TCustomIcon class

In unit Graphics

TCustomIcon - base class for TIcon.

Declaration

pascal

TCustomIcon = class(TRasterImage)

Inheritance

Descends from it: TCursorImage TIcnsIcon TIcon

Description

TCustomIcon is a TRasterImage descendant which implements the base class for TIcon. TIcon supports image files using the .ICO file format. An .ICO file typically contains several images with different sizes and/or color depths.

TCustomIcon extends the ancestor class to include an internal list of images, and provides overridden methods which use the list of images in their implementations. This includes the ReadData method used during LCL component streaming. ReadStream is overridden to handle not only multiple images but PNG and DIB image formats used in some Icon files.

When loading an icon file, the largest/most colorful image is selected as the current image. Other sizes and/or color depths are accessed by setting the value in the Current property, or using Size when Current is not already set, or by setting Current to the value from the GetBestIndexForSize method.

Use the Count, Add, Delete, Remove, Clear, and AssignImage methods to maintain the images in the internal list.

Please note that writing to an icon file is not currently implemented in TCustomIcon (or descendent classes).

Properties

`Current`	public	Ordinal position for the current image displayed for the icon.
`Count`	public	Number of images in the image list for the shared icon.

Methods

`MaskHandleNeeded`	protected	Ensures that a handle for the mask in the icon is valid.
`PaletteNeeded`	protected	An empty implementation in TCustomIcon.
`CanShareImage`	protected	Indicates whether the image class type has a shared handle.
`CheckRequestedSize`	protected	CheckRequestedSize - method to ensure correct size requested.
`GetIndex`	protected	GetIndex - returns the Index value of the Icon with specified format and size (.icn files can contain several versions of image).
`GetBitmapHandle`	protected	Gets the value for the BitmapHandle property.
`GetDefaultSize`	protected	GetDefaultSize - returns default size for Icon.
`GetMaskHandle`	protected	Gets the value for the MaskHandle property.
`GetPalette`	protected	Gets the value for the Palette property.
`GetPixelFormat`	protected	Gets the value for the PixelFormat property.
`GetRawImagePtr`	protected	Gets a pointer to the raw image data for the icon.
`GetRawImageDescriptionPtr`	protected	Gets a pointer to the metadata for the raw image data.
`GetTransparent`	protected	Gets the value for the Transparent property.
`GetSharedImageClass`	protected	Gets the class reference used to create new shared image instances in the class.
`GetStreamSignature`	protected	Gets the stream signature used for icon data.
`GetTypeID`	protected	Gets the icon type identifier used in the image list header.
`HandleNeeded`	protected	Ensures that a handle for the image has been allocated.
`InternalReleaseBitmapHandle`	protected	InternalReleaseBitmapHandle - releases Bitmap Handle and returns its value.
`InternalReleaseMaskHandle`	protected	InternalReleaseMaskHandle - releases Mask Handle and returns its value.
`InternalReleasePalette`	protected	InternalReleasePalette - releases Palette Handle and returns its value.
`IsStreamFormatSupported`	protected	Indicates whether the specified stream contains image data with a format supported for use in derived TCustomIcon classes.
`ReadData`	protected	Reads data for the class instance from a stream.
`ReadStream`	protected	Reads the content for the icon from the specified stream.
`SetPixelFormat`	protected	Sets the value for the PixelFormat property.
`SetTransparent`	protected	Sets the value for the Transparent property.
`UnshareImage`	protected	Unshares the shared image when the content in the icon is changed.
`UpdateCurrentView`	protected	UpdateCurrentView - updates the current appearance of the Icon.
`SetHandle`	protected	Unshares an existing shared image handle and set the new value.
`UpdateHandle`	protected	Updates the handle in the shared icon image top the specified value.
`UpdateHandles`	protected	Sets the Bitmap and Mask handles for the current image in the icon.
`WriteStream`	protected	Writes the content for the multi-image icon to the specified stream.
`Create`	public	Constructor for the class instance.
`Add`	public	Add - an Icon formatted as AFormat, with specified Height and Width.
`Assign`	public	Copies values from the specified persistent object into the current class instance.
`AssignImage`	public	Copies image data from the source image to the current icon image.
`Clear`	public	Removes the image content for the icon.
`Delete`	public	Deletes the image at the specified position in the list of images for the icon.
`Remove`	public	Removes an icon image with the specified attributes.
`GetDescription`	public	Gets metadata which describes the icon image at the specified position in the image list.
`SetSize`	public	Sets the size (width, height) for the image in the Icon.
`GetFileExtensions`	public	Gets a delimited list of file extensions supported for the image type.
`LazarusResourceTypeValid`	public	Determines if the specified resource type is valid for the image format.
`LoadFromResourceName`	public	Loads the icon with the specified resource name from the instance handle.
`LoadFromResourceID`	public	Load icon data from a resource with the specified integer resource identifier.
`LoadFromResourceHandle`	public	Loads icon data from the specified instance and resource handles.
`BitmapHandleAllocated`	public	Indicates if a handle for the icon image has been allocated.
`MaskHandleAllocated`	public	True if a handle has been allocated for the mask in the image.
`PaletteAllocated`	public	Determine if a handle has been allocated for the Palette in the icon.
`SetHandles`	public	Not implemented in TCustomIcon.
`Sort`	public	Sorts the images for the icon.
`GetBestIndexForSize`	public	Gets the ordinal position for the image closest to the requested size.
`ExportImage`	public	Exports the image for the icon at the specified index to another TFPImageBitmap class instance.