CreateStreamBuffer

This function creates a new StreamBuffer object. A StreamBuffer is a file stream that can be treated like a memory buffer.

Syntax

• shared_ptr<StreamBuffer> CreateStreamBuffer(shared_ptr<Stream> stream)
• shared_ptr<StreamBuffer> CreateStreamBuffer(shared_ptr<Stream> stream, uint64_t pos, uint64_t size)

Returns

If successful, returns a new StreamBuffer object.

If the specified range lies outside the position and size of the stream NULL will be returned.

If the specified size is zero NULL will be returned.

If the stream size is zero NULL will be returned.

If the stream is closed NULL will be returned.

Remarks

If the position and size are not specified the position will be zero and the size will be equal to the stream size.

If the Data method is called on a StreamBuffer object, it will return NULL since there is no pointer to data in memory.

if the Resize method is called on a StreamBuffer object, no resizing will take place and false will be returned.

Example

//---------------------------------------------------------------------------------------------------
// 
// This example will load a heightmap into a streambuffer and create a "virtual" pixmap, without 
// loading the entire file into memory. A sub-section of the heightmap will be extracted and saved.
// This can be used to work with very large image files that cannot be loaded in memory.
// 
//---------------------------------------------------------------------------------------------------

#include "UltraEngine.h"

using namespace UltraEngine;

int main(int argc, const char* argv[])
{
    //Load FreeImage plugin
    auto plugin = LoadPlugin("Plugins/FITextureLoader");
    if (plugin == NULL)
    {
        Print("Failed to load FreeImage plugin.");
        return 0;
    }

    //Load heightmap data
    auto stream = ReadFile("https://github.com/UltraEngine/Documentation/raw/master/Assets/Terrain/1024.r16");
    auto streambuffer = CreateStreamBuffer(stream, 0, stream->GetSize());
    auto pixmap = CreatePixmap(1024, 1024, TEXTURE_R16, streambuffer);

    //Create sub-image and save
    auto submap = CreatePixmap(256, 256, TEXTURE_R16);
    pixmap->CopyRect(0, 0, 256, 256, submap, 0, 0);
    submap = submap->Convert(TEXTURE_RGBA);
    submap->Save("output.png");

    RunFile("output.png");

    return 0;
}