From 373ca0cf9f6fe34352716fa98932f06fd12d029b Mon Sep 17 00:00:00 2001
From: Michal Vrba <michal.vrba@gmai.com>
Date: Wed, 7 Jan 2026 14:48:45 +0100
Subject: [PATCH] Add "Copy QR Code" button with clipboard support

Implemented a copy-to-clipboard button for QR codes, including Blazor logic for feedback and disabled states. Injected IJSRuntime for JS interop and added supporting JS functions for image copying and fallback download. Reduced QR code image size for better compatibility. Added responsive and accessible CSS for the new button. Cleaned up timers and feedback state on component disposal.
---
 QRPay/Pages/Home.razor     |  77 ++++++++++++++++++-
 QRPay/Pages/Home.razor.css | 102 ++++++++++++++++++++++++-
 QRPay/wwwroot/index.html   | 148 +++++++++++++++++++++++++++++++++++++
 3 files changed, 320 insertions(+), 7 deletions(-)

diff --git a/QRPay/Pages/Home.razor b/QRPay/Pages/Home.razor
index 55a60a2..81cee84 100644
--- a/QRPay/Pages/Home.razor
+++ b/QRPay/Pages/Home.razor
@@ -2,6 +2,7 @@
 @using QRCoder
 @using SixLabors.ImageSharp.Formats
 @using System.ComponentModel.DataAnnotations
+@inject IJSRuntime JSRuntime
 <PageTitle>QRPay - QR Payment Generator</PageTitle>
 
 <div class="qrpay-container">
@@ -72,7 +73,24 @@
             </div>
             
             <div class="qrcode-display">
-                <img src="@QRCodeStr" alt="Payment QR Code" />
+                <img id="qrcode-image" src="@QRCodeStr" alt="Payment QR Code" />
+                
+                <!-- Copy Button -->
+                <button class="btn-copy @(_isCopying ? "copying" : "")" @onclick="@CopyQRCodeToClipboard" disabled="@_isCopying">
+                    @if (_isCopying)
+                    {
+                        <span class="copy-spinner"></span>
+                        <span>Copying...</span>
+                    }
+                    else if (_copySuccess)
+                    {
+                        <span>✓ Copied!</span>
+                    }
+                    else
+                    {
+                        <span>📋 Copy QR Code</span>
+                    }
+                </button>
             </div>
             
             <div class="payment-details">
@@ -105,6 +123,9 @@
     private string QRCodeStr = string.Empty;
     private bool _showQRCode = false;
     private bool _isGenerating = false;
+    private bool _isCopying = false;
+    private bool _copySuccess = false;
+    private System.Threading.Timer? _copySuccessTimer;
 
     public class PaymentModel
     {
@@ -154,10 +175,11 @@
                     var payBySquare = new PayBySquareTextGenerator.PayBySquareOverkill(payment);
                     var stringData = payBySquare.GeneratePayBySquareOverkillString();
 
-                    // Generate QR code data
+                    // Generate QR code data - smaller size for better clipboard handling
                     using var qrCodeData = QRCodeGenerator.GenerateQrCode(stringData, QRCodeGenerator.ECCLevel.Q);
                     using var qrCode = new PngByteQRCode(qrCodeData);
-                    byte[] qrCodeImage = qrCode.GetGraphic(20);
+                    // Reduced from 20 to 10 for smaller clipboard image
+                    byte[] qrCodeImage = qrCode.GetGraphic(10);
 
                     QRCodeStr = $"data:image/png;base64,{Convert.ToBase64String(qrCodeImage)}";
                 }
@@ -172,11 +194,60 @@
         }
     }
 
+    public async Task CopyQRCodeToClipboard()
+    {
+        try
+        {
+            _isCopying = true;
+            _copySuccess = false;
+            StateHasChanged();
+
+            // Use JavaScript to copy the QR code image to clipboard with smaller size
+            var success = await JSRuntime.InvokeAsync<bool>("copyImageToClipboardSmall", "qrcode-image");
+            
+            _isCopying = false;
+            
+            if (success)
+            {
+                _copySuccess = true;
+                StateHasChanged();
+                
+                // Reset the success state after 3 seconds
+                _copySuccessTimer?.Dispose();
+                _copySuccessTimer = new System.Threading.Timer(_ =>
+                {
+                    InvokeAsync(() =>
+                    {
+                        _copySuccess = false;
+                        StateHasChanged();
+                    });
+                }, null, TimeSpan.FromSeconds(3), Timeout.InfiniteTimeSpan);
+            }
+            else
+            {
+                StateHasChanged();
+                // Could show an error message here if needed
+            }
+        }
+        catch (Exception)
+        {
+            _isCopying = false;
+            StateHasChanged();
+        }
+    }
+
     public void GoBack()
     {
         _showQRCode = false;
         QRCodeStr = string.Empty;
         paymentModel = new PaymentModel(); // Reset the form
+        _copySuccess = false;
+        _copySuccessTimer?.Dispose();
         StateHasChanged();
     }
+
+    public void Dispose()
+    {
+        _copySuccessTimer?.Dispose();
+    }
 }
\ No newline at end of file
diff --git a/QRPay/Pages/Home.razor.css b/QRPay/Pages/Home.razor.css
index 9854742..3681990 100644
--- a/QRPay/Pages/Home.razor.css
+++ b/QRPay/Pages/Home.razor.css
@@ -174,6 +174,63 @@
     background: rgba(74, 124, 89, 0.2);
 }
 
