TDBImage class

In unit DBCtrls

TDBImage - a data-aware Image box to display a single image from a dataset.

Declaration

pascal

TDBImage = class(TCustomImage)

Inheritance

Description

TDBImage is a TCustomImage descendant which implements a data-aware image control. TDBImage is used to retrieve or save a graphic image in a field in a dataset. The field is generally a Binary Large Object (BLOB). The control allows use of clipboard operations, like Copy/Cut/Paste to add or update the content in the image.

If an application doesn't need the data-aware capabilities of TDBImage, use a TImage control.

TDBImage, like most data-aware controls, provides DataSource and DataField properties to connect the control to a dataset and field. Internally, it uses a TFieldDataLink to maintain an association between the control and its database-related configuration settings.

Use the AutoDisplay, AutoSize, Stretch, Proportional, and Transparent properties to determine the display and sizing behavior for the graphic image.

Properties

`Field`	public	Definition for the field in the linked dataset where the control value is stored.
`PictureLoaded`	public	Indicates if the graphic content for the data-aware control has been loaded from its linked dataset.
`Align`	published	Specifies the placement of the control on its Parent control.
`Anchors`	published	The set of anchor definitions for this control.
`AntialiasingMode`	published	Indicates if anti-aliasing is used when rendering the image.
`AutoDisplay`	published	AutoDisplay - if True, automatically displays when focus is given.
`AutoSize`	published	Allows automatic adjustment of the size for the control, according to its content.
`BorderSpacing`	published	Determines the inner and outer border spacing for this control.
`Center`	published	Indicates if the image should be centered.
`Constraints`	published	Contains the minimum and maximum Width and Height for the control.
`DataField`	published	Contains the name of the field with the value for the control.
`DataSource`	published	Provides access to the dataset with content for the control.
`DragCursor`	published	The cursor shape shown during a drag operation.
`DragKind`	published	Indicates the action performed for a drag operation: drag-and-drop or drag-and-dock.
`DragMode`	published	Determines how a drag operation is started for the control.
`KeepOriginXWhenClipped`	published	Preserves the Left coordinate when a clipped image is centered.
`KeepOriginYWhenClipped`	published	Preserves the Top coordinate when a clipped image is centered.
`ParentShowHint`	published	If True, the value of ShowHint for the control will be the same as the one from the Parent. Default is True.
`Proportional`	published	True if image is proportional.
`QuickDraw`	published	QuickDraw - if True, quick drawing is implemented.
`ReadOnly`	published	Indicates if the control cannot modify the image in the field for the linked dataset.
`ShowHint`	published	Enables Hint display for the control.
`Stretch`	published	Indicates if the image is resized to the client area for the control.
`StretchInEnabled`	published	Allows the image to be resized proportionally when the image drawing area is shrunk.
`StretchOutEnabled`	published	Allows the image to be resized proportionally when the image drawing area is expanded.
`Transparent`	published	Indicates if the image has a clear, non-opaque background.
`Visible`	published	Allows the control, and all of its children, to be displayed or hidden.
`WriteHeader`	published	Write a header in the image stream.
`PopupMenu`	published	A context-sensitive menu that pops up when the right mouse button is clicked over this control.

Methods

`Notification`	protected	Handles notifications when a component in the class instance is added or removed.
`DataChange`	protected	Performs actions needed when the content in the linked dataset has been changed.
`UpdateData`	protected	Performs actions needed to validate and store the content for the image control.
`PictureChanged`	protected	Performs actions needed when the Picture property in the image control has been changed.
`WSRegisterClass`	protected	Register the component class with the widgetset.
`DoCopyToClipboard`	protected	Implements the clipboard Copy (Ctrl+C) command.
`Create`	public	Constructor for the class instance.
`Destroy`	public	Destructor for the class instance.
`ExecuteAction`	public	Provides support for TBasicAction in the control.
`UpdateAction`	public	Updates the specified action to reflect the current state in the linked dataset.
`Change`	public	Notifies the linked dataset when the value in the control is changed.
`LoadPicture`	public	Loads the graphic content for the control from a field in the linked dataset.
`CopyToClipboard`	public	Performs actions needed for the Clipboard Copy (Ctrl+C) command.
`CutToClipboard`	public	Performs actions needed for the Clipboard Cut (Ctrl+C) command.
`PasteFromClipboard`	public	Performs actions needed for the Clipboard Paste (Ctrl+V) command.

Events

`OnClick`	published	Notification handler for mouse clicks.
`OnContextPopup`	published	Invoked when a context-sensitive pop-up menu is requested.
`OnDblClick`	published	Event handler signalled when a mouse double click occurs in the control.
`OnDBImageRead`	published	Event to read a custom header from image stream.
`OnDBImageWrite`	published	Event to write a custom header into image stream.
`OnDragDrop`	published	Event handler signalled when an object is dropped onto the control.
`OnDragOver`	published	Event handler signalled when a control is dragged over the control instance.
`OnEndDrag`	published	Event handler signalled for the end of a drag-drop operation.
`OnMouseDown`	published	Event handler signalled when a mouse down event is handled for the control.
`OnMouseEnter`	published	Event handler signalled when the mouse pointer has entered the control.
`OnMouseLeave`	published	Event handler signalled when the mouse pointer has left the control.
`OnMouseMove`	published	Event handler signalled when the mouse pointer is moved in the control.
`OnMouseUp`	published	Event handler signalled when a mouse up event is handled for the control.
`OnMouseWheel`	published	Event handler for mouse wheel turned.
`OnMouseWheelDown`	published	Event handler signalled for a downward movement of the mouse wheel.
`OnMouseWheelUp`	published	Event handler signalled for an upward movement of the mouse wheel.
`OnResize`	published	Notification handler for a resize of the control.
`OnStartDrag`	published	Event handler signalled for the start of a dragging operation.