TFrame

Excellent — this is a fairly sophisticated Lazarus/Free Pascal GUI frame (TFrame) unit designed to display the details of a single "item" (a transaction or record) inside a tabbed interface (like in a notebook or multi-document viewer).

Let’s go over it clearly and systematically 👇

🧩 Overall Purpose

view.fra_showitem.pas defines a visual frame component (TfraShowItem) used to view the details of an item (probably a record in a database, or an entry in a list).
It is designed to be dynamically created inside a TTabSheet so each tab shows one "item".

🏗️ Main Architecture
1. Creation

CreateShowFrame() is the factory function:

function CreateShowFrame(anOwner: TWinControl; aViMo: ImemViewModelMain; anItem: ImemItem): TfraShowItem;


Creates a new TfraShowItem object.

Sets the parent (anOwner, usually a TTabSheet).

Registers its OnShow handler (FrameShow).

Initializes it with Init(aViMo, anItem).

So each tab/page will contain one frame showing one item.

2. Main Components on the Frame

From the declarations:

grdNvn — a TStringGrid showing a list of key/value/note data.

Several TPanels used as clickable labels and headers:

btnClose — acts like a "close tab" button.

lblTitleVal, lblExtraVal — display textual info (Title, Extra data).

pnlHead, pnlBottom, etc. — layout panels for header/footer organization.

3. Initialization

Init() sets up the frame:

procedure TfraShowItem.Init(aViMo: ImemViewModelMain; anItem: ImemItem);


Stores references to the ViewModel (fViMo) and the item data (anItem).

Creates a transaction object (fActiveTrx) and copies data from the item.

Updates the header and footer panels.

Calls SetupFrame() to fill the grid.

4. SetupFrame()

Populates the TStringGrid:

procedure TfraShowItem.SetupFrame;


Clears the grid.

Creates headers: Name, Value, Note.

Loops through fActiveTrx.Items — each line of data looks like "Name|Value|Note".

Uses helper functions like:

bcGetStrField() to split the |-separated string.

bcGridSetRowText() to insert rows.

5. User Interaction
Closing the Tab

The tab can be closed via:

Clicking the btnClose panel.

Pressing Backspace, Enter, Space, or Escape.

Double-clicking the grid.

btnCloseClick() posts a message to the parent form:

bcPostMessage(fParentForm.Handle, LM_CLOSETABSHEET, ptrint(fOwner), -1);


This means “ask the parent form to close this tab”.

Copying a Value

Pressing Ctrl+C in the grid copies the "Value" column of the selected row:

Clipboard.AsText := bcGetStrField(1, fActiveTrx.Items[aGridRow-1], '|');


And then notifies other parts of the app (via the ViewModel):

fViMo.Provider.NotifyConsumers(13, nil, bcStrNew('(i) "'+ls+'" copied to clipboard'));

Visual feedback

When hovering over buttons (btnClose or btnChoose), it changes color and font style (yellow + bold).

6. Grid Handling

grdNvnResize() adjusts column widths dynamically to fill the available width.

grdNvnSelection() just ensures the grid keeps focus.

It prevents losing focus after user input (that’s what all those if grdNvn.CanSetFocus then grdNvn.SetFocus lines are for).

7. Destruction

When the frame is about to be freed:

procedure TfraShowItem.BeforeDestruction;
begin
  if Assigned(fActiveTrx) then fActiveTrx.Obj.Free;
  inherited BeforeDestruction;
end;


It releases the current transaction object cleanly before the inherited cleanup.

🧠 In Simpler Words

Here’s what it does from a user’s point of view:

User Action Result
Opens an item in a new tab  A frame appears showing that item’s info in a grid.
Moves the window or resizes it  Columns auto-resize.
Double-clicks or presses ESC/Space/Enter/Backspace  The tab closes.
Presses Ctrl+C  Copies the “Value” of the selected row to clipboard and shows a “copied” message.
Hovers over the close button    It changes color for visual feedback.
🧩 Dependencies (other units)

These units provide helper functions:

bc.advstring → string utilities (splitting, formatting)

bc.pcthelp → likely parent-form helpers

bc.grdhelp → grid manipulation helpers

bc.messages → message constants (LM_CLOSETABSHEET)

model.decl, model.intf → interfaces and models (ImemItem, ImemTransaction, etc.)

clipbrd → clipboard support

🧾 Summary

TfraShowItem is a Lazarus GUI frame that:

Displays a data record’s details in a grid.

Lives inside a tab.

Allows copying grid values.

Can close itself.

Dynamically adjusts layout.

It’s a read-only, interactive viewer for structured item data, part of a larger “Memento”-style app that manages records or transactions.