+/* Copy Button Styles */
+.btn-copy {
+    background: rgba(16, 185, 129, 0.1);
+    color: #065f46;
+    border: 2px solid #10b981;
+    padding: 12px 20px;
+    border-radius: 10px;
+    font-size: 0.95rem;
+    font-weight: 600;
+    cursor: pointer;
+    transition: all 0.3s ease;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    gap: 6px;
+    margin-top: 16px;
+    min-height: 48px;
+    width: auto;
+    max-width: 200px;
+    margin-left: auto;
+    margin-right: auto;
+}
+
+.btn-copy:hover:not(:disabled) {
+    background: rgba(16, 185, 129, 0.15);
+    border-color: #059669;
+    color: #047857;
+    transform: translateY(-1px);
+    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.2);
+}
+
+.btn-copy:active:not(:disabled) {
+    transform: translateY(0);
+    box-shadow: 0 2px 6px rgba(16, 185, 129, 0.15);
+}
+
+.btn-copy:disabled {
+    opacity: 0.6;
+    cursor: not-allowed;
+    transform: none;
+}
+
+.btn-copy.copying {
+    background: rgba(16, 185, 129, 0.05);
+    border-color: #6ee7b7;
+    color: #059669;
+}
+
+.copy-spinner {
+    width: 16px;
+    height: 16px;
+    border: 2px solid rgba(6, 95, 70, 0.3);
+    border-radius: 50%;
+    border-top-color: #065f46;
+    animation: spin 1s ease-in-out infinite;
+}
+
 .spinner {
     width: 20px;
     height: 20px;
@@ -230,6 +287,8 @@
     max-width: 100%;
     height: auto;
     aspect-ratio: 1;
+    display: block;
+    margin: 0 auto 16px auto;
 }
 
 /* Payment Details */
@@ -323,6 +382,12 @@
     .form-control {
         font-size: 16px; /* Prevents zoom on iOS */
     }
+    
+    .btn-copy {
+        font-size: 0.9rem;
+        padding: 10px 16px;
+        max-width: 180px;
+    }
 }
 
 /* Portrait tablets and large phones */
@@ -376,6 +441,13 @@
         height: 240px;
     }
     
+    .btn-copy {
+        font-size: 0.85rem;
+        padding: 10px 14px;
+        max-width: 160px;
+        margin-top: 12px;
+    }
+    
     .payment-details {
         padding: 20px;
         margin-bottom: 24px;
@@ -471,6 +543,13 @@
         height: 200px;
     }
     
+    .btn-copy {
+        font-size: 0.8rem;
+        padding: 8px 12px;
+        max-width: 140px;
+        margin-top: 10px;
+    }
+    
     .payment-details {
         padding: 16px;
         margin-bottom: 20px;
@@ -518,6 +597,12 @@
         height: 180px;
     }
     
+    .btn-copy {
+        font-size: 0.75rem;
+        padding: 8px 10px;
+        max-width: 120px;
+    }
+    
     .form-control {
         padding: 12px 14px;
     }
@@ -557,6 +642,12 @@
         height: 160px;
     }
     
+    .btn-copy {
+        font-size: 0.8rem;
+        padding: 6px 10px;
+        max-width: 110px;
+    }
+    
     .payment-details {
         margin-bottom: 20px;
     }
@@ -565,7 +656,8 @@
 /* Touch improvements for mobile */
 @media (max-width: 768px) {
     .btn-generate:hover,
-    .btn-back:hover {
+    .btn-back:hover,
+    .btn-copy:hover {
         transform: none; /* Disable hover transforms on mobile */
     }
     
@@ -575,8 +667,9 @@
     
     /* Larger touch targets */
     .btn-generate,
-    .btn-back {
-        min-height: 48px; /* WCAG recommended minimum touch target */
+    .btn-back,
+    .btn-copy {
+        min-height: 44px; /* WCAG recommended minimum touch target */
     }
 }
 
