C builder master advanced
nxyc_twz@163.com
I bought this book "C Builder Depth Adventures", and regardless of this writing, the author's unique writing angle makes me. So I have an idea that I can write my experience in software development into a series of arts into a series of articles on 9CBS, which can not only improve their programming levels, but also with many masters on 9CBS. How do you talk to each other? In my writing plan, there will be a series of content including "C Builder Master Advanced", "InterBase Skills", "ODAC Use Detailed". The "C Builder Master Advanced" will mainly explain the application of the API function, write components with BCB, and the application in the MIS system, etc .; "Interbase Skills" (my favorite database server) is mainly Tell the various skills; "ODAC uses detailed explanation" (the preferred choice when using BCB is connected to Oracle) is mainly based on the help of translation ODAC, and can supplement the skills I am practical. I hope my thoughts can get everyone's support!
(3) Designing the DBTREEVIEW component with BCB
First, system analysis
Now use BCB, more and more, but you have a real thing, how many of your controls are written in C ? The answer will definitely make people can't stand it. Since it is unable to endure how to write a set of components belonging to BCB? I hope that from me, the masters can work together to create a component that really belongs to BCB's own! I don't want to tell the basics of BCB design components because they have a detailed introduction in the C Builder 5 Developer Guide.
Our DBTreeView is derived from the TtreeView component, so it will have all the features of the TTREEVIEW component, which we have to do is to have data perception, direct communication with data directly. To construct the TREE-shaped structure, we should make each node feature: Each node has a unique identifier ID and a parent ID ParentID, (the top-level node is empty) In order to display the content, it is also required to Display field fdisplayfield. The working principle of this component is very clear: through the ID of each node and the ParentID positioning data, then assign the relevant field content to the FDISPLAYFIELD display.
Second, the development frontier
The heaviest technology in this component is not in the data. Here, the data-aware technology is introduced:
To make a component become data perception, we must give it a required data connection to communicate with data training data, this data connection class is TFieldDataLink. Data perceived components have their own data connection classes, and data connection is responsible for creating, initializing, and destroying components. Establishing a connection usually takes 3 steps:
1. State the data connection class (tfielddataLink) to a member of the component;
2. Disclaimer properly, write access attributes;
3. Initialize the data connection.
Third, design process
// DBTREEVIEW header file
/ Add the following three lines in the header file, because / data connection classes need declarations in these three headers
#include
#include
#include
// Define an event to respond to setting a node bitmap event
Typedef void __fastcall (__closure * tdbtvsetimageIndexevent) (System :: Tobject * Sender, int ID, int parentid, int tent, int & imageindex, int & selectedindex); // Define node structure
Struct TDBTREENODATA
{
INT ID; // node unique identifier
INT PARENTID; // Node The parent logo, when it is empty, this node is the top node
}
Class Package TdbtreeView: Public TtreeView
{
Private:
TfieldDataLink * fdataLink; // Declaration data connection member
Ansistring fparentidfield; // parent identity field
Ansistring fprimaryidfield; // Main signature field
Ansistring fdisplayfield; // Display field
BOOL FACTIVE; / / Whether is an active state
BOOL FALLOWMODIFYDB; / / Do not modify
TDBTVSetImageIndexEvent FonseTimageIndex; // Declaration Event
Void __fastcall setActive (bool value); // setting status
Void __fastcall setDataSource (DB :: TDataSource * Value); // Setting the data source
TDataSource * __fastcall getDataSource (); // get data source
Void __fastcall clearllnodes (); // Delete all nodes
Void __fastcall fixtreenodes (int parentid, ttreenode * node); // Fill node
Void __fastcall FillChildtreenodes (int ParentID, Ttreenode * node, Bool Nest = false); // Fill a child node
Void __fastcall adddtonode (ttreenode * node, tdbtreenodedata & data); // Add data to node
protected:
/ / The following method is used to override TreeView by one method.
Virtual void __fastcall loaded (void); // load method
Virtual void __fastcall notification (classes :: tcomponent * Acomponent, classes :: top); // event
Dynamic void __fastcall edit (const tagtvitema & item); // edit method
Dynamic void __fastcall expand (ttreenode * node); // Expand method
Dynamic void __fastcall keydown (word & key, classes :: tshiftstate shift); / / keyboard event
Dynamic void __fastcall change (ttreenode * node); // node change event
Virtual Bool_fastcall CustomDrawItem (Ttreenode * Node, TcustomDrawState Stage, Bool & PaintImages); // Auto Node Event
PUBLIC:
__fastcall tdbtreeview (tComponent * Owner); // Constructor
__fastcall ~ tdbtreeView (); // Destructure function TDBTREENODEDATA __FASTCALL GETNODEDATA (TTREENODE * NODE); // Get specified node data
Void __fastcall fullxpand (void); // Expand all nodes
__Property Bool Active = {Read = Factive, Write = SetActive}; // Attribute Activity Status
__publish:
// The following attributes defined in the Properties Editor
__Property Bool AllowModifyDB = {Read = FallowModifyDB, Write = FallowModifyDB}; // Whether to allow editing
__property ansistring parentidfield = {read = fparentidfield, Write = fparentidfield}; // parent logo
__Property Ansistring PrimaryidField = {Read = fprimaryidfield, Write = fprimaryidfield}; // Master ID
__Property Ansistring DisplayField = {read = fdisplayfield, Write = fdisplayfield}; // Display field
__property tdataasource * DataSource = {read = getDataSource, Write = setDataSource}; // data source
__property tdbtvsetimageIndexevent oversetimageindex = {read = FonseTimageIndex, Write = FonseTImageIndex}; // Setting Node Bitchart Event
}
// The following class is used to fill the list list
Class TfieldNameProperty: Public TStringProperty
{
PUBLIC:
TPROPERTYATTRIBUTES __FASTCALL GETATITRIBUTES (VOID)
{
Return tpropertyAttributes () << pavaluelist;
}
Void __fastcall getValues (Classes :: TgetstrProc PROC);
}
"Not complete"
