feat: Implement lazy loading for existing sign images with a shimmer effect to improve performance.

static/src/css/sign_image_field.css

@@ -48,4 +48,20 @@ body div.o_sign_sign_item.o_sign_image_item span.o_placeholder {
     justify-content: center;
     width: 100%;
     height: 100%;
+    position: relative;
+}
+
+.o_sign_image_loading {
+    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
+    background-size: 200% 100%;
+    animation: o_sign_image_shimmer 1.5s infinite linear;
+}
+
+@keyframes o_sign_image_shimmer {
+    0% { background-position: 200% 0; }
+    100% { background-position: -200% 0; }
+}
+
+.o_sign_image_lazy {
+    transition: opacity 0.5s ease-in-out;
 }

static/src/js/sign_image_upload.js

@@ -107,6 +107,24 @@ patch(SignablePDFIframe.prototype, {
                 };
                 reader.readAsDataURL(file);
             });
+
+            // Performance Fix: Lazy Load existing images
+            const lazyImg = el.querySelector('.o_sign_image_lazy');
+            if (lazyImg && lazyImg.dataset.src) {
+                const observer = new IntersectionObserver((entries) => {
+                    entries.forEach(entry => {
+                        if (entry.isIntersecting) {
+                            lazyImg.src = lazyImg.dataset.src;
+                            lazyImg.onload = () => {
+                                lazyImg.classList.remove('o_sign_image_loading');
+                                lazyImg.style.opacity = 1;
+                            };
+                            observer.unobserve(lazyImg);
+                        }
+                    });
+                }, { rootMargin: '200px' }); // Load 200px before reaching viewport
+                observer.observe(lazyImg);
+            }
         }
     },
 

static/src/xml/sign_items_image.xml

@@ -8,7 +8,7 @@
              <div t-if="type == 'image'" t-att-data-id="id" t-att-title="role" t-attf-class="{{classes}} o_sign_sign_item o_sign_image_item" t-att-style="style" t-att-data-value="value" t-att-data-type="'image'" style="text-align:center; display:flex; align-items:center; justify-content:center;">
                 <input type="file" accept="image/*" class="o_sign_image_upload_input" style="display:none"/>
                 <t t-if="value">
-                     <img t-att-src="value" style="max-width:100%; max-height:100%; object-fit:contain;"/>
+                     <img t-att-data-src="value" src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="o_sign_image_lazy o_sign_image_loading" style="max-width:100%; max-height:100%; object-fit:contain; opacity: 0; transition: opacity 0.3s;"/>
                 </t>
                 <t t-else="">
                      <span class="o_placeholder" style="font-size:12px !important; color:#666; white-space:nowrap; overflow:hidden; text-overflow:ellipsis; line-height:1;">
@@ -23,9 +23,9 @@
     <t t-name="sign.imageSignItem">
          <div t-att-title="role" t-attf-class="{{classes}} o_sign_sign_item o_sign_image_item" t-att-data-id="id" t-att-style="style" t-att-data-type="'image'" style="text-align:center; display:flex; align-items:center; justify-content:center;">
             <div class="sign_item_body">
-                <t t-if="value">
+            <t t-if="value">
-                    <img t-att-src="value" style="max-width:100%; max-height:100%; object-fit:contain;"/>
+                <img t-att-data-src="value" src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="o_sign_image_lazy o_sign_image_loading" style="max-width:100%; max-height:100%; object-fit:contain; opacity: 0; transition: opacity 0.3s;"/>
-                </t>
+            </t>
                 <t t-else="">
                     <span class="o_placeholder" style="font-size:12px !important; color:#666; white-space:nowrap; overflow:hidden; text-overflow:ellipsis; line-height:1;">
                          <t t-esc="placeholder"/>