dsgnintf.pas

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                         need to be rendered and as such the name should be
                         rendered the full width of the inspector.
    GetComponent
      Returns the Index'th component being edited by this property editor.  This
      is used to retrieve the components.  A property editor can only refer to
      multiple components when paMultiSelect is returned from GetAttributes.
    GetEditLimit
      Returns the number of character the user is allowed to enter for the
      value.  The inplace editor of the object inspector will be have its
      text limited set to the return value.  By default this limit is 255.
    GetName
      Returns the name of the property.  By default the value is retrieved
      from the type information with all underbars replaced by spaces.  This
      should only be overridden if the name of the property is not the name
      that should appear in the Object Inspector.
    GetProperties
      Should be overridden to call PropertyProc for every sub-property (or
      nested property) of the property begin edited and passing a new
      TPropertyEdtior for each sub-property.  By default, PropertyProc is not
      called and no sub-properties are assumed.  TClassProperty will pass a
      new property editor for each published property in a class.  TSetProperty
      passes a new editor for each element in the set.
    GetPropType
      Returns the type information pointer for the property(s) being edited.
    GetValue
      Returns the string value of the property. By default this returns
      '(unknown)'.  This should be overridden to return the appropriate value.
    GetValues
      Called when paValueList is returned in GetAttributes.  Should call Proc
      for every value that is acceptable for this property.  TEnumProperty
      will pass every element in the enumeration.
    Initialize
      Called after the property editor has been created but before it is used.
      Many times property editors are created and because they are not a common
      property across the entire selection they are thrown away.  Initialize is
      called after it is determined the property editor is going to be used by
      the object inspector and not just thrown away.
    SetValue(Value)
      Called to set the value of the property.  The property editor should be
      able to translate the string and call one of the SetXxxValue methods. If
      the string is not in the correct format or not an allowed value, the
      property editor should generate an exception describing the problem. Set
      value can ignore all changes and allow all editing of the property be
      accomplished through the Edit method (e.g. the Picture property).
    ListMeasureWidth(Value, Canvas, AWidth)
      This is called during the width calculation phase of the drop down list
      preparation.
    ListMeasureHeight(Value, Canvas, AHeight)
      This is called during the item/value height calculation phase of the drop
      down list's render.  This is very similar to TListBox's OnMeasureItem,
      just slightly different parameters.
    ListDrawValue(Value, Canvas, Rect, Selected)
      This is called during the item/value render phase of the drop down list's
      render.  This is very similar to TListBox's OnDrawItem, just slightly
      different parameters.
    PropDrawName(Canvas, Rect, Selected)
      Called during the render of the name column of the property list.  Its
      functionality is very similar to TListBox's OnDrawItem, but once again
      it has slightly different parameters.
    PropDrawValue(Canvas, Rect, Selected)
      Called during the render of the value column of the property list.  Its
      functionality is similar to PropDrawName.  If multiple items are selected
      and their values don't match this procedure will be passed an empty
      value.

  Properties and methods useful in creating a new TPropertyEditor classes:

    Name property
      Returns the name of the property returned by GetName
    PrivateDirectory property
      It is either the .EXE or the "working directory" as specified in
      the registry under the key:
        "HKEY_CURRENT_USER\Software\Borland\Delphi\*\Globals\PrivateDir"
      If the property editor needs auxiliary or state files (templates, examples,
      etc) they should be stored in this directory.
    Value property
      The current value, as a string, of the property as returned by GetValue.
    Modified
      Called to indicate the value of the property has been modified.  Called
      automatically by the SetXxxValue methods.  If you call a TProperty
      SetXxxValue method directly, you *must* call Modified as well.
    GetXxxValue
      Gets the value of the first property in the Properties property.  Calls
      the appropriate TProperty GetXxxValue method to retrieve the value.
    SetXxxValue
      Sets the value of all the properties in the Properties property.  Calls
      the approprate TProperty SetXxxxValue methods to set the value.
    GetVisualValue
      This function will return the displayable value of the property.  If
      only one item is selected or all the multi-selected items have the same
      property value then this function will return the actual property value.
      Otherwise this function will return an empty string.}

