Render image previews from prepared model data and preserve aspect ratios

tools/chatgui/src/messagedelegate.cpp

@@ -600,6 +600,8 @@ MessageDelegate::Layout MessageDelegate::calcBodyLayout(
     if (L.isImage) {
         int barW = 3, barPad = 4;
         int thW = 220, thH = 160;
+        const int iw = index.data(MsgImageWidthRole).toInt(), ih = index.data(MsgImageHeightRole).toInt();
+        if (iw > 0 && ih > 0) thH = qBound(80, qRound((double)thW * ih / iw), 300);
         L.bubbleWidth = thW;
         L.totalHeight = qMax(thH, kAvatar) + kItemGap;
 
@@ -1332,14 +1334,8 @@ void MessageDelegate::paintBody(QPainter* painter, const QStyleOptionViewItem& o
         clip.addRoundedRect(L.imageThumbRect, kRadius, kRadius);
         painter->setClipPath(clip);
 
-        QPixmap img;
-        if (!filePath.isEmpty() && QFile::exists(filePath)) {
-            QImageReader reader(filePath);
-            reader.setAutoTransform(true);
-            reader.setScaledSize(L.imageThumbRect.size() * 2);
-            QImage im = reader.read();
-            if (!im.isNull()) img = QPixmap::fromImage(im);
-        }
+        const QImage image = index.data(MsgImagePreviewRole).value<QImage>();
+        const QPixmap img = QPixmap::fromImage(image);
 
         if (!img.isNull()) {
             painter->fillRect(L.imageThumbRect, QColor(20, 20, 24));
@@ -1353,7 +1349,8 @@ void MessageDelegate::paintBody(QPainter* painter, const QStyleOptionViewItem& o
             iconFont.setPointSize(iconFont.pointSize() + 10);
             painter->setFont(iconFont);
             painter->setPen(QColor(150, 150, 150));
-            painter->drawText(L.imageThumbRect, Qt::AlignCenter, QString::fromUtf8("\xF0\x9F\x93\xB7"));
+            painter->drawText(L.imageThumbRect, Qt::AlignCenter, index.data(MsgImageErrorRole).toBool()
+                ? QCoreApplication::translate("ChatGui", "Failed to load photo") : QString::fromUtf8("\xF0\x9F\x93\xB7"));
         }
 
         /* бейдж: разрешение · размер */

tools/chatgui/src/messagedelegate.h

@@ -55,6 +55,8 @@ enum MessageDataRole {
     MsgHighlightRole       = Qt::UserRole + 41,
     MsgEncryptedRole       = Qt::UserRole + 42,
     MsgVersionRole         = Qt::UserRole + 43,
+    MsgImagePreviewRole    = Qt::UserRole + 44, /* QImage ограниченного размера, подготовленный worker. */
+    MsgImageErrorRole      = Qt::UserRole + 45, /* Локальный файл не декодируется; показать читаемую ошибку. */
 };
 
 class MessageDelegate : public QStyledItemDelegate {