GDIPLUS::Image: how save it on a file in stream way?

**Elysia** · 10-03-2015

>>char *pBuff = new char[buffsize];
Use a vector, e.g.:
std::vectpr<char> Buffer(buffsize);
new [] shall also be paired with delete [], not delete.

>>lhs.write(reinterpret_cast<char*>(&buffsize),siz eof(int));
Type of variable buffsize can change; use sizeof(buffsize) instead.

>>lhs.write(pBuff,sizeof(pBuff));
sizeof of a pointer is 4 or 8 bytes. Use a vector and use vector.size(), e.g. Buff.size(). You are writing the incorrect amount of characters.

>>lhs.read(reinterpret_cast<char*>(&streamsize), sizeof(ULONG));
You wrote an int and now you are reading an ULONG? That's asking for trouble. If you write an int, read an int.

>>lhs.read(reinterpret_cast<char*>(&hg),sizeof(str eamsize));
Why do you think this will work? hg is not a buffer. Furthermore, the number of characters to read is NOT sizeof(streamsize). You are guessing! You need to stop guessing. If you write 4 + N bytes, you need to read 4 + N bytes back. It's that simple. Try a simple example first to see that what you get back is what you wrote!

**joaquim** · 10-03-2015

Originally Posted by Elysia

>>char *pBuff = new char[buffsize];
Use a vector, e.g.:
std::vectpr<char> Buffer(buffsize);
new [] shall also be paired with delete [], not delete.

>>lhs.write(reinterpret_cast<char*>(&buffsize),siz eof(int));
Type of variable buffsize can change; use sizeof(buffsize) instead.

>>lhs.write(pBuff,sizeof(pBuff));
sizeof of a pointer is 4 or 8 bytes. Use a vector and use vector.size(), e.g. Buff.size(). You are writing the incorrect amount of characters.

>>lhs.read(reinterpret_cast<char*>(&streamsize), sizeof(ULONG));
You wrote an int and now you are reading an ULONG? That's asking for trouble. If you write an int, read an int.

>>lhs.read(reinterpret_cast<char*>(&hg),sizeof(str eamsize));
Why do you think this will work? hg is not a buffer. Furthermore, the number of characters to read is NOT sizeof(streamsize). You are guessing! You need to stop guessing. If you write 4 + N bytes, you need to read 4 + N bytes back. It's that simple. Try a simple example first to see that what you get back is what you wrote!

i'm trying

now i get a memory leak:

Code:

friend std::ostream& operator << (std::ostream& lhs, const image& rhs)
    {

        //Create an empty IStream:
        IStream* pIStream = nullptr;
        HGLOBAL hg=NULL;
        if(CreateStreamOnHGlobal(hg, TRUE, (LPSTREAM*)&pIStream)!=S_OK)
            DebugText("error on creating an empty IStream");

        //choose image format for save it on IStream:
        // Get encoder class id for jpg compression
        // for other compressions use
        //    image/bmp
        //    image/jpeg
        //    image/gif
        //    image/tiff
        //    image/png
        CLSID pngClsid;
        if(GetEncoderClsid(L"image/gif", &pngClsid)!=S_OK)
            DebugText("error on image format");

        // Setup encoder parameters
        EncoderParameters encoderParameters;
        encoderParameters.Count = 1;
        encoderParameters.Parameter[0].Guid = EncoderQuality;
        encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;
        encoderParameters.Parameter[0].NumberOfValues = 1;

        // setup compression level
        ULONG quality = 50;
        encoderParameters.Parameter[0].Value = &quality;

        //  Save the image to the stream
        Status SaveStatus = rhs.img->Save(pIStream, &pngClsid, &encoderParameters);
        if(SaveStatus != Ok)
        {
            pIStream->Release();
            DebugText("error on saving to IStream");
        }

