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// Copyright 2022 The Pigweed Authors
// 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
// 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
#include <array>
#include "pw_color/color.h"
#include "pw_math/size.h"
#include "pw_math/vector2.h"
#include "pw_result/result.h"
constexpr size_t kNumCharsWide = 52;
constexpr size_t kNumRows = 9;
constexpr pw::color::color_rgb565_t kBlackColor = 0x0000;
constexpr pw::color::color_rgb565_t kWhiteColor = 0xffff;
// Maintain a scrolling buffer of text. The "drawing" cursor location starts
// at (0,0), and new characters are inserted right-to-left. Newline ('\n')
// characters cause the text to be scrolled up - eventually rolling off the
// top of the buffer to make space for new text rows at the bottom.
class TextBuffer {
// An ASCII character with a foreground and background color.
struct Char {
// Set to a cleared default state.
void Reset() {
ch = '\0';
foreground_color = kWhiteColor;
background_color = kBlackColor;
char ch = '\0';
pw::color::color_rgb565_t foreground_color = kWhiteColor;
pw::color::color_rgb565_t background_color = kBlackColor;
// A row of ASCII text characters.
struct TextRow {
void Clear() {
for (Char& ch : chars) {
std::array<Char, kNumCharsWide> chars;
// Insert a character at the current cursor location. The cursor will be
// moved right by one slot. Newline ('\n') characters will move the cursor to
// the next line, at column 0.
void DrawCharacter(const Char& ch);
// Return the size, in characters, of the text buffer.
pw::math::Size<int> GetSize() const {
return pw::math::Size<int>{kNumCharsWide, kNumRows};
// Return the character at the specified location.
pw::Result<Char> GetChar(pw::math::Vector2<int> loc) const;
void ScrollUp();
void InsertNewline();
pw::math::Vector2<int> cursor_ = {0, 0};
bool character_wrap_enabled_ = false;
std::array<TextRow, kNumRows> text_rows_;