[翻译] FastReport Class Hierarchy (FastReport 组件类层次结构)
"TfrxComponent" is the base class for all FastReport components. Objects of this type have attributes such as “coordinates”, “size”, “font” and “visibility” and have lists of subordinate objects. The class also has methods which allow for the saving and restoration of the object state to or from a stream.
"TfrxComponent" 是所有FastReport组件的基类。该类型的对象具有属性如"coordinates","size","font" 和"visibility" 并且有从属的对象列表。该类同
时提供方法允许对象的状态保存到流或从流中恢复。
- Clear clears object contents and deletes all its child objects //清除对象内容并删除所有包含的子对象
- CreateUniqueName creates unique name for object placed into report //为对象放置在报表中创建唯一的名称
- LoadFromStream loads object and all its child objects from stream //从流中加载对象和所有子对象
- SaveToStream saves object to stream //对象保存到流中
- SetBounds sets object coordinates and size //设置对象的坐标和大小
- FindObject searches for object with specified name among child objects //按名字在子对象列表中查找对象
- GetDescription returns object’s description //返回对象的描述
The following methods are called when modifying the corresponding properties. If additional handling is needed, you can override them:
以下方法被调用，当修改相应的属性时，如果需要额外的处理，你可以重写它们:
- SetParent
- SetLeft
- SetTop
- SetWidth
- SetHeight
- SetFont
- SetParentFont
- SetVisible
- FontChanged
The following properties are defined in the “TfrxComponent” class:
下面的属性被定义在"TfrxComponent" 类中：
- Objects list of child objects //子类对象列表
- AllObjects list of all subordinate objects //所有下属对象列表
- Parent link to parent object //父对象
- Page link to report page on which object resides //链接到该对象所在的报表页
- Report link to report in which object appears //链接到对象所在的的报表
- IsDesigning “True” if designer is running
- IsLoading “True” if object is being loaded from stream
- IsPrinting “True” if object is being printed out
- BaseName object base name; this value is used in “CreateUniqueName” method //组件的唯一名字
- Left object X-coordinate (relative to parent) // 对象的x坐标（相对于父容器）
- Top object Y-coordinate (relative to parent) // 对象的y坐标（相对于父容器）
- Width object width
- Height object height
- AbsLeft object absolute X-coordinate //对象的绝对x坐标
- AbsTop object absolute Y-coordinate
- Font object font
- ParentFont if “True” then uses parent object font settings
- Restrictions set of flags which restricts one or more object operations //限制一个或多个对象操作的标志集
- Visible object visibility //对象的可见性
The next base class is “TfrxReportComponent”. Objects of this type can be placed into a report design. This class has the “Draw” method for drawing the object and also the “BeforePrint/GetData/AfterPrint” methods, which are called when the report is running.
下一个基类是"TfrxReportComponent".这种类型的对象可以被放在一个设计的报表中。该类有Draw方法绘制对象，同时还有BeforePrint/GetData/AfterPrint，报表运行时调用这些方法。
TfrxReportComponent = class(TfrxComponent)
public
procedure Draw(Canvas: TCanvas;ScaleX, ScaleY, OffsetX, OffsetY: Extended); virtual; abstract;
procedure BeforePrint; virtual;
procedure GetData; virtual;
procedure AfterPrint; virtual;
function GetComponentText: String; virtual;
property OnAfterPrint: TfrxNotifyEvent;
property OnBeforePrint: TfrxNotifyEvent;
end;
The "Draw" method is called to draw the object, with parameters:
Draw方法绘制对象，参数是：
- Canvas on canvas
- Scale scaling along the X- and Y-axes //沿X轴和Y轴的缩放
- Offset offset relative to canvas edges //相对于画布边缘的偏移
The "BeforePrint" method is called immediately before object handling (during the report building process). This method saves the object state. //处理前调用，保存对象状态
The "GetData" method is called to load data into the object. //将数据加载到对象
The "AfterPrint" method is called after object handling. This method restores the object state. //对象处理完成后调用，恢复对象状态。
"TfrxDialogComponent" is the base class for writing non-visual components that can be used in dialogue forms in a report.
类"TfrxDialogComponent"是编写非可视化类组件的基类,用在报表中的对话框形式。
TfrxDialogComponent = class(TfrxReportComponent)
public
property Bitmap: TBitmap;
property Component: TComponent;
published
property Left;
property Top;
end;
“TfrxDialogControl” is the base class for writing common controls that can be used in dialogue forms in a report. This class has a large number of general properties and events shared by most of the common controls.
