pbio/drv/display: Add display driver abstraction.

The abstraction provides a way to access the display driver using a
platform agnostic way.

Refs pybricks/support#2154

Author: schodet

lib/pbio/drv/display/display_ev3.c

@@ -18,6 +18,7 @@
 #include "../core.h"
 
 #include <pbdrv/gpio.h>
+#include <pbdrv/display.h>
 #include <pbio/error.h>
 #include <pbio/util.h>
 
@@ -525,4 +526,20 @@ PROCESS_THREAD(pbdrv_display_ev3_init_process, ev, data) {
     PROCESS_END();
 }
 
+pbio_image_t *pbdrv_display_get_image(void) {
+    static pbio_image_t image;
+    pbio_image_init(&image, (uint8_t *)pbdrv_display_user_frame,
+        PBDRV_CONFIG_DISPLAY_NUM_COLS, PBDRV_CONFIG_DISPLAY_NUM_ROWS,
+        PBDRV_CONFIG_DISPLAY_NUM_COLS);
+    return &image;
+}
+
+uint8_t pbdrv_display_get_max_value(void) {
+    return 3;
+}
+
+void pbdrv_display_update(void) {
+    pbdrv_display_user_frame_update_requested = true;
+}
+
 #endif // PBDRV_CONFIG_DISPLAY_EV3

lib/pbio/include/pbdrv/display.h

@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2025 The Pybricks Authors
+
+/**
+ * @addtogroup DisplayDriver Driver: Display
+ * @{
+ */
+
+#ifndef _PBDRV_DISPLAY_H_
+#define _PBDRV_DISPLAY_H_
+
+#include <pbdrv/config.h>
+#include <pbio/image.h>
+
+#if PBDRV_CONFIG_DISPLAY
+
+/**
+ * Get an image container representing the display.
+ * @return  Image container, or NULL if no display.
+ */
+pbio_image_t *pbdrv_display_get_image(void);
+
+/**
+ * Get the maximum value of a pixel.
+ * @return  Maximum value, corresponding to black on a LCD screen.
+ */
+uint8_t pbdrv_display_get_max_value(void);
+
+/**
+ * Update the display to show current content of image container.
+ */
+void pbdrv_display_update(void);
+
+#else // PBDRV_CONFIG_DISPLAY
+
+static inline pbio_image_t *pbdrv_display_get_image(void) {
+    return NULL;
+}
+
+static inline uint8_t pbdrv_display_get_max_value(void) {
+    return 0;
+}
+
+static inline void pbdrv_display_update(void) {
+}
+
+#endif // PBDRV_CONFIG_DISPLAY
+
+#endif // _PBDRV_DISPLAY_H_
+
+/** @} */