v0.3.1

Adds the `convert_canvas_to_luma` and `convert_imagedata_to_luma` functions to simplify the task of getting data into the library.

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rxing-wasm"
-version = "0.3.0"
+version = "0.3.1"
 edition = "2021"
 description = "wasm bindings for rxing to provide commong barcode operations (decode/encode)"
 repository = "https://github.com/rxing-core/rxing-wasm"
@@ -18,6 +18,7 @@ decode_hints = []
 [dependencies]
 wasm-bindgen = "0.2.92"
 js-sys = "0.3.69"
+web-sys = {version =  "0.3.69", features = ["CanvasRenderingContext2d", "HtmlCanvasElement", "ImageData"]}
 
 # The `console_error_panic_hook` crate provides better debugging of panics by
 # logging them with `console.error`. This is great for development, but requires

README.md

@@ -24,6 +24,37 @@ function decodeBarcode(canvas) {
 }
 ```
 
+The `convert_canvas_to_luma` function is used to convert a canvas to the luma 8
+format that rxing expects. An example might look like to below.
+
+```javascript
+function decodeBarcode(canvas) {
+    let height = canvas.height;
+    let width = canvas.width;
+    let luma8Data = convert_canvas_to_luma(canvas);
+    let parsedBarcode = decode_barcode(luma8Data, width, height);
+
+    return parsedBarcode;
+}
+```
+
+The `convert_imagedata_to_luma` function is used to convert an ImageData object to the luma 8
+format that rxing expects. An example might look like to below.
+
+```javascript
+function decodeBarcode(canvas) {
+    let context = canvas.getContext('2d');
+    let height = canvas.height;
+    let width = canvas.width;
+    let imageData = context.getImageData(0, 0, width, height);
+
+    let luma8Data = convert_imagedata_to_luma(imageData);
+    let parsedBarcode = decode_barcode(luma8Data, width, height);
+
+    return parsedBarcode;
+}
+```
+
 ## Hints
 ### Using the `DecodeHintDictionary` class
 Add a hint with `set_hint(hint: DecodeHintTypes, value: string)`. The function returns `true` if the hint was added and `false` if it was not. The value of hint must be a `number` representing on of the enum values for `DecodeHintTypes`. The easiest way to use this is to simply pass in one of the values from `DecodeHintTypes`.

examples/webpack+js/index.html

@@ -106,4 +106,4 @@ <h1>RXing - Decode Barcodes</h1>
 </html>
 
 <!-- Copyright 2023 Henry Schimke -->
-<!-- Using rxing-wasm v0.3.0 -->
+<!-- Using rxing-wasm v0.3.1 -->

examples/webpack+js/index.js

@@ -1,4 +1,4 @@
-import { convert_js_image_to_luma, decode_barcode_with_hints, decode_multi, DecodeHintDictionary, DecodeHintTypes, BarcodeFormat } from "rxing-wasm";
+import { convert_js_image_to_luma, convert_canvas_to_luma, decode_barcode_with_hints, decode_multi, DecodeHintDictionary, DecodeHintTypes, BarcodeFormat } from "rxing-wasm";
 
 const text_hints = ["Other", "PossibleFormats", "CharacterSet", "AllowedLengths", "AllowedEanExtensions"];
 const bool_hints = ["PureBarcode", "TryHarder", "AssumeCode39CheckDigit", "ReturnCodabarStartEnd", "AssumeGs1", "AlsoInverted", "TelepenAsNumeric"]
@@ -32,16 +32,24 @@ function handleFiles(e) {
 function onClickScan() {
     output.innerHTML = '';
     const canvas = document.getElementById('cvs');
-    const context = canvas.getContext('2d');
-    const imageData = context.getImageData(0, 0, canvas.width, canvas.height);
-    const luma_data = convert_js_image_to_luma(imageData.data);
+    // const context = canvas.getContext('2d');
+    // const imageData = context.getImageData(0, 0, canvas.width, canvas.height);
+    // const luma_data = convert_js_image_to_luma(imageData.data);
     const filter_image = document.getElementById("FilterInput").checked;
+    let luma_data;
+    try {
+        luma_data = convert_canvas_to_luma(canvas);
+    } catch (e) {
+        alert("Issue decoding: " + e);
+        return;
+    }
     const hints = getHints();
     let result;
     try {
         result = decode_barcode_with_hints(luma_data, canvas.width, canvas.height, hints, filter_image);
     } catch (e) {
         alert("Issue decoding: " + e);
+        return;
     }
     write_results(result.format(), result.text(), result.raw_bytes(), result.result_points(), result.get_meta_data());