之前我問過listview sorting 也成功了,可是我不明白其中的功能,有人可以詳細解釋一下嗎,因為我的program是要寫report的,謝謝
以下附上code

var ColumnToSort: Integer;

procedure TForm1.ListView1ColumnClick(Sender: TObject; Column: TListColumn);
begin
ColumnToSort := Column.Index;
(Sender as TCustomListView).AlphaSort;
end;
// 寫 OnCompare 事件
procedure TForm1.ListView1Compare(Sender: TObject; Item1, Item2: TListItem; Data: Integer; var Compare: Integer);
var
ix: Integer;
begin
if ColumnToSort = 0 then
Compare := CompareText(Item1.Caption,Item2.Caption)
else begin
ix := ColumnToSort - 1;
Compare := CompareText(Item1.SubItems[ix],Item2.SubItems[ix]);
end;
end;


不明白到方
1.compare什麼時候觸發
2.(Sender as TCustomListView).AlphaSort;
這句到底是什麼??
3.CompareText()這個function又是什麼來的??

編輯記錄

請善用說明
This example shows how to use the OnColumnClick and OnCompare events of a list view to let users sort the columns in a report-style list view by clicking on the column headers. This requires a global variable to keep track of the column that was clicked:

var ColumnToSort: Integer;
The OnColumnClick event handler sets the global variable to indicate the column to sort and calls AlphaSort:
procedure TForm1.ListView1ColumnClick(Sender: TObject; Column: TListColumn);
begin
ColumnToSort := Column.Index;
(Sender as TCustomListView).AlphaSort;
end;

The OnCompare event handler causes the list view to sort on the selected column:
procedure TForm1.ListView1Compare(Sender: TObject; Item1, Item2: TListItem; Data: Integer; var Compare: Integer);
var
ix: Integer;
begin
if ColumnToSort = 0 then
Compare := CompareText(Item1.Caption,Item2.Caption)
else begin
ix := ColumnToSort - 1;
Compare := CompareText(Item1.SubItems[ix],Item2.SubItems[ix]);
end;
end;
Note: This OnCompare event handler uses the global CompareText function. An application may want to use AnsiCompareText, CompareStr, or AnsiCompareStr instead, depending on whether the comparison should be case-sensitive and whether the locale should be considered.

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額有朝天骨,眼中有靈光

有人可以用淺白的解釋一次嗎,小第很笨...

要回答下面問題要先知道ListView 是ComCtrl 底層運作方式透過SendMessage, 詳細部份請自行trace delphi source , 寫到完天都黑了


1.compare什麼時候觸發 --> 呼叫AlphaSort 時觸發
2.(Sender as TCustomListView).AlphaSort;
這句到底是什麼?? --> 將 Sender 轉型成 TCustomListView 然後呼叫AlphaSort
3.CompareText()這個function又是什麼來的??
--> 字串比對, 是delphi提供的function
Compares two strings by ordinal value without case sensitivity.
CompareText compares S1 and S2 and returns 0 if they are equal. If S1 is greater than S2, CompareText returns an integer greater than 0. If S1 is less than S2, CompareText returns an integer less than 0. CompareText is not case sensitive and is not affected by the current locale.

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額有朝天骨,眼中有靈光

編輯記錄

AlphaSort呢




到底是什麼???這個function是做什麼的

關於AlphaSort底下這邊看不懂我也沒辦法講的更詳細了

function TCustomListView.AlphaSort: Boolean;
begin
if HandleAllocated then
Result := ListView_SortItems(Handle, @DefaultListViewSort, 0)
else Result := False;
end;

function ListView_SortItems(hwndLV: HWND; pfnCompare: TLVCompare;
lPrm: Longint): Bool;
begin
Result := Bool( SendMessage(hwndLV, LVM_SORTITEMS, lPrm,
Longint(@pfnCompare)) );
end;

最終就是call windows 的api SendMessage



===================引 用 mahoihei 文 章===================
AlphaSort呢




到底是什麼???這個function是做什麼的

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額有朝天骨,眼中有靈光

提問者您好:


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我是機器人,我不接受簡訊.