Detailed Description

template<class Image, class PixelFormat = wxPixelFormatFor<Image>>
class wxPixelData< Image, PixelFormat >

A class template with ready to use implementations for getting direct and efficient access to wxBitmap's internal data and wxImage's internal data through a standard interface.

It is possible to extend this class (interface) to other types of image content.

Implemented on Windows, GTK+ and macOS:

wxNativePixelData: Class to access to wxBitmap's internal data without alpha channel (RGB).
wxAlphaPixelData: Class to access to wxBitmap's internal data with alpha channel (RGBA).

Implemented everywhere:

wxImagePixelData: Class to access to wxImage's internal data with alpha channel (RGBA).

wxMSW note: efficient access is only possible to the bits of the so called device independent bitmaps (DIB) under MSW. To ensure that wxBitmap uses a DIB internally and not a device dependent bitmap (DDB), you need to pass an explicit depth to its ctor, i.e. either 24 or 32, as by default wxBitmap creates a DDB of the screen depth.

Example:

wxBitmap bmp(width, size, 24); // explicit depth important under MSW
wxNativePixelData data(bmp);
if ( !data )
{
    // ... raw access to bitmap data unavailable, do something else ...
    return;
}
 
if ( data.GetWidth() < 20 || data.GetHeight() < 20 )
{
    // ... complain: the bitmap it too small ...
    return;
}
 
wxNativePixelData::Iterator p(data);
 
// we draw a (10, 10)-(20, 20) rect manually using the given r, g, b
p.Offset(data, 10, 10);
 
for ( int y = 0; y < 10; ++y )
{
    wxNativePixelData::Iterator rowStart = p;
 
    for ( int x = 0; x < 10; ++x, ++p )
    {
        p.Red() = r;
        p.Green() = g;
        p.Blue() = b;
    }
 
    p = rowStart;
    p.OffsetY(data, 1);
}

Library: wxCore

Category: Graphics Device Interface (GDI)

See also: wxBitmap, wxImage

Classes
class	Iterator
	The iterator of class wxPixelData. More...

Public Types
typedef Image	ImageType
	The type of the class we're working with. More...

Public Member Functions
	wxPixelData (Image &image)
	Create pixel data object representing the entire image. More...

	wxPixelData (Image &i, const wxRect &rect)
	Create pixel data object representing the area of the image defined by rect. More...

	wxPixelData (Image &i, const wxPoint &pt, const wxSize &sz)
	Create pixel data object representing the area of the image defined by pt and sz. More...

	operator bool () const
	Return true of if we could get access to bitmap data successfully. More...

Iterator	GetPixels () const
	Return the iterator pointing to the origin of the image. More...

wxPoint	GetOrigin () const
	Returns origin of the rectangular region this wxPixelData represents. More...

int	GetWidth () const
	Return width of the region this wxPixelData represents. More...

int	GetHeight () const
	Return height of the region this wxPixelData represents. More...

wxSize	GetSize () const
	Return the area which this wxPixelData represents in the image. More...

int	GetRowStride () const
	Return the distance between two rows. More...