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C++ GImage::encodeJPEG方法代码示例

本文整理汇总了C++中GImage::encodeJPEG方法的典型用法代码示例。如果您正苦于以下问题:C++ GImage::encodeJPEG方法的具体用法?C++ GImage::encodeJPEG怎么用?C++ GImage::encodeJPEG使用的例子?那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在GImage的用法示例。


在下文中一共展示了GImage::encodeJPEG方法的1个代码示例,这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞,您的评价将有助于系统推荐出更棒的C++代码示例。

示例1: encodeJPEG

void GImage::encodeJPEG(
    BinaryOutput&           out) const {

    if (channels != 3) {
        // Convert to three channel
        GImage tmp = *this;
        tmp.convertToRGB();
        tmp.encodeJPEG(out);
        return;
    }

    debugAssert(channels == 3);
    out.setEndian(G3D_LITTLE_ENDIAN);

    // Allocate and initialize a compression object
    jpeg_compress_struct    cinfo;
    jpeg_error_mgr          jerr;

    cinfo.err = jpeg_std_error(&jerr);
    jpeg_create_compress(&cinfo);

    // Specify the destination for the compressed data.
    // (Overestimate the size)
    int buffer_size = width * height * 3 + 200;
    JOCTET* compressed_data = (JOCTET*)System::malloc(buffer_size);
    jpeg_memory_dest(&cinfo, compressed_data, buffer_size);


    cinfo.image_width       = width;
    cinfo.image_height      = height;

    // # of color components per pixel
    cinfo.input_components  = 3;

    // colorspace of input image
    cinfo.in_color_space    = JCS_RGB; 
    cinfo.input_gamma       = 1.0;
    
    // Set parameters for compression, including image size & colorspace
    jpeg_set_defaults(&cinfo);
    jpeg_set_quality(&cinfo, jpegQuality, false);
    cinfo.smoothing_factor = 0;
    cinfo.optimize_coding = TRUE;
//    cinfo.dct_method = JDCT_FLOAT;
    cinfo.dct_method = JDCT_ISLOW;
    cinfo.jpeg_color_space = JCS_YCbCr;

    // Initialize the compressor
    jpeg_start_compress(&cinfo, TRUE);

    // Iterate over all scanlines from top to bottom
    // pointer to a single row
    JSAMPROW row_pointer[1];
    
    // JSAMPLEs per row in image_buffer
    int row_stride = cinfo.image_width * 3;
    while (cinfo.next_scanline < cinfo.image_height) {
        row_pointer[0] = &(_byte[cinfo.next_scanline * row_stride]);
        jpeg_write_scanlines(&cinfo, row_pointer, 1);
    }

    // Shut down the compressor
    jpeg_finish_compress(&cinfo);
    
    // Figure out how big the result was.
    int outLength = ((mem_dest_ptr)cinfo.dest)->count;

    //	Release the JPEG compression object
    jpeg_destroy_compress(&cinfo);

    // Copy into an appropriately sized output buffer.
    out.writeBytes(compressed_data, outLength);

    // Free the conservative buffer.
    System::free(compressed_data);
    compressed_data = NULL;
}
开发者ID:luaman,项目名称:g3d-cpp,代码行数:77,代码来源:GImage_jpeg.cpp


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