scritcher/src/magick.zig

// imagemagick plugins
const std = @import("std");
const images = @import("image.zig");

const log = std.log.scoped(.scritcher_magick);
const Image = images.Image;

const mc = @cImport({
    @cInclude("wand/magick_wand.h");
});

pub const MagickContext = struct {
    wand: *mc.MagickWand,

    pub fn init() !MagickContext {
        mc.InitializeMagick(null);

        var wand = mc.NewMagickWand();
        if (wand == null) return error.WandCreateFail;

        return MagickContext{
            .wand = wand.?,
        };
    }

    pub fn deinit(self: *MagickContext) void {
        _ = mc.DestroyMagickWand(self.wand);
        mc.DestroyMagick();
    }

    pub fn doErr(self: *MagickContext) !void {
        _ = self;
        return error.WandError;
    }
};

fn magickLoad(image: *Image) !MagickContext {
    var mctx = try MagickContext.init();
    errdefer mctx.deinit();

    var curpath = try image.allocator.dupeZ(u8, image.curpath);
    defer image.allocator.free(curpath);

    log.debug("loading '{s}'", .{curpath});

    if (mc.MagickReadImage(mctx.wand, curpath.ptr) != 1)
        return error.MagickReadFail;

    return mctx;
}

fn magickSave(image: *Image, wand: *mc.MagickWand) !void {
    const allocator = image.allocator;

    var tmpnam = try images.temporaryName(allocator);
    var c_tmpnam = try allocator.dupeZ(u8, tmpnam);
    defer allocator.free(c_tmpnam);

    log.debug("\tmagick: saving to '{s}'..", .{c_tmpnam});

    if (mc.MagickWriteImage(wand, c_tmpnam.ptr) != 1)
        return error.MagickWriteFail;

    log.debug("OK", .{});

    try image.reopen(tmpnam);
}

/// Rotate the given image.
/// bgfill must point to a null-terminated string.
pub fn runRotate(image: *Image, deg: f32, bgfill: []const u8) !void {
    var mctx = try magickLoad(image);
    defer mctx.deinit();

    var bg = mc.NewPixelWand();
    defer mc.DestroyPixelWand(bg);

    if (mc.PixelSetColor(bg, bgfill.ptr) != 1)
        return error.PixelSetColorFail;

    if (mc.MagickRotateImage(mctx.wand, bg, deg) != 1)
        return error.RotateFail;

    try magickSave(image, mctx.wand);
}