Fileman default open and Screenshot viewer (#1102)

* WIP expensive way

* Add default file handling to fileman

* Remove screenshot_reader and tests

* Read data in chunks

* Format

* Fix error text position

* PR feedback

---------

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

firmware/application/apps/ui_ss_viewer.cpp

@@ -0,0 +1,103 @@
+/*
+ * 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.
+ */
+
+#include "ui_ss_viewer.hpp"
+
+using namespace portapack;
+namespace fs = std::filesystem;
+
+namespace ui {
+
+ScreenshotViewer::ScreenshotViewer(
+    NavigationView& nav,
+    const std::filesystem::path& path)
+    : nav_{nav},
+      path_{path} {
+    set_focusable(true);
+}
+
+bool ScreenshotViewer::on_key(KeyEvent) {
+    nav_.pop();
+    return true;
+}
+
+void ScreenshotViewer::paint(Painter& painter) {
+    constexpr size_t pixel_width = 240;
+    constexpr size_t pixel_height = 320;
+    Style style_default{
+        .font = ui::font::fixed_8x16,
+        .background = ui::Color::black(),
+        .foreground = ui::Color::white()};
+    File file{};
+
+    painter.fill_rectangle({0, 0, pixel_width, pixel_height}, Color::black());
+
+    auto show_invalid = [&]() {
+        painter.draw_string({10, 160}, style_default, "Not a valid screenshot.");
+    };
+
+    auto error = file.open(path_);
+    if (error) {
+        painter.draw_string({10, 160}, style_default, error->what());
+        return;
+    }
+
+    // Screenshots from PNGWriter are all this size.
+    if (file.size() != 232383) {
+        show_invalid();
+        return;
+    }
+
+    constexpr size_t read_chunk = 80;  // NB: must be a factor of pixel_width.
+    constexpr size_t buffer_size = sizeof(ColorRGB888) * read_chunk;
+    uint8_t buffer[buffer_size];
+    std::array<Color, pixel_width> pixel_data;
+
+    // Seek past all the headers.
+    file.seek(43);
+
+    for (auto line = 0u; line < pixel_height; ++line) {
+        // Seek past the per-line header.
+        file.seek(file.tell() + 6);
+
+        // Per comment in PNGWriter, read in chunks of 80.
+        // NB: Reading in one large chunk caused corruption so there's
+        // likely a bug lurking in the SD Card/FatFs layer.
+        for (auto offset = 0u; offset < pixel_width; offset += read_chunk) {
+            auto read = file.read(buffer, buffer_size);
+
+            if (!read || *read != buffer_size) {
+                show_invalid();
+                return;
+            }
+
+            auto c8 = (ColorRGB888*)buffer;
+            for (auto i = 0u; i < read_chunk; ++i) {
+                pixel_data[i + offset] = Color(c8->r, c8->g, c8->b);
+                ++c8;
+            }
+        }
+
+        display.draw_pixels({0, (int)line, pixel_width, 1}, pixel_data);
+    }
+}
+
+}  // namespace ui