Main Page | Namespace List | Class Hierarchy | Alphabetical List | Class List | File List | Namespace Members | Class Members | File Members

QLabelRenderer Class Reference

This I/O class renders a gray-scale or RGB stream (via a QFrameBuffer) onto a QLabel widget. More...

#include <QLabelRenderer.hpp>

Inheritance diagram for QLabelRenderer:

VideoRenderer IO VThread List of all members.

Public Member Functions

 QLabelRenderer (const VideoESInfo *es, UncompressedVideoFrame::ColorSpace colorSpace, QLabel *qlabel, bool allowUpscaleX=false, QEvent::Type eventType=QEvent::User)
 Constructor.
virtual ~QLabelRenderer ()
 Destructor.
virtual int writeFrame (Frame *frm, ESInfo *out_es=NULL)
 Renders a frame to the destination QLabel widget.
virtual bool open ()
 Creates internal frame buffers and checks whether the stream to be rendered matches the widget dimensions.

Protected Member Functions

bool updateDisplayRegion ()
 Update frame_info (except size) and display_region.

Detailed Description

This I/O class renders a gray-scale or RGB stream (via a QFrameBuffer) onto a QLabel widget.

It is intended to be used as a DataSink connected to a DataChannel.

Video frames will be (down or up) scaled to fit into the QLabel widget by preserving the aspect ratio given in VideoESInfo.

The expected format of the gray-scale stream is: 1 byte per pixel.

The expected format of the RGB24 stream is: 3 bytes per pixel, in the order RGB (red, green, blue).

The expected format of the RGB32 stream is: 4 bytes per pixel, in the order BGRA (blue, green, red, alpha). This conforms to the PIX_FMT_RGBA32 format defined in ffmpeg/libavcodec/avcodec.h on little endian architectures.

Author:
Mario Taschwer
Version:
Id
QLabelRenderer.hpp,v 1.18 2006/01/20 15:37:18 mkropfbe Exp

Definition at line 82 of file QLabelRenderer.hpp.

Constructor & Destructor Documentation

QLabelRenderer::QLabelRenderer (  const VideoESInfo *  es,
UncompressedVideoFrame::ColorSpace  colorSpace,
QLabel *  qlabel,
bool  allowUpscaleX = false,
QEvent::Type  eventType = QEvent::User
) 
 

Constructor.

If the parameters are invalid, the open() method will fail.

Parameters:
es elementary stream information about the video stream to be rendered.
colorSpace the color space of the video stream to be rendered; must be one of: UncompressedVideoFrame::ColorSpaceGRAY8, UncompressedVideoFrame::ColorSpaceRGB24, UncompressedVideoFrame::ColorSpaceRGB565 UncompressedVideoFrame::ColorSpaceRGB32.
qlabel the QLabel object to render frames on; if not already set, it will be initialized with a pixmap of the same size.
allowUpscaleX if true, video frames may be upscaled in x-dimension to fit the qlabel, which may result in significant quality loss, since a very simple upscaling algorithm is used.
eventType the custom event type used internally to request displaying a video frame on the qlabel widget. The value of this parameter should be in the range [QEvent::User, QEvent::MaxUser].
Definition at line 56 of file QLabelRenderer.cpp.

References UncompressedVideoFrame::ColorSpace.

00058         : VideoRenderer(_es, colorSpace, qlabel->width(), qlabel->height(), false, true, allowUpscaleX)
00059 {
00060         dprintf_full("QLabelRenderer Construct %s ES %p\n",this->url, this->es);
00061   this->qlabel = qlabel;
00062   if (!qlabel->pixmap()) {
00063     QPixmap pixmap(qlabel->width(), qlabel->height());
00064     pixmap.fill(Qt::black);
00065     qlabel->setPixmap(pixmap);
00066   }
00067   qlabel->pixmap()->setOptimization(QPixmap::BestOptim);
00068   this->eventType = eventType;
00069         strcpy(this->url,"QLabelRenderer");
00070 }

Member Function Documentation

bool QLabelRenderer::open (   )  [virtual]
 

Creates internal frame buffers and checks whether the stream to be rendered matches the widget dimensions.