  TPropertyAttribute = (paValueList, paSubProperties, paDialog, paMultiSelect,
    paAutoUpdate, paSortList, paReadOnly, paRevertable, paFullWidthName);
  TPropertyAttributes = set of TPropertyAttribute;

  TPropertyEditor = class;

  TInstProp = record
    Instance: TPersistent;
    PropInfo: PPropInfo;
  end;

  PInstPropList = ^TInstPropList;
  TInstPropList = array[0..1023] of TInstProp;

  TGetPropEditProc = procedure(Prop: TPropertyEditor) of object;

  TPropertyEditor = class
  private
    FDesigner: IFormDesigner;
    FPropList: PInstPropList;
    FPropCount: Integer;
    function GetPrivateDirectory: string;
    procedure SetPropEntry(Index: Integer; AInstance: TPersistent;
      APropInfo: PPropInfo);
  protected
    constructor Create(const ADesigner: IFormDesigner; APropCount: Integer); virtual;
    function GetPropInfo: PPropInfo;
    function GetFloatValue: Extended;
    function GetFloatValueAt(Index: Integer): Extended;
    function GetInt64Value: Int64;
    function GetInt64ValueAt(Index: Integer): Int64;
    function GetMethodValue: TMethod;
    function GetMethodValueAt(Index: Integer): TMethod;
    function GetOrdValue: Longint;
    function GetOrdValueAt(Index: Integer): Longint;
    function GetStrValue: string;
    function GetStrValueAt(Index: Integer): string;
    function GetVarValue: Variant;
    function GetVarValueAt(Index: Integer): Variant;
    procedure Modified; 
    procedure SetFloatValue(Value: Extended);
    procedure SetMethodValue(const Value: TMethod);
    procedure SetInt64Value(Value: Int64);
    procedure SetOrdValue(Value: Longint);
    procedure SetStrValue(const Value: string);
    procedure SetVarValue(const Value: Variant);
  public
    destructor Destroy; override;
    procedure Activate; virtual;
    function AllEqual: Boolean; virtual;
    function AutoFill: Boolean; virtual;
    procedure Edit; virtual;
    function GetAttributes: TPropertyAttributes; virtual;
    function GetComponent(Index: Integer): TPersistent;
    function GetEditLimit: Integer; virtual;
    function GetName: string; virtual;
    procedure GetProperties(Proc: TGetPropEditProc); virtual;
    function GetPropType: PTypeInfo;
    function GetValue: string; virtual;
    function GetVisualValue: string;
    procedure GetValues(Proc: TGetStrProc); virtual;
    procedure Initialize; virtual;
    procedure Revert;
    procedure SetValue(const Value: string); virtual;
    function ValueAvailable: Boolean;
    procedure ListMeasureWidth(const Value: string; ACanvas: TCanvas;
      var AWidth: Integer); dynamic;
    procedure ListMeasureHeight(const Value: string; ACanvas: TCanvas;
      var AHeight: Integer); dynamic;
    procedure ListDrawValue(const Value: string; ACanvas: TCanvas;
      const ARect: TRect; ASelected: Boolean); dynamic;
    procedure PropDrawName(ACanvas: TCanvas; const ARect: TRect;
      ASelected: Boolean); dynamic;
    procedure PropDrawValue(ACanvas: TCanvas; const ARect: TRect;
      ASelected: Boolean); dynamic;
    property Designer: IFormDesigner read FDesigner;
    property PrivateDirectory: string read GetPrivateDirectory;
    property PropCount: Integer read FPropCount;
    property Value: string read GetValue write SetValue;
  end;

  TPropertyEditorClass = class of TPropertyEditor;

{ TOrdinalProperty
  The base class of all ordinal property editors.  It established that ordinal
  properties are all equal if the GetOrdValue all return the same value. }

  TOrdinalProperty = class(TPropertyEditor)
    function AllEqual: Boolean; override;
    function GetEditLimit: Integer; override;
  end;

{ TIntegerProperty
  Default editor for all Longint properties and all subtypes of the Longint
  type (i.e. Integer, Word, 1..10, etc.).  Restricts the value entered into
  the property to the range of the sub-type. }

