From 9f9ea255a83f86623cf4e11ce182bd2eaf13f210 Mon Sep 17 00:00:00 2001
From: Grzegorz Kucmierz <gkucmierz@gmail.com>
Date: Wed, 4 Mar 2026 03:18:06 +0000
Subject: [PATCH] feat(qr): implement background style and gradient support for
 QR generation

---
 src/components/tools/QrCode.vue | 34 +++++++++++++++++++++-------
 src/workers/qrcode.worker.js    | 39 +++++++++++++++++++++++++++------
 2 files changed, 58 insertions(+), 15 deletions(-)

diff --git a/src/components/tools/QrCode.vue b/src/components/tools/QrCode.vue
index 9c15e98..8547cfa 100644
--- a/src/components/tools/QrCode.vue
+++ b/src/components/tools/QrCode.vue
@@ -13,9 +13,10 @@ const router = useRouter()
 const text = useLocalStorage('text', '', 'qr-code')
 const ecc = useLocalStorage('ecc', 'M', 'qr-code')
 const size = useLocalStorage('size', 300, 'qr-code')
-const format = useLocalStorage('format', 'png', 'qr-code')
 const isBgTransparent = useLocalStorage('isBgTransparent', true, 'qr-code')
-const bgColor = useLocalStorage('bgColor', '#ffffff', 'qr-code')
+const bgType = useLocalStorage('bgType', 'solid', 'qr-code')
+const bgColor1 = useLocalStorage('bgColor1', '#ffffff', 'qr-code')
+const bgColor2 = useLocalStorage('bgColor2', '#e2e8f0', 'qr-code')
 const fgType = useLocalStorage('fgType', 'solid', 'qr-code')
 const fgColor1 = useLocalStorage('fgColor1', '#000000', 'qr-code')
 const fgColor2 = useLocalStorage('fgColor2', '#10b981', 'qr-code')
@@ -60,14 +61,16 @@ const generateQR = () => {
     text: text.value,
     ecc: ecc.value,
     isBgTransparent: isBgTransparent.value,
-    bgColor: bgColor.value,
+    bgType: bgType.value,
+    bgColor1: bgColor1.value,
+    bgColor2: bgColor2.value,
     fgType: fgType.value,
     fgColor1: fgColor1.value,
     fgColor2: fgColor2.value
   })
 }
 
-watch([text, ecc, isBgTransparent, bgColor, fgType, fgColor1, fgColor2], () => {
+watch([text, ecc, isBgTransparent, bgType, bgColor1, bgColor2, fgType, fgColor1, fgColor2], () => {
   generateQR()
 })
 
@@ -128,6 +131,11 @@ const downloadFile = async () => {
         if (format.value === 'jpeg' && isBgTransparent.value) {
           ctx.fillStyle = '#ffffff'
           ctx.fillRect(0, 0, size.value, size.value)
+        } else if (format.value === 'jpeg' && bgType.value !== 'solid') {
+          // Let the Canvas render the SVG's background gradient naturally instead of filling
+          // Though drawing bounding rect white might still be needed behind transparent parts
+          ctx.fillStyle = '#ffffff'
+          ctx.fillRect(0, 0, size.value, size.value)
         }
         ctx.drawImage(img, 0, 0, size.value, size.value)
 
@@ -204,10 +212,20 @@ const triggerDownload = (blob, filename) => {
         </div>
 
         <div class="control-group">
-          <label>Background</label>
+          <label>Background Style</label>
+          <select v-model="bgType" :disabled="isBgTransparent" class="select-input">
+            <option value="solid">Solid Color</option>
+            <option value="linear">Linear Gradient</option>
+            <option value="radial">Radial Gradient</option>
+          </select>
+        </div>
+
+        <div class="control-group">
+          <label>Background Color(s)</label>
           <div class="color-picker-wrapper">
-            <input type="color" v-model="bgColor" :disabled="isBgTransparent" class="color-input">
-            <label class="checkbox-label">
+            <input type="color" v-model="bgColor1" :disabled="isBgTransparent" class="color-input">
+            <input type="color" v-model="bgColor2" v-if="bgType !== 'solid'" :disabled="isBgTransparent" class="color-input">
+            <label class="checkbox-label" style="margin-left: 0.5rem">
               <input type="checkbox" v-model="isBgTransparent"> Transparent
             </label>
           </div>
@@ -216,7 +234,7 @@ const triggerDownload = (blob, filename) => {
 
