delphi - 使用 TVirtualStringTree.OnGetImageIndex 覆盖图像-6ren

delphi - 使用 TVirtualStringTree.OnGetImageIndex 覆盖图像

转载作者：行者123 更新时间：2023-12-03 15:41:59

我想将 vtTest 组件中的 ImageList1 中的图像显示为叠加层。

我在互联网上和这里找到了很多资源 - 例如 this - 但我无法让它们都正常工作。

我确信我错过了一些非常微不足道的东西，但我不知道它可能是什么。

<小时/>

我得到的: enter image description here 我想要的是:

<小时/>

这是包含显示我的问题的基本示例的表单。

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
      0000000000000000000000000000000000000000000000000000000000000000
      0000868686003535350000000000000000000000000000000000939393005757
      5700000000000000000000000000000000000000000000000000000000000000
      0000000000000000000000000000000000000000000000000000000000000000
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      000000000000000000000000000000000000000000000000000000000000D9D9
      D9000505050000000000B1B1B1000000000000000000FCFCFC00222222000000
      0000A2A2A2000000000000000000000000000000000000000000000000000000
      0000000000000000000000000000000000000000000000000000000000000000
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      0000000000000000000000000000000000000000000000000000000000000000
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      0000000000000000000000000000000000000000000000000000000000000000
      000000000000000000000000000000000000000000000000000000000000CCCC
      CC00353535007D7D7D002525250066666600939393001E1E1E00646464003434
      340085858500000000000000000000000000000000000000000000000000140C
      EB00B1AEF900FFFFFF00FFFFFF00FFFFFF00FFFFFF00FFFFFF00FFFFFF00B1AE
      F900140CEB000000000000000000000000000000000000000000000000000000
      0000000000000000000000000000000000000000000000000000000000000000
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      000000000000000000006E6E6E0000000000000000002E2E2E00000000000000
      0000000000000000000000000000000000000000000000000000140CEB000000
      00000300EA00B9B6F900FFFFFF00FFFFFF00FFFFFF00FFFFFF00B9B6F9000300
      EA0000000000140CEB0000000000000000000000000000000000000000000000
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      0000000000000000000000000000000000000000000000000000000000007171
      7100000000002F2F2F0015151500D0D0D000F0F0F00031313100252525002121
      21005F5F5F000000000000000000000000000000000000000000B1AEF9000300
      EA002018EC00160DEC00B9B6F900FFFFFF00FFFFFF00B9B6F900160DEC002018
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      000000000000000000000000000000000000424D3E000000000000003E000000
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      000000000000000000000000FFFFFF00F3CFFFFF00000000E187FFFF00000000
      E007E00700000000FC3FD00B00000000E007C00300000000E3C7C00300000000
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      F227C00300000000E007C00300000000E007D00B00000000F007E00700000000
      F00FFFFF00000000F81FFFFF0000000000000000000000000000000000000000
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  end
end

<小时/>

提示:

Delphi XE4 上的 VirtualTrees 版本为 5.2.1
ImageIndex := 1; 行在 vtTestGetImageIndex 函数中执行 - 设置断点后调试器将停止
索引 0 和 1 处的图像确实存在于 TImageList
我已经能够对不同类型的节点使用不同的图像，而无需叠加

最佳答案

您的项目缺少两件事。

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

当您检查 VTV 的源时，原因就会很清楚。

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，则从中选择叠加层的图像列表将为nil，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;

即使叠加层的图像索引 < 15 也不会被考虑，VTV 不会从索引中减去任何数字，因此您必须在图像列表中放置至少 15 个图像。

现在可以了:

关于delphi - 使用 TVirtualStringTree.OnGetImageIndex 覆盖图像，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/36909591/

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delphi - 使用 TVirtualStringTree.OnGetImageIndex 覆盖图像