Initial pass at SurfaceFlinger effects, night mode.

This change adds a mRenderEffect variable that can be used
to control rendering effects at runtime.  One example effect
of "night mode" is included which renders the entire system
in using a red-only filter.

In particular, this is useful on devices with OLED displays
where the power consumption of the red channel is much less
than green and blue.

Change-Id: I64fb47a186e5b1c6be5db7e179ab6796e66bf341

3 files changed, 44 insertions, 2 deletions

diff --git a/libs/surfaceflinger/LayerBase.cpp b/libs/surfaceflinger/LayerBase.cpp
index a8b735e..a77b20b 100644
--- a/libs/surfaceflinger/LayerBase.cpp
+++ b/libs/surfaceflinger/LayerBase.cpp
@@ -33,6 +33,10 @@
 #include "SurfaceFlinger.h"
 #include "DisplayHardware/DisplayHardware.h"
 
+#define RENDER_EFFECT_NIGHT 1
+#define RENDER_EFFECT_TERMINAL 2
+#define RENDER_EFFECT_AMBER 3
+#define RENDER_EFFECT_SALMON 4
 
 namespace android {
 
@@ -401,7 +405,10 @@ void LayerBase::drawWithOpenGL(const Region& clip, const Texture& texture) const
     
     glEnable(GL_TEXTURE_2D);
 
-    if (UNLIKELY(s.alpha < 0xFF)) {
+    int renderEffect = mFlinger->getRenderEffect();
+    bool noEffect = renderEffect == 0;
+
+    if (UNLIKELY(s.alpha < 0xFF) && noEffect) {
         // We have an alpha-modulation. We need to modulate all
         // texture components by alpha because we're always using 
         // premultiplied alpha.
@@ -423,7 +430,7 @@ void LayerBase::drawWithOpenGL(const Region& clip, const Texture& texture) const
         glEnable(GL_BLEND);
         glBlendFunc(src, GL_ONE_MINUS_SRC_ALPHA);
         glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, env);
-    } else {
+    } else if (noEffect) {
         glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
         glColor4x(0x10000, 0x10000, 0x10000, 0x10000);
         if (needsBlending()) {
@@ -433,6 +440,29 @@ void LayerBase::drawWithOpenGL(const Region& clip, const Texture& texture) const
         } else {
             glDisable(GL_BLEND);
         }
+    } else {
+        // Apply a render effect, which is simple color masks for now.
+        GLenum env, src;
+        env = GL_MODULATE;
+        src = mPremultipliedAlpha ? GL_ONE : GL_SRC_ALPHA;
+        const GGLfixed alpha = (s.alpha << 16)/255;
+        switch (renderEffect) {
+            case RENDER_EFFECT_NIGHT:
+                glColor4x(alpha, 0, 0, alpha);
+                break;
+            case RENDER_EFFECT_TERMINAL:
+                glColor4x(0, alpha, 0, alpha);
+                break;
+            case RENDER_EFFECT_AMBER:
+                glColor4x(alpha, alpha*0.75, 0, alpha);
+                break;
+            case RENDER_EFFECT_SALMON:
+                glColor4x(alpha, alpha*0.5, alpha*0.5, alpha);
+                break;
+        }
+        glEnable(GL_BLEND);
+        glBlendFunc(src, GL_ONE_MINUS_SRC_ALPHA);
+        glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, env);
     }
 
     Region::const_iterator it = clip.begin();
diff --git a/libs/surfaceflinger/SurfaceFlinger.cpp b/libs/surfaceflinger/SurfaceFlinger.cpp
index 0722fda..45ca215 100644
--- a/libs/surfaceflinger/SurfaceFlinger.cpp
+++ b/libs/surfaceflinger/SurfaceFlinger.cpp
@@ -184,6 +184,7 @@ SurfaceFlinger::SurfaceFlinger()
         mFreezeDisplayTime(0),
         mDebugRegion(0),
         mDebugBackground(0),
+        mRenderEffect(0),
         mDebugInSwapBuffers(0),
         mLastSwapBufferTime(0),
         mDebugInTransaction(0),
@@ -205,6 +206,8 @@ void SurfaceFlinger::init()
     mDebugRegion = atoi(value);
     property_get("debug.sf.showbackground", value, "0");
     mDebugBackground = atoi(value);
+    property_get("debug.sf.render_effect", value, "0");
+    mRenderEffect = atoi(value);
 
     LOGI_IF(mDebugRegion,           "showupdates enabled");
     LOGI_IF(mDebugBackground,       "showbackground enabled");
@@ -1692,12 +1695,18 @@ status_t SurfaceFlinger::onTransact(
                 reply->writeInt32(0);
                 reply->writeInt32(mDebugRegion);
                 reply->writeInt32(mDebugBackground);
+                reply->writeInt32(mRenderEffect);
                 return NO_ERROR;
             case 1013: {
                 Mutex::Autolock _l(mStateLock);
                 const DisplayHardware& hw(graphicPlane(0).displayHardware());
                 reply->writeInt32(hw.getPageFlipCount());
             }
+            case 1014: { // RENDER_EFFECT
+                // TODO: filter to only allow valid effects
+                mRenderEffect = data.readInt32();
+                return NO_ERROR;
+            }
             return NO_ERROR;
         }
     }
diff --git a/libs/surfaceflinger/SurfaceFlinger.h b/libs/surfaceflinger/SurfaceFlinger.h
index d75dc15..7cde719 100644
--- a/libs/surfaceflinger/SurfaceFlinger.h
+++ b/libs/surfaceflinger/SurfaceFlinger.h
@@ -174,6 +174,8 @@ public:
 
             overlay_control_device_t* getOverlayEngine() const;
 
+            inline int                  getRenderEffect() const { return mRenderEffect; }
+
             
     status_t removeLayer(const sp<LayerBase>& layer);
     status_t addLayer(const sp<LayerBase>& layer);
@@ -354,6 +356,7 @@ private:
                 // don't use a lock for these, we don't care
                 int                         mDebugRegion;
                 int                         mDebugBackground;
+                int                         mRenderEffect;
                 volatile nsecs_t            mDebugInSwapBuffers;
                 nsecs_t                     mLastSwapBufferTime;
                 volatile nsecs_t            mDebugInTransaction;