QR code example: add a feature to make the result transparent

rust/qrcode/Makefile

@@ -1,37 +1,26 @@
 .PHONY: all
-all: build
+all: deploy
 
 .PHONY: node_modules
 .SILENT: node_modules
 node_modules:
 	npm install
 
-.PHONY: build
-.SILENT: build
-build: node_modules
-	dfx canister create --all
-	dfx build
-
-.PHONY: install
-.SILENT: install
-install: build
-	dfx canister install --all
-
-.PHONY: upgrade
-.SILENT: upgrade
-upgrade: build
-	dfx canister install --all --mode=upgrade
+deploy: node_modules
+	dfx deploy
 
 .PHONY: test
 .SILENT: test
-test: install
+test: deploy
 	# Wait at least 2 seconds.
 	sleep 2
 	# Validate the image is generated as a query.
 	dfx canister call qrcode_backend qrcode_query '("test", record {add_gradient=false; add_logo=false})' | fgrep -q 'Image = blob' && echo PASS
 	dfx canister call qrcode_backend qrcode_query '("test", record {add_gradient=false; add_logo=true})' | fgrep -q 'Image = blob' && echo PASS
 	dfx canister call qrcode_backend qrcode_query '("test", record {add_gradient=true; add_logo=false})' | fgrep -q 'Image = blob' && echo PASS
 	dfx canister call qrcode_backend qrcode_query '("test", record {add_gradient=true; add_logo=true})' | fgrep -q 'Image = blob' && echo PASS
+	dfx canister call qrcode_backend qrcode_query '("test", record {add_gradient=true; add_logo=true; add_trasparency=opt true})' | fgrep -q 'Image = blob' && echo PASS
+	dfx canister call qrcode_backend qrcode_query '("test", record {add_gradient=true; add_logo=true; add_trasparency=opt false})' | fgrep -q 'Image = blob' && echo PASS
 	# Validate the image is generated as an update call.
 	dfx canister call qrcode_backend qrcode '("test", record {add_gradient=true; add_logo=true})' | fgrep -q 'Image = blob' && echo PASS
 

rust/qrcode/README.md

@@ -16,6 +16,7 @@ This example requires an installation of:
 - [x] Make sure your rust version is up-to-date (e.g., run `rustup update`).
 - [x] Add the `wasm32` target to your rust installation (by running `rustup target add wasm32-unknown-unknown`).
 - [x] Clone this project to a local directory.
+- [x] Install `node.js` dependencies by running `npm install`.
 
 ## Running locally
 

rust/qrcode/src/qrcode_backend/qrcode_backend.did

@@ -1,6 +1,7 @@
 type Options = record {
   add_logo: bool;
   add_gradient: bool;
+  add_transparency: opt bool;
 };
 
 type QrError = record {

rust/qrcode/src/qrcode_backend/src/core.rs

@@ -20,6 +20,10 @@ pub(super) fn generate(
     )?)
     .into_rgba8();
 
+    if options.add_transparency == Some(true) {
+        make_transparent(&mut qr);
+    }
+
     if options.add_logo {
         add_logo(&mut qr, logo);
     }
@@ -33,6 +37,16 @@ pub(super) fn generate(
     Ok(result)
 }
 
+/// Replaces white pixels in the image with transparent pixels.
+fn make_transparent(qr: &mut ImageBuffer<Rgba<u8>, Vec<u8>>) {
+    for (_x, _y, pixel) in qr.enumerate_pixels_mut() {
+        if pixel.0 == [255, 255, 255, 255] {
+            *pixel = image::Rgba([255, 255, 255, 0]);
+        }
+    }
+}
+
+
 /// Adds the given logo at the center of QR code image.
 /// It ensures that the logo does not cover more than 10% of the image, which is
 /// below the QR error threshold.
@@ -89,7 +103,7 @@ fn add_gradient(qr: &mut ImageBuffer<Rgba<u8>, Vec<u8>>) {
     // The gradient goes from the center of the image to its sides.
     let center = (image_size / 2) as u32;
     for (x, y, pixel) in qr.enumerate_pixels_mut() {
-        if pixel.0[0] == 0 {
+        if pixel.0 == [0, 0, 0, 255] {
             // Use a simple Manhattan distance as an estimate of how far the
             // pixel is from the center of the image.
             let distance = x.abs_diff(center) + y.abs_diff(center);

rust/qrcode/src/qrcode_backend/src/lib.rs

@@ -4,12 +4,14 @@ use std::include_bytes;
 mod core;
 
 const IMAGE_SIZE_IN_PIXELS: usize = 1024;
-const LOGO: &[u8] = include_bytes!("../assets/logo.png");
+const LOGO_TRANSPARENT: &[u8] = include_bytes!("../assets/logo_transparent.png");
+const LOGO_WHITE: &[u8] = include_bytes!("../assets/logo_white.png");
 
 #[derive(CandidType, Deserialize)]
 struct Options {
     add_logo: bool,
     add_gradient: bool,
+    add_transparency: Option<bool>,
 }
 
 #[derive(CandidType, Deserialize)]
@@ -24,7 +26,12 @@ enum QrResult {
 }
 
 fn qrcode_impl(input: String, options: Options) -> QrResult {
-    let result = match core::generate(input, options, LOGO, IMAGE_SIZE_IN_PIXELS) {
+    let logo = if options.add_transparency == Some(true) {
+        LOGO_TRANSPARENT
+    } else {
+        LOGO_WHITE
+    };
+    let result = match core::generate(input, options, logo, IMAGE_SIZE_IN_PIXELS) {
         Ok(blob) => QrResult::Image(blob),
         Err(err) => QrResult::Err(QrError {
             message: err.to_string(),

rust/qrcode/src/qrcode_frontend/assets/main.css

@@ -20,6 +20,7 @@ div {
 img {
     max-width: 80vw;
     border: 1px solid #555;
+    background-color: #ddd;
 }
 
 .qrcode {

rust/qrcode/src/qrcode_frontend/src/index.html

@@ -33,6 +33,15 @@ <h1>QR code generator</h1>
           &nbsp; add gradient
         </label>
       </div>
+      <div class="option">
+        <label>
+          <div class="toggle-switch">
+            <input type="checkbox" id="transparent">
+            <span class="slider"></span>
+          </div>
+          &nbsp; make transparent
+        </label>
+      </div>
       <div class="option">
         <label>
           <div class="toggle-switch">

rust/qrcode/src/qrcode_frontend/src/index.js

@@ -23,6 +23,7 @@ async function onGenerateButtonClick(event) {
     const options = {
       add_logo: document.getElementById("logo").checked,
       add_gradient: document.getElementById("gradient").checked,
+      add_transparency: [document.getElementById("transparent").checked],
     }
 
     // Call the backend and wait for the result.