更改组合框下拉列表中的突出显示颜色

Question

当我们滚动组合框中的项目时，我们需要替换蓝色突出显示。

我们怎么做？

我尝试了一个示例代码来处理组合下拉菜单的边框，下面是我的示例应用程序代码。

unit Unit1;
interface
uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, cxGraphics, cxControls, cxLookAndFeels, cxLookAndFeelPainters,
  cxContainer, cxEdit, cxTextEdit, cxMaskEdit, cxDropDownEdit, CXSComboBox, Vcl.StdCtrls;

 type
 TMycxComboBox = class (PDMCXSComboBox)
  protected
    procedure Loaded; override;
  end;

  PDMCXSComboBox = class (TMycxComboBox);


type
  TForm1 = class(TForm)
    cmbSelectionList: PDMCXSComboBox;
    cxComboBox1: TcxComboBox;
    procedure cmbSelectionListPropertiesInitPopup(Sender: TObject);
    procedure cmbSelectionListPropertiesPopup(Sender: TObject);
    procedure cmbSelectionListPropertiesDrawItem(AControl: TcxCustomComboBox; ACanvas: TcxCanvas; AIndex: Integer; const ARect: TRect; AState: TOwnerDrawState);
  private
    { Private declarations }
  public
    { Public declarations }
    procedure DoCustomDrawBorder(AViewInfo: TcxContainerViewInfo; ACanvas: TcxCanvas; const R: TRect; var AHandled: Boolean;
      out ABorderWidth: Integer);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TMycxComboBox.Loaded;
begin
  inherited;
  ContentParams.Offsets.Left := 20;
end;

procedure TForm1.cmbSelectionListPropertiesDrawItem(AControl: TcxCustomComboBox; ACanvas: TcxCanvas; AIndex: Integer; const ARect: TRect; AState: TOwnerDrawState);
Var
  AFlags : LongInt;
  R : TRect;
begin
  if (Integer(AIndex) >= 0) and (odSelected in AState) then
  begin
    //ACanvas.Brush.Color := clRed;
    //ACanvas.Font.Color := clHighlightText;
    ACanvas.Brush.Color := clWhite;// $00E5DFD7; //clRed
    ACanvas.Font.Color := $006c4e1f;
  end;
  ACanvas.FillRect(ARect);
  if (AIndex >= 0) and (AIndex < AControl.Properties.Items.Count) then
  begin
    R := ARect;
    AFlags := DrawTextBiDiModeFlags(DT_SINGLELINE or DT_VCENTER or DT_NOPREFIX);
    if not UseRightToLeftAlignment then
      Inc(R.Left,2)
    else
      Dec(R.Right,2);

    with AControl.Properties do
      DrawText(ACanvas.Handle,PChar(Items[AIndex]),Length(Items[AIndex]), R, AFlags);
  end;
end;

procedure TForm1.cmbSelectionListPropertiesInitPopup(Sender: TObject);
begin
  TcxComboBoxPopupWindow(PDMCXSComboBox(Sender).PopupWindow).ViewInfo.OnCustomDrawBorder := DoCustomDrawBorder;
end;

procedure TForm1.cmbSelectionListPropertiesPopup(Sender: TObject);
begin
TcxComboBoxListBox(PDMCXSComboBox(Sender).ILookupData.ActiveControl).Color := clWhite;
end;

procedure TForm1.DoCustomDrawBorder(AViewInfo: TcxContainerViewInfo;
  ACanvas: TcxCanvas; const R: TRect; var AHandled: Boolean;
  out ABorderWidth: Integer);
begin
  AHandled := True;
  ABorderWidth := 1;
  ACanvas.FrameRect(R, $00E5DFD7);
end;

end.