        //getting the stream size:
        if(GetHGlobalFromStream(pIStream,&hg)!=S_OK)
            DebugText("error on IStream information");

        int buffsize=GlobalSize(&hg);

        std::vector<char> pBuff(buffsize);
        ULONG ulBytesRead;

        //Read the stream to pBuff
        if(pIStream->Read(pBuff.data(),buffsize, &ulBytesRead)!=S_OK)
            DebugText("error on saving IStream to buffer");

        //write the stream size on file
        lhs.write(reinterpret_cast<char*>(&buffsize),sizeof(buffsize));

        //write pBuff data on file
        lhs.write(pBuff.data(),pBuff.size());

        //clean resources
        pIStream->Release();

        return lhs;
    }

    friend std::istream& operator >> (std::istream& lhs, image& rhs)
    {
        //getting IStream size:
        int streamsize;
        lhs.read(reinterpret_cast<char*>(&streamsize), sizeof(streamsize));

        IStream* pIStream = nullptr;

        // Create stream with 0 size
        HGLOBAL hg=NULL;
        lhs.read(reinterpret_cast<char*>(&hg),sizeof(hg));
        if(CreateStreamOnHGlobal(&hg, TRUE, (LPSTREAM*)&pIStream)!=S_OK)
            DebugText("error on creating an empty IStream");

        //reading IStream on Image class:
        if(rhs.img->FromStream(pIStream,FALSE)!=S_OK)
            DebugText("error reading stream to Image");

        //realease resources:
        pIStream->Release();
        return lhs;
    }

**Codeplug** · 10-03-2015

Line 76 - No. Read the documentation on how to use an HGLOBAL.

HGLOBAL is just a handle. I makes not sense to try and read/write a handle value.

Why don't you just read it into a vector buffer and get it working? Once working, then work on removing the vector on both sides and use the memory represented by the the HGLOBAL directly.

>>theres 2 things that i didn't understand:
eg. "rhs.pngClsid" and "rhs.encoderParameters" - where these have been pre-configured by the caller before calling operator<<.

gg

**Elysia** · 10-03-2015

joaquim, what is it you fail to grasp? We already told you hg is not a buffer and yet you read into it anyway.

Like I said, start with a simpler example. Write a string, read it back. Make sure you read it back correctly. Then you can tackle this problem.

**joaquim** · 10-04-2015

Originally Posted by Elysia

joaquim, what is it you fail to grasp? We already told you hg is not a buffer and yet you read into it anyway.

Like I said, start with a simpler example. Write a string, read it back. Make sure you read it back correctly. Then you can tackle this problem.

using the string, like you have seen on other thread it's easy... but not these

Code:

friend std::ostream& operator << (std::ostream& lhs, const image& rhs)
    {

        //Create an empty IStream:
        IStream* pIStream = nullptr;
        HGLOBAL hg=NULL;
        if(CreateStreamOnHGlobal(hg, FALSE, (LPSTREAM*)&pIStream)!=S_OK)
            DebugText("error on creating an empty IStream");

        //choose image format for save it on IStream:
        // Get encoder class id for jpg compression
        // for other compressions use
        //    image/bmp
        //    image/jpeg
        //    image/gif
        //    image/tiff
        //    image/png
        CLSID pngClsid;
        GetEncoderClsid(L"image/gif", &pngClsid);

        // Setup encoder parameters
        EncoderParameters encoderParameters;
        encoderParameters.Count = 1;
        encoderParameters.Parameter[0].Guid = EncoderQuality;
        encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;
        encoderParameters.Parameter[0].NumberOfValues = 1;

        // setup compression level
        ULONG quality = 50;
        encoderParameters.Parameter[0].Value = &quality;

        //  Save the image to the stream

        if(rhs.img->Save(pIStream, &pngClsid, &encoderParameters) != Ok)
        {
            pIStream->Release();
            DebugText("error on saving to IStream");
        }

        //getting the stream size:
        int buffsize=GlobalSize(&hg);

        char *pBuff = new char[buffsize];
        ULONG ulBytesRead;

