ColorBlock template

src/ColorBlock.h

@@ -0,0 +1,66 @@
+/*  Python-rgbcx Texture Compression Library
+    Copyright (C) 2021 Andrew Cassidy <drewcassidy@me.com>
+    Partially derived from rgbcx.h written by Richard Geldreich <richgel99@gmail.com>
+    and licenced under the public domain
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <array>
+#include <cstdint>
+#include <span>
+
+#include "blocks.h"
+
+template <size_t M, size_t N, class T> class ColorBlock {
+   public:
+    using row = std::span<T, N>;
+
+    ColorBlock(const std::array<T *, N> &rows) {
+        for (int i = 0; i < height(); i++) { this[i] = row(rows[i], rows[i] * N * sizeof(T)); }
+    }
+    ColorBlock(const std::array<row, N> &rows) {
+        for (int i = 0; i < height(); i++) { this[i] = rows[i]; }
+    }
+
+    ColorBlock(const T *pixels) {
+        for (int i = 0; i < height(); i++) { _rows[i] = std::span(pixels[i * width()]); }
+    }
+
+    ColorBlock(const T *image, int imageWidth, int imageHeight, int x = 0, int y = 0) {
+        int imageX = x * width();
+        int imageY = y * height();
+
+        assert(imageX > 0 && imageX + width() < imageWidth);
+        assert(imageY > 0 && imageY + height() < imageHeight);
+
+        T *start = &image[imageX + (imageY * imageWidth)];
+
+        for (int i = 0; i < height(); i++) { _rows[i] = std::span(start[i * imageWidth]); }
+    }
+
+    constexpr T &operator[](size_t n) noexcept { return _rows[n]; }
+
+    constexpr int width() noexcept { return N; }
+    constexpr int height() noexcept { return M; }
+    constexpr int size() noexcept { return N * M; }
+
+   private:
+    std::array<row, M> _rows;
+};
+
+using RGBABlock4x4 = ColorBlock<4, 4, Color32>;
+using RBlock4x4 = ColorBlock<4, 4, uint8_t>;