Class TQRbwZoomBox2

Description

Hierarchy

Fields

Methods

Properties

Unit

ZoomBox2

Declaration

type TQRbwZoomBox2 = class(TPanel)

Description

TQRbwZoomBox2 is used as an interface for handling drawing with real number coordinates.

The functions X, XCoord, Y, and YCoord can be used to convert between real-world and screen coordinates. By default, the real-world coordinates increase to the left and upward but these directions can be reversed with HorizontalDirection and VerticalDirection.

Zooming operations are performed with BeginZoom and FinishZoom

Panning can be turned on and off with Panning.

Drawing should be done on the subcomponent.

Hierarchy

TPanel
TQRbwZoomBox2

Overview

Fields

	`FEndX: Integer;`
	`FEndY: Integer;`
	`FExaggeration: real;`
	`FExaggerationDirection: TExaggerationDirection;`
	`FHorizontalDirection: THorizontalDirection;`
	`FImage32: TzbImage32;`
	`FImmediateResize: boolean;`
	`FMagnification: real;`
	`FOnPan: TPanEvent;`
	`FOriginX: real;`
	`FOriginY: real;`
	`FPanning: boolean;`
	`FPositionedLayer: TPositionedLayer;`
	`FStartX: Integer;`
	`FStartY: Integer;`
	`FStartXPosition: integer;`
	`FStartYPosition: integer;`
	`FStopXPosition: integer;`
	`FStopYPosition: integer;`
	`FVerticalDirection: TVerticalDirection;`
	`FZooming: boolean;`
	`FOnMagnificationChanged: TNotifyEvent;`

Methods

	`function GetCanZoomIn: boolean;`
	`function GetCanZoomOut: boolean;`
	`procedure PaintLayer(Sender: TObject; Buffer: TBitmap32);`
	`procedure PanMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);`
	`procedure PanUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);`
	`procedure SetExaggeration(const Value: real);`
	`procedure SetExaggerationDirection(const Value: TExaggerationDirection);`
	`procedure SetHorizontalDirection(const Value: THorizontalDirection);`
	`procedure SetImmediateResize(const Value: boolean);`
	`procedure SetMagnification(Value: real);`
	`procedure SetOriginX(const Value: real);`
	`procedure SetOriginY(const Value: real);`
	`procedure SetPanning(const Value: boolean);`
	`procedure SetVerticalDirection(const Value: TVerticalDirection);`
	`procedure ZoomBoxHitTest(Sender: TObject; X, Y: Integer; var Passed: Boolean);`
	`procedure ContinueZoom(X, Y: Integer);`
	`procedure FinishZoom(X, Y: Integer);`
	`procedure InitWidget;`
	`procedure MouseMove(Shift: TShiftState; X, Y: Integer); override;`
	`procedure MouseUp(Button: TMouseButton; Shift: TShiftState; X, Y: Integer); override;`
	`procedure Pan; virtual;`
	`procedure Resize; override;`
	`procedure AbortZoom;`
	`procedure BeginZoom(X, Y: Integer);`
	`constructor Create(AOwner: TComponent); override;`
	`procedure InvalidateImage32;`
	`function X(XCoord: integer): extended;`
	`function XCoord(X: extended): integer;`
	`function Y(YCoord: integer): extended;`
	`function YCoord(Y: extended): integer;`
	`procedure ZoomBy(Factor: extended);`
	`procedure ZoomByAt(Factor: extended; CenterX, CenterY: integer);`

Properties

	`property CanZoomIn: boolean read GetCanZoomIn;`
	`property CanZoomOut: boolean read GetCanZoomOut;`
	`property Panning: boolean read FPanning write SetPanning;`
	`property Exaggeration: real read FExaggeration write SetExaggeration;`
	`property ExaggerationDirection: TExaggerationDirection read FExaggerationDirection write SetExaggerationDirection default edVertical;`
	`property HorizontalDirection: THorizontalDirection read FHorizontalDirection write SetHorizontalDirection;`
	`property Image32: TzbImage32 read FImage32;`
	`property ImmediateResize: boolean read FImmediateResize write SetImmediateResize;`
	`property Magnification: real read FMagnification write SetMagnification;`
	`property OriginX: real read FOriginX write SetOriginX;`
	`property OriginY: real read FOriginY write SetOriginY;`
	`property VerticalDirection: TVerticalDirection read FVerticalDirection write SetVerticalDirection;`
	`property OnPan: TPanEvent read FOnPan write FOnPan;`
	`property OnMagnificationChanged: TNotifyEvent read FOnMagnificationChanged write FOnMagnificationChanged;`

Description

Fields

	`FEndX: Integer;`
`FEndX` is set to the mouse X coordinate in BeginZoom, ContinueZoom, and FinishZoom. See FStartX.

