ExportImage bug

It seems that the ExportImage function in the SDK has a bug. If I try to save with say the jpeg image filter and if the surface has an alpha channel, then the image will not be saved.

I know the filter works because I can save to the format if the surface does not contain an alpha channel, but as soon as I add an alpha channel, the image does not get saved.

If ExportImage can not be fixed then perhaps there should be a way to determine if a specific filter can handle alpha channels and if not then I could take action to remove the alpha channel from a temp surface and save that.

Thanks.

Odd... I don't see anything in the source code that would prevent the routine to work in this case. I'll take a look.

PS: the only filters that support alpha channels are PNG and TGA.

I know this, but if I try to save a surface that has an alpha channel to a format that doesn't support them, then I expect the alpha channel to just not be saved..

Yes, I said I didn't see anything that could cause this in the routine, so I'll try to take a look with a debugger to see what happens when I can find 5 minutes free.

Thanks. It might be a problem with the save method of the image filter class as well.

Once this is fixed I can release my new Overlay extension :).

vortex, wasnt it only BMP and PNG that would save when we tested?

Yeah. The reason that I think the bug is in the save method of the image filter class is because ExportImage returns false when it can't create the image (I know this to be true) and true when it can.

In the code for ExportImage we see:

[pre]
if ( !pFilter.CanSave() )
return FALSE;
[/pre]

and that might also be a cause of the problem. Perhaps the code for CanSave is flawed, or in this line:

[pre]
int error = pFilter.Save(pFileName, pbuf, nWidth, nHeight, nDepth, pSaveSf->GetPitch(), (LPLOGPALETTE)pSaveSf->GetPalette(), pAlpha, nAlphaPitch);
[/pre]

EDIT: hmm seems that the error that it returns is an Unsupported depth one. Apparently nDepth gets set to 32 because the surface has alpha channel ,and then the filter doesn't support this depth so it just throws an error.

Any luck fixing this? I would like to get this project out the door so I can start working on others.

Thanks.

Maybe when you get an error, you can try to use the same filter without alphachannel ? and if the saveimage failed again, you throw an error...

Quote:

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Any luck fixing this?

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I can't fix it before the next build is released, in a few weeks.

In the meantime I suggest that if the surface has an alphachannel and the filter ID is not the PNG or TGA filter ID, you clone the surface to a new surface without alpha channel.

Yves.

I've found a new bug in the this overlay :
- when pasting a rotated active object in overlay, the active is pasted at original angle.
- the image pasted of the active object has a column of pixel which is left near the right)...

I just spent 3 hours trying to work around the Export Image bug with no luck. Anything I try only allows me to save to like 2 filters or so.

Overlay development is on hold until this is fixed.

Err... can't you just compare the image filter and then create a surface without alpha channel if it's JPEG? Sounds easy... what's the problem?

I tried and it doesn't work. Sometimes the image doesn't even save without alpha channel attached.

There is definately some sort of problem with ExportImage and I can't release Overlay until it is fixed.

This is the code:

Code:

---

short WINAPI DLLExport actSaveImage(LPRDATA rdPtr, long param1, long param2)
{
        fprh        rhPtr = rdPtr->rHo.hoAdRunHeader;
        CImageFilterMgr* pImgMgr = rhPtr->rh4.rh4Mv->mvImgFilterMgr;
        DWORD mFilter=NULL;
        //pImgMgr=pImgMgr->CreateInstance();
#if defined(VITALIZE)
        return 0;
#else
        if(rdPtr->runSurface!= NULL)
        {
                mFilter=FindFilter(rdPtr,pImgMgr,(LPCSTR)param1);

                if(!ExportImage(pImgMgr,(LPCSTR)param1,rdPtr->runSurface,mFilter))
                {
                        LPSURFACE pProto = NULL;
                        int depth=24;
                        CImageFilter pFilter(pImgMgr);
                        pFilter.UseSpecificFilterID(mFilter);

                        if ( GetSurfacePrototype(&pProto, depth, ST_MEMORYWITHDC, SD_DIB) )
                        {
                                // OK
                                cSurface * wNA = new cSurface();
                                if (wNA!= NULL)
                                {
                                        wNA->Create(rdPtr->swidth,rdPtr->sheight,pProto);
                                        rdPtr->runSurface->Blit(*wNA,0,0,BMODE_OPAQUE,BOP_COPY,0);
                                        ExportImage(pImgMgr,(LPCSTR)param1,wNA,mFilter);
                                        delete wNA;
                                }

                        }
                }
        }

        return 0;
#endif
}

---

I can always save to PNG files, I can save to JPEG files, I can't save to GIF files and I can't save to JPG files. I also can't save to BMP files.

Here is the code to FindFilter:

Code:

---

DWORD FindFilter(LPRDATA rdPtr,CImageFilterMgr *pImgMgr,LPCSTR filepath)
{
        std::string FileStr=filepath;
        std::string::size_type findex = std::string::npos;
        int index=-1;
        int bmpindex=0;
        findex=FileStr.find_last_of('.')+1;
        for(int i=0;i<pImgMgr->GetFilterCount();i++)
        {
                if(pImgMgr->DoesFilterSupportImages(i))
                {
                        LPCSTR*mFileExts=pImgMgr->GetFilterExts(i);
                        LPCSTR ExtStr=NULL;
                        ExtStr=(*mFileExts++);
                        while(ExtStr!=NULL)
                        {
                                if(std::string(ExtStr)==std::string("bmp"))
                                        bmpindex=i;
                                if(FileStr.substr(findex)==std::string(ExtStr))
                                {
                                        index=i;
                                        break;
                                }
                                ExtStr=(*mFileExts++);
                        }
                        if(index!=-1)
                                break;
                }
        }
        if(index==-1)
                index=bmpindex;
        return pImgMgr->GetFilterID(index);
}

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I have tested the FindFilter function and it works without flaw. It is the ExportImage function that is the problem :( .

