decouple magick init/save into helper functions

examples/rotate.scri

@@ -0,0 +1,3 @@
+load :0;
+rotate 30;
+quicksave;

src/image.zig

@@ -67,7 +67,7 @@ fn sf_tell(file: *c.SNDFILE) i64 {
     return -frames;
 }
 
-fn temporaryName(allocator: *std.mem.Allocator) ![]u8 {
+pub fn temporaryName(allocator: *std.mem.Allocator) ![]u8 {
     const template_start = "/temp/temp_";
     const template = "/tmp/temp_XXXXXXXX";
     var nam = try allocator.alloc(u8, template.len);
@@ -146,6 +146,8 @@ pub const Image = struct {
     }
 
     pub fn close(self: *Image) void {
+        //self.allocator.free(self.path);
+        //self.allocator.free(self.curpath);
         var st: i32 = c.sf_close(self.sndfile);
 
         if (st != 0) {

src/magick.zig

@@ -4,6 +4,69 @@ const images = @import("image.zig");
 
 const Image = images.Image;
 
-pub fn runRotate(image: *Image) !void {
-    return error.NotImplementedYet;
+const mc = @cImport({
+    @cInclude("MagickWand/MagickWand.h");
+});
+
+pub const MagickContext = struct {
+    wand: *mc.MagickWand,
+
+    pub fn init() !MagickContext {
+        mc.MagickWandGenesis();
+
+        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.MagickWandTerminus();
+    }
+
+    pub fn doErr(self: *MagickContext) !void {
+        return error.WandError;
+    }
+};
+
+fn magickLoad(image: *Image) !MagickContext {
+    var mctx = try MagickContext.init();
+    errdefer mctx.deinit();
+
+    var curpath = try std.cstr.addNullByte(image.allocator, image.curpath);
+    defer image.allocator.free(curpath);
+
+    if (mc.MagickReadImage(mctx.wand, curpath.ptr) == .MagickFalse)
+        return error.MagickReadFail;
+
+    return mctx;
+}
+
+fn magickSave(image: *Image, mctx: *MagickContext) !void {
+    var tmpnam = try images.temporaryName(image.allocator);
+    defer image.allocator.free(tmpnam);
+
+    var c_tmpnam = try std.cstr.addNullByte(image.allocator, tmpnam);
+    defer image.allocator.free(c_tmpnam);
+
+    std.debug.warn(
+        "\tmagick: saving from '{}' to '{}'\n",
+        image.curpath,
+        c_tmpnam,
+    );
+
+    if (mc.MagickWriteImages(mctx.wand, c_tmpnam.ptr, .MagickTrue) == .MagickFalse)
+        return error.MagickWriteFail;
+}
+
+pub fn runRotate(image: *Image) !void {
+    var mctx = try magickLoad(image);
+    defer mctx.deinit();
+
+    // TODO run rotate here
+
+    try magickSave(image, &mctx);
 }