PDMCXSComboBox是我从tcxcombobox派生的自定义组件。

对于这个组合框，当我进行项目选择时，顶部和右边框是不可见的：

组件代码如下：

unit CXSComboBox;

interface

uses
  System.SysUtils, System.Classes, Vcl.Controls, cxControls, cxContainer, cxEdit, cxTextEdit,
  cxMaskEdit, cxDropDownEdit, cxGraphics, Winapi.Messages, Winapi.Windows, OvcCmbx;// OvcTccbx;

const
  ParamsLabel = 'Params: ';
  SQLLabel = 'SQL: ';

type
  TpMyKeyValue = ^TrMykeyValue;
  TrMyKeyValue= record
    key: string;
    value: string;
  end;

  TKeyValueShowOption = (soShowValueOnly, soShowKeyOnly, soShowAll);

type
  PDMCXSComboBox = class(TcxComboBox)
  private
    { Private declarations }
    FItemHeight: Integer;
    FOnOwnDrawItem: TcxEditDrawItemEvent;
    FOnPdmDrawItem: TcxEditDrawItemEvent;
    StringListKey: TStringList;
    StringListKey_SACOMBO: TStringList;
    StringListOKey: TStringList;
    FOldWndProc: pointer;
    FHintWin : THintWindow;
    FHintList : TStrings;
    FAutoWidthDropDown:Boolean;
    FShowItemsHint:Boolean;
    FListHandle: HWND;
    FUseDefaultValue: Boolean;
    FDefaultValue: String;
    FKeyValuePairs: Boolean;
    FKeyValueShowOption: TKeyValueShowOption;
    procedure CMFontChanged(var Message: TWMFontChange); message CM_FONTCHANGED;
    procedure CNMeasureItem(var Message: TWMMeasureItem); message CN_MEASUREITEM;
    procedure AdjustHeight;
    procedure SetSelKey(const Value: string);

    function  GetListIndex: Integer;
    procedure SetListIndex(Value: Integer);

    procedure SetKeyValuePairs(const Value: Boolean);
    function GetText_PDMADVCOMBO: string;
    procedure SetKeyValueShowOption(const Value: TKeyValueShowOption);
  protected
    { Protected declarations }
    FMRUList             : TOvcMRUList;
    FList                : TStringList;
    FListIndex : Integer;      {ItemIndex sans MRU Items}

    function GetItemHt: Integer; //override;
    procedure Loaded; override;
    //procedure Loaded_PDMCOMBO;
    procedure OwnDrawItem(Control: TcxCustomComboBox; Canvas:TCxCanvas; Index: Integer; const Rect: TRect; State: TOwnerDrawState);
    property OnOwnDrawItem: TcxEditDrawItemEvent read FOnOwnDrawItem write FOnOwnDrawItem;

    procedure PdmDrawItem(AControl: TcxCustomComboBox; ACanvas: TcxCanvas; AIndex: Integer; const ARect: TRect; AState: TOwnerDrawState);
    property OnPdmDrawItem: TCxEditDrawItemEvent read FOnPdmDrawItem write FOnPdmDrawItem;
  public
    { Public declarations }
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;

  published
    { Published declarations }
    property Value: string read GetSelKey write SetSelKey;
    property DefaultValue: string read FDefaultValue write FDefaultValue;
    property UseDefaultValue: boolean read FUseDefaultValue write FUseDefaultValue;
    property HintList: TStrings read FHintList write SetHintList;
    property ListHandle: HWND read FListHandle write FListHandle;
    property AutoWidthDropDown:Boolean read FAutoWidthDropDown write FAutoWidthDropDown;
    property ShowItemsHint:Boolean read FShowItemsHint write FShowItemsHint;
    property Align;
    property KeyValuePairs: Boolean read FKeyValuePairs write SetKeyValuePairs default True;
    property KeyValueShowOption: TKeyValueShowOption read FKeyValueShowOption write SetKeyValueShowOption default soShowValueOnly;
    property TextPDMADVCOMBO: string read GetText_PDMADVCOMBO;
  end;

  function CompareValueinMyKeyValue(item1, item2:TpMyKeyValue): Integer;
  procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('PDMCXComponents', [PDMCXSComboBox]);
end;

function CompareValueinMyKeyValue(item1,item2:TpMyKeyValue):integer;
begin
  Result := CompareText(item1.value,item2.value);
end;

procedure PDMCXSComboBox.Loaded;
begin
  inherited;
  if not (csDesigning in ComponentState) then
  begin
    // chain OnDraw events
    OnOwnDrawItem := Properties.OnDrawItem;
    Properties.OnDrawItem := OwnDrawItem;

