Fix empty region if the scale is smaller than 1

It may be used by Layer of SurfaceFlinger to calculate
touchable region. It should be able to scale a window
to a smaller size.

Bug: 111440400
Test: manual - An input-associated surface with a scaling
      matrix that has dsdx, dsdy < 1. Use "dumpsys input"
      to observe its touchable region.

Change-Id: I495bd16acec77f913fd39dcac90404eddc71cabb

4 files changed, 14 insertions, 11 deletions

diff --git a/libs/ui/Region.cpp b/libs/ui/Region.cpp
index 815093174c..618c7d62b1 100644
--- a/libs/ui/Region.cpp
+++ b/libs/ui/Region.cpp
@@ -325,14 +325,14 @@ Region& Region::translateSelf(int x, int y) {
     return *this;
 }
 
-Region& Region::scaleSelf(int sx, int sy) {
+Region& Region::scaleSelf(float sx, float sy) {
     size_t count = mStorage.size();
     Rect* rects = mStorage.editArray();
     while (count) {
-        rects->left *= sx;
-        rects->right *= sx;
-        rects->top *= sy;
-        rects->bottom *= sy;
+        rects->left = static_cast<int32_t>(rects->left * sx + 0.5f);
+        rects->right = static_cast<int32_t>(rects->right * sx + 0.5f);
+        rects->top = static_cast<int32_t>(rects->top * sy + 0.5f);
+        rects->bottom = static_cast<int32_t>(rects->bottom * sy + 0.5f);
         rects++;
         count--;
     }
diff --git a/libs/ui/include/ui/Region.h b/libs/ui/include/ui/Region.h
index c5e31c56f1..0a09960994 100644
--- a/libs/ui/include/ui/Region.h
+++ b/libs/ui/include/ui/Region.h
@@ -89,7 +89,7 @@ public:
 
             // these translate rhs first
             Region&     translateSelf(int dx, int dy);
-            Region&     scaleSelf(int sx, int sy);
+            Region&     scaleSelf(float sx, float sy);
             Region&     orSelf(const Region& rhs, int dx, int dy);
             Region&     xorSelf(const Region& rhs, int dx, int dy);
             Region&     andSelf(const Region& rhs, int dx, int dy);
diff --git a/services/inputflinger/InputDispatcher.cpp b/services/inputflinger/InputDispatcher.cpp
index bea4f911d9..0e258c8eb9 100644
--- a/services/inputflinger/InputDispatcher.cpp
+++ b/services/inputflinger/InputDispatcher.cpp
@@ -3518,7 +3518,7 @@ void InputDispatcher::dumpDispatchStateLocked(std::string& dump) {
                     dump += StringPrintf(INDENT3 "%zu: name='%s', displayId=%d, "
                             "paused=%s, hasFocus=%s, hasWallpaper=%s, "
                             "visible=%s, canReceiveKeys=%s, flags=0x%08x, type=0x%08x, layer=%d, "
-                            "frame=[%d,%d][%d,%d], globalScale=%f, windowScale=%f,%f"
+                            "frame=[%d,%d][%d,%d], globalScale=%f, windowScale=(%f,%f), "
                             "touchableRegion=",
                             i, windowInfo->name.c_str(), windowInfo->displayId,
                             toString(windowInfo->paused),
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 81456dfea9..58fd86618e 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -2069,10 +2069,13 @@ InputWindowInfo Layer::fillInputInfo(const Rect& screenBounds) {
     info.frameBottom = screenBounds.bottom - info.surfaceInset;
 
     ui::Transform t = getTransform();
-    info.windowXScale *= 1.0f / t.sx();
-    info.windowYScale *= 1.0f / t.sy();
-
-    info.touchableRegion.scaleSelf(t.sx(), t.sy());
+    const float xScale = t.sx();
+    const float yScale = t.sy();
+    if (xScale != 1.0f || yScale != 1.0f) {
+        info.windowXScale *= 1.0f / xScale;
+        info.windowYScale *= 1.0f / yScale;
+        info.touchableRegion.scaleSelf(xScale, yScale);
+    }
 
     info.touchableRegion = info.touchableRegion.translate(
             screenBounds.left,