item的样式

/*鼠标悬浮*/
QTreeView::item:hover {
    background: green;
    border: 1px solid red;
}
/*鼠标点击(选择)*/
QTreeView::item:selected {
    border: 1px solid orange;
}
QTreeView::item:selected:active {
    background: skyblue;
}
QTreeView::item:selected:!active {
    background: blue;
}

分支的样式-用颜色表示

/*节点用颜色表示*/
QTreeView::branch {
    background: palette(base);
}
/*节点展开 有兄弟节点, 但没有相邻项*/
QTreeView::branch:has-siblings:!adjoins-item {
    background: cyan;
}
/*相邻项且有兄弟节点,即不是该层级的最后一个节点*/
QTreeView::branch:has-siblings:adjoins-item {
    background: red;
}
/*不是相邻项, 没有孩子节点, 没有兄弟节点*/
QTreeView::branch:!has-children:!has-siblings:adjoins-item {
    background: blue;
}
/*有兄弟节点 又有孩子节点,节点未展开*/
QTreeView::branch:closed:has-children:has-siblings {
    background: pink;
}
/*有兄弟节点 又有孩子节点,节点展开*/
QTreeView::branch:open:has-children:has-siblings {
    background: magenta;
}
/*没有有兄弟节点 但有孩子节点,节点未展开*/
QTreeView::branch:has-children:!has-siblings:closed {
    background: gray;
}
/*没有有兄弟节点 但有孩子节点,节点展开*/
QTreeView::branch:open:has-children:!has-siblings {
    background: green;
}

分支的样式-用图片表示

/*有兄弟节点,但没有相邻项*/
QTreeView::branch:has-siblings:!adjoins-item {
    border-image: url(branch-vline.png) 0;
}
/*有相邻项, 有兄弟节点*/
QTreeView::branch:has-siblings:adjoins-item {
    border-image: url(branch-more.png) 0;
}
/*该层级节点的最后一个节点*/
QTreeView::branch:!has-children:!has-siblings:adjoins-item {
    border-image: url(branch-end.png) 0;
}
/* 节点关闭*/
QTreeView::branch:has-children:!has-siblings:closed,
QTreeView::branch:closed:has-children:has-siblings {
    border-image: none;
    image: url(branch-closed.png);
}
/* 节点展开*/
QTreeView::branch:open:has-children:!has-siblings,
QTreeView::branch:open:has-children:has-siblings {
    border-image: none;
    image: url(branch-open.png);
}

使用的图片：
branch-closed.png

branch-open.png

branch-vline.png

branch-more.png

branch-end.png