    // chain OnDraw events
    FOnPdmDrawItem := properties.OnDrawItem;
    properties.OnDrawItem := PdmDrawItem;
  end;
end;

{procedure PDMCXSComboBox.Loaded_PDMCOMBO;
begin
  inherited;
  if not (csDesigning in ComponentState) then
  begin
    // chain OnDraw events
    FOnPdmDrawItem := properties.OnDrawItem;
    properties.OnDrawItem := PdmDrawItem;
  end;
end; }

procedure PDMCXSComboBox.OwnDrawItem(Control: TcxCustomComboBox; Canvas:TCxCanvas; Index: Integer;
  const Rect: TRect; State: TOwnerDrawState);
var
  LCanvas: TcxCanvas;
  S: string;
  lRect : TRect;
begin
  lRect := Rect;
  if not (csDestroying in ComponentState) then
  begin
    LCanvas := (Control as PDMCXSComboBox).Canvas;
    LCanvas.FillRect(lRect);
    S := PDMCXSComboBox(Control).Properties.Items[Index];
    InflateRect(lRect, -2, -1);
    DrawText(LCanvas.Handle, S, Length(S), lRect,
      DT_LEFT or DT_NOCLIP or DT_VCENTER or DT_SINGLELINE or DT_NOPREFIX);

    // call chained event handler
    if Assigned(OnOwnDrawItem) then
      OnOwnDrawItem(Control,LCanvas, Index, lRect, State);
  end;
end;

procedure PDMCXSComboBox.PdmDrawItem(AControl: TcxCustomComboBox;
  ACanvas: TcxCanvas; AIndex: Integer; const ARect: TRect;
  AState: TOwnerDrawState);
var
  S: string;
  lRect   : Trect;
begin
  if not (csDestroying in ComponentState) then
  begin
    lRect := Arect;
    ACanvas.FillRect(lRect);
    S := PDMCXSComboBox(AControl).properties.Items[AIndex];
    InflateRect(lRect, -2, -1);
    DrawText(ACanvas.Handle, S, Length(S), lRect, DT_LEFT or DT_NOCLIP or DT_VCENTER or DT_SINGLELINE);
     // maybe developer need another drawing

    if Assigned(OnPdmDrawItem) then
      OnPdmDrawItem(AControl,Acanvas, AIndex, lRect, AState);
  end;
end;


constructor PDMCXSComboBox.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  StringListKey := TStringList.Create;
  StringListKey_SACOMBO := TStringList.Create;
  StringListOKey := TStringList.Create;
  FHintList := TStringList.Create;
  FHintWin := THintWindow.Create(Self);
  autosize := false;
  Height := 30;
  properties.DropDownwidth := 0;
  //Properties.ButtonGlyph.LoadFromFile('.\DROPDOWNICON.png');
  style.Font.Size := 10;
  style.Font.Name := 'Noto sans';
  style.Font.Color := $00757575;
  style.BorderStyle := ebssingle;
  style.ButtonStyle := btsSimple;
  style.BorderColor := $00e5dfd7;
  style.LookAndFeel.NativeStyle:= false;
end;

destructor PDMCXSComboBox.Destroy;
begin
  StringListKey.Free;
  StringListOKey.Free;
  FHintList.Free;
  if Assigned(FHintWin) then
    FHintWin.ReleaseHandle;
  if FListHandle <> 0 then
    SetWindowLong(FListHandle, GWL_WNDPROC, longint(FOldWndProc));
  inherited Destroy;
end;