Returns:
true on success, false on error.
See also:
IO::open()

Reimplemented from VideoRenderer.

Definition at line 90 of file QLabelRenderer.cpp.

References updateDisplayRegion().

00091 {
00092   if (!updateDisplayRegion()) {
00093     state = STREAMERR;
00094     return false;
00095   }
00096   /* initialize frameBuffer */
00097   if (frameBuffer) {
00098     delete frameBuffer;
00099     frameBuffer = NULL;
00100   }
00101   switch (colorSpace) {
00102   case UncompressedVideoFrame::ColorSpaceGRAY8:
00103     frame_info.size = frame_info.width * frame_info.height;
00104     // construct a frame buffer with 8 bpp and a color table of size 256
00105     frameBuffer = new QFrameBuffer(qlabel, 8, 256, true, eventType);
00106     break;
00107   case UncompressedVideoFrame::ColorSpaceRGB24:
00108     frame_info.size = frame_info.width * frame_info.height * 3;
00109     frameBuffer = new QFrameBuffer(qlabel, 24, 0, false, eventType);
00110     break;
00111   case UncompressedVideoFrame::ColorSpaceRGB32:
00112     frame_info.size = frame_info.width * frame_info.height * 4;
00113     frameBuffer = new QFrameBuffer(qlabel, 32, 0, false, eventType);
00114     break;
00115   default:
00116     dprintf_err("QLabelRenderer::open(): invalid color space: %d\n", colorSpace);
00117     state = STREAMERR;
00118     return false;
00119   }
00120 
00121   if (!frameBuffer) {
00122     dprintf_err("QLabelRenderer::open(): QFrameBuffer creation FAILED! (w = %d, h = %d)\n",
00123                 qlabel->width(), qlabel->height());
00124     state = STREAMERR;
00125     return false;
00126   }
00127 
00128         //setVideoFrameBuffer(frameBuffer);
00129   state = OPEN;
00130   framesSeen = 0;
00131   currentFrameNumber = 0;
00132   dprintf_small("QLabelRenderer::open(): initialized frame and display regions:\n"
00133                                                                 "    frame: width = %d, height = %d, size = %d, scaleX = %5.3f, scaleY = %5.3f\n"
00134                                                                 "    display: x(%d:%d), y(%d:%d), width = %d, height = %d\n",
00135                                                                 frame_info.width, frame_info.height, frame_info.size,
00136                                                                 FIXED2DOUBLE(frame_info.scaleX), FIXED2DOUBLE(frame_info.scaleY),
00137                                                                 display_region.left, display_region.left + display_region.width,
00138                                                                 display_region.top, display_region.top + display_region.height,
00139                                                                 display_region.width, display_region.height);
00140   return true;
00141 }

bool QLabelRenderer::updateDisplayRegion (   )  [protected]
 

Update frame_info (except size) and display_region.

This function is not thread-safe, and is internally called by the open() method.

Reimplemented from VideoRenderer.

Definition at line 76 of file QLabelRenderer.cpp.

References VideoRenderer::updateDisplayRegion().

Referenced by open().

00076                                          {
00077         
00078   if (!es || !es->isVisualStream() 
00079       || !qlabel || !qlabel->width() || !qlabel->height()) {
00080     dprintf_err("QLabelRenderer::updateDisplayRegion(): invalid members: es = %p, qlabel = %p\n",
00081                 es, qlabel);
00082                 ::exit(1);
00083     return false;
00084   }
00085 
00086         return VideoRenderer::updateDisplayRegion();
00087 
00088 }

int QLabelRenderer::writeFrame (  Frame *  frm,
ESInfo *  out_es = NULL
)  [virtual]
 

Renders a frame to the destination QLabel widget.

Returns:
1 on success, 0 on error.

Reimplemented from VideoRenderer.

Definition at line 144 of file QLabelRenderer.cpp.

References VideoRenderer::writeFrame().

00145 {
00146         return VideoRenderer::writeFrame(frm);
00147 }

The documentation for this class was generated from the following files: