From 46248d5ee65b42a9b616a736e98bef57a5a042d6 Mon Sep 17 00:00:00 2001
From: Mark <mark@betalupi.com>
Date: Thu, 23 Jun 2022 11:21:26 -0700
Subject: [PATCH] Added simple bitmap interface

---
 src/bitmap/bitmap.cpp | 133 ++++++++++++++++++++++++++++++++++++++++++
 src/bitmap/bitmap.hpp |  47 +++++++++++++++
 2 files changed, 180 insertions(+)
 create mode 100644 src/bitmap/bitmap.cpp
 create mode 100644 src/bitmap/bitmap.hpp

diff --git a/src/bitmap/bitmap.cpp b/src/bitmap/bitmap.cpp
new file mode 100644
index 0000000..7eab19b
--- /dev/null
+++ b/src/bitmap/bitmap.cpp
@@ -0,0 +1,133 @@
+#include "bitmap.hpp"
+
+Bitmap::Bitmap(size_t w, size_t h) {
+	this->width = w;
+	this->height = h;
+
+	this->data.reserve(h);
+	for (size_t r = 0; r < h; r++) {
+		data[r].reserve(w);
+	}
+
+	clear();
+}
+
+
+
+void Bitmap::dump_int_to_bytes(
+	uint64_t a,
+	uint8_t *array,
+	size_t index,
+	size_t num_bytes
+	) {
+	// Dump bytes of i into array starting at index.
+	// least-significant byte goes first.
+
+	if (num_bytes > 4) {
+		throw std::invalid_argument("Cannot dump more than 4 bytes.");
+	}
+
+	for (size_t i = 0; i < num_bytes; i++) {
+		array[index + i] =  (a >> (8 * i)) & 0xFF;
+	}
+}
+
+
+
+void Bitmap::clear() {
+	// Fill with white pixels
+	for (size_t r = 0; r < height; r++) {
+		for (size_t i = 0; i < width; i++) {
+			data[r][i] = std::make_tuple(
+				0xFF, 0xFF, 0xFF
+			);
+		}
+	}
+}
+
+
+
+void Bitmap::setpixel(
+		size_t row,
+		size_t col,
+		uint8_t r,
+		uint8_t g,
+		uint8_t b
+	) {
+	data[row][col] = std::make_tuple(r, g, b);
+}
+
+
+
+void Bitmap::save(const char *filename) const {
+
+	uint8_t header[54] = {
+		// Universal 14-byte header
+		0x42, 0x4D,              // Bitmap standard header
+		0x00, 0x00, 0x00, 0x00,  // file size (bit 2, overwritten)
+		0x00, 0x00, 0x00, 0x00,  // Reserved (leave as zero)
+		0x36, 0x00, 0x00, 0x00,  // Index of first byte of pixmap
+
+		// 40-byte BITMAPINFOHEADER
+		0x28, 0x00, 0x00, 0x00,  // Length of DIB
+		0x00, 0x00, 0x00, 0x00,  // width (px, bit 18, overwritten)
+		0x00, 0x00, 0x00, 0x00,  // height (px, bit 22, overwritten)
+		0x01, 0x00,              // Number of color planes (always 1)
+		0x18, 0x00,              // Number of bits per pixel (0x18 = 24)
+		0x00, 0x00, 0x00, 0x00,  // BI_RGB, no pixel array compression
+		0x00, 0x00, 0x00, 0x00,  // Size of raw bitmap data, incl. padding (bit 34, overwritten)
+		0xFF, 0x0A, 0x00, 0x00,  // Size of horizontal print resolution (px/m)
+		0xFF, 0x0A, 0x00, 0x00,  // Size of vertical print resolution (px/m)
+		0x00, 0x00, 0x00, 0x00,  // Size of colors in palette
+		0x00, 0x00, 0x00, 0x00   // 0 important colors => all colors are important
+	};
+
+
+	// How many bytes we need to store a row, including padding
+	size_t row_size = ((24 * width + 31) / 32) * 4;
+	// Total size of pixmap
+	uint64_t pixmap_size = row_size * height;
+	// Total size of file
+	uint64_t file_size = 54 + pixmap_size;
+
+	// Set values in header
+	dump_int_to_bytes(file_size, header, 2, 4);
+	dump_int_to_bytes(width, header, 18, 4);
+	dump_int_to_bytes(height, header, 22, 4);
+	dump_int_to_bytes(pixmap_size, header, 34, 4);
+
+
+	FILE *fp = fopen(filename, "wb");
+	fwrite(header, sizeof(header), 1, fp);
+
+	uint8_t r, g, b;
+	for (size_t row = 0; row < height; row++) {
+		size_t i = 0;
+
+		// Pixel data
+		while (i < width) {
+			std::tie(r, g, b) = data[height - row - 1][i];
+			fwrite(&b, sizeof(uint8_t), 1, fp);
+			fwrite(&g, sizeof(uint8_t), 1, fp);
+			fwrite(&r, sizeof(uint8_t), 1, fp);
+
+			i += 1;
+		}
+
+		i *= 3;
+		// Row Padding
+		r = 0;
+		while (i < row_size) {
+			fwrite(&r, sizeof(uint8_t), 1, fp);
+			i += 1;
+		}
+	}
+	fclose(fp);
+}
+
+/*
+int main() {
+	Bitmap b = Bitmap(200, 200);
+	b.save("file.bmp");
+}
+*/
\ No newline at end of file
diff --git a/src/bitmap/bitmap.hpp b/src/bitmap/bitmap.hpp
new file mode 100644
index 0000000..00fe569
--- /dev/null
+++ b/src/bitmap/bitmap.hpp
@@ -0,0 +1,47 @@
+#pragma once
+
+#include <iostream>
+#include <cstdint>
+#include <vector>
+#include <tuple>
+
+class Bitmap {
+	public:
+		Bitmap(size_t w, size_t h);
+
+
+		void clear();
+		void setpixel(
+			size_t row,
+			size_t col,
+			uint8_t r,
+			uint8_t g,
+			uint8_t b
+		);
+
+		void save(const char *filename) const;
+
+	private:
+		size_t width;
+		size_t height;
+
+		// Pixel data.
+		// First is a vector of rows,
+		// Second is a vector of pixels.
+		// RGB format.
+		std::vector<
+			std::vector<
+			std::tuple<
+				uint8_t,
+				uint8_t,
+				uint8_t
+			>>
+		> data;
+
+		static void dump_int_to_bytes(
+			uint64_t a,
+			uint8_t* bytes,
+			size_t index,
+			size_t num_bytes
+		);
+};
\ No newline at end of file