CPalette Class Reference
| class CPalette : public CBase |
Detailed Description
Provides user-definable palette support to the GDI.
A palette is a user-defined set of colours, which is a subset of the full range of 24-bit colours. This allows users the advantages of having a low bpp colour mode whilst being able to specify the colours available in that mode. To give an example, the EColor16 mode provides a palette of 16 colours as it provides a mapping between an integer index and a TRgb colour (see the table EGA Low-colour constants). Only a palette of 16 colour enables you to change the palette. Palettes are also used to allow 24-bit bitmaps to be stored in a more compressed form by finding the actual number of different colours used in the bitmap, creating a palette to allow the mapping of these colours to a smaller index space, and encoding the bitmaps pixels using indexes to this new index space.
A palette has a size which is set at its creation and cannot be altered the number of entries in the palette. Each entry in a palette is a mapping between that entrys index and a TRgb value. Palette entries can be got and set at any time between the palettes creation and destruction. The GDIs palette support also provides functions to find the nearest palette colour to a requested TRgb colour.
Member Attribute Documentation
iArray
iNumEntries
|
TInt
| iNumEntries | [protected] |
Constructor & Destructor Documentation
CPalette ( )
| IMPORT_C | CPalette | ( | ) | [protected] |
Member Function Documentation
Clear ( )
Clears all the entries in the palette to TRgb(0).
ConstructL ( TInt )
| void | ConstructL | ( | TInt | aNumberOfEntries | ) | [protected] |
Entries ( )
|
TInt
| Entries | ( | ) | const [inline] |
Gets the number of entries in the palette
- Return Value
- The number of entries in the palette.
GetDataPtr ( TInt, TInt, TPtr8 & )
| IMPORT_C void | GetDataPtr | ( | TInt | aFirstColor, |
| | TInt | aNumColors, |
| | TPtr8 & | aPtr |
| | ) | |
Returns a descriptor over the palette entries for the specifed colors. It is designed so that the descriptor can be passed to another thread and that thread copy the relevant entries.
| Parameters |
|---|
| aFirstColor | The first colour. |
| aNumColors | Number of colours. |
| aPtr | Descriptor. |
GetEntry ( TInt )
| IMPORT_C TRgb | GetEntry | ( | TInt | aPaletteIndex | ) | const |
Gets the RGB value of the palette entry at aPaletteIndex.
| Parameters |
|---|
| aPaletteIndex | The index of the palette entry to get. |
- Return Value
- The RGB value of the palette entry
NearestEntry ( const TRgb & )
| IMPORT_C TRgb | NearestEntry | ( | const TRgb & | aColor | ) | const |
Gets the colour in the palette which is closest to the specified colour.
| Parameters |
|---|
| aColor | The colour to find. |
- Return Value
- The colour in the palette which is closest to the specified colour.
NearestIndex ( const TRgb & )
| IMPORT_C TInt | NearestIndex | ( | const TRgb & | aColor | ) | const |
Gets the index of the colour in the palette which is closest to the specified colour.
| Parameters |
|---|
| aColor | The colour to find. |
- Return Value
- The index of the colour in the palette which is closest to the specified colour.
NewDefaultL ( TDisplayMode )
Creates a new default palette for the specified display mode. The default palette for a particular display mode has one entry for each possible colour in that display mode (2 entries for EGray2, 16 entries for EColor16 etc.); the colour of each index p in the default palette is set to its default value according to its display mode (e.g. if the mode is EColor16 then palette[p]==TRgb::Color16(p); if the mode is EGray4 then palette[p]==TRgb::_Gray4(p)).
| Parameters |
|---|
| aDispMode | The display mode for which the palette is to be created. |
- Return Value
- The newly created palette
NewL ( TInt )
Creates a new palette with the specified number of entries.
| Parameters |
|---|
| aNumberOfEntries | The number of entries in the palette being created. |
- Return Value
- The newly created palette.
SetEntry ( TInt, const TRgb & )
| IMPORT_C void | SetEntry | ( | TInt | aPaletteIndex, |
| | const TRgb & | aPaletteEntry |
| | ) | |
Sets the palette entry at aPaletteIndex to the RGB value aPaletteEntry.
| Parameters |
|---|
| aPaletteIndex | The index of the palette entry to be set. |
| aPaletteEntry | The RGB value to set that entry to. |