Add Notepad app (#1010)

* easier 'now', start adding text editor

* Adding scrolling to notepad

* Better scrolling

* Better scrolling, off-by-1 bugs

* MVP fit and finish

* Add tiny font and use in Notepad

* Font tweaking, tiny font cursor

* Fix warning

* Format changed files

---------

Co-authored-by: kallanreed <kallanreed@outlook.com>

firmware/application/apps/ui_text_editor.hpp

@@ -0,0 +1,170 @@
+/*
+ * Copyright (C) 2023 Kyle Reed
+ *
+ * This file is part of PortaPack.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __UI_TEXT_EDITOR_H__
+#define __UI_TEXT_EDITOR_H__
+
+#include "ui.hpp"
+#include "ui_font_fixed_5x8.hpp"
+#include "ui_navigation.hpp"
+#include "ui_painter.hpp"
+#include "ui_widget.hpp"
+//#include "ui_textentry.hpp"
+
+#include "file.hpp"
+#include "log_file.hpp"
+
+#include <string>
+#include <vector>
+
+namespace ui {
+
+enum class LineEnding : uint8_t {
+    LF,
+    CRLF
+};
+
+enum class ScrollDirection : uint8_t {
+    Vertical,
+    Horizontal
+};
+
+// TODO: RAM is _very_ limited. Need to
+// rework this to not store every line.
+// Should be able to get away with only
+// abount one screen of lines so long as
+// you can't scroll more than one screen
+// at a time.
+struct FileInfo {
+    /* Offsets of newlines. */
+    std::vector<uint32_t> newlines;
+    LineEnding line_ending;
+    File::Size size;
+    bool truncated;
+
+    uint32_t line_count() const {
+        return newlines.size();
+    }
+
+    uint32_t line_start(uint32_t line) const {
+        return line == 0 ? 0 : (newlines[line - 1] + 1);
+    }
+
+    uint16_t line_length(uint32_t line) const {
+        if (line >= line_count())
+            return 0;
+
+        auto start = line_start(line);
+        auto end = newlines[line];
+        return end - start;
+    }
+};
+
+/*class TextViewer : public Widget {
+};*/
+
+class TextEditorView : public View {
+   public:
+    TextEditorView(NavigationView& nav);
+    // TextEditorView(NavigationView& nav, const std::filesystem::path& path);
+
+    std::string title() const override {
+        return "Notepad";
+    };
+
+    void on_focus() override;
+    void paint(Painter& painter) override;
+    bool on_key(KeyEvent delta) override;
+    bool on_encoder(EncoderEvent delta) override;
+
+   private:
+    static constexpr uint8_t max_line = 32;
+    static constexpr uint8_t max_col = 48;
+    static constexpr int8_t char_width = 5;
+    static constexpr int8_t char_height = 8;
+
+    // TODO: should these be common somewhere?
+    static constexpr Style style_default{
+        .font = font::fixed_5x8,
+        .background = Color::black(),
+        .foreground = Color::white(),
+    };
+
+    /* Returns true if the cursor was updated. */
+    bool apply_scrolling_constraints(
+        int16_t delta_line,
+        int16_t delta_col);
+
+    void refresh_ui();
+    void refresh_file_info();
+    void open_file(const std::filesystem::path& path);
+    std::string read(uint32_t offset, uint32_t length = 30);
+
+    void paint_text(Painter& painter, uint32_t line, uint16_t col);
+    void paint_cursor(Painter& painter);
+
+    // Gets the length of the current line.
+    uint16_t line_length() const;
+
+    NavigationView& nav_;
+
+    File file_{};
+    FileInfo info_{};
+    // LogFile  log_{ };
+
+    struct {
+        // Previous cursor state.
+        uint32_t line{};
+        uint16_t col{};
+
+        // Previous draw state.
+        uint32_t first_line{};
+        uint16_t first_col{};
+        bool redraw_text{true};
+        bool has_file{false};
+    } paint_state_{};
+
+    struct {
+        uint32_t line{};
+        uint16_t col{};
+        ScrollDirection dir{ScrollDirection::Vertical};
+    } cursor_{};
+
+    /* 8px grid is 30 wide, 38 tall. */
+    /* 16px font height or 19 rows. */
+    /* Titlebar is 16px tall, so 18 rows left. */
+    /* 240 x 320, (304 with titlebar) */
+
+    // TODO: The scrollable view should be its own widget
+    // otherwise control navigation doesn't work.
+
+    Button button_open{
+        {24 * 8, 34 * 8, 6 * 8, 4 * 8},
+        "Open"};
+
+    Text text_position{
+        {0 * 8, 36 * 8, 24 * 8, 2 * 8},
+        ""};
+};
+
+}  // namespace ui
+
+#endif  // __UI_TEXT_EDITOR_H__