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      1 Name
      2 
      3     CHROMIUM_image
      4 
      5 Name Strings
      6 
      7     GL_CHROMIUM_image
      8 
      9 Version
     10 
     11     Last Modifed Date: Apr 30, 2014
     12 
     13 Dependencies
     14 
     15     OpenGL ES 2.0 is required.
     16 
     17 Overview
     18 
     19     This extension allows for more efficient uploading of texture data through
     20     Chromium's OpenGL ES 2.0 implementation as well as enable hardware overlay
     21     support by providing ability to create buffers capable of being scanned out
     22     directly by the display controller.
     23 
     24     For security reasons Chromium accesses the GPU from a separate process. User
     25     processes are not allowed to access the GPU directly. This multi-process
     26     architechure has the advantage that GPU operations can be secured and
     27     pipelined but it has the disadvantage that all data that is going to be
     28     passed to GPU must first be made available to the separate GPU process.
     29 
     30     This extension helps the application directly allocate and access texture
     31     memory.
     32 
     33 Issues
     34 
     35     None
     36 
     37 New Tokens
     38 
     39     Accepted by the <pname> parameter of GetImageParameterivCHROMIUM:
     40 
     41         IMAGE_ROWBYTES_CHROMIUM 0x78F0
     42 
     43     Accepted by the <usage> parameter of CreateImageCHROMIUM:
     44 
     45         IMAGE_MAP_CHROMIUM 0x78F1
     46         IMAGE_SCANOUT_CHROMIUM 0x78F2
     47 
     48 New Procedures and Functions
     49 
     50     GLuint CreateImageCHROMIUM(GLsizei width, GLsizei height,
     51                                GLenum internalformat, GLenum usage)
     52 
     53     Allocate an image with width equal to <width> and height equal
     54     to <height> stored in format <internalformat>.
     55 
     56     Returns a unique identifier for the allocated image that could be used
     57     in subsequent operations.
     58 
     59     INVALID_VALUE is generated if <width> or <height> is nonpositive.
     60 
     61     INVALID_ENUM is generated if <usage> is not one of
     62     IMAGE_MAP_CHROMIUM and IMAGE_SCANOUT_CHROMIUM.
     63 
     64     void DestroyImageCHROMIUM(GLuint image_id)
     65 
     66     Frees the image previously allocated by a call to CreateImageCHROMIUM.
     67 
     68     INVALID_OPERATION is generated if <image_id> is not a valid image id.
     69 
     70     void* MapImageCHROMIUM(GLuint image_id)
     71 
     72     Returns a pointer to in the user memory for the application to modify
     73     the image. It is illegal to call this function on an image not created
     74     with IMAGE_MAP_CHROMIUM usage.
     75 
     76     INVALID_OPERATION is generated if <image_id> is not a valid image id.
     77 
     78     INVALID_OPERATION is generated if the image was already mapped by a previous
     79     call to this method.
     80 
     81     void UnmapImageCHROMIUM(GLuint image_id)
     82 
     83     Removes the mapping created by a call to MapImageCHROMIUM.
     84 
     85     Note that after calling UnmapImageCHROMIUM the application should assume
     86     that the memory returned by MapImageCHROMIUM is off limits and is no longer
     87     accessible by the application. Accessing it after calling
     88     UnmapImageCHROMIUM will produce undefined results.
     89 
     90     INVALID_OPERATION is generated if <image_id> is not a valid image id.
     91 
     92     INVALID_OPERATION is generated if the image was not already mapped by a
     93     previous call to MapImageCHROMIUM.
     94 
     95     void GetImageParameterivCHROMIUM(GLuint image_id, GLenum pname,
     96                                      GLint* params)
     97 
     98     Sets <params> to the integer value of the parameter specified by <pname>
     99     for the image specified by <image_id>. <params> is expected to be
    100     properly allocated before calling this method.
    101 
    102     INVALID_OPERATION is generated if <image_id> is not a valid image id.
    103 
    104     INVALID_ENUM is generated if <pname> is not IMAGE_ROWBYTES_CHROMIUM.
    105 
    106 Errors
    107 
    108     None.
    109 
    110 New State
    111 
    112     None.
    113 
    114 Revision History
    115 
    116     5/9/2013    Documented the extension
    117     4/30/2014   Moved usage flag to creation function.
    118