        //Read the stream to pBuff
        if(pIStream->Read(pBuff,buffsize, &ulBytesRead)!=S_OK)
            DebugText("error on saving IStream to buffer");

        //write the stream size on file
        lhs << buffsize;

        //write pBuff data on file
        lhs << pBuff;

        //clean resources
        delete pBuff;
        pIStream->Release();

        return lhs;
    }

    friend std::istream& operator >> (std::istream& lhs, image& rhs)
    {
        //getting IStream size:
        int streamsize;
        lhs.read(reinterpret_cast<char*>(&streamsize), sizeof(streamsize));

        IStream* pIStream = nullptr;

        // Create stream with 0 size
        HGLOBAL hg= ::GlobalAlloc(GMEM_MOVEABLE,streamsize);
        GlobalLock(hg);
        lhs.read(reinterpret_cast<char*>(&hg),sizeof(streamsize));
        GlobalUnlock(hg);

        if(CreateStreamOnHGlobal(&hg, TRUE, (LPSTREAM*)&pIStream)!=S_OK)
            DebugText("error on creating an empty IStream");

        //reading IStream on Image class:
        if(rhs.img->FromStream(pIStream,TRUE)!=S_OK)
            DebugText("error reading stream to Image");

        //realease resources:
        pIStream->Release();
        GlobalFree(hg);
        return lhs;
    }

i'm sorry, but i'm trying, but these continues confused

i'm sorry

**Codeplug** · 10-04-2015

>> but these continues confused
What are you confused about?

gg

**joaquim** · 10-05-2015

Originally Posted by Codeplug

>> but these continues confused
What are you confused about?

gg

you(both) told me for i do in these way:
(for save it on file)
1 - create an empty IStream:

Code:

IStream* pIStream = nullptr;
        HGLOBAL hg=NULL;
        if(CreateStreamOnHGlobal(hg, FALSE, (LPSTREAM*)&pIStream)!=S_OK)

2 - save the Image to IStream:

Code:

CLSID pngClsid;
        GetEncoderClsid(L"image/gif", &pngClsid);

        // Setup encoder parameters
        EncoderParameters encoderParameters;
        encoderParameters.Count = 1;
        encoderParameters.Parameter[0].Guid = EncoderQuality;
        encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;
        encoderParameters.Parameter[0].NumberOfValues = 1;

        // setup compression level
        ULONG quality = 50;
        encoderParameters.Parameter[0].Value = &quality;

        //  Save the image to the stream

        if(rhs.img->Save(pIStream, &pngClsid, &encoderParameters) != Ok)

3 - getting IStream size:

Code:

int buffsize=GlobalSize(&hg);

4 - i must save the IStream on a buffer:

Code:

char *pBuff = new char[buffsize];
        ULONG ulBytesRead;

        //Read the stream to pBuff
        if(pIStream->Read(pBuff,buffsize, &ulBytesRead)!=S_OK)

5 -now save the buffer size on file and the buffer:

Code:

//write the stream size on file
        lhs << buffsize;

        //write pBuff data on file
        lhs << pBuff;

6 - we must delete the resources:

Code:

//clean resources
        delete[] pBuff;
        pIStream->Release();

PS: i know the file it's created, what i don't have sure if the data it's right on file.

now for read it from a file:

1 - create an empty IStream:

Code:

IStream* pIStream = nullptr;
        HGLOBAL hg=NULL;
        if(CreateStreamOnHGlobal(hg, FALSE, (LPSTREAM*)&pIStream)!=S_OK)

2 - read the buffer(inclued the buffer size) from the file to a new IStream:

Code:

/getting IStream size:
        int streamsize;
        lhs.read(reinterpret_cast<char*>(&streamsize), sizeof(streamsize));

        IStream* pIStream = nullptr;

