feat(PosterBuilder): 添加海报图片cover/contain适配模式支持

补充Image类型的mode属性定义，重构图片绘制的尺寸计算逻辑以适配两种缩放模式；同时更新签到详情页的活动logo配置，使用contain模式并调整其位置与尺寸参数

@@ -48,6 +48,7 @@ export interface Image {
   url: string;
   width: number;
   height: number;
+  mode?: 'cover' | 'contain';
   borderRadius?: number;
   borderRadiusGroup?: number[];
   borderWidth?: number;

@@ -251,7 +251,7 @@ export const batchGetImageInfo = (images) => {
  */
 export const getImageInfo = (item, index) =>
   new Promise((resolve, reject) => {
-    const { x, y, width, height, url, zIndex } = item;
+    const { x, y, width, height, url, zIndex, mode = 'cover' } = item;
     
     // 预先计算一些固定值，避免重复计算
     const borderRadius = item.borderRadius || 0;
@@ -265,21 +265,36 @@ export const getImageInfo = (item, index) =>
       Taro.getImageInfo({ src: imgPath })
         .then((imgInfo) => {
           // 获取图片信息
-          // 根据画布的宽高计算出图片绘制的大小，这里会保证图片绘制不变形， 即宽高比不变，截取再拉伸
+          // 根据画布的宽高计算出图片绘制的大小
           const imgWidth = toRpx(imgInfo.width); // 图片真实宽度 单位 px
           const imgHeight = toRpx(imgInfo.height); // 图片真实高度 单位 px
           
-          // 优化计算逻辑，减少重复计算
           const aspectRatio = imgWidth / imgHeight;
           const targetRatio = width / height;
 
-          let sx, sy; // 截图的起点坐标
-          if (aspectRatio <= targetRatio) {
-            sx = 0;
+          let sx = 0;
+          let sy = 0;
+          let sw = imgWidth;
+          let sh = imgHeight;
+          let drawX = x;
+          let drawY = y;
+          let drawW = width;
+          let drawH = height;
+
+          if (mode === 'contain') {
+            if (aspectRatio > targetRatio) {
+              drawH = width / aspectRatio;
+              drawY = y + (height - drawH) / 2;
+            } else {
+              drawW = height * aspectRatio;
+              drawX = x + (width - drawW) / 2;
+            }
+          } else if (aspectRatio <= targetRatio) {
             sy = (imgHeight - (imgWidth / width) * height) / 2;
+            sh = imgHeight - sy * 2;
           } else {
-            sy = 0;
             sx = (imgWidth - (imgHeight / height) * width) / 2;
+            sw = imgWidth - sx * 2;
           }
           
           // 给 canvas 画图准备参数，详见 ./draw.ts-drawImage
@@ -291,14 +306,15 @@ export const getImageInfo = (item, index) =>
             borderRadiusGroup,
             zIndex: itemZIndex,
             imgPath: imgPath, // 使用下载后的临时文件路径
+            mode,
             sx,
             sy,
-            sw: imgWidth - sx * 2,
-            sh: imgHeight - sy * 2,
-            x,
-            y,
-            w: width,
-            h: height
+            sw,
+            sh,
+            x: drawX,
+            y: drawY,
+            w: drawW,
+            h: drawH
           };
           resolve(result);
         })

@@ -448,11 +448,12 @@ const posterConfig = computed(() => {
       },
       // 活动logo
       {
-        x: 360, // 按比例调整 (450 * 0.8 = 360)
-        y: 32, // 按比例调整 (40 * 0.8 = 32)
-        width: 200, // 按比例调整 (250 * 0.8 = 200)
-        height: 64, // 按比例调整 (80 * 0.8 = 64)
+        x: 328,
+        y: 24,
+        width: 240,
+        height: 88,
         url: currentMockData.value.activity.logo,
+        mode: 'contain',
         zIndex: 2,
       },
       // 关卡徽章