使用 Delphi 在网格面板中移动控件

Question

在上一个问题中，我询问了有关在网格面板中拖放的问题。

Drag N Drop controls in a GridPanel

接下来的问题是，当我尝试在其他控件附近对角移动控件时，我的行为很奇怪。不应该移动的控件正在移动单元格。上下左右都可以。但是对角线移动，当移动的单元格内容与其他持有控件的单元格位于同一行/列时，将导致意外的移动。我已经尝试了 beginupdate/endupdate 的转变仍然发生。网格面板有一个 LOCK 功能，但可以锁定任何东西。当放置在一个空单元格上时会发生这种情况，甚至是已经有内容的单元格。

这里是测试项目（Delphi 2010 w/o exe） http://www.mediafire.com/?xmrgm7ydhygfw2r

type
  TForm1 = class(TForm)
    GridPanel1: TGridPanel;
    btn1: TButton;
    btn3: TButton;
    btn2: TButton;
    lbl1: TLabel;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
    procedure GridPanelDragDrop(Sender, Source: TObject; X, Y: Integer);
    procedure btnDragOver(Sender, Source: TObject; X, Y: Integer;
      State: TDragState; var Accept: Boolean);
    procedure btnDragDrop(Sender, Source: TObject; X, Y: Integer);
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure SetColumnWidths(aGridPanel: TGridPanel);
var
  i,pct: Integer;
begin
  aGridPanel.ColumnCollection.BeginUpdate;
  pct:=Round(aGridPanel.ColumnCollection.Count/100);
  for i := 0 to aGridPanel.ColumnCollection.Count - 1 do begin
    aGridPanel.ColumnCollection[i].SizeStyle := ssPercent;
    aGridPanel.ColumnCollection[i].Value     := pct;
  end;
  aGridPanel.ColumnCollection.EndUpdate;
end;

procedure SetRowWidths(aGridPanel: TGridPanel);
var
  i,pct: Integer;
begin
  aGridPanel.RowCollection.BeginUpdate;
  pct:=Round(aGridPanel.RowCollection.Count/100);
  for i := 0 to aGridPanel.RowCollection.Count - 1 do begin
    aGridPanel.RowCollection[i].SizeStyle := ssPercent;
    aGridPanel.RowCollection[i].Value     := pct;
  end;
  aGridPanel.RowCollection.EndUpdate;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  btn1.OnDragOver := btnDragOver;
  btn2.OnDragOver := btnDragOver;
  btn3.OnDragOver := btnDragOver;
  GridPanel1.OnDragOver := btnDragOver;
  GridPanel1.OnDragDrop := GridPanelDragDrop;

  btn1.OnDragDrop := btnDragDrop;
  btn2.OnDragDrop := btnDragDrop;
  btn3.OnDragDrop := btnDragDrop;

  SetColumnWidths(GridPanel1);
  SetRowWidths(GridPanel1);
end;

procedure TForm1.btnDragOver(Sender, Source: TObject; X, Y: Integer;
  State: TDragState; var Accept: Boolean);
begin
  Accept := (Source is TButton);
end;

procedure TForm1.btnDragDrop(Sender, Source: TObject; X, Y: Integer);
var
  src_x,src_y, dest_x, dest_y: Integer;
  btnNameSrc,btnNameDest: string;
  src_ctrlindex,dest_ctrlindex:integer;
begin
  if Source IS tBUTTON then
  begin
    //GridPanel1.ColumnCollection.BeginUpdate;
    btnNameSrc := (Source as TButton).Name;
    btnNameDest := (Sender as TButton).Name;
    src_ctrlindex := GridPanel1.ControlCollection.IndexOf(Source as tbutton);
    src_x := GridPanel1.ControlCollection.Items[src_ctrlindex].Column;
    src_y := GridPanel1.ControlCollection.Items[src_ctrlindex].Row;

    dest_ctrlindex := GridPanel1.ControlCollection.IndexOf(Sender as tbutton);
    dest_x := GridPanel1.ControlCollection.Items[dest_ctrlindex].Column;
    dest_y := GridPanel1.ControlCollection.Items[dest_ctrlindex].Row;

    GridPanel1.ControlCollection[src_ctrlindex].Column := dest_x;
    GridPanel1.ControlCollection[src_ctrlindex].Row := dest_y;
    //GridPanel1.ColumnCollection.EndUpdate;

    lbl1.Caption := Format('"%s" from cell %d:%d to Cell %s=%d:%d', [btnNameSrc,src_x,src_y,btnNameDest,dest_x,dest_y]);

  end;
end;

procedure TForm1.GridPanelDragDrop(Sender, Source: TObject; X, Y: Integer);
var
  DropPoint: TPoint;
  CellRect: TRect;
  i_col, i_row, src_x,src_y, dest_x, dest_y: Integer;
  btnNameSrc,btnNameDest: string;
  src_ctrlindex:integer;
begin
  if Source is tbutton then
  begin
    btnNameSrc := (Source as TButton).Name;
    btnNameDest := '';
    src_ctrlindex := GridPanel1.ControlCollection.IndexOf(Source as tbutton);
    src_x := GridPanel1.ControlCollection.Items[src_ctrlindex].Column;
    src_y := GridPanel1.ControlCollection.Items[src_ctrlindex].Row;

