TRasterImage class

In unit Graphics

Base class for a number of graphic controls, including TCustomBitmap and TCustomIcon, which use a raster of dots to display graphic information.

Declaration

pascal

TRasterImage = class(TGraphic)

Inheritance

TRasterImage
TGraphic
TPersistent
TObject

Descends from it: TCustomBitmap TCustomIcon

Description

TRasterImage is a TGraphic descendant which implements the base class for images displayed as rasterized pixels on a canvas. It is used as the ancestor class for TCustomBitmap ( TBitmap) and TCustomIcon ( TIcon).

TRasterImage introduces the shared properties and methods common to the image formats. It is also provides a shared, reference-counted image that reduces resource requirements in graphical applications. Support is provided for bitmaps which use DIB (Device-Independent Bitmap) or DDB (Device-Dependent Bitmap) handles as well as common pixel storage formats used in the RawImage data. Handles are provided for the Bitmap, Mask, and Palette resources used in an image. TRasterImage also includes a Canvas used to render the pixels for the image.

Many of the methods in TRasterImage are defined as abstract virtual methods, and must be implemented in a descendent class to provide support for a specific image format.

Properties

`Canvas`	public	The Canvas where the raster image is rendered.
`BitmapHandle`	public	BitmapHandle - the Handle that has been allocated for the Bitmap.
`Masked`	public	Masked - returns True if a Mask is being applied.
`MaskHandle`	public	The handle allocated for the Bitmap Mask.
`PixelFormat`	public	Storage format for the Pixels in the Image.
`RawImage`	public	Provides access to the raw image data for the image type.
`ScanLine`	public	Provides indexed access to a scan line in the raw image data.
`TransparentColor`	public	Color used to represent transparent pixels in the image.
`TransparentMode`	public	Determines how transparent pixels are represented in the image.

