Introduction
This article implements a fully customizable property grid as can be seen in the above screenshots. The grid supports various types of items: strings, combos, file pickers... It also supports fully customizable items that can define how they are drawn, how the user interacts with them and their behavior when edited.
Background
As developers, we are now all used to the Properties Window of Visual Studio and this article is an implementation of this. It does not support the help area and although the control supports different types of display (categorized, alphabetical...) standard buttons for this are not provided.
Using the code
The sample application provided shows almost all that can be done with the control. You are therefore encouraged to parse the source code to learn about the control!
First we have placed a dummy control in our dialog (in our case a Picture Control) and overridden the type of the control in the header file to be a CPropertyGrid. In the OnInitDialog of the dialog, we initialize the controls using various methods:
AddSection: used to add a group of properties (see "Basic Items" of the screenshot) AddXXXItem: used to add items to a section (see below for the various items types) SetXXXStrings: used to localize the standard dialogs used by the CPropertyGrid (see below)
Basically, if the only thing we want to do is to display standard properties, then we are done!
Standard item types
As said previously, the control supports different items, so here is a quick description of those types:
AddStringItem: a simple single line string item. The string can be edited in-place AddTextItem: a multiline string item. When edited, CPropertyGrid dynamically generates a dialog allowing the user to enter the text AddIntegerItem: an integer value item. An optional formatting mask can be provided AddDoubleItem: a floating point value item. An optional formatting mask can be provided AddComboItem: an item allowing to choose among a set of values. The possible values are passed as a vector<string> AddBoolItem: a boolean value item which behaves like a Combo Item. True and False texts can be set using SetTrueFalseStrings AddDateItem: a date value item chosen using a CMonthCalCtrl derived control. AddDateTimeItem: a date and time value set using a dynamically generated dialog AddFileItem: an item allowing to choose a file using a standard CFileDialog. A filter list can be provided AddFolderItem: an item allowing to choose a folder using a "standard" directory picker dialog AddColorItem: an item allowing to choose a color using a standard CColorDialog AddFontItem: an item allowing to choose a color using a standard CFontDialog
Custom items
CPropertyGrid also supports full custom items. To implement a custom item, simply create a new class and make it derive from ICustomItem and implement the various methods of this interface. Then create an instance of your class and add it the grid control using AddCustomItem. Two methods of ICustomItem are purely virtual and must be overridden:
GetEditMode: tells the grid what kind of interaction your control is using when editing the value. The sample application shows four custom items that implement the various edit modes. DrawItem: override this to draw your custom item. This can be as simple as calling DrawText on the provided CDC.
Next, depending on the edit mode, you may override more methods to customize your item. To better understand how this works it is recommended to check the various custom items implemented in the sample application: CSerialItem for in-place editing, CRectItem for modal editing, CTreeItem for dropdown editing and CGradientItem for a full custom item.
- In-place edited items should override
GetStringForInPlaceEdit (to tell the grid the string that should be edited) and OnItemEdited (return false to discard the edit)
- Dropdown custom items should override
ShowDropDown and show their dropdown control here
- Modal custom items should override
OnEditItem and show their modal dialog here
- Custom edit mode items should override
OnLButtonDown, OnMouseMove and OnLButtonUp to implement their mouse events specific handling
Display customization
Rendering of the grid can also be customized using various methods:
- Title shading: control if you want to have a different background color for section headers
- Draw lines: control if you want to display horizontal grid lines or not
- Gutter: control if you want to display the vertical line between property names and values. You can also control the width of the gutter
- Focus disabled: control if you want disabled items to be selectable or not
- Colors: use the various
SetXXXColor methods to change the colors used to draw the grid
Value editing
You can use the GetItemValue and SetItemValue overloads to get the value of a specific item. The HITEM expected is one returned when you called AddXXXItem when initializing your control. Make sure you call the good overload when calling this function: obviously you cannot get double from date item and you cannot set a LOGFONT in a text item. That's why all these functions return a boolean value indicating if things went well or not.
Points of Interest
I must warn you that this is some code that I wrote a while back and that has not changed much since. I always wanted to put this one on Codeproject but obviously did not find time to do it. Now it's done!
I only provided project files for Visual Studio 2005 but I see no reason as to why the code should not work with 2003 or even 6.0. Maybe some minor adjustments should be done but it should not be a big issue.
I am using two other articles available on codeproject.com:
Conclusion
This was a fun control to write especially supporting full custom items. My description of the control does not cover all aspects of the control and I encourage you to review its header file to discover things that I have not taken the time to talk about. Nevertheless, I hope that this short article let you see all the possibilities of the control!
