Add additional options for Drag Scroll config (#20523)

Author: doesntfazer

docs/feature_pointing_device.md

@@ -434,6 +434,75 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
 
 This allows you to toggle between scrolling and cursor movement by pressing the DRAG_SCROLL key.  
 
+### Advanced Drag Scroll
+
+Sometimes, like with the Cirque trackpad, you will run into issues where the scrolling may be too fast.
+
+Here is a slightly more advanced example of drag scrolling. You will be able to change the scroll speed based on the values in set in `SCROLL_DIVISOR_H` and `SCROLL_DIVISOR_V`. This bit of code is also set up so that instead of toggling the scrolling state with set_scrolling = !set_scrolling, the set_scrolling variable is set directly to record->event.pressed. This way, the drag scrolling will only be active while the DRAG_SCROLL button is held down.
+
+```c
+enum custom_keycodes {
+    DRAG_SCROLL = SAFE_RANGE,
+};
+
+bool set_scrolling = false;
+
+// Modify these values to adjust the scrolling speed
+#define SCROLL_DIVISOR_H 8.0
+#define SCROLL_DIVISOR_V 8.0
+
+// Variables to store accumulated scroll values
+float scroll_accumulated_h = 0;
+float scroll_accumulated_v = 0;
+
+// Function to handle mouse reports and perform drag scrolling
+report_mouse_t pointing_device_task_user(report_mouse_t mouse_report) {
+    // Check if drag scrolling is active
+    if (set_scrolling) {
+        // Calculate and accumulate scroll values based on mouse movement and divisors
+        scroll_accumulated_h += (float)mouse_report.x / SCROLL_DIVISOR_H;
+        scroll_accumulated_v += (float)mouse_report.y / SCROLL_DIVISOR_V;
+
+        // Assign integer parts of accumulated scroll values to the mouse report
+        mouse_report.h = (int8_t)scroll_accumulated_h;
+        mouse_report.v = (int8_t)scroll_accumulated_v;
+
+        // Update accumulated scroll values by subtracting the integer parts
+        scroll_accumulated_h -= (int8_t)scroll_accumulated_h;
+        scroll_accumulated_v -= (int8_t)scroll_accumulated_v;
+
+        // Clear the X and Y values of the mouse report
+        mouse_report.x = 0;
+        mouse_report.y = 0;
+    }
+    return mouse_report;
+}
+
+// Function to handle key events and enable/disable drag scrolling
+bool process_record_user(uint16_t keycode, keyrecord_t *record) {
+    switch (keycode) {
+        case DRAG_SCROLL:
+            // Toggle set_scrolling when DRAG_SCROLL key is pressed or released
+            set_scrolling = record->event.pressed;
+            break;
+        default:
+            break;
+    }
+    return true;
+}
+
+// Function to handle layer changes and disable drag scrolling when not in AUTO_MOUSE_DEFAULT_LAYER
+layer_state_t layer_state_set_user(layer_state_t state) {
+    // Disable set_scrolling if the current layer is not the AUTO_MOUSE_DEFAULT_LAYER
+    if (get_highest_layer(state) != AUTO_MOUSE_DEFAULT_LAYER) {
+        set_scrolling = false;
+    }
+    return state;
+}
+
+```
+
+
 ## Split Examples
 
 The following examples make use the `SPLIT_POINTING_ENABLE` functionality and show how to manipulate the mouse report for a scrolling mode.