Overview

EGLImage的存在是为了更方便地在EGL client API之间共享2D Image Data. 那什么是EGL client API呢？OpenGL, OpenGL ES, OpenVG都是EGL client API. EGLImage与下面3个EGL Extensions有关:

  • EGL_KHR_image
  • EGL_KHR_image_base
  • EGL_KHR_image_pixmap

后两个扩展其实是从第一个开离出来的。涉及EGLImage新增的Token和API都是在后两个扩展里定义的。

EGL_KHR_image_base

它定义了一个新的Opaque类型EGLImageKHR

1
typedef void * EGLImageKHR;

两者它定义了2个新API

1
2
3
4
5
6
7
8
9
10
11
12
EGLImageKHR eglCreateImageKHR(
EGLDisplay dpy,
EGLContext ctx,
EGLenum target,
EGLClientBuffer buffer,
const EGLint *attrib_list
);

EGLBoolean eglDestroyImageKHR(
EGLDisplay dpy,
EGLImageKHR image
);

其中，EGLClientBuffer也是Opaque类型

1
typedef void * EGLClientBuffer;

eglCreateImageKHR可以接受的target的值有:

target Notes
EGL_GL_TEXTURE_2D Used for GL 2D texture images
EGL_GL_TEXTURE_CUBE_MAP_POSITIVE_X Used for the +X face of GL cubemap texture images
EGL_GL_TEXTURE_CUBE_MAP_NEGATIVE_X Used for the -X face of GL cubemap texture images
EGL_GL_TEXTURE_CUBE_MAP_POSITIVE_Y Used for the +Y face of GL cubemap texture images
EGL_GL_TEXTURE_CUBE_MAP_NEGATIVE_Y Used for the -Y face of GL cubemap texture images
EGL_GL_TEXTURE_CUBE_MAP_POSITIVE_Z Used for the +Z face of GL cubemap texture images
EGL_GL_TEXTURE_CUBE_MAP_NEGATIVE_Z Used for the -Z face of GL cubemap texture images
EGL_GL_TEXTURE_3D Used for GL 3D texture images
EGL_GL_RENDERBUFFER Used for GL renderbuffer images
EGL_NATIVE_PIXMAP_KHR Used for X11 Pixmap (added EGL_KHR_image_pixmap)

EGL_KHR_image_pixmap