TVirtualStringTree.OnGetImageIndex 的叠加图像

Question

我想在 vtTest 组件中显示来自 ImageList1 的图像作为叠加层。

我在 Internet 和 SO 中找到了很多资源 - 比如 this - 但我无法让其中的 none 正常工作。

我确定我遗漏了一些非常微不足道的东西，但我不知道它可能是什么。

我得到的：我想要的：

这是包含显示我的问题的基本示例的表格。

Unit1.pas

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, VirtualTrees, Vcl.ImgList;

type
  PMyVtTestData = ^TMyVtTestData;
  TMyVtTestData = record
    isLocked: Boolean;
  end;

  TForm1 = class(TForm)
    vtTest: TVirtualStringTree;
    ImageList1: TImageList;
    procedure FormCreate(Sender: TObject);
    procedure vtTestGetImageIndex(Sender: TBaseVirtualTree; Node: PVirtualNode;
      Kind: TVTImageKind; Column: TColumnIndex; var Ghosted: Boolean;
      var ImageIndex: Integer);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
var
  i, j, m: Integer;
  Node, Node1, Node2: PVirtualNode;

  procedure SetCustomNodeDataValue(const Node: PVirtualNode; const Value: Boolean = False);
  var
    Data: PMyVtTestData;
  begin
    Data := vtTest.GetNodeData(Node);
    Data^.isLocked := Value;
  end;
begin
  vtTest.NodeDataSize := SizeOf(TMyVtTestData);

  //initialize some node
  //every TMyVtTestData.isLocked = False, except the 3rd TMyVtTestData.isLocked which is True
  Randomize;
  for i := 0 to Random(3)+3 do begin
    Node := vtTest.AddChild(nil);
    SetCustomNodeDataValue(Node, i = 2);
    for j := 0 to Random(3)+2 do begin
      Node1 := vtTest.AddChild(Node);
      SetCustomNodeDataValue(Node1);
      for m := 0 to Random(5) do begin
        Node2 := vtTest.AddChild(Node1);
        SetCustomNodeDataValue(Node2);
      end;
    end;
  end;
end;

procedure TForm1.vtTestGetImageIndex(Sender: TBaseVirtualTree;
  Node: PVirtualNode; Kind: TVTImageKind; Column: TColumnIndex;
  var Ghosted: Boolean; var ImageIndex: Integer);
var
  Data: PMyVtTestData;
begin

  if Node = nil then
    Exit;

  case Column of
    0: begin
      if Kind in [ikNormal, ikSelected] then
        ImageIndex := 0
      else if Kind = ikOverlay then begin
        Data := Sender.GetNodeData(Node);
        if Data^.isLocked then
          ImageIndex := 1;
      end;
    end;

  end;
end;

end.

Unit1.dfm

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 300
  ClientWidth = 313
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  DesignSize = (
    313
    300)
  PixelsPerInch = 96
  TextHeight = 13
  object vtTest: TVirtualStringTree
    Left = 8
    Top = 8
    Width = 298
    Height = 284
    Anchors = [akLeft, akTop, akRight, akBottom]
    Header.AutoSizeIndex = -1
    Header.Font.Charset = DEFAULT_CHARSET
    Header.Font.Color = clWindowText
    Header.Font.Height = -11
    Header.Font.Name = 'Tahoma'
    Header.Font.Style = []
    Header.Images = ImageList1
    Header.Options = [hoColumnResize, hoDrag, hoShowSortGlyphs, hoVisible]
    Images = ImageList1
    TabOrder = 0
    OnGetImageIndex = vtTestGetImageIndex
    Columns = <
      item
        Position = 0
        Width = 200
        WideText = 'column'
      end>
  end
  object ImageList1: TImageList
    Left = 256
    Top = 240
    Bitmap = {
      494C010102000500040010001000FFFFFFFFFF10FFFFFFFFFFFFFFFF424D3600
      0000000000003600000028000000400000001000000001002000000000000010
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      0000868686003535350000000000000000000000000000000000939393005757
      5700000000000000000000000000000000000000000000000000000000000000
      0000000000000000000000000000000000000000000000000000000000000000
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      000000000000000000000000000000000000000000000000000000000000D9D9
      D9000505050000000000B1B1B1000000000000000000FCFCFC00222222000000
      0000A2A2A2000000000000000000000000000000000000000000000000000000
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      000000000000000000000000000000000000000000000000000000000000CCCC
      CC00353535007D7D7D002525250066666600939393001E1E1E00646464003434
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  end
end

