From f712d04bed78552ef6be68b79e868dc07266a1be Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Franti=C5=A1ek=20Boh=C3=A1=C4=8Dek?=
 <fandabohacek@gmail.com>
Date: Mon, 14 Jun 2021 21:33:15 +0200
Subject: [PATCH] feat: add cursor functions

---
 image-viewer/include/cursor.h | 37 +++++++++++++
 image-viewer/src/cursor.c     | 98 +++++++++++++++++++++++++++++++++++
 2 files changed, 135 insertions(+)
 create mode 100644 image-viewer/include/cursor.h
 create mode 100644 image-viewer/src/cursor.c

diff --git a/image-viewer/include/cursor.h b/image-viewer/include/cursor.h
new file mode 100644
index 0000000000000000000000000000000000000000..2304d8be87ac6dde4c43c6bc6f6f860424f4b787
--- /dev/null
+++ b/image-viewer/include/cursor.h
@@ -0,0 +1,37 @@
+#ifndef __CURSOR_H__
+#define __CURSOR_H__
+
+#include "display_utils.h"
+#include "image.h"
+#include <time.h>
+#include <stdint.h>
+
+#define CURSOR_SIZE 10
+
+typedef struct {
+  uint16_t x;
+  uint16_t y;
+
+  bool shown;
+  time_t shown_at;
+
+  display_pixel_t previous_display_data[CURSOR_SIZE * 2 - 1];
+} cursor_t;
+
+typedef enum {
+  UP,
+  LEFT,
+  DOWN,
+  RIGHT,
+} direction_t;
+
+const display_pixel_t CURSOR_COLOR = {.fields = {.r = (uint8_t)DISPLAY_MAX_RED, .g = 0, .b = 0}};
+
+cursor_t cursor_create();
+void cursor_center(cursor_t *cursor, image_region_t *region);
+void cursor_move(cursor_t *cursor, image_region_t *region, direction_t direction, uint8_t amount);
+
+void cursor_show(cursor_t *cursor, display_t *display);
+void cursor_hide(cursor_t *cursor, display_t *display);
+
+#endif // __CURSOR_H__
diff --git a/image-viewer/src/cursor.c b/image-viewer/src/cursor.c
new file mode 100644
index 0000000000000000000000000000000000000000..69f997699168d8979b3f287e9faf7a08a2a019cb
--- /dev/null
+++ b/image-viewer/src/cursor.c
@@ -0,0 +1,98 @@
+#include "cursor.h"
+#include "display_utils.h"
+#include "image.h"
+
+cursor_t cursor_create() {
+  cursor_t cursor = {
+    .x = 0,
+    .y = 0,
+    .shown = false,
+    .shown_at = 0,
+  };
+
+  return cursor;
+}
+
+void cursor_center(cursor_t *cursor, image_region_t *region) {
+  cursor->x = region->x + region->width / 2;
+  cursor->y = region->y + region->height / 2;
+}
+
+void cursor_move(cursor_t *cursor, image_region_t *region, direction_t direction, uint8_t amount) {
+  uint16_t x = cursor->x, y = cursor->y;
+
+  switch (direction) {
+  case LEFT:
+    x -= amount;
+    break;
+  case RIGHT:
+    x += amount;
+    break;
+  case UP:
+    y -= amount;
+    break;
+  case DOWN:
+    y += amount;
+    break;
+  }
+
+  if (x < region->x) {
+    x = region->x;
+  } else if (x > region->x + region->width - 1) {
+    x = region->x + region->width - 1;
+  }
+
+  if (y < region->y) {
+    y = region->y;
+  } else if (y > region->y + region->height - 1) {
+    y = region->y + region->height - 1;
+  }
+
+  cursor->x = x;
+  cursor->y = y;
+}
+
+void cursor_show(cursor_t *cursor, display_t *display) {
+  cursor_hide(cursor, display);
+  cursor->shown_at = time(NULL);
+  cursor->shown = true;
+
+  uint16_t base_x = cursor->x;
+  uint16_t base_y = cursor->x;
+
+  uint16_t first_x = base_x - CURSOR_SIZE / 2;
+  uint16_t first_y = base_y - CURSOR_SIZE / 2;
+
+  for (int i = 0; i < CURSOR_SIZE; i++) {
+    uint16_t x = first_x + i;
+    uint16_t y = first_y + i;
+
+    cursor->previous_display_data[i] = display_get_pixel(display, base_x, y);
+    cursor->previous_display_data[i + CURSOR_SIZE] = display_get_pixel(display, x, base_y);
+
+    display_set_pixel(display, base_x, y, CURSOR_COLOR);
+    display_set_pixel(display, x, base_y, CURSOR_COLOR);
+  }
+}
+
+void cursor_hide(cursor_t *cursor, display_t *display) {
+  if (!cursor->shown) {
+    return;
+  }
+
+  uint16_t base_x = cursor->x;
+  uint16_t base_y = cursor->x;
+
+  uint16_t first_x = base_x - CURSOR_SIZE / 2;
+  uint16_t first_y = base_y - CURSOR_SIZE / 2;
+
+  for (int i = 0; i < CURSOR_SIZE; i++) {
+    uint16_t x = first_x + i;
+    uint16_t y = first_y + i;
+
+    display_set_pixel(display, base_x, y, cursor->previous_display_data[i]);
+    display_set_pixel(display, x, base_y, cursor->previous_display_data[i + CURSOR_SIZE]);
+  }
+
+  cursor->shown = false;
+}