procedure PDMCXSComboBox.CreateParams(var Params: TCreateParams);
begin
  inherited;
  Params.Style := Params.Style or CBS_OWNERDRAWVARIABLE;
end;

procedure PDMCXSComboBox.AdjustHeight;
var
  I: Integer;
  DC: HDC;
  SaveFont: HFont;
  SysMetrics, Metrics: TTextMetric;
begin
  DC := GetDC(0);
  try
    GetTextMetrics(DC, SysMetrics);
    SaveFont := SelectObject(DC, Font.Handle);
    GetTextMetrics(DC, Metrics);
    SelectObject(DC, SaveFont);
  finally
    ReleaseDC(0, DC);
  end;
  if NewStyleControls then
  begin
    if Ctl3D then I := 4 else I := 2;
    I := GetSystemMetrics(SM_CYBORDER) * I;
  end else
  begin
    I := SysMetrics.tmHeight;
    if I > Metrics.tmHeight then I := Metrics.tmHeight;
    I := I div 4 + GetSystemMetrics(SM_CYBORDER) * 4;
  end;
  FItemHeight := Metrics.tmHeight + I;
end;

procedure PDMCXSComboBox.CMFontChanged(var Message: TWMFontChange);
begin
  AdjustHeight;
  RecreateWnd;
end;

procedure PDMCXSComboBox.CNMeasureItem(var Message: TWMMeasureItem);
begin
  Message.MeasureItemStruct.itemHeight :=  FItemHeight;// Properties.ItemHeight;
end;

end.

Answer 1

我已经解决了这个问题，它正在按预期工作。我唯一做的就是我已经处理了OnDrawItem两次，所以我必须在组件设计中禁用它。

unit CXSComboBox;

interface

uses
  System.SysUtils, System.Classes, Vcl.Controls, cxControls, cxContainer, cxEdit, cxTextEdit,
  cxMaskEdit, cxDropDownEdit, cxGraphics, Winapi.Messages, Winapi.Windows, OvcCmbx;// OvcTccbx;

const
  ParamsLabel = 'Params: ';
  SQLLabel = 'SQL: ';

type
  TpMyKeyValue = ^TrMykeyValue;
  TrMyKeyValue= record
    key: string;
    value: string;
  end;

  TKeyValueShowOption = (soShowValueOnly, soShowKeyOnly, soShowAll);

type
  PDMCXSComboBox = class(TcxComboBox)
  private
    { Private declarations }
    FItemHeight: Integer;
    StringListKey: TStringList;
    StringListKey_SACOMBO: TStringList;
    StringListOKey: TStringList;
    FOldWndProc: pointer;
    FHintWin : THintWindow;
    FHintList : TStrings;
    FAutoWidthDropDown:Boolean;
    FShowItemsHint:Boolean;
    FListHandle: HWND;
    FUseDefaultValue: Boolean;
    FDefaultValue: String;
    FKeyValuePairs: Boolean;
    FKeyValueShowOption: TKeyValueShowOption;
    procedure CMFontChanged(var Message: TWMFontChange); message CM_FONTCHANGED;
    procedure CNMeasureItem(var Message: TWMMeasureItem); message CN_MEASUREITEM;
    procedure AdjustHeight;
    procedure SetSelKey(const Value: string);

    function  GetListIndex: Integer;
    procedure SetListIndex(Value: Integer);

    procedure SetKeyValuePairs(const Value: Boolean);
    function GetText_PDMADVCOMBO: string;
    procedure SetKeyValueShowOption(const Value: TKeyValueShowOption);
  protected
    { Protected declarations }
    FMRUList             : TOvcMRUList;
    FList                : TStringList;
    FListIndex : Integer;      {ItemIndex sans MRU Items}

    function GetItemHt: Integer; //override;

  public
    { Public declarations }
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;

