EasyPlayerPro Windows播放器电子放大/局部放大播放功能实现

背景描述

在视频监控软件中，我们看到很多的软件都有电子放大功能, 按住鼠标左键不放，框选一个区域，再松开鼠标左键，即对选中的区域进行放大显示, 且可以重复该操作，逐步放大所需显示的区域, 有没有觉得，这个功能在视频监控软件中还是有他的用武地. 今天我们就来实现该功能；

实现流程

//设置电子放大起起始点
int     SetElectronicZoomStartPoint(int channelId, float fXPercent, float fYPercent, unsigned char showBox);
//设置电子放大结束点(在鼠标移动过程中可一直调用该函数)
int     SetElectronicZoomEndPoint(int channelId, float fXPercent, float fYPercent);
//设置是否放大显示
int     SetElectronicZoom(int channelId, int zoomIn);
//复位
void    ResetElectronicZoom(int channelId);
//直接设置显示区域,用于电子放大, 在某些场合, 需要直接进行缩放显示, 即可调用该函数实现
int     SetRenderRect(int channelId, LPRECT lpSrcRect);

代码实现

int ChannelManager::ElectronicZoomProcess(MEDIA_VIDEO_CHANNEL_OBJ_T *pMediaChannel, EASY_FRAME_INFO *frameInfo)
{
if (NULL == pMediaChannel)              return 0;
if (NULL == frameInfo)                  return 0;

ELECTRONIC_ZOOM_T *pElectoricZoom = pMediaChannel->pElectoricZoom;
if (NULL == pElectoricZoom)             return 0;

int nLeft = 0, nTop = 0, nRight = 0, nBottom = 0;
if (pElectoricZoom->zoomIn >= 0x01)
{
    RECT rcClient;
    GetClientRect(pMediaChannel->mediaDisplay.hWnd, &rcClient);

    float fLeftPercent =    pElectoricZoom->fStartPointX;
    float fTopPercent  =    pElectoricZoom->fStartPointY;
    float fRightPercent =   pElectoricZoom->fEndPointX;
    float fBottomPercent  = pElectoricZoom->fEndPointY;

    if (fRightPercent > fLeftPercent && fBottomPercent > fTopPercent)               //逐步放大
    {
        if (pElectoricZoom->fVideoWidth > 0)
        {
            int video_width = (int)pElectoricZoom->fVideoWidth;
            int video_height= (int)pElectoricZoom->fVideoHeight;
            nLeft = (int)((float)video_width / 100.0f * fLeftPercent);
            nTop  = (int)((float)video_height/ 100.0f * fTopPercent);
            nRight = (int)((float)video_width / 100.0f * fRightPercent);
            nBottom  = (int)((float)video_height/ 100.0f * fBottomPercent);

            if (nRight > nLeft && nBottom > nTop)
            {
                pElectoricZoom->fVideoWidth = (float)(nRight - nLeft);
                pElectoricZoom->fVideoHeight = (float)(nBottom - nTop);

                nLeft = pElectoricZoom->startVideoLeft + nLeft;
                nTop = pElectoricZoom->startVideoTop + nTop;
                nRight = pElectoricZoom->startVideoLeft + nRight;
                nBottom = pElectoricZoom->startVideoTop + nBottom;

                pElectoricZoom->startVideoLeft = nLeft;
                pElectoricZoom->startVideoTop = nTop;