提示：

Delphi XE4
ImageIndex := 1; 行在 vtTestGetImageIndex 函数中执行 - 调试器在设置断点时停在那里
索引 0 和 1 处的图像确实存在于 TImageList
我已经能够在没有覆盖的情况下为不同类型的节点使用不同的图像

Answer 1

您的项目缺少两件事。

仅当索引 >= 15 时才会绘制叠加层
您需要使用 OnGetImageIndexEx，而不是普通的 OnGetImageIndex。

当您查看 VTV 的源代码时，原因就很清楚了。

procedure TBaseVirtualTree.PaintImage(var PaintInfo: TVTPaintInfo; ImageInfoIndex: TVTImageInfoIndex; DoOverlay: Boolean);
....
  // Now, draw the overlay. This circumnavigates limitations in the overlay mask index (it has to be 4 bits in size,
  // anything larger will be truncated by the ILD_OVERLAYMASK).
  // However this will only be done if the overlay image index is > 15, to avoid breaking code that relies
  // on overlay image indices (e.g. when using system image lists).
  if PaintInfo.ImageInfo[iiOverlay].Index >= 15 then  //<<------!
    // Note: XPos and YPos are those of the normal images.
    DrawImage(ImageInfo[iiOverlay].Images, ImageInfo[iiOverlay].Index, Canvas, XPos, YPos,
      Style[ImageInfo[iiOverlay].Images.ImageType] or ExtraStyle, DrawEnabled);

!! Overlays with index < 15 do not get considered !!

如果您不使用 OnGetImageIndexEx 从中选择叠加层的图像列表将为零，请参阅：

function TBaseVirtualTree.DoGetImageIndex(Node: PVirtualNode; Kind: TVTImageKind; Column: TColumnIndex;
  var Ghosted: Boolean; var Index: Integer): TCustomImageList;

// Queries the application/descendant about certain image properties for a node.
// Returns a custom image list if given by the callee, otherwise nil.

begin
  Result := nil;

  // First try the enhanced event to allow for custom image lists.
  if Assigned(FOnGetImageEx) then
    FOnGetImageEx(Self, Node, Kind, Column, Ghosted, Index, Result)
  else  !! only the ....EX works for me !!
    if Assigned(FOnGetImage) then
      FOnGetImage(Self, Node, Kind, Column, Ghosted, Index);
end;

如果我使用以下代码，您的叠加层将起作用：

procedure TForm1.vtTestGetImageIndexEx(Sender: TBaseVirtualTree; Node: PVirtualNode; Kind: TVTImageKind;
  Column: TColumnIndex; var Ghosted: Boolean; var ImageIndex: Integer; var ImageList: TCustomImageList);
var
  Data: PMyVtTestData;
begin

  if Node = nil then Exit;

  case Column of
    0: begin
      if Kind in [ikNormal, ikSelected] then ImageIndex:= 0
      else if Kind = ikOverlay then begin
        Data:= Sender.GetNodeData(Node);
        if Data^.isLocked then
          ImageIndex:= 1+16;
      end;
    end;
  end;
  ImageList:= Self.ImageList1;  //Or use a separate imagelist for overlays.
end;

即使不考虑叠加层的图像索引 < 15，VTV 也不会从索引中减去任何数字，因此 您被迫在图像列表中放置至少 15 张图像。

现在可以使用了：

Answer 2

您需要通过TImageList.Overlay指定要叠加的图像，例如：

procedure TForm1.FormCreate(Sender: TObject);
begin
  ImageList1.Overlay(1 , 0); // 1 = "Lock" index; 0=overlay index

  // second overlay - just for example:
  ImageList1.Overlay(7 , 1); // 7 = "Shortcut" index; 1=overlay index
end;

在 OnGetImageIndex 中，您需要使用 ImageList overlay 索引，而不是图像索引，例如：

...
if Kind = ikOverlay then begin
  if Data^.isLocked then
    ImageIndex := 0
  else
  if Data^.isShortcut then
    ImageIndex := 1
end

TVirtualStringTree.OnGetImageIndex 的叠加图像

Overlaid images with TVirtualStringTree.OnGetImageIndex

delphi

virtualtreeview

tvirtualstringtree