fix SF buffer cropping

When a buffer had a crop (meaning its content is scaled to the window size)
and a window crop was defined, the resulting crop couldn't be expressed
properly because h/w composer's API was limited to integers, since
this is fixed in h/w composer 1.3, we take adventage of this to
make sure we get the correct crop.

this bug could result in the buffer being scaled by an incorrect ratio and
be slightly offset; moreover, it would produce different results from the
GL code path, which is always correct.

Change-Id: I8e20e00b6e26177d14f4ab4d2cd581e26c818892

3 files changed, 63 insertions, 4 deletions

diff --git a/services/surfaceflinger/DisplayHardware/FloatRect.h b/services/surfaceflinger/DisplayHardware/FloatRect.h
new file mode 100644
index 0000000..b08a951
--- /dev/null
+++ b/services/surfaceflinger/DisplayHardware/FloatRect.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_SF_FLOAT_RECT
+#define ANDROID_SF_FLOAT_RECT
+
+#include <utils/TypeHelpers.h>
+
+namespace android {
+
+class FloatRect
+{
+public:
+    float left;
+    float top;
+    float right;
+    float bottom;
+
+    inline FloatRect() { }
+    inline FloatRect(const Rect& other)
+        : left(other.left), top(other.top), right(other.right), bottom(other.bottom) { }
+
+    inline float getWidth() const { return right - left; }
+    inline float getHeight() const { return bottom - top; }
+};
+
+}; // namespace android
+
+#endif // ANDROID_SF_FLOAT_RECT
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 5082192..1cdabc4 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -24,6 +24,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
+#include <math.h>
 
 #include <utils/CallStack.h>
 #include <utils/Errors.h>
@@ -880,10 +881,25 @@ public:
         getLayer()->transform = transform;
     }
     virtual void setFrame(const Rect& frame) {
-        reinterpret_cast<Rect&>(getLayer()->displayFrame) = frame;
+        getLayer()->displayFrame = reinterpret_cast<hwc_rect_t const&>(frame);
     }
-    virtual void setCrop(const Rect& crop) {
-        reinterpret_cast<Rect&>(getLayer()->sourceCrop) = crop;
+    virtual void setCrop(const FloatRect& crop) {
+        if (hwcHasApiVersion(mHwc, HWC_DEVICE_API_VERSION_1_3)) {
+            getLayer()->sourceCropf = reinterpret_cast<hwc_frect_t const&>(crop);
+        } else {
+            /*
+             * Since h/w composer didn't support a flot crop rect before version 1.3,
+             * using integer coordinates instead produces a different output from the GL code in
+             * Layer::drawWithOpenGL(). The difference can be large if the buffer crop to
+             * window size ratio is large and a window crop is defined
+             * (i.e.: if we scale the buffer a lot and we also crop it with a window crop).
+             */
+            hwc_rect_t& r = getLayer()->sourceCrop;
+            r.left  = int(ceilf(crop.left));
+            r.top   = int(ceilf(crop.top));
+            r.right = int(floorf(crop.right));
+            r.bottom= int(floorf(crop.bottom));
+        }
     }
     virtual void setVisibleRegionScreen(const Region& reg) {
         // Region::getSharedBuffer creates a reference to the underlying
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.h b/services/surfaceflinger/DisplayHardware/HWComposer.h
index a20da08..0462bcc 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.h
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.h
@@ -47,6 +47,7 @@ namespace android {
 
 class GraphicBuffer;
 class Fence;
+class FloatRect;
 class Region;
 class String8;
 class SurfaceFlinger;
@@ -158,7 +159,7 @@ public:
         virtual void setBlending(uint32_t blending) = 0;
         virtual void setTransform(uint32_t transform) = 0;
         virtual void setFrame(const Rect& frame) = 0;
-        virtual void setCrop(const Rect& crop) = 0;
+        virtual void setCrop(const FloatRect& crop) = 0;
         virtual void setVisibleRegionScreen(const Region& reg) = 0;
         virtual void setBuffer(const sp<GraphicBuffer>& buffer) = 0;
         virtual void setAcquireFenceFd(int fenceFd) = 0;