  published
    { Published declarations }
    property Value: string read GetSelKey write SetSelKey;
    property DefaultValue: string read FDefaultValue write FDefaultValue;
    property UseDefaultValue: boolean read FUseDefaultValue write FUseDefaultValue;
    property HintList: TStrings read FHintList write SetHintList;
    property ListHandle: HWND read FListHandle write FListHandle;
    property AutoWidthDropDown:Boolean read FAutoWidthDropDown write FAutoWidthDropDown;
    property ShowItemsHint:Boolean read FShowItemsHint write FShowItemsHint;
    property Align;
    property KeyValuePairs: Boolean read FKeyValuePairs write SetKeyValuePairs default True;
    property KeyValueShowOption: TKeyValueShowOption read FKeyValueShowOption write SetKeyValueShowOption default soShowValueOnly;
    property TextPDMADVCOMBO: string read GetText_PDMADVCOMBO;
  end;

  function CompareValueinMyKeyValue(item1, item2:TpMyKeyValue): Integer;
  procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('PDMCXComponents', [PDMCXSComboBox]);
end;

function CompareValueinMyKeyValue(item1,item2:TpMyKeyValue):integer;
begin
  Result := CompareText(item1.value,item2.value);
end;


constructor PDMCXSComboBox.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  StringListKey := TStringList.Create;
  StringListKey_SACOMBO := TStringList.Create;
  StringListOKey := TStringList.Create;
  FHintList := TStringList.Create;
  FHintWin := THintWindow.Create(Self);
  autosize := false;
  Height := 30;
  properties.DropDownwidth := 0;
  //Properties.ButtonGlyph.LoadFromFile('.\DROPDOWNICON.png');
  style.Font.Size := 10;
  style.Font.Name := 'Noto sans';
  style.Font.Color := $00757575;
  style.BorderStyle := ebssingle;
  style.ButtonStyle := btsSimple;
  style.BorderColor := $00e5dfd7;
  style.LookAndFeel.NativeStyle:= false;
end;

destructor PDMCXSComboBox.Destroy;
begin
  StringListKey.Free;
  StringListOKey.Free;
  FHintList.Free;
  if Assigned(FHintWin) then
    FHintWin.ReleaseHandle;
  if FListHandle <> 0 then
    SetWindowLong(FListHandle, GWL_WNDPROC, longint(FOldWndProc));
  inherited Destroy;
end;

procedure PDMCXSComboBox.CreateParams(var Params: TCreateParams);
begin
  inherited;
  Params.Style := Params.Style or CBS_OWNERDRAWVARIABLE;
end;

procedure PDMCXSComboBox.AdjustHeight;
var
  I: Integer;
  DC: HDC;
  SaveFont: HFont;
  SysMetrics, Metrics: TTextMetric;
begin
  DC := GetDC(0);
  try
    GetTextMetrics(DC, SysMetrics);
    SaveFont := SelectObject(DC, Font.Handle);
    GetTextMetrics(DC, Metrics);
    SelectObject(DC, SaveFont);
  finally
    ReleaseDC(0, DC);
  end;
  if NewStyleControls then
  begin
    if Ctl3D then I := 4 else I := 2;
    I := GetSystemMetrics(SM_CYBORDER) * I;
  end else
  begin
    I := SysMetrics.tmHeight;
    if I > Metrics.tmHeight then I := Metrics.tmHeight;
    I := I div 4 + GetSystemMetrics(SM_CYBORDER) * 4;
  end;
  FItemHeight := Metrics.tmHeight + I;
end;

procedure PDMCXSComboBox.CMFontChanged(var Message: TWMFontChange);
begin
  AdjustHeight;
  RecreateWnd;
end;

procedure PDMCXSComboBox.CNMeasureItem(var Message: TWMMeasureItem);
begin
  Message.MeasureItemStruct.itemHeight :=  FItemHeight;// Properties.ItemHeight;
end;

end.