@@ -591,7 +684,8 @@
         animation: none;
     }
     
-    .spinner {
+    .spinner,
+    .copy-spinner {
         animation: none;
     }
     
diff --git a/QRPay/wwwroot/index.html b/QRPay/wwwroot/index.html
index bff5d8b..1ce9077 100644
--- a/QRPay/wwwroot/index.html
+++ b/QRPay/wwwroot/index.html
@@ -54,6 +54,154 @@
         <a href="." class="reload">Reload</a>
         <span class="dismiss">🗙</span>
     </div>
+
+    <!-- JavaScript functions for clipboard operations -->
+    <script>
+        // Original function for normal copy (kept for compatibility)
+        window.copyImageToClipboard = async function (imageId) {
+            try {
+                // Check if Clipboard API is supported
+                if (!navigator.clipboard || !navigator.clipboard.write) {
+                    console.warn('Clipboard API not supported');
+                    return false;
+                }
+
+                const img = document.getElementById(imageId);
+                if (!img) {
+                    console.error('Image element not found');
+                    return false;
+                }
+
+                // Create a canvas to convert the image to blob
+                const canvas = document.createElement('canvas');
+                const ctx = canvas.getContext('2d');
+
+                // Set canvas dimensions to match image
+                canvas.width = img.naturalWidth || img.width;
+                canvas.height = img.naturalHeight || img.height;
+
+                // Draw the image on canvas
+                ctx.drawImage(img, 0, 0);
+
+                // Convert canvas to blob
+                return new Promise((resolve) => {
+                    canvas.toBlob(async (blob) => {
+                        if (!blob) {
+                            console.error('Failed to create blob from canvas');
+                            resolve(false);
+                            return;
+                        }
+
+                        try {
+                            // Create ClipboardItem and write to clipboard
+                            const clipboardItem = new ClipboardItem({ 'image/png': blob });
+                            await navigator.clipboard.write([clipboardItem]);
+                            console.log('Image copied to clipboard successfully');
+                            resolve(true);
+                        } catch (error) {
+                            console.error('Failed to copy image to clipboard:', error);
+                            resolve(false);
+                        }
+                    }, 'image/png');
+                });
+
+            } catch (error) {
+                console.error('Error copying image to clipboard:', error);
+                return false;
+            }
+        };
+
+        // New function for copying smaller images to clipboard
+        window.copyImageToClipboardSmall = async function (imageId) {
+            try {
+                // Check if Clipboard API is supported
+                if (!navigator.clipboard || !navigator.clipboard.write) {
+                    console.warn('Clipboard API not supported');
+                    return false;
+                }
+
+                const img = document.getElementById(imageId);
+                if (!img) {
+                    console.error('Image element not found');
+                    return false;
+                }
+
+                // Create a canvas to convert the image to blob
+                const canvas = document.createElement('canvas');
+                const ctx = canvas.getContext('2d');
+
+                // Set smaller canvas dimensions (max 512x512 for better clipboard handling)
+                const maxSize = 512;
+                let { width, height } = img.naturalWidth && img.naturalHeight ?
+                    { width: img.naturalWidth, height: img.naturalHeight } :
+                    { width: img.width, height: img.height };
+
+                // Scale down if image is too large
+                if (width > maxSize || height > maxSize) {
+                    const scale = Math.min(maxSize / width, maxSize / height);
+                    width = Math.floor(width * scale);
+                    height = Math.floor(height * scale);
+                }
+
+                canvas.width = width;
+                canvas.height = height;
+
+                // Draw the image on canvas with scaling
+                ctx.drawImage(img, 0, 0, width, height);
+
+                // Convert canvas to blob with higher compression
+                return new Promise((resolve) => {
+                    canvas.toBlob(async (blob) => {
+                        if (!blob) {
+                            console.error('Failed to create blob from canvas');
+                            resolve(false);
+                            return;
+                        }
+
+                        try {
+                            // Create ClipboardItem and write to clipboard
+                            const clipboardItem = new ClipboardItem({ 'image/png': blob });
+                            await navigator.clipboard.write([clipboardItem]);
+                            console.log('Smaller image copied to clipboard successfully');
+                            resolve(true);
+                        } catch (error) {
+                            console.error('Failed to copy image to clipboard:', error);
+                            resolve(false);
+                        }
+                    }, 'image/png', 0.8); // Lower quality for smaller size
+                });
+
+            } catch (error) {
+                console.error('Error copying image to clipboard:', error);
+                return false;
+            }
+        };
+
+        // Fallback function for browsers that don't support Clipboard API
+        window.downloadQRCode = function (imageId, filename = 'qrcode.png') {
+            try {
+                const img = document.getElementById(imageId);
+                if (!img) {
+                    console.error('Image element not found');
+                    return false;
+                }
+
+                // Create a temporary link element
+                const link = document.createElement('a');
+                link.href = img.src;
+                link.download = filename;
+                document.body.appendChild(link);
+                link.click();
+                document.body.removeChild(link);
+
+                return true;
+            } catch (error) {
+                console.error('Error downloading image:', error);
+                return false;
+            }
+        };
+    </script>
+
     <script src="_framework/blazor.webassembly#[.{fingerprint}].js"></script>
 </body>