Obsidian-Main/20.01. Programming/QT/Dropdown button.md

!

1. Button必須是QToolButton.
2. 建立menu.
3. 建立action.
4. 把action加到menu裡面
5. 把menu設定給button
6. code example:

   QMenu* saveFrameMenu = new QMenu;
   saveRawAction = new QAction(QIcon(QPixmap(":/image/resources/button-raw.png")), "SaveRaw", this);
   saveJpgAction = new QAction(QIcon(QPixmap(":/image/resources/button-jpg.png")), "SaveJpg", this);
   saveBmpAction = new QAction(QIcon(QPixmap(":/image/resources/button-bmp.png")), "SaveBmp", this);
   saveFrameMenu->addAction(saveRawAction);
   saveFrameMenu->addAction(saveJpgAction);
   saveFrameMenu->addAction(saveBmpAction);
   ui.toolButtonSaveFrame->setMenu(saveFrameMenu);
   ui.toolButtonSaveFrame->setDefaultAction(saveJpgAction);
   ui.toolButtonSaveFrame->setToolButtonStyle(Qt::ToolButtonTextBesideIcon);
   ui.toolButtonSaveFrame->setPopupMode(QToolButton::MenuButtonPopup);