drm: Add separate cursor and pointer options

Pointer event delivery in the DRM platform was gated on cursor.enabled,
which only becomes true after init_cursor() successfully allocates a
hardware cursor plane. Drivers that lack a DRM_PLANE_TYPE_CURSOR plane
(e.g. drm_simple_kms_helper panels) silently dropped every libinput
pointer event, making COG_PLATFORM_DRM_CURSOR effectively the master
switch for pointer input rather than just the on-screen cursor sprite
as its name implies.

Split into two independent options, each settable via env var,
configuration file [drm] section, or -O command-line parameter:

  cursor   draw a hardware cursor plane sprite (COG_PLATFORM_DRM_CURSOR)
  pointer  forward libinput pointer events to WPE (COG_PLATFORM_DRM_POINTER)

Both default to off; cursor=on implies pointer=on so the legacy
single-flag behaviour of COG_PLATFORM_DRM_CURSOR=1 is preserved.

Author: zhovner

docs/platform-drm.md

@@ -19,11 +19,13 @@ The DRM platform plug-in additionally requires the following libraries:
 If a section named `drm` is found in the configuration file (see
 [property@Cog.Shell:config-file]), the following options will be honored:
 
-| Option                       | Type    | Default  |
-|:-----------------------------|:--------|:---------|
-| `device-scale-factor`        | float   | `1.0`    |
-| `disable-atomic-modesetting` | boolean | *detect* |
-| `renderer`                   | string | `"modeset"` |
+| Option                       | Type    | Default     |
+|:-----------------------------|:--------|:------------|
+| `device-scale-factor`        | float   | `1.0`       |
+| `disable-atomic-modesetting` | boolean | *detect*    |
+| `renderer`                   | string  | `"modeset"` |
+| `cursor`                     | boolean | `false`     |
+| `pointer`                    | boolean | `false`     |
 
 The `device-scale-factor` option indicates a scaling factor to be applied to
 the rendered content. This is particularly useful for displays with a high
@@ -44,23 +46,34 @@ the output. Using the value `"gles"` will “paint” frames onto a quad using
 OpenGL ES. The main reason to use the latter is that it supports [output
 rotation](#output-rotation).
 
+The `cursor` and `pointer` options control whether the hardware cursor
+sprite is drawn and whether `libinput` pointer events are forwarded to
+the page, respectively. See [Pointer Input](#pointer-input) for details.
+
 
 ## Parameters
 
 The following parameters can be passed to the platform plug-in during
 initialization (e.g. using `cog --platform-params=…`):
 
-| Parameter  | Type   | Default   |
-|:-----------|:-------|:----------|
-| `renderer` | string | `modeset` |
-| `rotation` | number | `0`       |
+| Parameter  | Type    | Default   |
+|:-----------|:--------|:----------|
+| `renderer` | string  | `modeset` |
+| `rotation` | number  | `0`       |
+| `cursor`   | boolean | `false`   |
+| `pointer`  | boolean | `false`   |
 
 The `renderer` parameter is the same as the [configuration file
 option](#configuration-file-options) of the same name.
 
 The `rotation` parameter indicates the initial [output
 rotation](#output-rotation) applied.
 
+The `cursor` and `pointer` parameters are the same as the
+[configuration file options](#configuration-file-options) of the same
+name. See [Pointer Input](#pointer-input) for details. Boolean values
+accept `true`, `on`, `1`, `false`, `off`, or `0`.
+
 
 ## Environment Variables
 
@@ -70,8 +83,9 @@ DRM plug-in operates:
 | Variable | Type | Default |
 |:---------|:-----|--------:|
 | `COG_PLATFORM_DRM_VIDEO_MODE` | string | *(unset*) |
-| `COG_PLATFORM_DRM_MODE_MAX` | string | *(unset)* |
-| `COG_PLATFORM_DRM_CURSOR` | string | *(unset)* |
+| `COG_PLATFORM_DRM_MODE_MAX`   | string | *(unset)* |
+| `COG_PLATFORM_DRM_CURSOR`     | string | *(unset)* |
+| `COG_PLATFORM_DRM_POINTER`    | string | *(unset)* |
 
 By default the preferred mode for the first found connected output is used
 (if available), otherwise the mode with highest resolution.
@@ -83,8 +97,45 @@ mode strings in the format `WxR` (`W`idth and `H`eight in pixels).
 a refresh rate in the format `WxH@R`.
 for example `1920x1080@60` for a typical Full-HD mode.
 