        // Create stream with 0 size
        HGLOBAL hg= ::GlobalAlloc(GMEM_MOVEABLE,streamsize);
        GlobalLock(hg);
        lhs.read(reinterpret_cast<char*>(&hg),sizeof(streamsize));
        GlobalUnlock(hg);

        if(CreateStreamOnHGlobal(&hg, TRUE, (LPSTREAM*)&pIStream)!=S_OK)
            DebugText("error on creating an empty IStream");

(i don't get any error)
3 - reading IStream to Image class:

Code:

if(rhs.img->FromStream(pIStream,TRUE)!=S_OK)
            DebugText("error reading stream to Image");

4 - clean resources:

Code:

//realease resources:
        pIStream->Release();
        GlobalFree(hg);

i see what i must do(unless i miss something). but if the FromStream() give me an error, means the IStream isn't right. i don't understand why.. i'm totaly confused.
sorry to all, but i'm trying to understand and see what isn't right

**adeyblue** · 10-06-2015

This:

Code:

GlobalLock(hg);        
lhs.read(reinterpret_cast<char*>(&hg),sizeof(streamsize));

wants to be something like this. Otherwise all you're doing is overwriting the HGLOBAL.

Code:

void* p = GlobalLock(hg);        
lhs.read(static_cast<char*>(p), streamsize);

This

Code:

if(CreateStreamOnHGlobal(&hg, TRUE, (LPSTREAM*)&pIStream)!=S_OK)

Also wants to lose the first ampersand since it only takes a HGLOBAL, not a pointer to one

Code:

if(CreateStreamOnHGlobal(hg, TRUE, (LPSTREAM*)&pIStream)!=S_OK)

**Codeplug** · 10-06-2015

>> if(GetHGlobalFromStream(pIStream,&hg)!=S_OK)
Why was that removed?

>> int buffsize=GlobalSize(&hg);
That does not take a pointer to HGLOBAL either.

gg

**joaquim** · 10-06-2015

thanks to both about correct me.
but Codeplug(thanks for that. i'm confused and sometimes i can do mistakes.. sorry about that) how can i get the IStream size?
i'm reading these: https://msdn.microsoft.com/en-us/lib...=vs.85%29.aspx
but: "error: 'IStream_Size' was not declared in this scope"
i had include the Shlwapi.h file, but seems not be used with GNU or something

**Codeplug** · 10-06-2015

In my SDK, you only get the IStream_Size declaration if:
#if (_WIN32_IE >= _WIN32_IE_IE501)

But you don't need it. When writing, GlobalSize() give you the size of the stream. When reading, the istream itself contains the size.

gg

**joaquim** · 10-06-2015

Originally Posted by Codeplug

In my SDK, you only get the IStream_Size declaration if:
#if (_WIN32_IE >= _WIN32_IE_IE501)

But you don't need it. When writing, GlobalSize() give you the size of the stream. When reading, the istream itself contains the size.

gg

see what i did now:

Code:

//Create an empty IStream:
        IStream* pIStream = nullptr;
        HGLOBAL hg=NULL;
        if(CreateStreamOnHGlobal(hg, FALSE, (LPSTREAM*)&pIStream)!=S_OK)
            DebugText("error on creating an empty IStream");

        //choose image format for save it on IStream:
        // Get encoder class id for jpg compression
        // for other compressions use
        //    image/bmp
        //    image/jpeg
        //    image/gif
        //    image/tiff
        //    image/png
        CLSID pngClsid;
        GetEncoderClsid(L"image/gif", &pngClsid);

        // Setup encoder parameters
        EncoderParameters encoderParameters;
        encoderParameters.Count = 1;
        encoderParameters.Parameter[0].Guid = EncoderQuality;
        encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;
        encoderParameters.Parameter[0].NumberOfValues = 1;

        // setup compression level
        ULONG quality = 50;
        encoderParameters.Parameter[0].Value = &quality;

        //  Save the image to the stream

        if(rhs.img->Save(pIStream, &pngClsid, &encoderParameters) != Ok)
        {
            pIStream->Release();
            DebugText("error on saving to IStream");
        }

