feat(phone-image): 生成圖片SnapDOM截圖流程改造

- 新增captureDomPages(): 從右側DOM容器串行截圖
- 新增generateLongImageFromCanvases(): canvas拼接長圖
- saveImages()條件分支: useDomPreview走DOM截圖, 否則走舊路徑
- 截圖參數scale=2, backgroundColor=#ffffff
- 保留doCapturePages/capturePagesFromStaging作為備用

public/static/js/phone-image.js

@@ -1644,7 +1644,119 @@ var PhoneImageEngine = (function () {
     }
 
     /**
-     * 将页面渲染到隐藏区域并高质量截图（用于保存）
+     * 从右侧DOM分页容器截图（DOM预览模式）
+     * 串行截图每个 .dom-page-container，避免并行导致内存溢出
+     * @param {Function} [onProgress] 进度回调 function(current, total)
+     * @returns {jQuery Deferred} resolves with canvas array
+     */
+    function captureDomPages(onProgress) {
+        var deferred = $.Deferred();
+
+        var containers = document.querySelectorAll('#paginated-preview .dom-page-container');
+        if (!containers || containers.length === 0) {
+            deferred.reject('未找到DOM分页容器');
+            return deferred.promise();
+        }
+
+        var sizeConfig = config.sizes[config.size] || config.sizes.xiaohongshu;
+        var outputWidth = sizeConfig.width * 2;   // scale=2
+        var outputHeight = sizeConfig.height * 2;
+        var totalPages = containers.length;
+        var canvases = [];
+
+        console.log('[PhoneImage] DOM截图开始，共' + totalPages + '页');
+        PhoneImageLogPanel.log('DOM截图开始，共' + totalPages + '页', 'info');
+
+        var idx = 0;
+
+        function captureNext() {
+            if (idx >= totalPages) {
+                console.log('[PhoneImage] DOM截图完成，成功' + canvases.length + '/' + totalPages + '页');
+                PhoneImageLogPanel.log('DOM截图完成，成功' + canvases.length + '/' + totalPages + '页', 'success');
+                deferred.resolve(canvases);
+                return;
+            }
+
+            // 进度显示
+            if (onProgress) onProgress(idx + 1, totalPages);
+            PhoneImageLogPanel.log('截图中 ' + (idx + 1) + '/' + totalPages, 'info');
+
+            try {
+                snapdom.toCanvas(containers[idx], {
+                    scale: 2,
+                    backgroundColor: '#ffffff'
+                }).then(function (canvas) {
+                    // 确保尺寸正确
+                    if (canvas.width !== outputWidth || canvas.height !== outputHeight) {
+                        var resizedCanvas = document.createElement('canvas');
+                        resizedCanvas.width = outputWidth;
+                        resizedCanvas.height = outputHeight;
+                        var ctx = resizedCanvas.getContext('2d');
+                        ctx.drawImage(canvas, 0, 0, outputWidth, outputHeight);
+                        canvas = resizedCanvas;
+                    }
+
+                    canvases.push(canvas);
+                    idx++;
+                    captureNext();
+                }).catch(function (err) {
+                    console.error('[PhoneImage] 第' + (idx + 1) + '页截图失败:', err);
+                    PhoneImageLogPanel.log('第' + (idx + 1) + '页截图失败: ' + err, 'error');
+                    // 继续下一页
+                    idx++;
+                    captureNext();
+                });
+            } catch (e) {
+                console.error('[PhoneImage] 第' + (idx + 1) + '页截图异常:', e);
+                PhoneImageLogPanel.log('第' + (idx + 1) + '页截图异常: ' + e, 'error');
+                idx++;
+                captureNext();
+            }
+        }
+
+        captureNext();
+        return deferred.promise();
+    }
+
+    /**
+     * 将canvas数组拼接为长图base64
+     * @param {Array} canvases - canvas对象数组
+     * @returns {jQuery Deferred} resolves with base64 string or null
+     */
+    function generateLongImageFromCanvases(canvases) {
+        var deferred = $.Deferred();
+
+        if (!canvases || canvases.length === 0) {
+            deferred.resolve(null);
+            return deferred.promise();
+        }
+
+        var maxWidth = 0;
+        var totalHeight = 0;
+        for (var i = 0; i < canvases.length; i++) {
+            totalHeight += canvases[i].height;
+            if (canvases[i].width > maxWidth) {
+                maxWidth = canvases[i].width;
+            }
+        }
+
+        var longCanvas = document.createElement('canvas');
+        longCanvas.width = maxWidth;
+        longCanvas.height = totalHeight;
+        var ctx = longCanvas.getContext('2d');
+
+        var y = 0;
+        for (var j = 0; j < canvases.length; j++) {
+            ctx.drawImage(canvases[j], 0, y);
+            y += canvases[j].height;
+        }
+
+        deferred.resolve(longCanvas.toDataURL('image/jpeg', 0.85));
+        return deferred.promise();
+    }
+
+    /**
+     * 将页面渲染到隐藏区域并高质量截图（用于保存，旧流程备用）
      * @returns {jQuery Deferred} resolves with canvas array
      */
     function capturePagesFromStaging() {
@@ -1695,15 +1807,32 @@ var PhoneImageEngine = (function () {
         var deferred = $.Deferred();
 
         // 第一步：生成分页图片和长图
-        capturePagesFromStaging().then(function (canvases) {
+        // DOM预览模式：直接从右侧DOM容器截图；旧模式：从隐藏渲染区截图
+        var capturePromise;
+        if (config.useDomPreview) {
+            capturePromise = captureDomPages(function (current, total) {
+                if (onProgress) onProgress(current, total, null);
+            });
+        } else {
+            capturePromise = capturePagesFromStaging();
+        }
+
+        capturePromise.then(function (canvases) {
             if (onProgress) onProgress(canvases.length, canvases.length, null);
             var pagesData = [];
             for (var i = 0; i < canvases.length; i++) {
                 pagesData.push(canvases[i].toDataURL('image/jpeg', 0.92));
             }
 
-            // 第二步：生成长图
-            return generateLongImageBase64().then(function(longBase64) {
+            // 第二步：生成长图（DOM模式用canvas拼接，旧模式用编辑器DOM截图）
+            var longImagePromise;
+            if (config.useDomPreview) {
+                longImagePromise = generateLongImageFromCanvases(canvases);
+            } else {
+                longImagePromise = generateLongImageBase64();
+            }
+
+            return longImagePromise.then(function(longBase64) {
                 return { pages: pagesData, longImage: longBase64 };
             });
         }).then(function(result) {