54 lines
2.1 KiB
Zig
54 lines
2.1 KiB
Zig
const std = @import("std");
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const stb_image = @import("stb_image");
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// https://en.wikipedia.org/wiki/ICO_(file_format)#Icon_file_structure
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pub fn main() !void {
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var gpa = std.heap.GeneralPurposeAllocator(.{}){};
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const allocator = gpa.allocator();
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defer _ = gpa.deinit();
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const args = try std.process.argsAlloc(allocator);
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defer std.process.argsFree(allocator, args);
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if (args.len != 3) {
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std.debug.print("Usage: ./png-to-icon <png-file> <output-ico>", .{});
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std.process.exit(1);
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}
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const cwd = std.fs.cwd();
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const input_png_path = args[1];
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const output_ico_path = args[2];
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const input_png_data = try cwd.readFileAlloc(allocator, input_png_path, 1024 * 1024 * 5);
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defer allocator.free(input_png_data);
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const png_image = try stb_image.load(input_png_data);
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defer png_image.deinit();
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std.debug.assert(png_image.width > 0 and png_image.width <= 256);
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std.debug.assert(png_image.height > 0 and png_image.height <= 256);
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const output_ico_file = try std.fs.cwd().createFile(output_ico_path, .{ });
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defer output_ico_file.close();
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const writer = output_ico_file.writer();
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// ICONDIR structure
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try writer.writeInt(u16, 0, .little); // Must always be zero
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try writer.writeInt(u16, 1, .little); // Image type. 1 for .ICO
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try writer.writeInt(u16, 1, .little); // Number of images
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// ICONDIRENTRY structure
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try writer.writeInt(u8, @truncate(png_image.width), .little); // Image width
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try writer.writeInt(u8, @truncate(png_image.height), .little); // Image height
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try writer.writeInt(u8, 0, .little); // Number of colors in color pallete. 0 means that color pallete is not used
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try writer.writeInt(u8, 0, .little); // Must always be zero
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try writer.writeInt(u16, 0, .little); // Color plane
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try writer.writeInt(u16, 32, .little); // Bits per pixel
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try writer.writeInt(u32, @intCast(input_png_data.len), .little); // Image size in bytes
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try writer.writeInt(u32, 22, .little); // Offset to image data from the start
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// PNG image data
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try writer.writeAll(input_png_data);
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} |