使用TVirtualStringTree.OnGetImageIndex叠加图像

时间：2016-04-28 08:45:14

标签： delphi virtualtreeview tvirtualstringtree

我想将ImageList1组件中vtTest的图片显示为叠加层。

我在互联网上找到了很多资源，而且这些资源就像this一样 - 但我不能让它们都无法正常工作。

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。

我得到了什么：enter image description here我想要的是：enter image description here

以下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
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      000000000000000000000000000000000000000000000000000000000000CCCC
      CC00353535007D7D7D002525250066666600939393001E1E1E00646464003434
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      EB00B1AEF900FFFFFF00FFFFFF00FFFFFF00FFFFFF00FFFFFF00FFFFFF00B1AE
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      7100000000002F2F2F0015151500D0D0D000F0F0F00031313100252525002121
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  end
end

提示：

  • VirtualTrees版本在Delphi XE4上是5.2.1
  • 行ImageIndex := 1;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的图片确实存在于TImageList
  • 我已经能够在不使用覆盖
    • 的情况下为不同类型的节点使用不同的图像

2 个答案:

答案 0 :(得分：6)

您的项目中缺少两件事。

  1. 仅当叠加层具有索引＆gt; = 15
    2. 时才会绘制叠加层
  2. 您需要使用OnGetImageIndexEx，而不是普通OnGetImageIndex。

    3. 当您查看VTV的来源时，原因就变得清晰了。

    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，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;

    即使叠加的图像索引＆lt; 15不要考虑VTV不会从索引中减去任何数字，所以你被迫在图像列表中放置至少15张图像。

    现在可行：

    enter image description here

答案 1 :(得分：4)

您需要通过TImageList.Overlay指定要叠加的图片，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，NOT image-index例如：

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