Add half-float IOSurface GpuMemoryBuffer support

gpu/command_buffer/common/gpu_memory_buffer_support.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/common/gpu_memory_buffer_support.h"
 
 #include <GLES2/gl2.h>
 #include <GLES2/gl2extchromium.h>
 
 #include "base/logging.h"
@@ skipping 66 matching lines @@
     case gfx::BufferFormat::RG_88:
     case gfx::BufferFormat::RGBA_8888:
     case gfx::BufferFormat::YVU_420:
     case gfx::BufferFormat::YUV_420_BIPLANAR:
     case gfx::BufferFormat::UYVY_422:
       return format == BufferFormatForInternalFormat(internalformat);
     case gfx::BufferFormat::BGR_565:
     case gfx::BufferFormat::RGBX_8888:
       return internalformat == GL_RGB;
     case gfx::BufferFormat::RGBA_4444:
+    case gfx::BufferFormat::RGBA_F16:
       return internalformat == GL_RGBA;
   }
 
   NOTREACHED();
   return false;
 }
 
 bool IsGpuMemoryBufferFormatSupported(gfx::BufferFormat format,
                                       const gpu::Capabilities& capabilities) {
   switch (format) {
@@ skipping 11 matching lines @@
       return capabilities.texture_format_etc1;
     case gfx::BufferFormat::R_8:
     case gfx::BufferFormat::RG_88:
       return capabilities.texture_rg;
     case gfx::BufferFormat::UYVY_422:
       return capabilities.image_ycbcr_422;
     case gfx::BufferFormat::BGR_565:
     case gfx::BufferFormat::RGBA_4444:
     case gfx::BufferFormat::RGBA_8888:
     case gfx::BufferFormat::RGBX_8888:
+    case gfx::BufferFormat::RGBA_F16:
+      return capabilities.texture_half_float_linear;

[Daniele Castagna, 2017/03/30 21:47:10]

Does this return false on all the non-mac platforms?
Does having support for texture_half_float_linear means we can also allocate
Gmbs with that format?

What if we're allocating shmem GMBs?

[ccameron, 2017/03/30 23:07:03]

Ops, this affected the behavior of the above cases. Fixed that.

IIUC this returns true if we can texture out of this GMB type, which should be
okay for any platform (even the ones where we can't create native half-float
GMBs).

But I may not understand the function's purpose completely.

[Daniele Castagna, 2017/03/31 00:25:20]

Looking at IsGpuMemoryBufferFormatSupported makes me think this returning true
means we can allocate a GBM with that format.

For gfx::BufferFormat::UYVY_422 for example, image_ycbcr_422 is true only on
mac:
https://cs.chromium.org/chromium/src/gpu/command_buffer/service/feature_info....

Should this return false on all the platforms where we can't allocate a RGBA_F16
GMB?

     case gfx::BufferFormat::YVU_420:
       return true;
     case gfx::BufferFormat::YUV_420_BIPLANAR:
 #if defined(OS_CHROMEOS) && defined(ARCH_CPU_ARM_FAMILY)
       // TODO(dcastagna): Determine ycbcr_420v_image on CrOS at runtime
       // querying minigbm. crbug.com/646148
       return true;
 #else
       return capabilities.image_ycbcr_420v;
 #endif
@@ skipping 15 matching lines @@
       // by the block size.
       return size.width() % 4 == 0 && size.height() % 4 == 0;
     case gfx::BufferFormat::R_8:
     case gfx::BufferFormat::RG_88:
     case gfx::BufferFormat::BGR_565:
     case gfx::BufferFormat::RGBA_4444:
     case gfx::BufferFormat::RGBA_8888:
     case gfx::BufferFormat::RGBX_8888:
     case gfx::BufferFormat::BGRA_8888:
     case gfx::BufferFormat::BGRX_8888:
+    case gfx::BufferFormat::RGBA_F16:
       return true;
     case gfx::BufferFormat::YVU_420:
     case gfx::BufferFormat::YUV_420_BIPLANAR:
       // U and V planes are subsampled by a factor of 2.
       return size.width() % 2 == 0 && size.height() % 2 == 0;
     case gfx::BufferFormat::UYVY_422:
       return size.width() % 2 == 0;
   }
 
   NOTREACHED();
   return false;
 }
 
 }  // namespace gpu