Check if fbo is srgb

Author: misl6

kivy/graphics/cgl.pxd

@@ -177,6 +177,7 @@ cdef extern from "gl_redirect.h":
     int GL_ALPHA
     int GL_RGB
     int GL_RGBA
+    int GL_SRGB
     int GL_LUMINANCE
     int GL_LUMINANCE_ALPHA
 
@@ -342,6 +343,7 @@ cdef extern from "gl_redirect.h":
     int GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME
     int GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL
     int GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE
+    int GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING
 
     int GL_COLOR_ATTACHMENT0
     int GL_DEPTH_ATTACHMENT

kivy/graphics/fbo.pyx

@@ -98,6 +98,12 @@ if platform == "darwin":
 # Adding it to headers can be complicated because it doesn't exists in gl2.h
 cdef int GL_DEPTH_STENCIL_ATTACHMENT = 0x821A
 
+cdef srgb_to_linear(c):
+    if (c <= 0.04045):
+        return c / 12.92
+    else:
+        return pow((c + 0.055) / 1.055, 2.4)
+
 
 cdef class Fbo(RenderContext):
     '''Fbo class for wrapping the OpenGL Framebuffer extension. The Fbo support
@@ -493,12 +499,31 @@ cdef class Fbo(RenderContext):
 
         .. versionadded:: 1.8.0
         """
+        cdef GLint encoding
+
         if wx > self._width or wy > self._height:
             # window coordinates should not exceed the
             # frame buffer size
             return (0, 0, 0, 0)
+
         self.bind()
+
         data = py_glReadPixels(wx, wy, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE)
+
+        cgl.glGetFramebufferAttachmentParameteriv(
+            GL_FRAMEBUFFER,
+            GL_COLOR_ATTACHMENT0,
+            GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING,
+            &encoding
+        )
+
+        if encoding == GL_SRGB:
+            # convert from sRGB to linear RGB
+            data[0] = srgb_to_linear(data[0] / 255.0)
+            data[1] = srgb_to_linear(data[1] / 255.0)
+            data[2] = srgb_to_linear(data[2] / 255.0)
+            data[3] = data[3] / 255.0
+
         self.release()
 
         return [i for i in data]

kivy/graphics/opengl.pyx

@@ -171,6 +171,7 @@ GL_DEPTH_COMPONENT = cgldef.GL_DEPTH_COMPONENT
 GL_ALPHA = cgldef.GL_ALPHA
 GL_RGB = cgldef.GL_RGB
 GL_RGBA = cgldef.GL_RGBA
+GL_SRGB = cgldef.GL_SRGB
 GL_LUMINANCE = cgldef.GL_LUMINANCE
 GL_LUMINANCE_ALPHA = cgldef.GL_LUMINANCE_ALPHA
 GL_UNSIGNED_SHORT_4_4_4_4 = cgldef.GL_UNSIGNED_SHORT_4_4_4_4
@@ -312,6 +313,7 @@ GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE = cgldef.GL_FRAMEBUFFER_ATTACHMENT_OBJECT_
 GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME = cgldef.GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME
 GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL = cgldef.GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL
 GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE = cgldef.GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE
+GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING = cgldef.GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING
 GL_COLOR_ATTACHMENT0 = cgldef.GL_COLOR_ATTACHMENT0
 GL_DEPTH_ATTACHMENT = cgldef.GL_DEPTH_ATTACHMENT
 GL_STENCIL_ATTACHMENT = cgldef.GL_STENCIL_ATTACHMENT

kivy/include/common_subset.h

@@ -154,6 +154,7 @@ typedef khronos_ssize_t  GLsizeiptr;
 #define GL_ALPHA                          0x1906
 #define GL_RGB                            0x1907
 #define GL_RGBA                           0x1908
+#define GL_SRGB                           0x8C40
 #define GL_LUMINANCE                      0x1909
 #define GL_LUMINANCE_ALPHA                0x190A
 #define GL_UNSIGNED_SHORT_4_4_4_4         0x8033
@@ -450,6 +451,7 @@ GL_APICALL void         GL_APIENTRY glViewport (GLint x, GLint y, GLsizei width,
 #define GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME           0x8CD1
 #define GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL         0x8CD2
 #define GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE 0x8CD3
+#define GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING    0x8210
 #define GL_COLOR_ATTACHMENT0              0x8CE0
 #define GL_DEPTH_ATTACHMENT               0x8D00
 #define GL_STENCIL_ATTACHMENT             0x8D20

kivy/tools/gles_compat/gl2.h

@@ -246,6 +246,7 @@ typedef khronos_ssize_t  GLsizeiptr;
 #define GL_ALPHA                          0x1906
 #define GL_RGB                            0x1907
 #define GL_RGBA                           0x1908
+#define GL_SRGB                           0x8C40
 #define GL_LUMINANCE                      0x1909
 #define GL_LUMINANCE_ALPHA                0x190A
 
@@ -448,6 +449,7 @@ typedef khronos_ssize_t  GLsizeiptr;
 #define GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME           0x8CD1
 #define GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL         0x8CD2
 #define GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE 0x8CD3
+#define GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING    0x8210
 
 #define GL_COLOR_ATTACHMENT0              0x8CE0
 #define GL_DEPTH_ATTACHMENT               0x8D00