commit 0e34880ca2147073b6daf3fd4b251f0be3fca635
author Octavian Purdila <octavian.purdila@intel.com> Fri Jul 01 17:57:45 2011 +0300
committer Andrew Boie <andrew.p.boie@intel.com> Wed Jul 11 15:32:11 2012 -0700
tree 6ad60b01a557da81d85e587b31137fabd5fa2477
parent ea17e320b0bc4437e8a881026f296b71fa02ad3e

graphics: add support for "single buffering"

When we don't have enough video memory for double buffering we
fallback to "single buffering".

Change-Id: I8bfab6d8cd6b54f0cc6c67edc41a4c37d8fbd4ba
Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>

minui/graphics.c

diff --git a/minui/graphics.c b/minui/graphics.c
index de1cfdf..296e2e0 100644
--- a/minui/graphics.c
+++ b/minui/graphics.c
@@ -57,6 +57,7 @@
 static GGLSurface gr_framebuffer[2];
 static GGLSurface gr_mem_surface;
 static unsigned gr_active_fb = 0;
+static unsigned double_buffering = 0;
 
 static int gr_fb_fd = -1;
 static int gr_vt_fd = -1;
@@ -139,6 +140,12 @@
 
     fb++;
 
+    /* check if we can use double buffering */
+    if (vi.yres * fi.line_length * 2 > fi.smem_len)
+        return fd;
+
+    double_buffering = 1;
+
     fb->version = sizeof(*fb);
     fb->width = vi.xres;
     fb->height = vi.yres;
@@ -161,7 +168,7 @@
 
 static void set_active_framebuffer(unsigned n)
 {
-    if (n > 1) return;
+    if (n > 1 || !double_buffering) return;
     vi.yres_virtual = vi.yres * PIXEL_SIZE;
     vi.yoffset = n * vi.yres;
     vi.bits_per_pixel = PIXEL_SIZE * 8;
@@ -175,7 +182,8 @@
     GGLContext *gl = gr_context;
 
     /* swap front and back buffers */
-    gr_active_fb = (gr_active_fb + 1) & 1;
+    if (double_buffering)
+        gr_active_fb = (gr_active_fb + 1) & 1;
 
     /* copy data from the in-memory surface to the buffer we're about
      * to make active. */