如何根据内容显示不同的背景颜色？
参照ECMWF的Metview源码实现。
Qt的Model中不同类型的数据用role区分，Qt的宏ItemDataRole提供了一些角色：
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enum ItemDataRole { DisplayRole = 0, DecorationRole = 1, EditRole = 2, ToolTipRole = 3, StatusTipRole = 4, WhatsThisRole = 5, // Metadata FontRole = 6, TextAlignmentRole = 7, BackgroundColorRole = 8, BackgroundRole = 8, TextColorRole = 9, ForegroundRole = 9, CheckStateRole = 10, // Accessibility AccessibleTextRole = 11, AccessibleDescriptionRole = 12, // More general purpose SizeHintRole = 13, InitialSortOrderRole = 14, // Internal UiLib roles. Start worrying when public roles go that high. DisplayPropertyRole = 27, DecorationPropertyRole = 28, ToolTipPropertyRole = 29, StatusTipPropertyRole = 30, WhatsThisPropertyRole = 31, // Reserved UserRole = 32 }; |
也可以自定义角色，只要数值大于UserRole即可。
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enum ImageNavigtionModelRole{ CachedImageRole = Qt::UserRole + 100, ImageMetaDataRole = Qt::UserRole +200 }; |
Qt的Model使用data函数、setData函数来获取和设置各种角色的具体数值。当我们需要修改背景颜色时，可以修改BackgroundColorRole角色的返回数据：
C++
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QVariant ImageNavigationModel::data(const QModelIndex &index, int role) const { if(role == Qt::BackgroundRole) { QStandardItem* node = itemFromIndex(index.sibling(index.row(),0)); // 每行颜色均相同 QVariant cached_image_role = node->data(CachedImageRole); if(!cached_image_role.isNull()) { if(index.row()%2 == 0) return QColor("#FFE6BF"); else return QColor("#FFF2DE"); } else { return QStandardItemModel::data(index, role); } } return QStandardItemModel::data(index, role); } |
这样就可以自定义数据的背景色。