samples: input: draw_touch_events: avoid avoid OOB writes

When CROSS_DIM doesn’t evenly divide the panel WIDTH/HEIGHT, the last
tile on the right/bottom edge can extend past the display bounds.

Fix by clipping the edge tiles.

Signed-off-by: Charles Dias <charlesdias.cd@outlook.com>

Author: CharlesDias

samples/subsys/input/draw_touch_events/src/main.c

@@ -70,7 +70,14 @@ static void clear_screen(void)
 
 	for (x = 0; x < WIDTH; x += CROSS_DIM) {
 		for (y = 0; y < HEIGHT; y += CROSS_DIM) {
-			display_write(display_dev, x, y, &buf_desc, buffer_cross_empty);
+			struct display_buffer_descriptor ddesc = buf_desc;
+			uint16_t rem_w = WIDTH - x;
+			uint16_t rem_h = HEIGHT - y;
+			ddesc.width = MIN(buf_desc.width, rem_w);
+			ddesc.height = MIN(buf_desc.height, rem_h);
+			ddesc.buf_size = ddesc.width * ddesc.height * BPP;
+
+			display_write(display_dev, x, y, &ddesc, buffer_cross_empty);
 		}
 	}
 }
@@ -126,6 +133,15 @@ int main(void)
 		LOG_ERR("Unsupported BPP=%d", BPP);
 		return 0;
 	}
+
+	/* Ensure driver pixel format matches our buffer layout from DT */
+	int rc = display_set_pixel_format(display_dev, PIXEL_FORMAT);
+
+	if (rc < 0) {
+		LOG_WRN("display_set_pixel_format(%d) failed: %d, continuing with driver default",
+			PIXEL_FORMAT, rc);
+	}
+
 	fill_cross_buffer();
 	display_blanking_off(display_dev);