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204 lines
7.4 KiB
Markdown
204 lines
7.4 KiB
Markdown
# Menu Button Control
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Functions of a menu button are generally the same as that of a normal pull-down
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combo box. Actually, in the early version of MiniGUI, the menu button acts as
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the alternate of the combo box. Of course, the menu button has much limitation,
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e.g., it cannot be edited, and does not provide scrolling of list items, etc.
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In appearance, the menu button is like a normal push button. The difference is
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that the menu button has a small rectangle (shown as a down arrow in `FLAT`
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style) on the right side of the rectangular button region. When the user clicks
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the control, a menu would pop up, and when the user clicks an item of the menu
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with the mouse, the button content will change to the content of this item, as
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shown in Figure 1.
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Figure 1 Menu button (The left is normal status, the right is effect after menu
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pops up)
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Calling `CreateWindow` function with `CTRL_MENUBUTTON` as the control class
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name can create a menu button.
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## Styles of Menu Button
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The menu button has some special styles of its own. Generally, we use the
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following style combination when creating a menu button.
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```
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```
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- `MBS_SORT:` Sorting the menu items
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- `MBS_LEFTARROW:` The menu pull-down arrow will be display at the left of the
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text.
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- `MBS_NOBUTTON:` The control have not push button
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- `MBS_ALIGNLEFT:` The text on menubutton is left-align
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- `MBS_ALIGNRIGHT:` The text on menubutton is right-align
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- `MBS_ALIGNCENTER:` The text on menubutton is center-align
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The position of bitmap cannot be affected by align-style when it is set
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## Messages of Menu Button
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### Adding Items to Menu Button Control
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`MBM_ADDITEM` message is used to add items to a menu button. You should pass an
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initialized `MENUBUTTONITEM` structure when calling `SendMessage,` as shown in
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the following:
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```
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```
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Here `hMbtnWnd` is the handle of a menu button control. `SendMessage` will
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return the index of the new menu item, and return `MB_ERR_SPACE` when the
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memory is not enough.
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### Deleting Items from Menu Button Control
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Items can be deleted form a menu button by using `MBM_DELITEM` message and
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specifying the index of the menu item to be deleted, as shown in the following:
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```
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```
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Here, index is the index of an item.
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### Deleting All Items in the Menu
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As the same as a list box, the menu button also provides the message to delete
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all items, i.e. `MBM_RESETCTRL` message, which is shown as follows:
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```
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```
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### Setting Current Selected Item
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Similarly, you can use `MBM_SETCURITEM` message to set the selected item, and
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the text of the selected item will be displayed on the menu button, shown as
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follows:
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```
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```
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Here, index is the index of the item to be set.
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### Getting Current Selected Item
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You can get the index of the current selected item with `MBM_GETCURITEM`
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message, shown as follows:
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```
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```
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This message returns the index of the current selected item.
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### Getting/Setting Data of Menu Item
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You can use `MBM_GETITEMDATA` and `MBM_SETITEMDATA` messages to get and set the
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data of a menu item, respectively. When using these two messages, `wParam`
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should be used to pass the index of the menu item to be gotten or set, `lParam`
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should be used to pass a pointer to `MENUBUTTONITEM` structure, which includes
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the text of the menu item, bitmap object, and additional data.
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It should be noted that, `MENUBUTTONITEM` structure includes a member called
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which. This member specifies which data of the menu item to be gotten or set
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(text, bitmap object and/or additional data), and is generally the combination
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of the following values:
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- `MB_WHICH_TEXT:` Indicate the text of the menu item to be gotten or set. Here
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the text member of the structure must point to a valid buffer.
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- `MB_WHICH_BMP:` Indicate the bitmap object of the menu item to be gotten or
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set.
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- `MB_WHICH_ATTDATA:` Indicate the additional data of the menu item to be
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gotten or set.
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The example is as follows:
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```
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```
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Here, menubtn is the handle of the menu button.
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### Other Messages
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When using `MBS_SORT` style, because item sorting is involved, MiniGUI also
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provides `MBM_SETSTRCMPFUNC` message for the application to set a customized
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sorting function. Generally speaking, the application should use this message
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to set the new text string comparing function before adding items.
