Import of the watch repository from Pebble

src/fw/applib/graphics/text_layout_private.h

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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.
+ */
+
+#pragma once
+
+//! Private layout interface (ie for unit testing)
+
+#include "util/iterator.h"
+#include "applib/fonts/codepoint.h"
+#include "text.h"
+#include "gtypes.h"
+#include "utf8.h"
+
+#include <stdint.h>
+
+typedef struct {
+  const Utf8Bounds* utf8_bounds; //<! start and end of utf-8 codepoints
+  GRect box;
+  GFont font;
+  GTextOverflowMode overflow_mode;
+  GTextAlignment alignment;
+  int16_t line_spacing_delta;
+} TextBoxParams;
+
+//! Parameters required to render a line 
+typedef struct {
+  utf8_t* start;
+  GPoint origin; //<! Relative to text_box_params origin
+  int16_t height_px;
+  int16_t width_px;
+  int16_t max_width_px; //<! Maximum length of the line
+  Codepoint suffix_codepoint;
+} Line;
+
+//! Definition of a word:
+//!  "A brown   dog\njumps" becomes:
+//!   - "A"
+//!   - " brown" // whitespace is trimmed if word wraps
+//!   - "   dog" // whitespace is trimmed if word wraps
+//!   - "\n"
+//!   - "jumps"
+//! 
+//! - Word start points to first printable codepoint in word, inclusive,
+//!   including whitespace
+//! - Word end points to codepoint after the last printable codepoint in a word,
+//!   excluding whitespace (eg, end of word, exclusive); note this codepoint may
+//!   not be valid since it may be the end of the string
+//! - The preceeding whitespace of a word is trimmed if the word wraps
+//! - Reserved codepoints are skipped
+//! - Newlines are treated as stand-alone words so as to not mess up the height
+//!   and width word metrics
+typedef struct {
+  utf8_t* start;
+  utf8_t* end;
+  int16_t width_px;
+} Word;
+
+#define WORD_EMPTY ((Word){ 0, 0, 0 })
+
+typedef struct {
+  const TextBoxParams* text_box_params;
+  Iterator utf8_iter;
+  Utf8IterState utf8_iter_state;
+} CharIterState;
+
+//! Uses character iterator to iterate over characters
+typedef struct {
+  GContext* ctx;
+  const TextBoxParams* text_box_params;
+  Word current;
+} WordIterState;
+
+#define WORD_ITER_STATE_EMPTY ((WordIterState){ 0, 0, WORD_EMPTY })
+
+typedef struct {
+  GContext *ctx;
+  Line *current;
+  Iterator word_iter;
+  WordIterState word_iter_state;
+} LineIterState;
+
+typedef struct {
+  TextBoxParams text_box;
+  Line line;
+  LineIterState line_iter_state;
+} TextDrawState;
+
+void char_iter_init(Iterator* char_iter, CharIterState* char_iter_state, const TextBoxParams* const text_box_params, utf8_t* start);
+void word_iter_init(Iterator* word_iter, WordIterState* word_iter_state, GContext* ctx, const TextBoxParams* const text_box_params, utf8_t* start);
+void line_iter_init(Iterator* line_iter, LineIterState* line_iter_state, GContext* ctx);
+
+bool word_init(GContext* ctx, Word* word, const TextBoxParams* const text_box_params, utf8_t* start);
+
+bool char_iter_next(IteratorState state);
+bool char_iter_prev(IteratorState state);
+bool word_iter_next(IteratorState state);
+bool line_iter_next(IteratorState state);
+
+typedef void (*LastLineCallback)(GContext* ctx, Line* line,
+                                 const TextBoxParams* const text_box_params,
+                                 const bool is_text_remaining);
+typedef void (*RenderLineCallback)(GContext* ctx, Line* line,
+                                   const TextBoxParams* const text_box_params);
+typedef void (*LayoutUpdateCallback)(TextLayout* layout, Line* line,
+                                     const TextBoxParams* const text_box_params);
+typedef bool (*StopConditionCallback)(GContext* ctx, Line* line,
+                                      const TextBoxParams* const text_box_params);
+
+bool line_add_word(GContext* ctx, Line* line, Word* word, const TextBoxParams* const text_box_params);
+bool line_add_words(Line* line, Iterator* word_iter, LastLineCallback last_line_cb);
+
+typedef struct {
+  LastLineCallback last_line_cb;
+  RenderLineCallback render_line_cb;
+  LayoutUpdateCallback layout_update_cb;
+  StopConditionCallback stop_condition_cb;
+} WalkLinesCallbacks;
+
+#define WALK_LINE_CALLBACKS_EMPTY ((WalkLinesCallbacks){ 0, 0, 0, 0 })
+