	`FEndY: Integer;`
`FEndY` is set to the mouse Y coordinate in BeginZoom, ContinueZoom, and FinishZoom. See FStartY.

	`FExaggeration: real;`
See Exaggeration.

	`FExaggerationDirection: TExaggerationDirection;`
See ExaggerationDirection.

	`FHorizontalDirection: THorizontalDirection;`
See HorizontalDirection.

	`FImage32: TzbImage32;`
`FImage32` is used for the actual drawing in `TQRbwZoomBox2`

	`FImmediateResize: boolean;`
See ImmediateResize.

	`FMagnification: real;`
See Magnification.

	`FOnPan: TPanEvent;`
See OnPan.

	`FOriginX: real;`
See OriginX.

	`FOriginY: real;`
See OriginY.

	`FPanning: boolean;`
See Panning.

	`FPositionedLayer: TPositionedLayer;`
`FPositionedLayer` is used for drawing the zoom window during zooming operations.

	`FStartX: Integer;`
`FStartX` is set to the mouse X coordinate in BeginZoom. See FEndX.

	`FStartY: Integer;`
`FStartY` is set to the mouse Y coordinate in BeginZoom. See FEndY.

	`FStartXPosition: integer;`
`FStartXPosition` is set to the mouse X coordinate in SetPanning.

	`FStartYPosition: integer;`
`FStartYPosition` is set to the mouse Y coordinate in SetPanning.

	`FStopXPosition: integer;`
`FStopXPosition` is set to the mouse X coordinate in Pan.

	`FStopYPosition: integer;`
`FStopYPosition` is set to the mouse Y coordinate in Pan.

	`FVerticalDirection: TVerticalDirection;`
See VerticalDirection.

	`FZooming: boolean;`
`FZooming` is `True` when a zooming operation is underway.

	`FOnMagnificationChanged: TNotifyEvent;`

Methods

	`function GetCanZoomIn: boolean;`
`GetCanZoomIn` returns true if Magnification is less than the maximum magnification.

	`function GetCanZoomOut: boolean;`
`GetCanZoomOut` returns true if Magnification is greater than the minimum magnification.

	`procedure PaintLayer(Sender: TObject; Buffer: TBitmap32);`
`PaintLayer` is responsible for painting the zoom window during zooming.

	`procedure PanMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);`
`PanMove` is the event handler for OnZbMove. If FZooming is `True`, FEndX and FEndY are updated and Image32 is redrawn.

	`procedure PanUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);`
`PanUp` is the event handler for OnZbUp. If FZooming is `True`, the zooming operation is either aborted or finished. See AbortZoom and FinishZoom. It is aborted if the mouse is not over the TQRbwZoomBox2.

	`procedure SetExaggeration(const Value: real);`
See Exaggeration.

	`procedure SetExaggerationDirection(const Value: TExaggerationDirection);`
See ExaggerationDirection.

	`procedure SetHorizontalDirection(const Value: THorizontalDirection);`
See HorizontalDirection.

	`procedure SetImmediateResize(const Value: boolean);`
See ImmediateResize.

	`procedure SetMagnification(Value: real);`
See Magnification.

	`procedure SetOriginX(const Value: real);`
See OriginX.

	`procedure SetOriginY(const Value: real);`
See OriginY.

	`procedure SetPanning(const Value: boolean);`
See Panning.

	`procedure SetVerticalDirection(const Value: TVerticalDirection);`
See VerticalDirection.

	`procedure ZoomBoxHitTest(Sender: TObject; X, Y: Integer; var Passed: Boolean);`
`ZoomBoxHitTest` changes Passed to `True` so that a mouse down event in FPositionedLayer will always succeed.

procedure ContinueZoom(X, Y: Integer);

If BeginZoom has been called, and neither AbortZoom nor FinishZoom have yet been called, ContinueZoom will invalidate Image32 so that the zoome window will be drawn. One of the corners of the shape will be at the location where the zoom began. The other will be at X, and Y. X and Y are screen coordinates in the Image32 in the TQRbwZoomBox2. You can get X and Y in OnMouseMove. ContinueZoom is called in the private method PanMove.

	`procedure FinishZoom(X, Y: Integer);`
`FinishZoom` terminates a zoom operation. X, and Y are the X and Y screen coordinates of the Image32 in the TQRbwZoomBox2. You can get X and Y in OnMouseUp. FinishZoom sets the zoom level so that the area outlined by the X, and Y parameters in BeginZoom and the X, and Y parameters in FinishZoom is displayed in the TQRbwZoomBox2.

	`procedure InitWidget;`
`InitWidget` sets the Parent, Align, and Anchors properties of Image32. It also assigns event handlers for OnZbMove and OnZbUp.

	`procedure MouseMove(Shift: TShiftState; X, Y: Integer); override;`
`MouseMove` calls the inherited `MouseMove` and then calls Pan.

