delphi - 使用 TVirtualStringTree.OnGetImageIndex 覆盖图像

Question

我想将组件中的图像显示ImageList1为vtTest叠加层。

我在 Internet 上和 SO 中找到了许多资源 - 就像这样- 但我无法让它们都正常工作。

我确定我错过了一些非常微不足道的东西，但我无法弄清楚它可能是什么。

我得到在此处输入图像描述什么：我想要什么：

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
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      0000868686003535350000000000000000000000000000000000939393005757
      5700000000000000000000000000000000000000000000000000000000000000
      0000000000000000000000000000000000000000000000000000000000000000
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      D9000505050000000000B1B1B1000000000000000000FCFCFC00222222000000
      0000A2A2A2000000000000000000000000000000000000000000000000000000
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      000000000000000000000000000000000000000000000000000000000000CCCC
      CC00353535007D7D7D002525250066666600939393001E1E1E00646464003434
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  end
end

提示：

Delphi XE4 上的 VirtualTrees 版本为 5.2.1
该行在函数ImageIndex := 1;中执行vtTestGetImageIndex- 设置断点时调试器停在那里
索引处的图像0确实1存在于TImageList
我已经能够为不同类型的节点使用不同的图像而无需覆盖

score 8 · Accepted Answer

您的项目缺少两件事。

仅当索引 >= 15 时才会绘制叠加层
你需要使用OnGetImageIndexEx，而不是平原OnGetImageIndex。

当您查看 VTV 的来源时，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，因此您必须在 imagelist 中放置至少 15 个图像。

现在它起作用了：

score 4 · Accepted Answer

您需要通过指定要覆盖的图像TImageList.Overlay，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您需要使用 ImageList覆盖索引，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

delphi - 使用 TVirtualStringTree.OnGetImageIndex 覆盖图像

2 回答 2

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