CPicture Class Reference

class CPicture : public CBase

Abstract base class for: drawing a picture to a graphics context, storing and restoring the picture.

The class defines the protocol for a number of concrete picture classes. Its main role is to support glass doors used in object embedding.

The class provides a protocol for the provision of scaling and cropping functions by derived classes, together with default implementations.

Its main function is Draw(), which draws the picture onto the graphics context at a particular point. It also has two important pure virtual functions: ExternalizeL() and GetOriginalSizeInTwips().

A picture has both an original representation and an on-screen representation. The original representation has a size in twips, and can somehow be drawn. The on-screen representation is assumed to be drawn under the control of an application which may wish to re-size or scale the original in some way, to crop it at the edges, and/or to ensure it fits within a particular defined area on the screen.

The class provides several functions that allow an application to set scaling and cropping before invoking the Draw() function to draw the picture on-screen. It is up to the internal workings of the function to determine the order of application cropping and scaling.

Inherits from

Constructor & Destructor Documentation

CPicture()

IMPORT_CCPicture()[protected]

~CPicture()

IMPORT_C~CPicture()[virtual]

Frees all resources owned by the object prior to its destruction.

Member Functions Documentation

AddCropInPixels(MGraphicsDeviceMap *, const TMargins &)

IMPORT_C voidAddCropInPixels(MGraphicsDeviceMap *aMap,
const TMargins &aMargins
)

Adds pixel cropping margins to the picture.

Parameters

MGraphicsDeviceMap * aMapThe pixels to twips mapping interface of the graphics device
const TMargins & aMarginsThe additional pixel cropping margins for the picture, in pixels.

Capability()

IMPORT_C TPictureCapabilityCapability()const [virtual]

Gets the picture's capabilities.

These include whether it is scalable and croppable.

DetachFromStoreL(TDetach)

voidDetachFromStoreL(TDetach = EDetachFull)[inline, virtual]

Parameters

TDetach  = EDetachFull

Draw(CGraphicsContext &, const TPoint &, const TRect &, MGraphicsDeviceMap *)

voidDraw(CGraphicsContext &aGc,
const TPoint &aTopLeft,
const TRect &aClipRect,
MGraphicsDeviceMap *aMap
)const [pure virtual]

Draws a picture.

Parameters

CGraphicsContext & aGcThe graphics context.
const TPoint & aTopLeftThe co-ordinates where the top left corner pixel of the picture should be placed. Note that whether this is actually drawn depends on the clipping area defined.
const TRect & aClipRectA clipping rectangle that defines the area to which the function should draw. An implementation should never draw outside this rectangle. Note that the graphics context may also have a clipping rectangle set on it.
MGraphicsDeviceMap * aMapThe device map for the graphics device. The implementation should use this to find the scaling to apply to the picture.

ExternalizeL(RWriteStream &)

voidExternalizeL(RWriteStream &aStream)const [pure virtual]

Externalises the picture to a stream.

The presence of this function means that the standard templated stream operator<<() is available to externalise objects of this class.

A derived class must supply an implementation of this function.

Parameters

RWriteStream & aStreamThe write stream.

GetCropInTwips(TMargins &)

IMPORT_C voidGetCropInTwips(TMargins &aMargins)const [virtual]

Gets the cropping margins of a picture in twips.

These margins are relative to the original unscaled size of the picture.

Parameters

TMargins & aMarginsThe cropping margins of the picture, in twips

GetOriginalSizeInTwips(TSize &)

voidGetOriginalSizeInTwips(TSize &aSize)const [pure virtual]

Gets the pictur's original size, in twips.

Parameters

TSize & aSizeThe size of the picture, in twips

GetSizeInPixels(MGraphicsDeviceMap *, TSize &)

IMPORT_C voidGetSizeInPixels(MGraphicsDeviceMap *aMap,
TSize &aSize
)const

Gets the picture's size in pixels.

This is calculated from the original size of the picture, taking cropping and scaling into account.

Parameters

MGraphicsDeviceMap * aMapThe pixels to twips mapping interface of the graphics device
TSize & aSizeThe size of the picture, in pixels.

GetSizeInTwips(TSize &)

IMPORT_C voidGetSizeInTwips(TSize &aSize)const

Gets the picture's size, in twips.

This size is calculated from the original size of the picture, taking cropping and scaling into account.

Parameters

TSize & aSizeThe size of the picture, in twips.

LineBreakPossible(TUint, TBool, TBool)

IMPORT_C TBoolLineBreakPossible(TUintaClass,
TBoolaBeforePicture,
TBoolaHaveSpaces
)const [virtual]

States whether a line break is possible, either before or after a picture.

The default implementation returns ETrue, implying that there is a break opportunity both before and after the picture, whether or not a space is present.

This may be overridden for special types of pictures.

Parameters

TUint aClassThe line breaking class of the adjacent character. Line breaking classes are defined in the header file, tagma.h
TBool aBeforePictureETrue, if the adjacent character is before the picture; EFalse, if the adjacent character is afterwards.
TBool aHaveSpacesETrue, if spaces occur between the adjacent character and the picture; EFalse, otherwise.

NativePixelSize(TSize &)

IMPORT_C TBoolNativePixelSize(TSize &aPixelSize)[virtual]

Derived classes might be implemented as bitmaps, in that case it might be interesting to now the native pixel size of the bitmap.

Parameters

TSize & aPixelSize

ResetToOriginal()

IMPORT_C voidResetToOriginal()

Resets the picture's scaling and cropping attributes to their original values.

ScaleFactorHeight()

IMPORT_C TIntScaleFactorHeight()const [virtual]

Gets the pictures height scale factor.

ScaleFactorWidth()

IMPORT_C TIntScaleFactorWidth()const [virtual]

Gets the picture's width scale factor.

SetCropInTwips(const TMargins &)

IMPORT_C voidSetCropInTwips(const TMargins &aMargins)[virtual]

Sets the cropping margins of a picture in twips.

These are relative to the original unscaled size of the picture.

Parameters

const TMargins & aMarginsThe cropping margins of the picture, in twips.

SetScaleFactor(TInt, TInt)

IMPORT_C voidSetScaleFactor(TIntaScaleFactorWidth,
TIntaScaleFactorHeight
)[virtual]

Sets the picture's scale factors.

Parameters

TInt aScaleFactorWidthThe width scale factor, in percent.
TInt aScaleFactorHeightThe height scale factor, in percent.

SetSizeInPixels(MGraphicsDeviceMap *, const TSize &)

IMPORT_C voidSetSizeInPixels(MGraphicsDeviceMap *aMap,
const TSize &aSize
)

Sets the picture's size in pixels.

Parameters

MGraphicsDeviceMap * aMapThe pixels to twips mapping interface of the graphics device.
const TSize & aSizeThe size of the picture, in pixels.

SetSizeInTwips(const TSize &)

IMPORT_C voidSetSizeInTwips(const TSize &aSize)

Sets the picture's size, in twips

Parameters

const TSize & aSizeThe size of the picture, in twips.

StoreL(CStreamStore &)

IMPORT_C TStreamIdStoreL(CStreamStore &aStore)const [virtual]

Stores the picture to the specified store.

The default implementation assumes that the content of the picture is externalized to a single stream. The implementation may need to be changed for those derived classes that have components.

Parameters

CStreamStore & aStoreThe store.

Member Enumerations Documentation

Enum TDetach

Options for detaching pictures from stores. Used by DetachFromStoreL().

Enumerators

EDetachFull

Internalise all data that is required to fully store the picture later; null any references to containing stores.

EDetachDraw

Internalise enough information to draw the picture (and no more); null any references to containing stores.