Methods

`CanShareImage`	protected	CanShareImage - returns True if specified class of image can be shared.
`Changed`	protected	Changed - method to call when properties have changed.
`CreateDefaultBitmapHandle`	protected	Gets the default value for the Bitmap handle used in the class instance.
`Draw`	protected	Renders the image to the specified canvas.
`GetEmpty`	protected	Gets the value for the Empty property.
`GetHandle`	protected	Gets the value for the handle used in the image.
`GetBitmapHandle`	protected	Gets the value for the BitmapHandle property.
`GetMasked`	protected	Gets the value for the Masked property.
`GetMaskHandle`	protected	Gets the value for the MaskHandle property.
`GetMimeType`	protected	Gets the value for the MimeType property.
`GetPixelFormat`	protected	GetPixelFormat - returns the pixel format for the Image.
`GetRawImagePtr`	protected	Gets a pointer with the raw image data.
`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.
`GetHeight`	protected	Gets the value for the Height property.
`GetWidth`	protected	Gets the value for the Width property.
`BitmapHandleNeeded`	protected	Ensures that handles for the image and mask are valid for the raw image data.
`HandleNeeded`	protected	Ensures that a handle for the image is allocated in widgetset classes.
`MaskHandleNeeded`	protected	Ensures that a handle is allocated for the image mask (when needed).
`PaletteNeeded`	protected	Ensures that a handle for the palette is 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.
`SetBitmapHandle`	protected	Sets the value for the BitmapHandle property.
`SetMasked`	protected	Sets the value for the Masked property.
`SetMaskHandle`	protected	Sets the value for the MaskHandle property.
`SetTransparent`	protected	Sets the value for the Transparent property.
`UnshareImage`	protected	Unshares a shared image when its handle is changed or the save stream is freed.
`UpdateHandles`	protected	Updates image handles when the raw image data is loaded.
`SaveStreamNeeded`	protected	Ensures that the save stream for the shared image is allocated.
`FreeSaveStream`	protected	Frees the save stream assigned to the internal shared image.
`ReadData`	protected	Reads image data during component streaming.
`ReadStream`	protected	ReadStream - loads image data into the raw image.
`SetSize`	protected	SetSize - specifies height and width of Image.
`SetHandle`	protected	Sets the handle used for the image.
`SetHeight`	protected	Sets the value for the Height property.
`SetWidth`	protected	Sets the value for the Width property.
`SetTransparentMode`	protected	Sets the value for the TransparentMode property.
`SetPixelFormat`	protected	Sets the value for the PixelFormat property.
`WriteData`	protected	Writes raw image data to the specified stream.
`WriteStream`	protected	Writes the image content to the specified stream instance.
`RequestTransparentColor`	protected	Gets the color used to represent transparent pixels in the image.
`ApplyTransparent`	protected	Applies transparency to an image based on the settings in Transparent, TransparentColor, and TransparentMode.
`Create`	public	Constructor for the class instance.
`Destroy`	public	Destroy is the destructor for TRasterImage: frees the canvas, and releases image then calls inherited Destroy.
`Assign`	public	Assign - copies details from Source according to data type.
`Clear`	public	Removes raw image data and frees the internal save stream.
`BeginUpdate`	public	BeginUpdate - start the update process.
`EndUpdate`	public	EndUpdate - finishes the update process.
`FreeImage`	public	Frees the image by resetting its handle.
`BitmapHandleAllocated`	public	BitmapHandleAllocated - returns True if a handle has been allocated for the Bitmap.
`MaskHandleAllocated`	public	MaskHandleAllocated - returns True if a handle has been allocated for the Mask.
`PaletteAllocated`	public	PaletteAllocated - returns True if a Palette has been allocated.
`LoadFromBitmapHandles`	public	Loads the image data from the specified Bitmap and Mask handles.
`LoadFromDevice`	public	Loads image data from the specified device context.
`LoadFromStream`	public	LoadFromStream - loads data for the image from a specified data stream, optionally supplying its size.
`LoadFromMimeStream`	public	Loads image data from a stream for the specified MIME type.
`LoadFromRawImage`	public	Loads image data from the specified TRawImage instance.
`LoadFromIntfImage`	public	Loads the image from a TLazIntfImage instance.
`SaveToStream`	public	Saves image data to the specified stream.
`GetSupportedSourceMimeTypes`	public	Gets a list of supported MIME types for image data used in the image type.
`GetSize`	public	Gets the image Width and Height from the metadata for the raw image.
`Mask`	public	Applies the color used for transparent pixels to the image.
`SetHandles`	public	Sets handles for the bitmap and the mask to the specified values.
`ReleaseBitmapHandle`	public	Releases the handle in the shared image without freeing the BitmapHandle.
`ReleaseMaskHandle`	public	ReleaseMaskHandle - releases the Handle used for the Mask.
`ReleasePalette`	public	ReleasePalette - release the Handle used for the Palette.
`CreateIntfImage`	public	CreateIntfImage - creates an image on the Interface.
`HandleAllocated`	public	Indicates if a handle has been assigned for the shared image in the class.

Fields

FSharedImage protected Shared image with existing handles, canvases, etc.

Inherited

From TGraphic (29)

DefineProperties Empty Equals GetFileExtensions GetPalette GetResourceType Height IsStreamFormatSupported LazarusResourceTypeValid LoadFromClipboardFormat LoadFromClipboardFormatID LoadFromFile LoadFromLazarusResource LoadFromResourceID LoadFromResourceName MimeType Modified OnChange OnProgress Palette PaletteModified Progress SaveToClipboardFormat SaveToClipboardFormatID SaveToFile SetModified SetPalette Transparent Width

From TPersistent (6)

AssignTo FPOAttachObserver FPODetachObserver FPONotifyObservers GetNamePath GetOwner

From TObject (39)

AfterConstruction BeforeDestruction CheckDisposed ClassInfo ClassName ClassNameIs ClassParent ClassType CleanupInstance DefaultHandler DefaultHandlerStr Dispatch DispatchStr Disposed DisposeOf FieldAddress Free FreeInstance GetDisposed GetHashCode GetInterface GetInterfaceByStr GetInterfaceEntry GetInterfaceEntryByStr GetInterfaceTable GetInterfaceWeak GetLastCastErrorInfo InheritsFrom InitInstance InstanceSize MethodAddress MethodName newinstance QualifiedClassName SafeCallException StringMessageTable SystemHasExtendedRTTI ToString UnitName

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.