ffdshow 源代码分析 4：位图覆盖滤镜（滤镜部分Filter）

/*
 *雷霄骅
 *leixiaohua1020@126.com
 *中国传媒大学/数字电视技术
 */

#ifndef _TIMGFILTERBITMAP_H_
#define _TIMGFILTERBITMAP_H_
//叠加一张位图
#include "TimgFilter.h"
#include "Tfont.h"

struct TffPict;
struct TbitmapSettings;
//特别的声明方式 = =
DECLARE_FILTER(TimgFilterBitmap, public, TimgFilter)
private:
//图像
TffPict *bitmap;
//内存
Tbuffer bitmapbuf;
char_t oldflnm[MAX_PATH];
typedef void (*Tblendplane)(const TcspInfo &cspInfo, const unsigned int dx[3], const unsigned int dy[3], unsigned char *dst[3], const stride_t dststride[3], const unsigned char *src[3], const stride_t srcstride[3], int strength, int invstrength);
//注意 这个类有一个实例，名字叫w
class TrenderedSubtitleLineBitmap : public TrenderedSubtitleWordBase
{
public:
    TrenderedSubtitleLineBitmap(void): TrenderedSubtitleWordBase(false) {}
    TffPict *pict;
    const TbitmapSettings *cfg;
	//叠加
    Tblendplane blend;
	//打印
    virtual void print(int startx, int starty /* not used */, unsigned int dx[3], int dy1[3], unsigned char *dstLn[3], const stride_t stride[3], const unsigned char *bmp[3], const unsigned char *msk[3], REFERENCE_TIME rtStart = REFTIME_INVALID) const;
} w;
TrenderedSubtitleLine l;
//是TrenderedSubtitleLine的一个vector
TrenderedSubtitleLines ls;
int oldmode;
//几种叠加方式
template<class _mm> static void blend(const TcspInfo &cspInfo, const unsigned int dx[3], const unsigned int dy[3], unsigned char *dst[3], const stride_t dststride[3], const unsigned char *src[3], const stride_t srcstride[3], int strength, int invstrength);
template<class _mm> static void add(const TcspInfo &cspInfo, const unsigned int dx[3], const unsigned int dy[3], unsigned char *dst[3], const stride_t dststride[3], const unsigned char *src[3], const stride_t srcstride[3], int strength, int invstrength);
template<class _mm> static void darken(const TcspInfo &cspInfo, const unsigned int dx[3], const unsigned int dy[3], unsigned char *dst[3], const stride_t dststride[3], const unsigned char *src[3], const stride_t srcstride[3], int strength, int invstrength);
template<class _mm> static void lighten(const TcspInfo &cspInfo, const unsigned int dx[3], const unsigned int dy[3], unsigned char *dst[3], const stride_t dststride[3], const unsigned char *src[3], const stride_t srcstride[3], int strength, int invstrength);
template<class _mm> static void softlight(const TcspInfo &cspInfo, const unsigned int dx[3], const unsigned int dy[3], unsigned char *dst[3], const stride_t dststride[3], const unsigned char *src[3], const stride_t srcstride[3], int strength, int invstrength);
template<class _mm> static void exclusion(const TcspInfo &cspInfo, const unsigned int dx[3], const unsigned int dy[3], unsigned char *dst[3], const stride_t dststride[3], const unsigned char *src[3], const stride_t srcstride[3], int strength, int invstrength);
//获取叠加方式
template<class _mm> static Tblendplane getBlend(int mode);
protected:
virtual bool is(const TffPictBase &pict, const TfilterSettingsVideo *cfg);
virtual uint64_t getSupportedInputColorspaces(const TfilterSettingsVideo *cfg) const
{
    return FF_CSPS_MASK_YUV_PLANAR;
}
public:
TimgFilterBitmap(IffdshowBase *Ideci, Tfilters *Iparent);
virtual ~TimgFilterBitmap();
//核心函数（Filter配置信息队列，图像，配置信息）
virtual HRESULT process(TfilterQueue::iterator it, TffPict &pict, const TfilterSettingsVideo *cfg0);
};

#endif

再来看看TimgFilterBitmap.cpp

这个文件本身代码量是比较大的，只是其他部分我都还没有仔细分析，确实没那没多时间。。。在这里仅简要分析一下最核心的函数process()。正是这个函数真正实现了滤镜的功能。在这个位图叠加滤镜中，process()实现了位图在视频上面的叠加功能。

//核心函数（Filter配置信息队列，图像，配置信息）
HRESULT TimgFilterBitmap::process(TfilterQueue::iterator it, TffPict &pict, const TfilterSettingsVideo *cfg0)
{
	//都有这一句= =
    if (is(pict, cfg0)) {
		//Bitmap的配置信息
        const TbitmapSettings *cfg = (const TbitmapSettings*)cfg0;
        init(pict, cfg->full, cfg->half);
        unsigned char *dst[4];
        bool cspChanged = getCurNext(FF_CSPS_MASK_YUV_PLANAR, pict, cfg->full, COPYMODE_DEF, dst);
		//处理
        if (!bitmap || cspChanged || stricmp(oldflnm, cfg->flnm) != 0) {
            ff_strncpy(oldflnm, cfg->flnm, countof(oldflnm));
            if (bitmap) {
                delete bitmap;
            }
			//新建一张图
			//通过cfg->flnm路径
			//载入bitmapbuf
            bitmap = new TffPict(csp2, cfg->flnm, bitmapbuf, deci);
			//3个颜色分量？
            for (int i = 0; i < 3; i++) {
                w.dx[i] = bitmap->rectFull.dx >> bitmap->cspInfo.shiftX[i];
                w.dy[i] = bitmap->rectFull.dy >> bitmap->cspInfo.shiftY[i];
                w.bmp[i] = bitmap->data[i];
                w.bmpmskstride[i] = bitmap->stride[i];
            }
            w.dxChar = w.dx[0];
            w.dyChar = w.dy[0];
        }

        if (bitmap->rectFull.dx != 0) {
            if (oldmode != cfg->mode)
                if (Tconfig::cpu_flags & FF_CPU_SSE2) {
					//获取叠加方式（SSE2）
					//在cfg的mode里
                    w.blend = getBlend<Tsse2>(oldmode = cfg->mode);
                } else {
					//获取叠加方式（MMX）
                    w.blend = getBlend<Tmmx>(oldmode = cfg->mode);
                }
			//输出到屏幕上的设置
            TprintPrefs prefs(deci, NULL);
			//各种参数
            prefs.dx = dx2[0];
            prefs.dy = dy2[0];
            prefs.xpos = cfg->posx;
            prefs.ypos = cfg->posy;
			//模式不同的话
            if (cfg->posmode == 1) {
                prefs.xpos *= -1;
                prefs.ypos *= -1;
            }
            prefs.align = cfg->align;
            prefs.linespacing = 100;
            prefs.csp = pict.csp;
            w.pict = &pict;
            w.cfg = cfg;
			//打印，需要用到TprintPrefs
            ls.print(prefs, dst, stride2);
        }
    }
	//最后都是这一句？
    return parent->processSample(++it, pict);
}

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ffdshow 源代码分析 4：位图覆盖滤镜（滤镜部分Filter）

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