1 files changed, 96 insertions, 0 deletions
diff --git a/src/canvas/sixel.cpp b/src/canvas/sixel.cpp
new file mode 100644
index 0000000..17bf1d4
--- /dev/null
+++ b/src/canvas/sixel.cpp
@@ -0,0 +1,96 @@
+// Display images inside a terminal
+// Copyright (C) 2023  JustKidding
+//
+// 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 3 of the License, 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.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "sixel.hpp"
+#include "dimensions.hpp"
+#include "terminal.hpp"
+#include "util.hpp"
+
+#include <filesystem>
+#include <iostream>
+
+namespace fs = std::filesystem;
+
+Sixel::Sixel(std::unique_ptr<Image> new_image, std::mutex *stdout_mutex)
+    : image(std::move(new_image)),
+      stdout_mutex(stdout_mutex)
+{
+    const auto dims = image->dimensions();
+    x = dims.x + 1;
+    y = dims.y + 1;
+    horizontal_cells = std::ceil(static_cast<double>(image->width()) / dims.terminal->font_width);
+    vertical_cells = std::ceil(static_cast<double>(image->height()) / dims.terminal->font_height);
+
+    const auto draw_callback = [](char *data, int size, void *priv) -> int {
+        auto *str = static_cast<std::string *>(priv);
+        str->append(data, size);
+        return size;
+    };
+    sixel_output_new(&output, draw_callback, &str, nullptr);
+
+    const auto file_size = fs::file_size(image->filename());
+    constexpr auto reserve_ratio = 50;
+    str.reserve(file_size * reserve_ratio);
+
+    // create dither and palette from image
+    sixel_dither_new(&dither, -1, nullptr);
+    sixel_dither_initialize(dither, const_cast<unsigned char *>(image->data()), image->width(), image->height(),
+                            SIXEL_PIXELFORMAT_RGB888, SIXEL_LARGE_LUM, SIXEL_REP_CENTER_BOX, SIXEL_QUALITY_HIGH);
+}
+
+Sixel::~Sixel()
+{
+    can_draw.store(false);
+    if (draw_thread.joinable()) {
+        draw_thread.join();
+    }
+    sixel_dither_destroy(dither);
+    sixel_output_destroy(output);
+
+    const std::scoped_lock lock{*stdout_mutex};
+    util::clear_terminal_area(x, y, horizontal_cells, vertical_cells);
+}
+
+void Sixel::draw()
+{
+    if (!image->is_animated()) {
+        generate_frame();
+        return;
+    }
+
+    // start drawing loop
+    draw_thread = std::thread([this] {
+        while (can_draw.load()) {
+            generate_frame();
+            image->next_frame();
+            std::this_thread::sleep_for(std::chrono::milliseconds(image->frame_delay()));
+        }
+    });
+}
+
+void Sixel::generate_frame()
+{
+    // output sixel content to stream
+    sixel_encode(const_cast<unsigned char *>(image->data()), image->width(), image->height(), 3 /*unused*/, dither,
+                 output);
+
+    const std::scoped_lock lock{*stdout_mutex};
+    util::save_cursor_position();
+    util::move_cursor(y, x);
+    std::cout << str << std::flush;
+    util::restore_cursor_position();
+    str.clear();
+}