-Setting `COG_PLATFORM_DRM_CURSOR` to a non-empty string enables showing
-the mouse cursor pointer.
+Setting `COG_PLATFORM_DRM_CURSOR` or `COG_PLATFORM_DRM_POINTER` to any
+non-empty value enables the corresponding option from
+[Pointer Input](#pointer-input).
+
+
+## Pointer Input
+
+Two independent options control how the DRM platform handles
+mouse / touchpad input. Both default to off, in which case the plug-in
+still delivers keyboard and touchscreen events to the loaded page but
+ignores pointer-class devices entirely.
+
+The `pointer` option forwards `libinput` pointer motion, button, and
+scroll events to WPE. The page then sees them as DOM `pointermove`,
+`pointerdown`, `pointerup`, and `wheel` events. This is independent of
+whether anything is drawn on screen; the page is responsible for any
+visual cursor (e.g. one drawn on a `<canvas>`).
+
+The `cursor` option allocates a hardware cursor plane and draws a
+16×16 sprite on top of the rendered output, moved on every pointer-motion
+event. This requires the underlying DRM driver to expose a
+`DRM_PLANE_TYPE_CURSOR` plane; many minimal drivers (e.g. SPI/MIPI panels
+using `drm_simple_kms_helper`) do not, in which case this option has no
+visible effect even when enabled.
+
+For backwards compatibility, enabling `cursor` implies `pointer`. The
+four combinations:
+
+| `cursor` | `pointer` | Pointer events to WPE | Hardware cursor sprite |
+|:--------:|:---------:|:---------------------:|:----------------------:|
+| off      | off       | no                    | no                     |
+| off      | on        | yes                   | no                     |
+| on       | off       | yes (implied)         | yes (if plane exists)  |
+| on       | on        | yes                   | yes (if plane exists)  |
+
+Configuration precedence is: command-line parameter overrides
+configuration file, which overrides environment variable. The legacy
+behaviour of `COG_PLATFORM_DRM_CURSOR=1` (enabling both pointer dispatch
+and the sprite) is preserved by the `cursor` ⇒ `pointer` implication.
 
 
 ## Output Rotation

platform/drm/cog-platform-drm.c

@@ -68,6 +68,8 @@ struct _CogDrmPlatform {
     CogDrmRenderer        *renderer;
     CogGLRendererRotation  rotation;
     GList                 *rotatable_input_devices;
+    bool                   draw_cursor;
+    bool                   dispatch_pointer;
     bool                   use_gles;
 };
 
@@ -192,6 +194,8 @@ static struct {
     uint32_t input_width;
     uint32_t input_height;
 
+    bool dispatch_pointer;
+
     struct keyboard_event repeating_key;
 
     struct wpe_input_touch_event_raw touch_points[10];
@@ -203,6 +207,7 @@ static struct {
     .rotation = COG_GL_RENDERER_ROTATION_0,
     .input_width = 0,
     .input_height = 0,
+    .dispatch_pointer = false,
     .repeating_key = {0, 0},
     .last_touch_type = wpe_input_touch_event_type_null,
     .last_touch_id = 0,
@@ -226,13 +231,30 @@ static struct {
     struct wpe_view_backend *backend;
 } wpe_view_data;
 
+static bool
+parse_bool(const char *value, bool *out)
+{
+    if (g_strcmp0(value, "true") == 0 || g_strcmp0(value, "on") == 0 || g_strcmp0(value, "1") == 0) {
+        *out = true;
+        return true;
+    }
+    if (g_strcmp0(value, "false") == 0 || g_strcmp0(value, "off") == 0 || g_strcmp0(value, "0") == 0) {
+        *out = false;
+        return true;
+    }
+    return false;
+}
+
 static void
 init_config(CogDrmPlatform *self, CogShell *shell, const char *params_string)
 {
     drm_data.device_scale = cog_shell_get_device_scale_factor (shell);
     g_debug ("init_config: overriding device_scale value, using %.2f from shell",
              drm_data.device_scale);
 
+    self->draw_cursor = g_getenv("COG_PLATFORM_DRM_CURSOR") != NULL;
+    self->dispatch_pointer = g_getenv("COG_PLATFORM_DRM_POINTER") != NULL;
+
     GKeyFile *key_file = cog_shell_get_config_file (shell);
 
     if (key_file) {
@@ -266,6 +288,20 @@ init_config(CogDrmPlatform *self, CogShell *shell, const char *params_string)
             else if (value)
                 g_warning("Invalid renderer '%s', using default.", value);
         }
+
+        {
+            g_autoptr(GError) lookup_error = NULL;
+            gboolean value = g_key_file_get_boolean(key_file, "drm", "cursor", &lookup_error);
+            if (!lookup_error)
+                self->draw_cursor = value;
+        }
+
+        {
+            g_autoptr(GError) lookup_error = NULL;
+            gboolean value = g_key_file_get_boolean(key_file, "drm", "pointer", &lookup_error);
+            if (!lookup_error)
+                self->dispatch_pointer = value;
+        }
     }
 
     if (params_string) {
@@ -295,11 +331,20 @@ init_config(CogDrmPlatform *self, CogShell *shell, const char *params_string)
                     g_warning("Invalid value '%s' for parameter '%s'.", v, k);
                 else
                     self->rotation = val;
+            } else if (g_strcmp0(k, "cursor") == 0) {
+                if (!parse_bool(v, &self->draw_cursor))
+                    g_warning("Invalid value '%s' for parameter '%s'.", v, k);
+            } else if (g_strcmp0(k, "pointer") == 0) {
+                if (!parse_bool(v, &self->dispatch_pointer))
+                    g_warning("Invalid value '%s' for parameter '%s'.", v, k);
             } else {
                 g_warning("Invalid parameter '%s'.", k);
             }
         }
     }
+
+    if (self->draw_cursor)
+        self->dispatch_pointer = true;
 }
 
 static void
@@ -636,11 +681,6 @@ init_cursor (void)
         return FALSE;
     }
 