    DropPoint := Point(X, Y);
    for i_col := 0 to GridPanel1.ColumnCollection.Count-1 do
      for i_row := 0 to GridPanel1.RowCollection.Count-1 do
      begin
        CellRect := GridPanel1.CellRect[i_col, i_row];
        if PtInRect(CellRect, DropPoint) then
        begin
          // Button was dropped over Cell[i_col, i_row]
          dest_x := i_col;
          dest_y := i_row;
          Break;
        end;
      end;
    lbl1.Caption := Format('"%s" from cell %d:%d to Cell %s=%d:%d', [btnNameSrc,src_x,src_y,btnNameDest,dest_x,dest_y]);

    GridPanel1.ControlCollection[src_ctrlindex].Column := dest_x;
    GridPanel1.ControlCollection[src_ctrlindex].Row := dest_y;
  end;
end;

Answer 1

这与拖动无关，当一个项目的列和行都在更改时，更改分两步进行。使用您的代码，首先是列，然后是行。如果在列变化中，f.i.，恰好已经有另一个控件，这个另一个控件被推到一边，即使它的单元格不是移动控件的目标单元格的最终位置。

Begin/EndUpdate 将不起作用，控制集合从不检查更新计数。你能做的是使用受保护的黑客来访问控制项的InternalSetLocation 方法。此方法有一个“MoveExisting”参数，您可以传递“False”。

type
  THackControlItem = class(TControlItem);

procedure TForm1.GridPanelDragDrop(Sender, Source: TObject; X, Y: Integer);
var
  [...]
begin
  if Source is tbutton then
  begin

    [...]

    lbl1.Caption := Format('"%s" from cell %d:%d to Cell %s=%d:%d', [btnNameSrc,src_x,src_y,btnNameDest,dest_x,dest_y]);

    THackControlItem(GridPanel1.ControlCollection[src_ctrlindex]).
        InternalSetLocation(dest_x, dest_y, False, False);
//    GridPanel1.ControlCollection[src_ctrlindex].Column := dest_x;
//    GridPanel1.ControlCollection[src_ctrlindex].Row := dest_y;
  end;
end;

您可能需要在调用“InternalSetLocation”之前测试目标单元格是否为空，具体取决于您期望的正确控制移动。

Answer 2

我使用一种完全不同的方式来完成这项工作...创建一个完整的单元只是为了向ExtCtrls.TControlCollection 添加一个方法而不接触单元ExtCtrls（第一次破解）并使这种方法使用InternalSetLocation（第二次破解）。我还在这篇文章中解释了这两种技巧。

然后我只需要将这样的单元添加到 implementation uses 部分（在 gridpanel 声明之前）并调用我创建的方法......非常易于使用。

我是这样一步一步做的：

1. 我将我为此类工作制作的此类单元包含到项目中（添加文件）
2. 我添加到我的 TForm 界面使用部分这样的单元（或我需要它的地方）
3. 我使用我的方法AddControlAtCell 而不是ExtCtrls.TControlCollection.AddControl

这是我为此类工作创建的单元，将其保存为unitTGridPanel_WithAddControlAtCell：

unit unitTGridPanel_WithAddControlAtCell;

interface

uses
    Controls
   ,ExtCtrls
   ;

type TGridPanel=class(ExtCtrls.TGridPanel)
   private
   public
     procedure AddControlAtCell(AControl:TControl;AColumn:Integer;ARow:Integer); // Add Control on specifed cell, if there already exists a Control it will be deleted
 end;

implementation

uses
    SysUtils
   ;

type
    THackControlItem=class(TControlItem); // To get internal access to InternalSetLocation procedure
procedure TGridPanel.AddControlAtCell(AControl:TControl;AColumn:Integer;ARow:Integer);
var
   TheControlItem:TControlItem; // To let it be added in a specified cell, since ExtCtrls.TControlCollection.AddControl contains multiply BUGs
begin // Add Control on specifed cell, if there already exists a Control it will be deleted
     if   (-1<AColumn)and(AColumn<ColumnCollection.Count) // Cell with valid Column
       and // Cell inside valid range
          (-1<ARow)and(ARow<RowCollection.Count) // Cell with valid Row
     then begin // Valid cell, must check if there is already a control
               if   (Nil<>ControlCollection.ControlItems[AColumn,ARow]) // Check if there are any controls
                 and // A control is already on the cell
                    (Nil<>ControlCollection.ControlItems[AColumn,ARow].Control) // Check if cell has a control
               then begin // There is already a control, must be deleted
                         ControlCollection.Delete(ControlCollection.IndexOf(ControlCollection.ControlItems[AColumn,ARow].Control)); // Delete the control
                    end;
               TheControlItem:=ControlCollection.Add; // Create the TControlItem
               TheControlItem.Control:=TControl(AControl); // Put the Control in the specified cell without altering any other cell
               THackControlItem(ControlCollection.Items[ControlCollection.IndexOf(AControl)]).InternalSetLocation(AColumn,ARow,False,False); // Put the ControlItem in the cell without altering any other cell
          end
     else begin // Cell is out of range
               raise Exception.CreateFmt('Cell [%d,%d] out of range on ''%s''.',[AColumn,ARow,Name]);
          end;
end;

