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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