-    cursor.x = (cursor.device->screens[0]->width - cursor.cursor->width) / 2;
-    cursor.y = (cursor.device->screens[0]->height - cursor.cursor->height) / 2;
-    cursor.screen_width = cursor.device->screens[0]->width;
-    cursor.screen_height = cursor.device->screens[0]->height;
-
     if (kms_plane_set(cursor.plane, cursor.cursor, cursor.x, cursor.y)) {
         g_clear_pointer(&cursor.device, kms_device_free);
         g_clear_pointer(&cursor.cursor, kms_framebuffer_free);
@@ -893,7 +933,7 @@ input_handle_touch_event (enum libinput_event_type touch_type, struct libinput_e
 static void
 input_handle_pointer_motion_event(struct libinput_event_pointer *pointer_event, bool absolute)
 {
-    if (!cursor.enabled)
+    if (!input_data.dispatch_pointer)
         return;
 
     if (absolute) {
@@ -927,13 +967,14 @@ input_handle_pointer_motion_event(struct libinput_event_pointer *pointer_event,
     };
 
     wpe_view_backend_dispatch_pointer_event(wpe_view_data.backend, &event);
-    kms_plane_set(cursor.plane, cursor.cursor, cursor.x, cursor.y);
+    if (cursor.enabled)
+        kms_plane_set(cursor.plane, cursor.cursor, cursor.x, cursor.y);
 }
 
 static void
 input_handle_pointer_button_event (struct libinput_event_pointer *pointer_event)
 {
-    if (!cursor.enabled)
+    if (!input_data.dispatch_pointer)
         return;
 
     struct wpe_input_pointer_event event = {
@@ -953,6 +994,9 @@ input_handle_pointer_button_event (struct libinput_event_pointer *pointer_event)
 static void
 input_handle_pointer_discrete_scroll_event(struct libinput_event_pointer *pointer_event)
 {
+    if (!input_data.dispatch_pointer)
+        return;
+
     struct wpe_input_axis_2d_event event = {
         .base.type = wpe_input_axis_event_type_mask_2d | wpe_input_axis_event_type_motion,
         .base.time = libinput_event_pointer_get_time(pointer_event),
@@ -975,6 +1019,9 @@ input_handle_pointer_discrete_scroll_event(struct libinput_event_pointer *pointe
 static void
 input_handle_pointer_smooth_scroll_event(struct libinput_event_pointer *pointer_event)
 {
+    if (!input_data.dispatch_pointer)
+        return;
+
     struct wpe_input_axis_2d_event event = {
         .base.type = wpe_input_axis_event_type_mask_2d | wpe_input_axis_event_type_motion_smooth,
         .base.time = libinput_event_pointer_get_time(pointer_event),
@@ -997,6 +1044,9 @@ input_handle_pointer_smooth_scroll_event(struct libinput_event_pointer *pointer_
 static void
 input_handle_pointer_axis_event(struct libinput_event_pointer *pointer_event)
 {
+    if (!input_data.dispatch_pointer)
+        return;
+
     struct wpe_input_axis_2d_event event = {
         .base.type = wpe_input_axis_event_type_mask_2d,
         .base.time = libinput_event_pointer_get_time(pointer_event),
@@ -1291,6 +1341,7 @@ init_input(CogDrmPlatform *platform)
         return FALSE;
 
     input_data.rotation = platform->rotation;
+    input_data.dispatch_pointer = platform->dispatch_pointer;
 
     int ret = libinput_udev_assign_seat (input_data.libinput, "seat0");
     if (ret)
@@ -1303,6 +1354,11 @@ init_input(CogDrmPlatform *platform)
         touch_point->type = wpe_input_touch_event_type_null;
     }
 
+    cursor.screen_width = input_data.input_width;
+    cursor.screen_height = input_data.input_height;
+    cursor.x = cursor.screen_width / 2;
+    cursor.y = cursor.screen_height / 2;
+
     return TRUE;
 }
 
@@ -1457,7 +1513,7 @@ cog_drm_platform_setup(CogPlatform *platform, CogShell *shell, const char *param
         return FALSE;
     }
 
-    if (g_getenv ("COG_PLATFORM_DRM_CURSOR")) {
+    if (self->draw_cursor) {
         if (!init_cursor ()) {
             g_warning ("Failed to initialize cursor");
         }