fix a bug where fading in/out of opaque 32-bits windows wasn't working

opaque 32-bits windows are now allocated as RGBX_8888 buffers and
SurfaceFlinger always uses GL_MODULATE instead of trying to
optimize to GL_REPLACE when possible (makes no sense on
h/w accelerated GL).

we still have a small hack for devices that don't support
RGBX_8888 in their gralloc implementation where we revert to
RGBA_8888.

2 files changed, 19 insertions, 22 deletions

diff --git a/libs/surfaceflinger/LayerBase.cpp b/libs/surfaceflinger/LayerBase.cpp
index 76733a9..7ab74b4 100644
--- a/libs/surfaceflinger/LayerBase.cpp
+++ b/libs/surfaceflinger/LayerBase.cpp
@@ -379,33 +379,21 @@ void LayerBase::drawWithOpenGL(const Region& clip, const Texture& texture) const
     
     glEnable(GL_TEXTURE_2D);
 
+    GLenum src = mPremultipliedAlpha ? GL_ONE : GL_SRC_ALPHA;
     if (UNLIKELY(s.alpha < 0xFF)) {
-        // We have an alpha-modulation. We need to modulate all
-        // texture components by alpha because we're always using 
-        // premultiplied alpha.
-        
-        // If the texture doesn't have an alpha channel we can
-        // use REPLACE and switch to non premultiplied alpha
-        // blending (SRCA/ONE_MINUS_SRCA).
-        
-        GLenum env, src;
-        if (needsBlending()) {
-            env = GL_MODULATE;
-            src = mPremultipliedAlpha ? GL_ONE : GL_SRC_ALPHA;
+        const GLfloat alpha = s.alpha * (1.0f/255.0f);
+        if (mPremultipliedAlpha) {
+            glColor4f(alpha, alpha, alpha, alpha);
         } else {
-            env = GL_REPLACE;
-            src = GL_SRC_ALPHA;
+            glColor4f(1, 1, 1, alpha);
         }
-        const GLfloat alpha = s.alpha * (1.0f/255.0f);
-        glColor4f(alpha, alpha, alpha, alpha);
         glEnable(GL_BLEND);
         glBlendFunc(src, GL_ONE_MINUS_SRC_ALPHA);
-        glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, env);
+        glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
     } else {
-        glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
         glColor4f(1, 1, 1, 1);
+        glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
         if (needsBlending()) {
-            GLenum src = mPremultipliedAlpha ? GL_ONE : GL_SRC_ALPHA;
             glEnable(GL_BLEND);
             glBlendFunc(src, GL_ONE_MINUS_SRC_ALPHA);
         } else {
diff --git a/libs/ui/GraphicBuffer.cpp b/libs/ui/GraphicBuffer.cpp
index ba1fd9c..35e4af3 100644
--- a/libs/ui/GraphicBuffer.cpp
+++ b/libs/ui/GraphicBuffer.cpp
@@ -122,11 +122,20 @@ status_t GraphicBuffer::reallocate(uint32_t w, uint32_t h, PixelFormat f,
 status_t GraphicBuffer::initSize(uint32_t w, uint32_t h, PixelFormat format,
         uint32_t reqUsage)
 {
-    if (format == PIXEL_FORMAT_RGBX_8888)
-        format = PIXEL_FORMAT_RGBA_8888;
-
     GraphicBufferAllocator& allocator = GraphicBufferAllocator::get();
     status_t err = allocator.alloc(w, h, format, reqUsage, &handle, &stride);
+
+    if (err<0 && format == PIXEL_FORMAT_RGBX_8888) {
+        /*
+         * There is currently a bug with some gralloc implementations
+         * not supporting RGBX_8888. In this case, we revert to using RGBA_8888
+         * which is not exactly the same, as GL_REPLACE will yield a different
+         * result.
+         */
+        format = PIXEL_FORMAT_RGBA_8888;
+        err = allocator.alloc(w, h, format, reqUsage, &handle, &stride);
+    }
+
     if (err == NO_ERROR) {
         this->width  = w;
         this->height = h;