framebuffer.cpp

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

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#include <qpixmap.h>
#include "framebuffer.h"


/*!
  \class FrameBuffer framebuffer.h
  \brief This class is specific to the mediaplayer apps.

    It is currently private to those apps, and its API,
    and therefore binary compatibilty may change in later
    versions.

    This class provides a way to abstract drawing in to
    either a QImage's bits, or directly to the screen from
    the bits returned by QDirectPainter. It also handles
    rotation of buffers allowing for example rotation from
    a QImage direct to the screen if a FrameBuffer object
    has been contructed around both. This class is specific
    for the VideoOutput class for allowing it to decode
    video frames either directly to the screen when it can
    without rotation or clipping, and when it can't to
    be able to rotate efficently, or fall back to painting
    a QImage with a QPainter in the worst case.
*/


FrameBuffer::FrameBuffer() : jt(0), x(0), y(0), w(0), h(0), bits(0), lineStep(0)
{
}


FrameBuffer::~FrameBuffer()
{
    delete []jt;
}


void FrameBuffer::create( uchar *b, int ls, int x1, int y1, int width, int height )
{
    if ( bits == b && ls == lineStep && x == x1 && y == y1 && w == width && h == height )
	return;

    delete []jt;
    jt = new uchar*[height];

    x = x1;
    y = y1;
    bits = b;
    lineStep = ls;
    w = width;
    h = height;
    uchar *fp = bits + lineStep * y + QPixmap::defaultDepth() * x / 8;

    for ( int i = 0; i < h; i++, fp += lineStep ) 
	jt[i] = fp;
}


uchar **FrameBuffer::jumpTable()
{
    return jt;
}


int FrameBuffer::width()
{
    return w;
}


int FrameBuffer::height()
{
    return h;
}


template<class T>
static inline void rotateLoopTemplate(
        uchar *src, int srcBytesPerLine, uchar *dst, int dstBytesPerLine,
        int width, int height, int quadrants )
{
    int dstXAdd = 0;
    int dstYAdd = 0;
    int dstXOfs = 0;
    int dstYOfs = 0;
    int srcYAdd = srcBytesPerLine - width * sizeof(T);

    switch (quadrants) {
	case 1:
            dstXOfs = 0;
            dstYOfs = width - 1;
            dstXAdd = -dstBytesPerLine;
            dstYAdd = 1 * sizeof(T) + width * dstBytesPerLine;
	    break;
	case 2:
            dstXOfs = width - 1;
            dstYOfs = height - 1;
            dstXAdd = -sizeof(T);
            dstYAdd = -dstBytesPerLine + width * sizeof(T);
	    break;
	case 3:
            dstXOfs = height - 1;
            dstYOfs = 0;
            dstXAdd = dstBytesPerLine;
            dstYAdd = -1 * sizeof(T) - width * dstBytesPerLine;
	    break;
	default:
            dstXOfs = 0;
            dstYOfs = 0;
            dstXAdd = sizeof(T);
            dstYAdd = dstBytesPerLine - width * sizeof(T);
    }

    T *dstPtr = (T *)(dst + dstYOfs * dstBytesPerLine) + dstXOfs;
    T *srcPtr = (T *)src;
    for ( int y = 0; y < height; y++ ) {
        for ( int x = 0; x < width; x++ ) {
            *dstPtr = *srcPtr++;
            dstPtr = (T *)((uchar*)dstPtr + dstXAdd); // add dstXAdd number of bytes
        }
        srcPtr = (T *)((uchar*)srcPtr + srcYAdd); // add srcYAdd number of bytes
        dstPtr = (T *)((uchar*)dstPtr + dstYAdd); // add dstYAdd number of bytes
    }
}


void FrameBuffer::rotateToBuffer( FrameBuffer *dst, int dstX, int dstY, int srcX, int srcY, int w, int h, int quadrants )
{
    int dd = QPixmap::defaultDepth();
    uchar *srcPtr = jt[srcY] + dd * srcX / 8;
    uchar *dstPtr = dst->jt[dstY] + dd * dstX / 8;

    // Optimized image rotation code for nice bit depths
    switch ( dd ) {
	case 16:
	    rotateLoopTemplate<ushort>( srcPtr, lineStep, dstPtr, dst->lineStep, w, h, quadrants );
	    break;
	case 8:
	case 32:
	    rotateLoopTemplate<uint>( srcPtr, lineStep, dstPtr, dst->lineStep, w, h, quadrants );
	    break;
    }
}