implement drawCharacter function

AsciiPrintableStep.zig

@@ -57,7 +57,7 @@ fn make(step: *std.build.Step, _: *std.Progress.Node) !void {
         });
         defer file.close();
         const writer = file.writer();
-        try writer.print("const chars = [_][]u8 {{\n", .{});
+        try writer.print("pub const chars = &[_][]const u8{{\n", .{});
 
         for (0..32) |_| {
             try writer.print("  \"\",\n", .{});

src/main.zig

@@ -220,7 +220,6 @@ fn convertImage(alloc: std.mem.Allocator, filename: [:0]u8, pixels: *[WIDTH * HE
     defer {
         if (mw) |w| mw = c.DestroyMagickWand(w);
     }
-    var merged: ?*c.MagickWand = undefined;
 
     // Reading an image into ImageMagick is problematic if it isn't a bmp
     // as the library needs a bunch of dependencies available
@@ -276,20 +275,64 @@ fn convertImage(alloc: std.mem.Allocator, filename: [:0]u8, pixels: *[WIDTH * HE
     if (status == c.MagickFalse)
         return error.CouldNotSetExtent;
 
-    // At this point, we will add our text. This needs a whole lot more than this,
+    mw = try drawCharacter(
-    // but let's get started
+        mw.?,
-    {
+        '4',
+        -5 * 3,
+        -8,
+    );
+    mw = try drawCharacter(
+        mw.?,
+        '2',
+        -5 * 4,
+        -8,
+    );
+    // We make the image monochrome by quantizing the image with 2 colors in the
+    // gray colorspace. See:
+    // https://www.imagemagick.org/Usage/quantize/#monochrome
+    // and
+    // https://stackoverflow.com/questions/18267432/using-the-c-api-for-imagemagick-on-iphone-to-convert-to-monochrome
+    //
+    // We do this at the end so we have pure black and white. Otherwise the
+    // resizing oprations will generate some greyscale that we don't want
+    status = c.MagickQuantizeImage(mw, // MagickWand
+        2, // Target number colors
+        c.GRAYColorspace, // Colorspace
+        1, // Optimal depth
+        c.MagickTrue, // Dither
+        c.MagickFalse // Quantization error
+    );
+
+    if (status == c.MagickFalse)
+        return error.CouldNotQuantizeImage;
+
+    status = c.MagickExportImagePixels(mw, 0, 0, WIDTH, HEIGHT, "I", c.CharPixel, @ptrCast(*anyopaque, pixels));
+
+    if (status == c.MagickFalse)
+        return error.CouldNotExportImage;
+
+    for (0..WIDTH * HEIGHT) |i| {
+        switch (pixels[i]) {
+            0x00 => pixels[i] = 0xFF,
+            0xFF => pixels[i] = 0x00,
+            else => {},
+        }
+    }
+}
+
+fn drawCharacter(mw: ?*c.MagickWand, char: u8, x: isize, y: isize) !?*c.MagickWand {
     // Create a second wand. Does this need to exist after the block?
     var cw = c.NewMagickWand();
     defer {
         if (cw) |dw| cw = c.DestroyMagickWand(dw);
-            if (merged) |mergeme| {
+        // if (merged) |mergeme| {
-                _ = c.DestroyMagickWand(mw);
+        //     _ = c.DestroyMagickWand(mw);
-                mw = mergeme;
+        //     mw = mergeme;
+        // }
     }
-        }
+    const image_char = chars[char];
-        const characters = @embedFile("images/test.bmp");
+    if (image_char.len == 0) return error.CharacterNotSupported;
-        status = c.MagickReadImageBlob(cw, characters, characters.len);
+    var status = c.MagickReadImageBlob(cw, @ptrCast(?*const anyopaque, image_char), image_char.len);
     if (status == c.MagickFalse) unreachable; // Something is terribly wrong if this fails
 
     // For character placement, we need to set the image to the correct
@@ -314,10 +357,8 @@ fn convertImage(alloc: std.mem.Allocator, filename: [:0]u8, pixels: *[WIDTH * HE
             cw,
             WIDTH,
             HEIGHT,
-                -6 * 8,
+            x,
-                -8,
+            y,
-                // -@intCast(isize, (WIDTH - resize_dimensions.width) / 2),
-                // -@intCast(isize, (HEIGHT - resize_dimensions.height) / 2),
         );
         if (status == c.MagickFalse)
             return error.CouldNotSetExtent;
@@ -331,41 +372,10 @@ fn convertImage(alloc: std.mem.Allocator, filename: [:0]u8, pixels: *[WIDTH * HE
     // I this only works with two images...
     // c.MagickResetIterator(mw);
     c.MagickSetFirstIterator(mw);
-        merged = c.MagickMergeImageLayers(mw, c.FlattenLayer);
+    defer {
-        // merged = c.MagickMergeImageLayers(mw, c.CompositeLayer);
+        if (mw) |w| _ = c.DestroyMagickWand(w);
-        // if (status == c.MagickFalse) return error.CouldNotFlattenImage;
-    }
-    // We make the image monochrome by quantizing the image with 2 colors in the
-    // gray colorspace. See:
-    // https://www.imagemagick.org/Usage/quantize/#monochrome
-    // and
-    // https://stackoverflow.com/questions/18267432/using-the-c-api-for-imagemagick-on-iphone-to-convert-to-monochrome
-    //
-    // We do this at the end so we have pure black and white. Otherwise the
-    // resizing oprations will generate some greyscale that we don't want
-    status = c.MagickQuantizeImage(merged, // MagickWand
-        2, // Target number colors
-        c.GRAYColorspace, // Colorspace
-        1, // Optimal depth
-        c.MagickTrue, // Dither
-        c.MagickFalse // Quantization error
-    );
-
-    if (status == c.MagickFalse)
-        return error.CouldNotQuantizeImage;
-
-    status = c.MagickExportImagePixels(merged, 0, 0, WIDTH, HEIGHT, "I", c.CharPixel, @ptrCast(*anyopaque, pixels));
-
-    if (status == c.MagickFalse)
-        return error.CouldNotExportImage;
-
-    for (0..WIDTH * HEIGHT) |i| {
-        switch (pixels[i]) {
-            0x00 => pixels[i] = 0xFF,
-            0xFF => pixels[i] = 0x00,
-            else => {},
-        }
     }
+    return c.MagickMergeImageLayers(mw, c.FlattenLayer);
 }
 
 const Dimensions = struct {