Import of the watch repository from Pebble

src/fw/applib/graphics/perimeter.c

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+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "applib/graphics/perimeter.h"
+
+#include "system/passert.h"
+#include "util/math.h"
+
+static uint16_t prv_triangle_side(uint16_t hypotenuse, uint16_t side) {
+  // third side of triangle based on pythagorean theorem
+  return integer_sqrt(ABS(((uint32_t)hypotenuse * hypotenuse) - ((uint32_t)side * side)));
+}
+
+T_STATIC GRangeHorizontal perimeter_for_circle(GRangeVertical vertical_range, GPoint center,
+                                      int32_t radius) {
+  radius = MAX(0, radius);
+  int32_t height = 0;
+  int32_t width = 0;
+
+  const int32_t top = center.y - radius;
+  const int32_t bottom = center.y + radius;
+
+  int32_t range_start = vertical_range.origin_y;
+  int32_t range_end = vertical_range.origin_y + vertical_range.size_h;
+
+  // Check if both top and bottom are outside but not surrounding the perimeter
+  if ((range_start < top && range_end < top) ||
+      (range_start > bottom && range_end > bottom)) {
+    return (GRangeHorizontal){0, 0};
+  }
+
+  range_start = CLIP(range_start, top, bottom);
+  range_end = CLIP(range_end, top, bottom);
+
+  // height of triangle from center to range start
+  height = ABS(center.y - range_start);
+  const int32_t start_width = prv_triangle_side(radius, height);
+
+  // height of triangle from center to range end
+  height = ABS(center.y - range_end);
+  const int32_t end_width = prv_triangle_side(radius, height);
+
+  width = MIN(start_width, end_width);
+
+  return (GRangeHorizontal){.origin_x = center.x - width, .size_w = width * 2};
+}
+
+T_STATIC GRangeHorizontal perimeter_for_display_round(const GPerimeter *perimeter,
+                                                      const GSize *ctx_size,
+                                                      GRangeVertical vertical_range,
+                                                      uint16_t inset) {
+  const GRect frame = (GRect) { GPointZero, *ctx_size };
+  const GPoint center = grect_center_point(&frame);
+  const int32_t radius = grect_shortest_side(frame) / 2 - inset;
+  return perimeter_for_circle(vertical_range, center, radius);
+}
+
+T_STATIC GRangeHorizontal perimeter_for_display_rect(const GPerimeter *perimeter,
+                                                     const GSize *ctx_size,
+                                                     GRangeVertical vertical_range,
+                                                     uint16_t inset) {
+  return (GRangeHorizontal){.origin_x = inset, .size_w = MAX(0, ctx_size->w - 2 * inset)};
+}
+
+const GPerimeter * const g_perimeter_for_display = &(const GPerimeter) {
+  .callback = PBL_IF_RECT_ELSE(perimeter_for_display_rect, perimeter_for_display_round),
+};