end.

我希望 cmets 足够清楚，请阅读它们以了解我为什么以及如何这样做。

然后，当我需要在指定单元格的网格面板中添加控件时，我会执行下一个简单的调用：

TheGridPanel.AddControlAtCell(TheControl,ACloumn,ARow); // Add it at desired cell without affecting other cells

在特定单元格添加运行时新创建的 TCheckBox 的一个非常非常基本的示例可能是这样的：

// AColumn      is of Type Integer
// ARow         is of Type Integer
// ACheckBox    is of Type TCheckBox
// TheGridPanel is of Type TGridPanel
ACheckBox:=TCheckBox.Create(TheGridPanel); // Create the Control to be added (a CheckBox)
ACheckBox.Visible:=False; // Set it to not visible, for now (optimization on speed, e tc)
ACheckBox.Color:=TheGridPanel.Color; // Just to use same background as on the gridpanel
ACheckBox.Parent:=TheGridPanel; // Set the parent of the control as the gridpanel (mandatory)
TheGridPanel.AddControlAtCell(ElCheckBox,ACloumn,ARow); // Add it at desired cell without affecting other cells
ElCheckBox.Visible:=True; // Now it is added, make it visible
ElCheckBox.Enabled:=True; // And of course, ensure it is enabled if needed

请注意，我使用了这两个 Hack：

1. type THackControlItem 让我访问方法InternalSetLocation。
2. type TGridPanel=class(ExtCtrls.TGridPanel) 让我添加一个方法到 ExtCtrls.TGridPanel 甚至不用触摸（也不需要 ExtCtrls 的来源）

重要提示：还请注意，我提到它需要将单元添加到您要使用方法AddControlAtCell 的每个表单的界面的使用中；那是针对普通人的，高级人员也可以创建另一个单元，等等...“概念”是在声明您要使用它的 GridPanel 之前使用该单元...例如：如果 GridPanel 是在设计时放在表单上......它必须继续实现这种表单单元的使用。

希望这对其他人有所帮助。

Answer 3

以下解决方案无需任何黑客攻击即可工作。

我的代码在 C++ Builder 中，但我认为它只是为了让 Delphi 用户理解，因为它只依赖于 VCL 函数。 PS：请注意，我拖动 TPanels 而不是 TButtons（一个非常小的变化）。

void TfrmVCL::ButtonDragDrop(TObject *Sender, TObject *Source, int X, int Y)
{
  TRect CurCellRect;
  TRect DestCellRect;
  int Col;
  int Row;
  int destCol; int destRow;
  int srcIndex; int destIndex;
  TPanel *SrcBtn;
  TPanel *DestBtn;

  SrcBtn = dynamic_cast<TPanel *>(Source);
  if (SrcBtn)
     {
     int ColCount = GridPnl->ColumnCollection->Count ;
     int RowCount = GridPnl->RowCollection->Count ;

     // SOURCE
     srcIndex = GridPnl->ControlCollection->IndexOf( SrcBtn );

     // DESTINATION
     // we get coordinates of the button I drag onto
     DestBtn= dynamic_cast<TPanel *>(Sender);
     if (!DestBtn) return;
     destIndex    = GridPnl->ControlCollection->IndexOf( DestBtn );
     destCol      = GridPnl->ControlCollection->Items[ destIndex ]->Column;  // the column for the dragged button
     destRow      = GridPnl->ControlCollection->Items[ destIndex ]->Row;
     DestCellRect = GridPnl->CellRect[ destCol ][ destRow ];

     // Check all cells
     for ( Col = 0 ; Col < ColCount ; Col++ )
        {
        for ( Row = 0 ; Row < RowCount ; Row++ )
           {
             // Get the bounding rect for this cell
             CurCellRect = GridPnl->CellRect[ Col ][ Row ];

             if (IntersectRect_ForReal(DestCellRect, CurCellRect))
                {
                GridPnl->ControlCollection->Items[srcIndex]->SetLocation(Col, Row, false);
                return;
                }
           }
        }
     }
}