  TIntegerProperty = class(TOrdinalProperty)
  public
    function GetValue: string; override;
    procedure SetValue(const Value: string); override;
  end;

{ TCharProperty
  Default editor for all Char properties and sub-types of Char (i.e. Char,
  'A'..'Z', etc.). }

  TCharProperty = class(TOrdinalProperty)
  public
    function GetValue: string; override;
    procedure SetValue(const Value: string); override;
  end;

{ TEnumProperty
  The default property editor for all enumerated properties (e.g. TShape =
  (sCircle, sTriangle, sSquare), etc.). }

  TEnumProperty = class(TOrdinalProperty)
  public
    function GetAttributes: TPropertyAttributes; override;
    function GetValue: string; override;
    procedure GetValues(Proc: TGetStrProc); override;
    procedure SetValue(const Value: string); override;
  end;

  TBoolProperty = class(TEnumProperty)
    function GetValue: string; override;
    procedure GetValues(Proc: TGetStrProc); override;
    procedure SetValue(const Value: string); override;
  end;

{ TInt64Property
  Default editor for all Int64 properties and all subtypes of Int64.  }

  TInt64Property = class(TPropertyEditor)
  public
    function AllEqual: Boolean; override;
    function GetEditLimit: Integer; override;
    function GetValue: string; override;
    procedure SetValue(const Value: string); override;
  end;

{ TFloatProperty
  The default property editor for all floating point types (e.g. Float,
  Single, Double, etc.) }

  TFloatProperty = class(TPropertyEditor)
  public
    function AllEqual: Boolean; override;
    function GetValue: string; override;
    procedure SetValue(const Value: string); override;
  end;

{ TStringProperty
  The default property editor for all strings and sub types (e.g. string,
  string[20], etc.). }

  TStringProperty = class(TPropertyEditor)
  public
    function AllEqual: Boolean; override;
    function GetEditLimit: Integer; override;
    function GetValue: string; override;
    procedure SetValue(const Value: string); override;
  end;

{ TNestedProperty
  A property editor that uses the parent's Designer, PropList and PropCount.
  The constructor and destructor do not call inherited, but all derived classes
  should.  This is useful for properties like the TSetElementProperty. }

  TNestedProperty = class(TPropertyEditor)
  public
    constructor Create(Parent: TPropertyEditor); reintroduce;
    destructor Destroy; override;
  end;

{ TSetElementProperty
  A property editor that edits an individual set element.  GetName is
  changed to display the set element name instead of the property name and
  Get/SetValue is changed to reflect the individual element state.  This
  editor is created by the TSetProperty editor. }

  TSetElementProperty = class(TNestedProperty)
  private
    FElement: Integer;
  protected
    constructor Create(Parent: TPropertyEditor; AElement: Integer); reintroduce;
  public
    function AllEqual: Boolean; override;
    function GetAttributes: TPropertyAttributes; override;
    function GetName: string; override;
    function GetValue: string; override;
    procedure GetValues(Proc: TGetStrProc); override;
    procedure SetValue(const Value: string); override;
   end;

{ TSetProperty
  Default property editor for all set properties. This editor does not edit
  the set directly but will display sub-properties for each element of the
  set. GetValue displays the value of the set in standard set syntax. }

  TSetProperty = class(TOrdinalProperty)
  public
    function GetAttributes: TPropertyAttributes; override;
    procedure GetProperties(Proc: TGetPropEditProc); override;
    function GetValue: string; override;
  end;

{ TClassProperty
  Default property editor for all objects.  Does not allow modifying the
  property but does display the class name of the object and will allow the
  editing of the object's properties as sub-properties of the property. }

  TClassProperty = class(TPropertyEditor)
  public
    function GetAttributes: TPropertyAttributes; override;
    procedure GetProperties(Proc: TGetPropEditProc); override;
    function GetValue: string; override;
  end;

{ TMethodProperty
  Property editor for all method properties. }

  TMethodProperty = class(TPropertyEditor)
  public
    function AllEqual: Boolean; override;
    procedure Edit; override;
    function GetAttributes: TPropertyAttributes; override;
    function GetEditLimit: Integer; override;