;
+    case IMV_EVENT_MOUSE_SCROLL:
+      {
+        double x, y;
+        imv_window_get_mouse_position(imv->window, &x, &y);
+        imv_viewport_zoom(imv->view, imv->current_image, IMV_ZOOM_MOUSE,
+            x, y, -e->data.mouse_scroll.dy);
+      }
+      break;
     case IMV_EVENT_CUSTOM:
       consume_internal_event(imv, e->data.custom);
       break;
@@ -464,15 +472,6 @@ static void event_handler(void *data, const struct imv_event *e)
 
 }
 
-/* static void scroll_callback(GLFWwindow *window, double x, double y)*/
-/* {*/
-/*   (void)x;*/
-/*   struct imv *imv = glfwGetWindowUserPointer(window);*/
-/*   imv_viewport_zoom(imv->view, imv->current_image, IMV_ZOOM_MOUSE,*/
-/*                     imv->last_cursor_position.x,*/
-/*                     imv->last_cursor_position.y, -y);*/
-/* }*/
-
 static void log_to_stderr(enum imv_log_level level, const char *text, void *data)
 {
   (void)data;
diff --git a/src/window.c b/src/window.c
index fd1986f..de188c0 100644
--- a/src/window.c
+++ b/src/window.c
@@ -52,6 +52,10 @@ struct imv_window {
       bool last;
       bool current;
     } mouse1;
+    struct {
+      double dx;
+      double dy;
+    } scroll;
   } pointer;
 
   struct {
@@ -205,11 +209,15 @@ static void pointer_button(void *data, struct wl_pointer *pointer,
 static void pointer_axis(void *data, struct wl_pointer *pointer,
     uint32_t time, uint32_t axis, wl_fixed_t value)
 {
-  (void)data;
   (void)pointer;
   (void)time;
-  (void)axis;
-  (void)value;
+
+  struct imv_window *window = data;
+  if (axis == WL_POINTER_AXIS_VERTICAL_SCROLL) {
+    window->pointer.scroll.dy += wl_fixed_to_double(value);
+  } else if (axis == WL_POINTER_AXIS_HORIZONTAL_SCROLL) {
+    window->pointer.scroll.dx += wl_fixed_to_double(value);
+  }
 }
 
 static void pointer_frame(void *data, struct wl_pointer *pointer)
@@ -251,6 +259,21 @@ static void pointer_frame(void *data, struct wl_pointer *pointer)
     imv_window_push_event(window, &e);
   }
 
+  if (window->pointer.scroll.dx || window->pointer.scroll.dy) {
+    struct imv_event e = {
+      .type = IMV_EVENT_MOUSE_SCROLL,
+      .data = {
+        .mouse_scroll = {
+          .dx = window->pointer.scroll.dx,
+          .dy = window->pointer.scroll.dy
+        }
+      }
+    };
+    imv_window_push_event(window, &e);
+    window->pointer.scroll.dx = 0;
+    window->pointer.scroll.dy = 0;
+  }
+
 }
 
 static void pointer_axis_source(void *data, struct wl_pointer *pointer,
@@ -565,6 +588,16 @@ bool imv_window_get_mouse_button(struct imv_window *window, int button)
   return false;
 }
 
+void imv_window_get_mouse_position(struct imv_window *window, double *x, double *y)
+{
+  if (x) {
+    *x = window->pointer.x.last;
+  }
+  if (y) {
+    *y = window->pointer.y.last;
+  }
+}
+
 void imv_window_present(struct imv_window *window)
 {
   eglSwapBuffers(window->egl_display, window->egl_surface);
diff --git a/src/window.h b/src/window.h
index d6e317e..3e61043 100644
--- a/src/window.h
+++ b/src/window.h
@@ -11,6 +11,7 @@ enum imv_event_type {
   IMV_EVENT_KEYBOARD,
   IMV_EVENT_MOUSE_MOTION,
   IMV_EVENT_MOUSE_BUTTON,
+  IMV_EVENT_MOUSE_SCROLL,
   IMV_EVENT_CUSTOM
 };
 
@@ -34,6 +35,9 @@ struct imv_event {
       int button;
       bool pressed;
     } mouse_button;
+    struct {
+      double dx, dy;
+    } mouse_scroll;
     void *custom;
   } data;
 };
@@ -54,6 +58,8 @@ void imv_window_set_fullscreen(struct imv_window *window, bool fullscreen);
 
 bool imv_window_get_mouse_button(struct imv_window *window, int button);
 
+void imv_window_get_mouse_position(struct imv_window *window, double *x, double *y);
+
 void imv_window_present(struct imv_window *window);
 
 void imv_window_wait_for_event(struct imv_window *window, double timeout);
-- 
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