	`procedure MouseUp(Button: TMouseButton; Shift: TShiftState; X, Y: Integer); override;`
`MouseUp` calls the inherited `MouseUp` and then calls Pan.

	`procedure Pan; virtual;`
If Panning is true, FStopXPosition and FStopYPosition are moved to follow the mouse. Then OnPan is called.

	`procedure Resize; override;`
If ImmediateResize is `True`, `Resize` causes Image32 to be resized to fit ClientWidth and ClientHeight.

	`procedure AbortZoom;`
If for some reason you want to terminate a zoom operation without doing the zoom, call `AbortZoom` instead of FinishZoom. `AbortZoom` is called from PanUp.

	`procedure BeginZoom(X, Y: Integer);`
`BeginZoom` starts a zooming operation. X, and Y are the X and Y screen coordinates of the Image32 in the TQRbwZoomBox2. You can get those in OnMouseDown.

	`constructor Create(AOwner: TComponent); override;`
`Create` creates an instance of TQRbwZoomBox2.

	`procedure InvalidateImage32;`
`InvalidateImage32` checks that Image32 can be drawn and, if so, calls Invalidate for it.

	`function X(XCoord: integer): extended;`
X converts a screen coordinate into a real-number X coordinate.

	`function XCoord(X: extended): integer;`
XCoord converts a real-number X coordinate into a screen coordinate.

	`function Y(YCoord: integer): extended;`
Y converts a screen coordinate into a real-number Y coordinate.

	`function YCoord(Y: extended): integer;`
YCoord converts a real-number Y coordinate into a screen coordinate.

	`procedure ZoomBy(Factor: extended);`
`ZoomBy` increase the magnification by Factor by calling ZoomByAt and using the center of the TQRbwZoomBox2 as (CenterX, CenterY).

procedure ZoomByAt(Factor: extended; CenterX, CenterY: integer);

ZoomByAt changes the magnification by Factor and then adjusts OriginX and OriginY so that the point represented by the screen coordinates (CenterX, CenterY) will still have screen coordinates (CenterX, CenterY). For example, suppose there is a point with real-world coordinates of (1,1) and screen coordinates of (100,100). If the OnMouseUp event was used to call ZoomByAt with (CenterX,CenterY) = (100, 100), the point will still have screen coordinates of (100, 100) after applying ZoomByAt.

Properties

	`property CanZoomIn: boolean read GetCanZoomIn;`
Read `CanZoomIn` to determine whether it is possible to zoom in.

	`property CanZoomOut: boolean read GetCanZoomOut;`
Read `CanZoomOut` to determine whether it is possible to zoom out.

	`property Panning: boolean read FPanning write SetPanning;`
Set `Panning` to `True` to start a panning operation. Set `Panning` to `False` to stop a panning operation. See Pan for what happens during a panning operation.

	`property Exaggeration: real read FExaggeration write SetExaggeration;`
`Exaggeration` is used to allow either vertical or horizontal exaggeration. `Exaggeration` affects how screen coordinates map to real-world coordinates. See ExaggerationDirection.

	`property ExaggerationDirection: TExaggerationDirection read FExaggerationDirection write SetExaggerationDirection default edVertical;`
`ExaggerationDirection` controls the direction in which Exaggeration is applied.

	`property HorizontalDirection: THorizontalDirection read FHorizontalDirection write SetHorizontalDirection;`
`HorizontalDirection` indicates the direction in which the X-coordinates increase. hdRight indicates they increase towards the right, hdLeft indicates they increase towards the left.

	`property Image32: TzbImage32 read FImage32;`
`Image32` is used for the actual drawing in `TQRbwZoomBox2`

	`property ImmediateResize: boolean read FImmediateResize write SetImmediateResize;`
See Resize.

	`property Magnification: real read FMagnification write SetMagnification;`
`Magnification` is the ratio of distances in screen coordinates to corresponding distances in real-world coordinates. Usually `Magnification` is not set directly. See BeginZoom, FinishZoom, ZoomBy and ZoomByAt.

	`property OriginX: real read FOriginX write SetOriginX;`
`OriginX` is the screen X-coordinate that corresponds to a real-world X-coordinate of zero.

	`property OriginY: real read FOriginY write SetOriginY;`
`OriginY` is the screen Y-coordinate that corresponds to a real-world Y-coordinate of zero.

	`property VerticalDirection: TVerticalDirection read FVerticalDirection write SetVerticalDirection;`
`VerticalDirection` indicates the direction in which the Y-coordinates increase. vdDown indicates they increase downward, vdUp indicates they increase upward.

	`property OnPan: TPanEvent read FOnPan write FOnPan;`
`OnPan` is called during panning operations to indicate the amount of panning. See Pan.

	`property OnMagnificationChanged: TNotifyEvent read FOnMagnificationChanged write FOnMagnificationChanged;`

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