Zig

Get the Nth Binary Part of a Content-Type into BinData

Demonstrates the Chilkat Email.GetNthBinaryPartOfTypeBd method, which loads the binary bytes of the Nth MIME sub-part matching a content-type pattern into a BinData object. The arguments are the zero-based index among the matching parts, the content-type pattern, an inlineOnly flag, an excludeAttachments flag, and the BinData that receives the bytes. This example extracts the first image/png part.

Background: This is the binary, type-targeted way to pull a specific part out of a message — ideal for extracting, say, every image/png or the one application/pdf from a complex MIME tree without caring whether it is an attachment, an inline image, or a body part. Reading into a BinData keeps the raw bytes exact, ready to save, hash, or re-transmit.

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Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // Demonstrates the GetNthBinaryPartOfTypeBd method, which loads the binary bytes of the Nth
    // MIME sub-part matching a Content-Type pattern into a BinData object.  The arguments are
    // the zero-based index among matching parts, the Content-Type pattern, inlineOnly,
    // excludeAttachments, and the BinData that receives the bytes.

    const email = try chilkat.Email.init();
    defer email.deinit();
    email.setSubject("GetNthBinaryPartOfTypeBd example");
    email.setBody("See the attached image.");

    // Load the image from a file into a BinData object and attach it (binary data belongs
    // in a BinData, never in a string).
    const bd_image = try chilkat.BinData.init();
    defer bd_image.deinit();
    bd_image.loadFile("qa_data/images/photo.png") catch {
        std.debug.print("{s}\n", .{try bd_image.getLastErrorText(alloc)});
        return;
    };

    email.addAttachmentBd("photo.png", bd_image, "image/png") catch {
        std.debug.print("{s}\n", .{try email.getLastErrorText(alloc)});
        return;
    };

    // Load the bytes of the first (index 0) image/png part into a BinData object.
    const bd = try chilkat.BinData.init();
    defer bd.deinit();
    email.getNthBinaryPartOfTypeBd(0, "image/png", false, false, bd) catch {
        std.debug.print("{s}\n", .{try email.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("image/png part size (bytes) = {d}\n", .{bd.getNumBytes()});

    // Note: The path "qa_data/images/photo.png" is a relative local filesystem path,
    // relative to the current working directory of the running application.
}