Added an adjustable quality setting (#4)

Makefile

@@ -3,3 +3,4 @@ all: wasm-thumbnail-py/src/wasm_thumbnail/data/wasm_thumbnail.wasm
 wasm-thumbnail-py/src/wasm_thumbnail/data/wasm_thumbnail.wasm: wasm-thumbnail/src/lib.rs
 	cd wasm-thumbnail && cargo build --release
 	cp wasm-thumbnail/target/wasm32-unknown-unknown/release/wasm_thumbnail.wasm wasm-thumbnail-py/src/wasm_thumbnail/data/
+	cp wasm-thumbnail/target/wasm32-unknown-unknown/release/wasm_thumbnail.wasm wasm-thumbnail-rb/lib/wasm/thumbnail/rb/data/

wasm-thumbnail-py/src/wasm_thumbnail/thumbnail.py

@@ -21,7 +21,7 @@ def decode_padded_image(data):
 
     return data[4:4 + payload_length]
 
-def resize_and_pad_image(image_bytes, width, height, size):
+def resize_and_pad_image(image_bytes, width, height, size, quality = 80):
     """Resize an image and pad to fit size, output is prefixed by image length without padding.
     Throws an error if the resized image does not fit in size or is not a supported format"""
     instance = Instance(module, import_object)
@@ -31,7 +31,7 @@ def resize_and_pad_image(image_bytes, width, height, size):
     memory = instance.exports.memory.uint8_view(input_pointer)
     memory[0:image_length] = image_bytes
 
-    output_pointer = instance.exports.resize_and_pad(input_pointer, image_length, width, height, size)
+    output_pointer = instance.exports.resize_and_pad(input_pointer, image_length, width, height, size, quality)
     instance.exports.deallocate(input_pointer, image_length)
 
     memory = instance.exports.memory.uint8_view(output_pointer)

wasm-thumbnail-rb/lib/wasm/thumbnail/rb.rb

@@ -13,7 +13,7 @@ def self.register_panic(_msg_ptr = nil, _msg_len = nil, _file_ptr = nil, _file_l
         puts("WASM panicked")
       end
 
-      def self.resize_and_pad_with_header(file_bytes:, width:, height:, size:)
+      def self.resize_and_pad_with_header(file_bytes:, width:, height:, size:, quality: 80)
         # Let's compile the module to be able to execute it!
         wasm_instance = Wasm::Thumbnail::Rb::GetWasmInstance.call
 
@@ -36,7 +36,8 @@ def self.resize_and_pad_with_header(file_bytes:, width:, height:, size:)
                                                                      image_length,
                                                                      width,
                                                                      height,
-                                                                     size)
+                                                                     size,
+                                                                     quality)
         rescue RuntimeError
           raise "Error processing the image."
         end
@@ -54,8 +55,12 @@ def self.resize_and_pad_with_header(file_bytes:, width:, height:, size:)
         bytes
       end
 
-      def self.resize_and_pad(file_bytes:, width:, height:, size:)
-        bytes = resize_and_pad_with_header(file_bytes: file_bytes, width: width, height: height, size: size + 4)
+      def self.resize_and_pad(file_bytes:, width:, height:, size:, quality: 80)
+        bytes = resize_and_pad_with_header(file_bytes: file_bytes,
+                                           width: width,
+                                           height: height,
+                                           size: size + 4,
+                                           quality: quality)
 
         # The first 4 bytes are a header until the image. The actual image probably ends well before
         # the whole buffer, but we keep the junk data on the end to make all the images the same size

wasm-thumbnail-rb/test/wasm/thumbnail/rb_test.rb

@@ -7,7 +7,17 @@ def test_that_it_has_a_version_number
     refute_nil ::Wasm::Thumbnail::Rb::VERSION
   end
 
-  def test_it_does_something_useful
+  def test_it_resizes_with_custom_quality
+    file_bytes = File.binread("#{__dir__}/brave.png").unpack("C*")
+    image = Wasm::Thumbnail::Rb.resize_and_pad(file_bytes: file_bytes,
+                                               width: 100,
+                                               height: 200,
+                                               size: 250_000,
+                                               quality: 40)
+    puts "Image resized and padded to size #{image.length}"
+  end
+
+  def test_it_resizes_with_default_quality
     file_bytes = File.binread("#{__dir__}/brave.png").unpack("C*")
     image = Wasm::Thumbnail::Rb.resize_and_pad(file_bytes: file_bytes,
                                                width: 100,

wasm-thumbnail/src/lib.rs

@@ -21,6 +21,7 @@ pub extern "C" fn resize_and_pad(
     nwidth: u32,
     nheight: u32,
     nsize: usize,
+    nquality: u8
 ) -> *const u8 {
     register_panic_hook();
 
@@ -43,7 +44,7 @@ pub extern "C" fn resize_and_pad(
     out.extend_from_slice(&[0, 0, 0, 0]);
 
     result
-        .write_to(&mut out, ImageOutputFormat::Jpeg(80))
+        .write_to(&mut out, ImageOutputFormat::Jpeg(nquality))
         .expect("can save as jpeg");
 
     assert!(out.len() <= nsize);