类"TfrxDialogControl"是编写可视化公共控件的基类，用在报表中的对话框形式。该类有大多数公共控件共有的一般属性和事件。
TfrxDialogControl = class(TfrxReportComponent)
protected
procedure InitControl(AControl: TControl);
public
property Caption: String;
property Color: TColor;
property Control: TControl;
property OnClick: TfrxNotifyEvent;
property OnDblClick: TfrxNotifyEvent;
property OnEnter: TfrxNotifyEvent;
property OnExit: TfrxNotifyEvent;
property OnKeyDown: TfrxKeyEvent;
property OnKeyPress: TfrxKeyPressEvent;
property OnKeyUp: TfrxKeyEvent;
property OnMouseDown: TfrxMouseEvent;
property OnMouseMove: TfrxMouseMoveEvent;
property OnMouseUp: TfrxMouseEvent;
published
property Left;
property Top;
property Width;
property Height;
property Font;
property ParentFont;
property Enabled: Boolean;
property Visible;
end;
When writing your own custom control, you should inherit from this class, move the required properties to the “published” section, and then add new properties for your common control. The writing of custom controls will be discussed in detail in the next chapter.
当写自己的控件时，你应该从这个类继承，把需要的属性移到published区，并添加你自己新的属性。自定义控件的编写将在下一章中详细讨论。
"TfrxView" is the base class for most components that can be placed on the report design page. Objects of this class have attributes such as “Frame” and “Filling” and can also be connected to a data source. Most FastReport standard objects inherit from this class.
类"TfrxView"是大多在报表设计页上放置的组件的基类。此类对象有属性如Frame ,Filling，并且可以连接到一个数据源。多数FastReport标准对象继承自该类。
TfrxView = class(TfrxReportComponent)
protected
FX, FY, FX1, FY1, FDX, FDY, FFrameWidth: Integer;
FScaleX, FScaleY: Extended;
FCanvas: TCanvas;
procedure BeginDraw(Canvas: TCanvas; ScaleX, ScaleY, OffsetX, OffsetY: Extended); virtual;
procedure DrawBackground;
procedure DrawFrame;
procedure DrawLine(x, y, x1, y1, w: Integer);
public
function IsDataField: Boolean;
property BrushStyle: TBrushStyle;
property Color: TColor;
property DataField: String;
property DataSet: TfrxDataSet;
property Frame: TfrxFrame;
published
property Align: TfrxAlign;
property Printable: Boolean;
property ShiftMode: TfrxShiftMode;
property TagStr: String;
property Left;
property Top;
property Width;
property Height;
property Restrictions;
property Visible;
property OnAfterPrint;
property OnBeforePrint;
end;
The following methods are defined in this class:
- BeginDraw called by the “Draw” method; calculates integer-valued coordinates and size of drawing area.
Calculated values are exposed as FX, FY, FX1, FY1, FDX and FDY variables. Frame width (exposed as FFrameWidth) is also calculated
调用Draw方法，计算区域的坐标和大小。
- DrawBackground draws object background //绘制对象背景
- DrawFrame draws object frame //绘制对象边框
- DrawLine draws line with specified coordinates and width //绘制具有指定坐标和宽度的行
- IsDataField returns “True” if DataSet and DataField properties contain non-empty values
One can refer to the following properties after calling the “BeginDraw” method:
- FX, FY, FX1, FY1,FDX, FDY,
FFrameWidth the object frame coordinates, sizes and width calculated using the Scale and Offset parameters
- FscaleX,FScaleY X & Y-scaling, which are copies of the ScaleX and ScaleY parameters from the Draw method
- FCanvas the canvas, which is a copy of the Canvas parameter from the Draw method
The class defines the following properties, which are found in most report objects:
类定义了大多数报表对象中的下列属性：
- BrushStyle object fill style
- Color object fill color
- DataField name of data field to which object is connected
- DataSet data source
- Frame object frame
- Align object alignment relative to its parent
- Printable defines whether given object can be printed out //定义给定的对象是否可以打印出来
- ShiftMode shift mode of object in cases when a stretchable object is placed above it //换档模式对象的情况时，可延伸的对象放在上面
- TagStr field for storing user information //存储用户信息的字段(用户可以自己使用，类似Tag)
"TfrxStretcheable" is the base class for writing components which modify their height depending on the data placed in them.
类"TfrxStretcheable"是编写那些高度由数据内容的高度决定的组件的基类。(意即组件高度是动态的)
TfrxStretcheable = class(TfrxView)
public
function CalcHeight: Extended; virtual;
function DrawPart: Extended; virtual;
procedure InitPart; virtual;
published
property StretchMode: TfrxStretchMode;
end;
Objects of this class can be stretched vertically and also split into smaller pieces when the objects don't have sufficient width on the output page. The objects are split enough times to fit all of their data into the available space.
此类型的对象可以垂直拉伸和分裂成更小的片段，当对象在输出页上没有足够的宽度时。该对象被分割足够的时间，以适应所有的数据到可用的空间。
The following methods are defined in this class:
- CalcHeight calculates and returns object height according to the data placed in it //根据所放置的数据计算并返回对象高度
- InitPart called before object splitting //对象分割前调用
- DrawPart draws next data chunk placed in object “Return value” is the amount of unused space where it was impossible to display data
//绘制对象的下一个数据块，返回值是无法显示的数据未使用空间的量。
以上是FastReport报表中几个重要的基类，以及类中重要的方法，属性。
TfrxComponent
TfrxReportComponent
TfrxDialogComponent
TfrxDialogControl
TfrxView
TfrxStretcheable
