[waffle] [PATCH] core, man: Fix range and default value of WAFFLE_*_SIZE attrs

[Chad Versace]

For each of the WAFFLE_*_SIZE attributes:
  - change the default value from WAFFLE_DONT_CARE(-1) to 0, and
  - change the valid range of values from [-1, +inf) to [0, +inf).

This change aligns waffle's behavior to that of GLX [1], EGL [2], and (if
I interpreted the CGL documentation correctly) CGL [3].

This fixes a bug where, if the user didn't specify the value of a size
attribute, then waffle passed WAFFLE_DONT_CARE(-1) to glXChooseFBConfig
and eglChooseConfig. Per the GLX, EGL specs, -1 is an illegal value for
size attributes.

[1] GLX 1.4 spec (2005.12.16), Table 3.4
[2] EGL 1.4 spec (2011.04.06), Table 3.4
[3] https://developer.apple.com/library/mac/documentation/graphicsimaging/reference/CGL_OpenGL/Reference/reference.html#//apple_ref/c/func/CGLChoosePixelFormat

Reported-by: Brian Paul <brian.e.paul at gmail.com>
Signed-off-by: Chad Versace <chad.versace at linux.intel.com>
---
 man/waffle_config.3.xml              |  6 +++++-
 src/waffle/core/wcore_config_attrs.c | 20 +++++++++++++-------
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/man/waffle_config.3.xml b/man/waffle_config.3.xml
index 402ed26..00631af 100644
--- a/man/waffle_config.3.xml
+++ b/man/waffle_config.3.xml
@@ -352,7 +352,11 @@ struct waffle_config;
         <term><constant>WAFFLE_STENCIL_SIZE</constant></term>
         <listitem>
           <para>
-            The default value for each size attribute is <constant>WAFFLE_DONT_CARE</constant>. If the requested size
+            The default value for each size attribute is <constant>0</constant>.
+
+            The range of valid values is the non-negative integers.
+
+            If the requested size
             for a channel is 0, then any surface created with the config will lack that channel. If the requested size
             for a channel is positive, then the number of bits in that channel for any surface created with the config
             will be at least the requested size.
diff --git a/src/waffle/core/wcore_config_attrs.c b/src/waffle/core/wcore_config_attrs.c
index 1276e56..fa75e44 100644
--- a/src/waffle/core/wcore_config_attrs.c
+++ b/src/waffle/core/wcore_config_attrs.c
@@ -279,13 +279,19 @@ parse_context_profile(struct wcore_config_attrs *attrs,
 static bool
 set_misc_defaults(struct wcore_config_attrs *attrs)
 {
+    // Per the GLX [1] and EGL [2] specs, the default value of each size
+    // attribute and `samples` is 0.
+    //
+    // [1] GLX 1.4 spec (2005.12.16), Table 3.4
+    // [2] EGL 1.4 spec (2011.04.06), Table 3.4
+
     attrs->rgba_size            = 0;
-    attrs->red_size             = WAFFLE_DONT_CARE;
-    attrs->green_size           = WAFFLE_DONT_CARE;
-    attrs->blue_size            = WAFFLE_DONT_CARE;
-    attrs->alpha_size           = WAFFLE_DONT_CARE;
-    attrs->depth_size           = WAFFLE_DONT_CARE;
-    attrs->stencil_size         = WAFFLE_DONT_CARE;
+    attrs->red_size             = 0;
+    attrs->green_size           = 0;
+    attrs->blue_size            = 0;
+    attrs->alpha_size           = 0;
+    attrs->depth_size           = 0;
+    attrs->stencil_size         = 0;
     attrs->sample_buffers       = 0;
     attrs->samples              = 0;
     attrs->double_buffered      = true;
@@ -306,7 +312,7 @@ parse_misc(struct wcore_config_attrs *attrs,
 
             #define CASE_INT(enum_name, struct_memb)                           \
                 case enum_name:                                                \
-                    if (value < -1) {                                          \
+                    if (value < 0) {                                           \
                         wcore_errorf(WAFFLE_ERROR_BAD_ATTRIBUTE,               \
                                      #enum_name " has bad value %d", value);   \
                                      return false;                             \
-- 
1.8.0.3