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Reference for unit 'Graphics' (#lcl)

TPicture

[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

TPicture is a TGraphic container, used in place of a TGraphic if the graphic can be of any TGraphic class.

Declaration

Source position: graphics.pp line 880

`type TPicture = class(TPersistent)`
`protected`
`procedure AssignTo(); override;`		`AssignTo` if `Dest` is of correct (Graphic) type, calls `Assign` for `Dest`, otherwise calls inherited `AssignTo`
`procedure Changed(); virtual;`		`Changed` - software emulation of a call to the `OnChange` event
`procedure DefineProperties(); override;`
`procedure Progress(); virtual;`		Monitor progress of drawing process
`procedure LoadFromStreamWithClass();`
`public`
`constructor Create;`		`Create` - constructor for TPicture: performs inherited `Create` then loads file and clipboard formats
`destructor Destroy; override;`		`Destroy` - destructor for `TPicture`: frees graphic then performs inherited `Destroy`
`procedure Clear; virtual;`		`Clear` - removes the graphic
`procedure LoadFromClipboardFormat();`		`LoadFromClipboardFormat` - Reads the picture from the handle provided in the given clipboard format
`procedure LoadFromClipboardFormatID();`		Reads the picture from a clipboard of type `ClipboardType` using the format `FormatID`
`procedure LoadFromFile();`		`LoadFromFile` - Reads a picture from disk
`procedure LoadFromLazarusResource();`
`procedure LoadFromStream();`
`procedure LoadFromStreamWithFileExt();`		Loads picture from a named data stream with a specified file extension
`procedure SaveToClipboardFormat();`		`SaveToClipboardFormats` - Allocates a global handle and writes the picture in its native clipboard format
`procedure SaveToFile();`		`SaveToFile` - Writes the picture to disk
`procedure SaveToStream();`
`procedure SaveToStreamWithFileExt();`
`public`
`class function SupportsClipboardFormat();`		`SupportsClipboardFormat` - Returns true if the given clipboard format is supported by `LoadFromClipboardFormat`
`public`
`procedure Assign(); override;`		`Assign` - if the Source is a valid graphic type, copy the relevant details to the current object, otherwise call inherited `Assign`
`public`
`class procedure RegisterFileFormat();`		`RegisterFileFormat` - Register a new `TGraphic` class for use in `LoadFromFile`
`class procedure RegisterClipboardFormat();`		`RegisterClipboardFormat` - Registers a new `TGraphic` class for use in `LoadFromClipboardFormat`
`class procedure UnregisterGraphicClass();`		`UnRegisterGraphicClass` - Removes all references to the specified `TGraphic`
`public`
`function FindGraphicClassWithFileExt();`		Finds a graphic class with the named file extension `Ext`, returning an exception if not found
`property Bitmap: TBitmap; [rw]`		`Bitmap` - Returns a bitmap
`property Icon: TIcon; [rw]`		`Icon` contained within the picture
`property Jpeg: TJpegImage; [rw]`		`Jpeg` - returns a JPEG image
`property Pixmap: TPixmap; [rw]`		`Pixmap` - Returns a pixmap
`property PNG: TPortableNetworkGraphic; [rw]`		`PNG` - Returns a png
`property PNM: TPortableAnyMapGraphic; [rw]`		`PNM` - a PortableAnyMapGraphic image
`property Graphic: TGraphic; [rw]`		`Graphic` - The `TGraphic` object contained by the `TPicture`
`property Height: Integer; [r]`		`Height` - The native, unstretched, height of the picture
`property Width: Integer; [r]`		`Width` - The native, unstretched, width of the picture
`property OnChange: TNotifyEvent; [rw]`		`OnChange` - Event handler for any change in the picture
`property OnProgress: TProgressEvent; [rw]`		`OnProgress` - Event handler for monitoring progress in drawing the picture
`end;`

Inheritance

`TPicture`		`TPicture` is a `TGraphic` container, used in place of a `TGraphic` if the graphic can be of any `TGraphic` class.
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`TPersistent`
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`TObject`

Description

TPicture is a TGraphic container. It is used in place of a TGraphic if the graphic can be of any TGraphic class.

It is not a direct descendant of TGraphic, so you will not see TGraphic listed in the Inheritance chart, but it contains a property Graphic, of type TGraphic, so can contain all the properties of a TGraphic

Defines many private methods for getting and storing various sorts of images such as bitmaps, pixmaps, icons, PNGs etc

It does not itself contain a defined area for displaying the image, but this is supplied by the descendant classes such as BitMap, PixMap, PNG or Icon, which define a Canvas property.

LoadFromFile and SaveToFile are polymorphic. For example, if the TPicture is holding an Icon, you can LoadFromFile a bitmap file, whereas if the class is TIcon you could only read .ICO files.

LoadFromFile - Reads a picture from disk. The TGraphic class created is determined by the file extension of the file. If the file extension is not recognized an exception is generated.
SaveToFile - Writes the picture to disk.
LoadFromClipboardFormat - ToDo: Reads the picture from the handle provided in the given clipboard format. If the format is not supported, an exception is generated.
SaveToClipboardFormats - ToDo: Allocates a global handle and writes the picture in its native clipboard format (CF_BITMAP for bitmaps, CF_METAFILE for metafiles, etc.). Formats will contain the formats written. Returns the number of clipboard items written to the array pointed to by Formats and Datas or would be written if either Formats or Datas are nil.
SupportsClipboardFormat - Returns true if the given clipboard format is supported by LoadFromClipboardFormat
Assign - Copies the contents of the given TPicture. Used most often in the implementation of TPicture properties.
RegisterFileFormat - Register a new TGraphic class for use in LoadFromFile.
RegisterClipboardFormat - Registers a new TGraphic class for use in LoadFromClipboardFormat.
UnRegisterGraphicClass - Removes all references to the specified TGraphic class and all its descendants from the file format and clipboard format internal lists.
Height - The native, unstretched, height of the picture.
Width - The native, unstretched, width of the picture.
Graphic - The TGraphic object contained by the TPicture
Bitmap - Returns a bitmap. If the contents is not already a bitmap, the contents are thrown away and a blank bitmap is returned.
Pixmap - Returns a pixmap. If the contents is not already a pixmap, the contents are thrown away and a blank pixmap is returned.
PNG - Returns a png. If the contents is not already a png, the contents are thrown away and a blank png ( TPortableNetworkGraphic) is returned.
PNM - Returns a pnm. If the contents is not already a pnm, the contents are thrown away and a blank pnm ( TPortableAnyMapGraphic) is returned.
Jpeg - Returns a jpeg. If the contents is not already a jpeg, the contents are thrown away and a blank jpeg ( TJPegImage) is returned.

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