用TVirtualStringTree.OnGetImageIndex覆蓋圖像

Question

我想以vtTest組件中的ImageList1作爲覆蓋圖顯示圖像。

我在互聯網上發現了很多資源，並在這裏像this - 但我不能讓他們都無法正常工作。

我確定我錯過了一些極其微不足道的東西，但我無法弄清楚它可能是什麼。

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我能得到什麼：             我想什麼有：   

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這裏是包含這說明我的問題的基本連接的形式。

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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    end 
end 

---

TIPS：

• VirtualTrees版本5.2.1德爾福XE4
• 線ImageIndex := 1;在vtTestGetImageIndex功能執行 - 調試器停止時有斷點在指數0設置
• 圖像和1在TImageList
確實存在
• 我已經能夠使用不同的圖像爲不同類型的節點沒有覆蓋

Answer 1

您的項目中缺少兩件事。

1. 疊加只會拿得出，如果他們有一個指數> = 15
2. 您需要使用OnGetImageIndexEx，而不是普通的OnGetImageIndex。

當您檢查VTV的來源時，原因就變得很清楚。

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 !! 

如果你不使用OnGetImageIndexEx從您的覆蓋被選中將是零的圖像列表，請參閱：

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; 

如果我用下面的代碼您的覆蓋工程：

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; 

雖然圖像索引覆蓋< 15沒有得到考慮VTV不會從索引中減去任何數字，所以你不得不把一個至少15張圖片在圖片列表中。

現在，它的工作原理：

Answer 2

你需要指定通過TImageList.Overlay疊加的影像，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你需要使用的ImageList 覆蓋指數， NOT image-index例如：

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