                if (pElectoricZoom->zoomIndex + 1 <MAX_ZOOM_IN_TIMES)
                {
                    SetRect(&pElectoricZoom->zoomParam[pElectoricZoom->zoomIndex].rect, nLeft, nTop, nRight, nBottom);
                    pElectoricZoom->zoomParam[pElectoricZoom->zoomIndex].fVideoWidth = pElectoricZoom->fVideoWidth;
                    pElectoricZoom->zoomParam[pElectoricZoom->zoomIndex].fVideoHeight = pElectoricZoom->fVideoHeight;
                    pElectoricZoom->zoomParam[pElectoricZoom->zoomIndex].startVideoLeft = pElectoricZoom->startVideoLeft;
                    pElectoricZoom->zoomParam[pElectoricZoom->zoomIndex].startVideoTop = pElectoricZoom->startVideoTop;
                    pElectoricZoom->zoomIndex ++;
                }
            }
            else
            {
                int idx = pElectoricZoom->zoomIndex-2;
                if (idx > 0)
                {
                    nLeft = pElectoricZoom->zoomParam[idx].rect.left;
                    nTop = pElectoricZoom->zoomParam[idx].rect.top;
                    nRight = pElectoricZoom->zoomParam[idx].rect.right;
                    nBottom = pElectoricZoom->zoomParam[idx].rect.bottom;

                    pElectoricZoom->fVideoWidth = pElectoricZoom->zoomParam[idx].fVideoWidth;
                    pElectoricZoom->fVideoHeight = pElectoricZoom->zoomParam[idx].fVideoHeight;
                    pElectoricZoom->startVideoLeft = pElectoricZoom->zoomParam[idx].startVideoLeft;
                    pElectoricZoom->startVideoTop = pElectoricZoom->zoomParam[idx].startVideoTop;
                }
            }
        }
        else
        {
            int video_width = frameInfo->width;
            int video_height= frameInfo->height;
            nLeft = (int)((float)video_width / 100.0f * fLeftPercent);
            nTop  = (int)((float)video_height/ 100.0f * fTopPercent);
            nRight = (int)((float)video_width / 100.0f * fRightPercent);
            nBottom  = (int)((float)video_height/ 100.0f * fBottomPercent);

            pElectoricZoom->startVideoLeft = nLeft;
            pElectoricZoom->startVideoTop = nTop;
            pElectoricZoom->fVideoWidth = (float)(nRight - nLeft);
            pElectoricZoom->fVideoHeight = (float)(nBottom - nTop);

            SetRect(&pElectoricZoom->zoomParam[0].rect, nLeft, nTop, nRight, nBottom);
            pElectoricZoom->zoomParam[0].fVideoWidth = pElectoricZoom->fVideoWidth;
            pElectoricZoom->zoomParam[0].fVideoHeight = pElectoricZoom->fVideoHeight;
            pElectoricZoom->zoomParam[0].startVideoLeft = pElectoricZoom->startVideoLeft;
            pElectoricZoom->zoomParam[0].startVideoTop = pElectoricZoom->startVideoTop;
            pElectoricZoom->zoomIndex ++;
        }
    }
    else
    {
        if (pElectoricZoom->zoomIndex > 1)
        {
            int idx = pElectoricZoom->zoomIndex-2;

            nLeft = pElectoricZoom->zoomParam[idx].rect.left;
            nTop = pElectoricZoom->zoomParam[idx].rect.top;
            nRight = pElectoricZoom->zoomParam[idx].rect.right;
            nBottom = pElectoricZoom->zoomParam[idx].rect.bottom;

            pElectoricZoom->fVideoWidth = pElectoricZoom->zoomParam[idx].fVideoWidth;
            pElectoricZoom->fVideoHeight = pElectoricZoom->zoomParam[idx].fVideoHeight;
            pElectoricZoom->startVideoLeft = pElectoricZoom->zoomParam[idx].startVideoLeft;
            pElectoricZoom->startVideoTop = pElectoricZoom->zoomParam[idx].startVideoTop;

            pElectoricZoom->zoomIndex --;
        }
        else
        {
            pElectoricZoom->fVideoWidth = 0.0f;

            nLeft = 0;
            nTop = 0;
            nRight = frameInfo->width;
            nBottom = frameInfo->height;

            pElectoricZoom->zoomIndex = 0;
        }
    }


    RECT rcSrc;
    SetRect(&rcSrc, nLeft, nTop, nRight, nBottom);
    CopyRect(&pMediaChannel->mediaDisplay.rcSrcRender, &rcSrc);

    pElectoricZoom->zoomIn --;
}

return 0;
}

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