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Usage of the message can refer to `LB_SETSTRCMPFUNC` message of list box.
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## Notification Codes of Menu Button
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The menu button has not `MBS_NOTIFY` style, so any menu button control can
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generate the following notification codes:
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- `MBN_ERRSPACE:` Memory allocation error occurs, and the memory space is not
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enough.
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- `MBN_SELECTED:` Selection is made for the menu button control. Whether or not
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the selected menu item changes, this notification will be generated.
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- `MBN_CHANGED:` The selected item of the menu button control changes.
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- `MBN_STARTMENU:` The user activates the popup menu of a menu button.
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- `MBN_ENDMENU:` The popup menu closed.
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## Sample Program
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List 1 gives an example for using menu button. This program section makes a
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little change on the program of List 1, i.e., a menu button replaces the
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pull-down combo box in program of List 1. Please refer to menubutton.c file of
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demo program package `mg-samples` of this guide for the complete source code.
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The running effect of the program is as shown in Figure 2.
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List 1 Example of using menu button
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```
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```
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Figure 2 Use of menu button</center>
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-- Main.XiaodongLi - 26 Oct 2009
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----
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[<< ](MiniGUIProgGuidePart.md) |
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[Table of Contents](README.md) |
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[ >>](MiniGUIProgGuidePart.md)
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[Release Notes for MiniGUI 3.2]: /supplementary-docs/Release-Notes-for-MiniGUI-3.2.md
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[Release Notes for MiniGUI 4.0]: /supplementary-docs/Release-Notes-for-MiniGUI-4.0.md
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[Showing Text in Complex or Mixed Scripts]: /supplementary-docs/Showing-Text-in-Complex-or-Mixed-Scripts.md
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[Supporting and Using Extra Input Messages]: /supplementary-docs/Supporting-and-Using-Extra-Input-Messages.md
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[Using CommLCD NEWGAL Engine and Comm IAL Engine]: /supplementary-docs/Using-CommLCD-NEWGAL-Engine-and-Comm-IAL-Engine.md
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[Using Enhanced Font Interfaces]: /supplementary-docs/Using-Enhanced-Font-Interfaces.md
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[Using Images and Fonts on System without File System]: /supplementary-docs/Using-Images-and-Fonts-on-System-without-File-System.md
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[Using SyncUpdateDC to Reduce Screen Flicker]: /supplementary-docs/Using-SyncUpdateDC-to-Reduce-Screen-Flicker.md
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[Writing DRI Engine Driver for Your GPU]: /supplementary-docs/Writing-DRI-Engine-Driver-for-Your-GPU.md
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[Writing MiniGUI Apps for 64-bit Platforms]: /supplementary-docs/Writing-MiniGUI-Apps-for-64-bit-Platforms.md
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[Quick Start]: /user-manual/MiniGUIUserManualQuickStart.md
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[Building MiniGUI]: /user-manual/MiniGUIUserManualBuildingMiniGUI.md
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[Compile-time Configuration]: /user-manual/MiniGUIUserManualCompiletimeConfiguration.md
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[Runtime Configuration]: /user-manual/MiniGUIUserManualRuntimeConfiguration.md
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[Tools]: /user-manual/MiniGUIUserManualTools.md
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[Feature List]: /user-manual/MiniGUIUserManualFeatureList.md
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[MiniGUI Overview]: /MiniGUI-Overview.md
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[MiniGUI User Manual]: /user-manual/README.md
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[MiniGUI Programming Guide]: /programming-guide/README.md
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[MiniGUI Porting Guide]: /porting-guide/README.md
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[MiniGUI Supplementary Documents]: /supplementary-docs/README.md
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[MiniGUI API Reference Manuals]: /api-reference/README.md
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[MiniGUI Official Website]: http://www.minigui.com
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[Beijing FMSoft Technologies Co., Ltd.]: https://www.fmsoft.cn
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[FMSoft Technologies]: https://www.fmsoft.cn
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[HarfBuzz]: https://www.freedesktop.org/wiki/Software/HarfBuzz/
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