OK, I'll take a look at the code.

Quote:

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I can't save to GIF files

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Yes, the GIF and TGA filters can't save pictures. The Export feature is implemented only in the PNG, JPEG and BMP filters.

Eh why? Also why not add a function "DoesFilterSupportImageExport" or something so we can tell which filters will even allow for export?

If I had access to the filter SDK then I could develop a DevIL SDK that could support a ton of image formats with import and export.

Time problem maybe :) as the TGA and GIF filters use my own routines while PNG and JPEG use standard libraries where Save is implemented.

Just use DevIL then ;).

THere is a CanSave function in the CImageFilter class.

Ah. I guess DevIL won't work like I thought anyway, apparently they want you to release the source to it :(. I guess that isn't a concern when you are making freeware.

EDIT: Anyway I hope this can be fixed soon.

Good Luck and thanks for the help :) .

I would recommend looking into GDI+. Adding support for it would make saving and loading images a ton easier and it would give the cSurface class a lot more graphics capabilities. It might cause some issues but the DLL I have on my computer is from 2001 so I can imagine that it wouldn't be too much to ask for users to download the redistributable if they have problems (And that would only be for machines running Windows 98..)

We could distribute the DLL in a patch and people could provide a version in their product installers just to ensure people have it..

I don't see that using techology just because it works without anything extra in Windows 98 is worth the loss in functionality and the increased hassle. With the release of Windows Vista we need to adapt "new" technologies if the product is to survive. Sometimes that means needing to have people using Windows 98 and Windows 2000 get a DLL (that most if not all already have as a ton of applications use GDI+) but with the release of Windows Vista I think it would be a good idea.

EDIT: Also I checked in depth and DevIL can be used in commercial projects... So a combo of both DevIL and GDI+ should allow for much great flexibility when it comes to images. Between the two there is support to export png, gif, tga, jpg, bmp, ect.

About your code, something like that should work (I say "should" because I haven't tried to compile it) :

Code:

---

short WINAPI DLLExport actSaveImage(LPRDATA rdPtr, long param1, long param2)
{
        fprh        rhPtr = rdPtr->rHo.hoAdRunHeader;
        CImageFilterMgr* pImgMgr = rhPtr->rh4.rh4Mv->mvImgFilterMgr;
        DWORD mFilter=NULL;
        //pImgMgr=pImgMgr->CreateInstance();
#if defined(VITALIZE)
        return 0;
#else
        if(rdPtr->runSurface!= NULL)
        {
                mFilter=FindFilter(rdPtr,pImgMgr,(LPCSTR)param1);

                CImageFilter pFilter(pImgMgr);
                pFilter.UseSpecificFilterID(mFilter);
                if ( !pFilter.CanSave() )
                        mFilter = FILTERID_BMP;

                cSurface* pSf = rdPtr->runSurface;
                if ( pSf->HasAlpha() && mFilter != FILTERID_PNG && mFilter != FILTERID_TGA )
                {
                        LPSURFACE pProto = NULL;
                        GetSurfacePrototype(&pProto, 24, ST_MEMORYWITHDC, SD_DIB) )
                        pSf = new cSurface();
                        pSf->Create(rdPtr->swidth,rdPtr->sheight,pProto);
                        rdPtr->runSurface->Blit(*pSf,0,0,BMODE_OPAQUE,BOP_COPY,0,0);
                }

                ExportImage(pImgMgr,(LPCSTR)param1,pSf,mFilter);

                if ( pSf != rdPtr->runSurface )
                        delete pSf;
        }

        return 0;
#endif
}

---

Also, possible problem in the FindFilter function: in the string class is the operator '==' case sensitive? if so there is a problem, you should convert the input string to low case.

I will test the code tommorow. Only thing is, doesn't testing mFilter for FILTERID_PNG and FILTERID_TGA after testing to see if it can save and if not setting it to FILTERID_BMP kind of moot? Obviously if the two filters can't save images then CanSave returns false and mFilter isn't TGA or PNG anymore...

Also you are right about the FindFilter problem and I already knew about it. For testing purposes I have only been using lowercase file extensions though.

Thanks.

Quote:

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Obviously if the two filters can't save images then CanSave returns false and mFilter isn't TGA or PNG anymore...

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No, TGA and PNG can save image files. This test is just to avoid images with alpha channels to be saved with filters that don't support alpha channels, until the bug is fixed.

Quote:

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Originally Posted by Yves

Yes, the GIF and TGA filters can't save pictures

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Quote:

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Originally Posted by Yves

No, TGA and PNG can save image files

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Ok so TGA can both save and not save pictures? ;)

I misunderstood the code because I thought that TGA pictures couldn't be saved O_o. Sorry about that.

Ah LOL, you are right, sorry... TGA can't save files. Replace this line by if ( pSf->HasAlpha() && mFilter != FILTERID_PNG ).

It's ok ^^. Just wanted to be sure.

Thanks.