kc3-lang/angle/extensions/EGL_ANGLE_window_fixed_size.txt

Branch : - branch - main - tag -

• Show log

  Commit

• Author : LRN
  Date : 2018-07-14 13:31:35
  Hash : 03d132eb
  Message : Support EGL_(WIDTH|HEIGHT) in eglSurfaceAttrib(), fixed resize Setting EGL_WIDTH or EGL_HEIGHT results in mFixedWidth and mFixedHeight changing their values. Whenever the swap chain is tested for needing a resize, surfaces with mFixedSize are treated as if they should be resized to mFixedWidth and mFixedHeight from their current size. This way fixed-size surfaces can be resized - it's enough to do a couple of eglSurfaceAttrib() calls and then either let ANGLE check surface for needing a resize in due course, or force that by calling eglWaitNative(). BUG=angleproject:2725 Change-Id: I2932d8ecd5a2f10500e4aa8583a169aa09bf01bb Reviewed-on: https://chromium-review.googlesource.com/1139055 Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>

• extensions/EGL_ANGLE_window_fixed_size.txt

• Name
  
      ANGLE_window_fixed_size
  
  Name Strings
  
      EGL_ANGLE_window_fixed_size
  
  Contributors
  
      John Bauman
      Shannon Woods
      Geoff Lang
  
  Contacts
  
      John Bauman, Google Inc. (jbauman 'at' google.com)
  
  Status
  
      Complete
  
  Version
  
      Version 5, July 23, 2018
  
  Number
  
      EGL Extension #??
  
  Dependencies
  
      This extension is written against the wording of the EGL 1.4
      Specification.
  
  Overview
  
      This extension allows creating a window surface that does not resize
      automatically.
  
  New Types
  
      None
  
  New Procedures and Functions
  
      None
  
  New Tokens
  
      Accepted by the <attribute> parameter of eglQuerySurface and by the
      <attrib_list> parameter of eglCreateWindowSurface:
  
      EGL_FIXED_SIZE_ANGLE        0x3201
  
  Additions to Chapter 3 of the EGL 1.4 Specification:
  
      Modify the third paragraph of Section 3.5.1 (Creating On-Screen Rendering
      Surfaces)
  
      "<attrib_list> specifies a list of attributes for the window. The list has
      the same structure as described for eglChooseConfig.  Attributes that can
      be specified in <attrib_list> include EGL_RENDER_BUFFER,
      EGL_VG_COLORSPACE, EGL_VG_ALPHA_FORMAT, EGL_FIXED_SIZE_ANGLE, EGL_WIDTH,
      and EGL_HEIGHT."
  
      Add before the last paragraph of Section 3.5.1
  
      "EGL_FIXED_SIZE_ANGLE specifies whether the surface must be resized by the
      implementation when the native window is resized.  The default value is
      EGL_FALSE.  Its value can be EGL_TRUE, in which case the size must be
      specified when the window is created, or EGL_FALSE, in which case the size
      is taken from the native window. Its default value is EGL_FALSE.
  
      If the value of EGL_FIXED_SIZE_ANGLE is EGL_TRUE, the window surface's
      size in pixels is specified by the EGL_WIDTH and EGL_HEIGHT attributes.
      If its value is EGL_FALSE, then the values of EGL_WIDTH and EGL_HEIGHT
      are ignored and the window surface must be resized by the implementation
      subsequent to the native window being resized, and prior to copying its
      contents to the native window (e.g. in eglSwapBuffers, as described in
      section 3.9.1.1). The default values for EGL_WIDTH and EGL_HEIGHT are zero.
      If the value specified for either of EGL_WIDTH or EGL_HEIGHT is less than
      zero then an EGL_BAD_PARAMETER error is generated."
  
      Add the following entry to Table 3.5
      (Queryable surface attributes and types)
  
      Attribute            Type    Description
      -------------------- ------- ---------------------------------------------
      EGL_FIXED_SIZE_ANGLE boolean Surface will not be resized with a native
                                   window
  
      Replace the last paragraph on page 37 in Section 3.5.6 (Surface Attributes)
  
      "Querying EGL_WIDTH and EGL_HEIGHT returns respectively the width and
      height, in pixels, of the surface. For a pixmap surface or window surface
      with EGL_FIXED_SIZE_ANGLE set to EGL_FALSE, these values are initially
      equal to the width and height of the native window or pixmap with respect
      to which the surface was created. If the native window is resized and the
      corresponding window surface is not fixed size, the corresponding window
      surface will eventually be resized by the implementation to match (as
      discussed in section 3.9.1). If there is a discrepancy because EGL has not
      yet resized the window surface, the size returned by eglQuerySurface will
      always be that of the EGL surface, not the corresponding native window."
  
      Alter the beginning of the first paragraph of Section 3.5.6 (Surface
      Attributes)
  
      "The specified attribute of surface is set to value. Attributes that can
      be specified are EGL_MIPMAP_LEVEL, EGL_MULTISAMPLE_RESOLVE,
      EGL_SWAP_BEHAVIOR, EGL_WIDTH, and EGL_HEIGHT."
  
      Add the following paragraph to Section 3.5.6 (Surface Attributes)
  
      "If attribute is EGL_WIDTH or EGL_HEIGHT then the value specifies the new
      surface width or height respectively. The new width and height are not
      guarenteed to be applied until the next call to eglSwapBuffers or
      eglWaitNative. If the surface does not have EGL_FIXED_SIZE_ANGLE set then
      an EGL_BAD_MATCH error is generated."
  
      Add the following paragraph to Section 3.5.6 (Surface Attributes)
  
      "Querying EGL_FIXED_SIZE_ANGLE returns EGL_FALSE if the surface will be
      resized to match a native window, and EGL_TRUE if the surface cannot be
      resized."
  
      Alter the beginning of the first paragraph of Section 3.9.1.1 (Native
      Window Resizing)
  
      "If the surface has EGL_FIXED_SIZE_ANGLE set and EGL_WIDTH or EGL_HEIGHT
      have changed or the surface does not have EGL_FIXED_SIZE_ANGLE set and its
      corresponding native window has been resized prior to the swap, surface
      must be resized to match".
  
  Issues
  
      1. Should there be a way to resize a window surface that had its size
      specified initially.
  
      RESOLVED: No. Surfaces that have their sizes specified initially must have
      EGL_FIXED_SIZE_ANGLE set and can never be resized.
  
      RESOLVED(rev 5): Fixed size surfaces can now be resized by setting
      EGL_WIDTH and EGL_HEIGHT surface attributes. This is the best way to give
      users explicit control of the size of window surfaces without re-creating
      them on each resize.
  
  Revision History
  
      Version 5, 2018/07/23 - Allow reizing fixed size surfaces.
  
      Version 4, 2014/02/24 - formatting changes.
  
      Version 3, 2014/02/12 - ignore EGL_WIDTH and EGL_HEIGHT if
      EGL_FIXED_SIZE_ANGLE is EGL_FALSE
  
      Version 2, 2014/02/07 - rename to EGL_ANGLE_window_fixed_size, and add an
      EGL_FIXED_SIZE_ANGLE token.
  
      Version 1, 2014/02/05 - first draft.