        //getting the stream size:
        int buffsize=GlobalSize(hg);
        if(buffsize==0)
            DebugText("error on getting IStream size");

i get that message... maybe i miss something on CreateStreamOnHGlobal()

**joaquim** · 10-06-2015

yes i did another mistake. the hg was not correctly created:

Code:

friend std::ostream& operator << (std::ostream& lhs, const image& rhs)
    {

        //Create an empty IStream:
        IStream* pIStream = nullptr;
        HGLOBAL hg=GlobalAlloc(GMEM_MOVEABLE,NULL);
        if(CreateStreamOnHGlobal(hg, FALSE, (LPSTREAM*)&pIStream)!=S_OK)
            DebugText("error on creating an empty IStream");

        //choose image format for save it on IStream:
        // Get encoder class id for jpg compression
        // for other compressions use
        //    image/bmp
        //    image/jpeg
        //    image/gif
        //    image/tiff
        //    image/png
        CLSID pngClsid;
        GetEncoderClsid(L"image/gif", &pngClsid);

        // Setup encoder parameters
        EncoderParameters encoderParameters;
        encoderParameters.Count = 1;
        encoderParameters.Parameter[0].Guid = EncoderQuality;
        encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;
        encoderParameters.Parameter[0].NumberOfValues = 1;

        // setup compression level
        ULONG quality = 50;
        encoderParameters.Parameter[0].Value = &quality;

        //  Save the image to the stream

        if(rhs.img->Save(pIStream, &pngClsid, &encoderParameters) != Ok)
        {
            pIStream->Release();
            DebugText("error on saving to IStream");
        }

        //getting the stream size:
        if(GlobalFlags(hg)== GMEM_INVALID_HANDLE)
            DebugText("error: invalid handle");
        int buffsize=GlobalSize(hg);
        if(buffsize==0)
            DebugText("error on getting IStream size");
        char *pBuff = new char[buffsize];
        ULONG ulBytesRead;

        //Read the stream to pBuff
        if(pIStream->Read(pBuff,buffsize, &ulBytesRead)!=S_OK)
            DebugText("error on saving IStream to buffer");

        //write the stream size on file
        lhs << buffsize;

        //write pBuff data on file
        lhs << pBuff;

        //clean resources
        delete[] pBuff;
        pIStream->Release();

        return lhs;
    }

here i don't have errors, but i don't have sure if is correctly on file.
now see the read code:

Code:

friend std::istream& operator >> (std::istream& lhs, image& rhs)
    {
        //getting IStream size:
        int streamsize;
        lhs.read(reinterpret_cast<char*>(&streamsize), sizeof(streamsize));

        IStream* pIStream = nullptr;

        // Create stream with 0 size
        HGLOBAL hg= ::GlobalAlloc(GMEM_MOVEABLE,NULL);
        void* p =GlobalLock(hg);
        lhs.read(reinterpret_cast<char*>(p),sizeof(streamsize));
        GlobalUnlock(hg);

        if(CreateStreamOnHGlobal(hg, TRUE, (LPSTREAM*)&pIStream)!=S_OK)
            DebugText("error on creating an empty IStream");
        GetHGlobalFromStream(pIStream,&hg);
        //reading IStream on Image class:
        if(rhs.img->FromStream(pIStream,TRUE)!=S_OK)
            DebugText("error reading stream to Image");

        //realease resources:
        pIStream->Release();
        GlobalFree(hg);
        return lhs;
    }

i don't see the image, but i get a memory leak

**Codeplug** · 10-06-2015

Write:
Line 6: remove
Line 7: pass NULL for HGLOBAL
Line 39: call GetHGlobalFromStream() to get the value of hg
Line 54, 57: stop using formatted output. Use lhs.write()

Read:
Line 10: second parameter is incorrect
Line 17: remove
Line 24: remove, or change the second parameter to CreateStreamOnHGlobal()

gg