refactor: 背景色兜底用 canvas 背景色替代硬编码

convert-w2p.js

@@ -468,7 +468,13 @@ function convert(input) {
           const g = parseInt(tc.slice(2,4), 16);
           const b = parseInt(tc.slice(4,6), 16);
           const lum = (r * 299 + g * 587 + b * 114) / 1000;
-          slideBg = lum > 128 ? { color: '1A1A1A' } : { color: 'FAFAFA' };
+          // 浅色文字 → 深色背景（用 canvas 背景色），深色文字 → 浅色背景（取反）
+          if (lum > 128) {
+            const canvasBg = canvas.backgroundColor ? rgbaToHex(canvas.backgroundColor) : null;
+            slideBg = { color: canvasBg || '1A1A1A' };
+          } else {
+            slideBg = { color: 'FAFAFA' };
+          }
         }
       }
     }
@@ -661,9 +667,16 @@ function convert(input) {
       if (n.styles.display === 'none' || n.styles.visibility === 'hidden') { continue; }
 
       let fillColor = null;
+      let fillTransparency = null;
       const bg = n.styles.backgroundColor;
       if (bg && bg !== 'rgba(0, 0, 0, 0)' && bg !== 'transparent') {
         fillColor = rgbaToHex(bg);
+        // 提取 alpha 通道作为 transparency
+        const alphaMatch = bg.match(/rgba?\(\s*\d{1,3}\s*,\s*\d{1,3}\s*,\s*\d{1,3}\s*,\s*([\d.]+)\s*\)/);
+        if (alphaMatch) {
+          const alpha = parseFloat(alphaMatch[1]);
+          if (alpha < 1) fillTransparency = Math.round((1 - alpha) * 100);
+        }
       }
       if (!fillColor) {
         const bgImg = n.styles.backgroundImage;
@@ -674,9 +687,12 @@ function convert(input) {
       }
       if (fillColor) {
         var shapeOpts = { x: opts.x, y: opts.y, w: opts.w, h: opts.h, fill: { color: fillColor } };
-        // 透明度
+        // 透明度（来自 alpha 通道）
+        if (fillTransparency) shapeOpts.fill.transparency = fillTransparency;
+        // 透明度（来自 CSS opacity）
         if (n.styles.opacity !== undefined && n.styles.opacity !== '' && parseFloat(n.styles.opacity) < 1) {
-          shapeOpts.transparency = Math.round((1 - parseFloat(n.styles.opacity)) * 100);
+          var opTrans = Math.round((1 - parseFloat(n.styles.opacity)) * 100);
+          shapeOpts.fill.transparency = Math.max(shapeOpts.fill.transparency || 0, opTrans);
         }
         
         // 圆角
@@ -883,13 +899,12 @@ if (require.main === module) {
           const st = { rect: 'rect', roundRect: 'roundRect', ellipse: 'ellipse' }[obj.shapeName] || 'rect';
           const shapeOpts = {
             x: o.x, y: o.y, w: o.w, h: o.h,
-            fill: o.fill ? { color: o.fill.color } : undefined
+            fill: o.fill ? { color: o.fill.color, transparency: o.fill.transparency } : undefined
           };
           if (o.line) shapeOpts.line = o.line;
           else shapeOpts.line = { type: 'none' };  // 去掉 pptxgenjs 默认边框
           if (o.shadow) shapeOpts.shadow = o.shadow;
           if (o.rectRadius) shapeOpts.rectRadius = o.rectRadius;
-          if (o.transparency !== undefined) shapeOpts.transparency = o.transparency;
           slide.addShape(pres.ShapeType[st] || pres.ShapeType.rect, shapeOpts);
         } else if (obj.type === 'image') {
           slide.addImage({