qwt_plot_rasteritem.cpp File Reference

#include <qapplication.h>
#include <qdesktopwidget.h>
#include <qpaintdevice.h>
#include <qpainter.h>
#include "qwt_legend.h"
#include "qwt_legend_item.h"
#include "qwt_scale_map.h"
#include "qwt_plot_rasteritem.h"

Go to the source code of this file.

Classes
class	QwtPlotRasterItem::PrivateData
struct	QwtPlotRasterItem::PrivateData::ImageCache
Functions
static QImage	toRgba (const QImage &image, int alpha)

---

Function Documentation

static QImage toRgba	(	const QImage &	image,
		int	alpha
	)		[static]

Definition at line 39 of file qwt_plot_rasteritem.cpp.

Referenced by QwtPlotRasterItem::draw().

{
    if ( alpha < 0 || alpha >= 255 )  
        return image;

#if QT_VERSION < 0x040000
    QImage alphaImage(image.size(), 32);
    alphaImage.setAlphaBuffer(true);
#else
    QImage alphaImage(image.size(), QImage::Format_ARGB32);
#endif

    const QRgb mask1 = qRgba(0, 0, 0, alpha);
    const QRgb mask2 = qRgba(255, 255, 255, 0);
    const QRgb mask3 = qRgba(0, 0, 0, 255);

    const int w = image.size().width();
    const int h = image.size().height();

    if ( image.depth() == 8 )
    {
        for ( int y = 0; y < h; y++ )
        {
            QRgb* alphaLine = (QRgb*)alphaImage.scanLine(y);
            const unsigned char *line = image.scanLine(y);

            for ( int x = 0; x < w; x++ )
                *alphaLine++ = (image.color(*line++) & mask2) | mask1;
        }
    }
    else if ( image.depth() == 32 )
    {
        for ( int y = 0; y < h; y++ )
        {
            QRgb* alphaLine = (QRgb*)alphaImage.scanLine(y);
            const QRgb* line = (const QRgb*) image.scanLine(y);

            for ( int x = 0; x < w; x++ )
            {
                const QRgb rgb = *line++;
                if ( rgb & mask3 ) // alpha != 0
                    *alphaLine++ = (rgb & mask2) | mask1;
                else
                    *alphaLine++ = rgb;
            }
        }
    }

    return alphaImage;
}