       <div class="preview-section" v-if="text" ref="previewRef" :style="{ height: previewHeight }">
         <div class="qr-container">
-          <div class="qr-frame" :style="{ background: isBgTransparent ? 'white' : bgColor }" v-html="svgContent"></div>
+          <div class="qr-frame" :style="{ background: isBgTransparent ? 'white' : bgType === 'solid' ? bgColor1 : (bgType === 'linear' ? `linear-gradient(to bottom right, ${bgColor1}, ${bgColor2})` : `radial-gradient(circle, ${bgColor1}, ${bgColor2})`) }" v-html="svgContent"></div>
         </div>
 
         <div class="download-settings">
diff --git a/src/workers/qrcode.worker.js b/src/workers/qrcode.worker.js
index e5e64c7..956bc94 100644
--- a/src/workers/qrcode.worker.js
+++ b/src/workers/qrcode.worker.js
@@ -1,7 +1,7 @@
 import QRCode from 'qrcode'
 
 self.onmessage = async (e) => {
-  const { id, text, ecc, isBgTransparent, bgColor, fgType, fgColor1, fgColor2 } = e.data
+  const { id, text, ecc, isBgTransparent, bgType, bgColor1, bgColor2, fgType, fgColor1, fgColor2 } = e.data
 
   if (!text) {
     self.postMessage({ id, svgContent: '' })
@@ -15,19 +15,44 @@ self.onmessage = async (e) => {
       margin: 1,
       color: {
         dark: fgType === 'solid' ? fgColor1 : '#000000',
-        light: isBgTransparent ? '#00000000' : bgColor
+        light: isBgTransparent ? '#00000000' : (bgType === 'solid' ? bgColor1 : '#00000000')
       }
     })
 
+    let defsHtml = ''
+
     if (fgType !== 'solid') {
       const isLinear = fgType === 'linear'
-      const defs = isLinear
-        ? `<defs><linearGradient id="qr-grad" x1="0%" y1="0%" x2="100%" y2="100%"><stop offset="0%" stop-color="${fgColor1}" /><stop offset="100%" stop-color="${fgColor2}" /></linearGradient></defs>`
-        : `<defs><radialGradient id="qr-grad" cx="50%" cy="50%" r="50%"><stop offset="0%" stop-color="${fgColor1}" /><stop offset="100%" stop-color="${fgColor2}" /></radialGradient></defs>`
+      defsHtml += isLinear
+        ? `<linearGradient id="qr-fg-grad" x1="0%" y1="0%" x2="100%" y2="100%"><stop offset="0%" stop-color="${fgColor1}" /><stop offset="100%" stop-color="${fgColor2}" /></linearGradient>`
+        : `<radialGradient id="qr-fg-grad" cx="50%" cy="50%" r="50%"><stop offset="0%" stop-color="${fgColor1}" /><stop offset="100%" stop-color="${fgColor2}" /></radialGradient>`
+    }
 
-      svgContent = svgContent.replace('shape-rendering="crispEdges">', `shape-rendering="crispEdges">${defs}`)
+    if (!isBgTransparent && bgType !== 'solid') {
+      const isLinear = bgType === 'linear'
+      defsHtml += isLinear
+        ? `<linearGradient id="qr-bg-grad" x1="0%" y1="0%" x2="100%" y2="100%"><stop offset="0%" stop-color="${bgColor1}" /><stop offset="100%" stop-color="${bgColor2}" /></linearGradient>`
+        : `<radialGradient id="qr-bg-grad" cx="50%" cy="50%" r="50%"><stop offset="0%" stop-color="${bgColor1}" /><stop offset="100%" stop-color="${bgColor2}" /></radialGradient>`
+    }
+
+    if (defsHtml) {
+      svgContent = svgContent.replace('shape-rendering="crispEdges">', `shape-rendering="crispEdges"><defs>${defsHtml}</defs>`)
+    }
+
+    if (fgType !== 'solid') {
       // qrcode outputs <path stroke="#000000"...> so it's safe to replace
-      svgContent = svgContent.replace(/stroke="#000000"/g, 'stroke="url(#qr-grad)"')
+      svgContent = svgContent.replace(/stroke="#000000"/g, 'stroke="url(#qr-fg-grad)"')
+    }
+
+    if (!isBgTransparent && bgType !== 'solid') {
+      // Find viewBox to inject background rect
+      const viewBoxMatch = svgContent.match(/viewBox="0 0 (\d+) (\d+)"/)
+      if (viewBoxMatch) {
+        const w = viewBoxMatch[1]
+        const h = viewBoxMatch[2]
+        // Inject a rect immediately inside the svg
+        svgContent = svgContent.replace('</defs>', `</defs><rect width="${w}" height="${h}" fill="url(#qr-bg-grad)" />`)
+      }
     }
 
     self.postMessage({ id, svgContent })