diff --git a/scene/PicDateItem.cpp b/scene/PicDateItem.cpp
index 7bde8e3..3a3a5d4 100644
--- a/scene/PicDateItem.cpp
+++ b/scene/PicDateItem.cpp
@@ -1,9 +1,80 @@
 #include "PicDateItem.h"
 #include <QDebug>
 #include <QRegExp>
+#include <QPainter>
+#include <QElapsedTimer>
 #include "LogInfo.h"
 #include "ItemCommon.h"
 
+// 生成可能的最长时间字符串供尺寸计算使用（基于像素宽度）
+static QString generateMaxDateTimeString(const DateItemModel &model, const QFont &font)
+{
+    if (model.datetimePattern.isEmpty())
+        return QString();
+
+    QString s = model.datetimePattern;
+
+    QFontMetrics fm(font);
+
+    auto longestFromList = [&fm] (const QStringList &lst, const QString &fallback) {
+        int bestW = -1;
+        QString best;
+        for (const auto &v : lst) {
+            int w = fm.horizontalAdvance(v);
+            if (w > bestW) { bestW = w; best = v; }
+        }
+        return best.isEmpty() ? fallback : best;
+    };
+
+    int i = s.indexOf("yyyy");
+    if (i != -1) {
+        QString repl;
+        if (!model.yearsMap.isEmpty()) {
+            for (auto v : model.yearsMap.values()) if (v.length() > repl.length()) repl = v;
+        } else {
+            repl = QString::number(QDate::currentDate().year());
+        }
+        s.replace(i, 4, repl);
+    }
+
+    i = s.indexOf("YY");
+    if (i != -1) {
+        // 以像素宽度为准，'88' 通常足够宽
+        s.replace(i, 2, QString("88"));
+    }
+
+    i = s.indexOf("MM");
+    if (i != -1) {
+        s.replace(i, 2, longestFromList(model.monthsMap, QString("88")));
+    }
+
+    i = s.indexOf("dd");
+    if (i != -1) {
+        s.replace(i, 2, longestFromList(model.daysMap, QString("88")));
+    }
+
+    i = s.indexOf("HH");
+    if (i != -1) {
+        s.replace(i, 2, longestFromList(model.hoursMap, QString("88")));
+    }
+
+    QRegExp minutePattern("mm");
+    if (s.contains(minutePattern)) s.replace(minutePattern, QString("88"));
+
+    QRegExp secondPattern("ss");
+    if (s.contains(secondPattern)) s.replace(secondPattern, QString("88"));
+
+    i = s.indexOf("w");
+    if (i != -1) {
+        s.replace(i, 1, longestFromList(model.weeksMap, QString("888")));
+    }
+
+    QRegExp weekNumberPattern("c");
+    if (s.contains(weekNumberPattern)) s.replace(weekNumberPattern, QString("88"));
+
+    return s;
+}
+
 PicDateItem::PicDateItem(QGraphicsItem *parent, QGraphicsScene *scene, const SourceType type)
     :PicTextItem(parent, scene, type)
 {
@@ -33,6 +104,27 @@ void PicDateItem::setSource(QVariant var)
 void PicDateItem::setModel(DateItemModel model)
 {
     m_model = std::move(model);
+
+    // 计时：测量生成最长字符串和字体度量两段耗时
+    QElapsedTimer t1;
+    t1.start();
+    m_maxDateTimeStr = generateMaxDateTimeString(m_model, font());
+    qint64 genUs = t1.nsecsElapsed() / 1000; // microseconds
+
+    QElapsedTimer t2;
+    t2.start();
+    if (m_maxDateTimeStr.isEmpty()) {
+        m_maxSize = QSize();
+    } else {
+        QFontMetrics fm(font());
+        int w = fm.horizontalAdvance(m_maxDateTimeStr);
+        int h = fm.height();
+        m_maxSize = QSize(w, h);
+    }
+    qint64 fmUs = t2.nsecsElapsed() / 1000; // microseconds
+
+    qDebug() << "PicDateItem::setModel timing(us): generate=" << genUs << ", fm=" << fmUs << ", total=" << (genUs + fmUs);
+
     setSource(m_model.datetimePattern);
 }
 
@@ -84,6 +176,38 @@ QImage PicDateItem::itemImage()
     if(m_model.datetimePattern.isEmpty())
         return QImage();
 
-    auto ret = strToImage(m_currDateTimeStr);
-    return ret;
+    auto currImg = strToImage(m_currDateTimeStr);
+
+    if (m_maxSize.isEmpty())
+        return currImg;
+
+    int width = qMax(currImg.width(), m_maxSize.width());
+    int height = qMax(currImg.height(), m_maxSize.height());
+
+    QImage img(width, height, QImage::Format_ARGB32);
+    img.fill(QColor(0,0,0,0).rgba());
+
+    QPainter painter(&img);
+    int y = (height - currImg.height()) / 2;
+    painter.drawImage(0, y, currImg);
+    painter.end();
+
+    return img;
+}
+
+QRectF PicDateItem::boundingRect() const
+{
+    // 优先使用已经应用变换后的 m_itemImage（与 PicTextItem 保持一致）
+    if (!m_itemImage.isNull()) {
+        return QRectF(0, 0, m_itemImage.width(), m_itemImage.height());
+    }
+
+    // 否则基于缓存的最大像素尺寸和粗体倍数估算
+    int w = m_maxSize.width();
+    int h = m_maxSize.height();
+    if (w <= 0 || h <= 0)
+        return QGraphicsTextItem::boundingRect();
+
+    qreal bw = qreal(w) * qMax(1, m_boldMultiple);
+    return QRectF(0, 0, bw, qreal(h));
 }
\ No newline at end of file
diff --git a/scene/PicDateItem.h b/scene/PicDateItem.h
index 86f6e2d..32c01ae 100644
--- a/scene/PicDateItem.h
+++ b/scene/PicDateItem.h
@@ -35,6 +35,10 @@ private:
 
     DateItemModel m_model;
     QString m_currDateTimeStr;
+    QString m_maxDateTimeStr;
+    QSize m_maxSize; // 缓存最长字符串的像素宽高
+
+    virtual QRectF boundingRect() const override;
 };
 
 #endif // PIC_DATE_ITEM_H