Sanitize display list properties

The comparisons used in the various properties setters could fail badly
in some specific conditions. The scale properties in particular did not
use the same comparisons.

This change also clamps alpha to the 0..1 range which avoids overflow
issues with lowp registers in GLSL computations.

Change-Id: I3e73b584e907a14e2c33d0865ca0d2d4d5bff31d

3 files changed, 11 insertions, 14 deletions

diff --git a/libs/hwui/DisplayListRenderer.h b/libs/hwui/DisplayListRenderer.h
index 93b065d..0ba4078 100644
--- a/libs/hwui/DisplayListRenderer.h
+++ b/libs/hwui/DisplayListRenderer.h
@@ -170,9 +170,10 @@ public:
     }
 
     void setAlpha(float alpha) {
+        alpha = fminf(1.0f, fmaxf(0.0f, alpha));
         if (alpha != mAlpha) {
             mAlpha = alpha;
-            mMultipliedAlpha = (int)(255 * alpha);
+            mMultipliedAlpha = (int) (255 * alpha);
         }
     }
 
@@ -184,7 +185,7 @@ public:
         if (translationX != mTranslationX) {
             mTranslationX = translationX;
             mMatrixDirty = true;
-            if (ALMOST_EQUAL(mTranslationX, 0) && ALMOST_EQUAL(mTranslationY, 0)) {
+            if (mTranslationX == 0.0f && mTranslationY == 0.0f) {
                 mMatrixFlags &= ~TRANSLATION;
             } else {
                 mMatrixFlags |= TRANSLATION;
@@ -196,7 +197,7 @@ public:
         if (translationY != mTranslationY) {
             mTranslationY = translationY;
             mMatrixDirty = true;
-            if (ALMOST_EQUAL(mTranslationX, 0) && ALMOST_EQUAL(mTranslationY, 0)) {
+            if (mTranslationX == 0.0f && mTranslationY == 0.0f) {
                 mMatrixFlags &= ~TRANSLATION;
             } else {
                 mMatrixFlags |= TRANSLATION;
@@ -208,7 +209,7 @@ public:
         if (rotation != mRotation) {
             mRotation = rotation;
             mMatrixDirty = true;
-            if (ALMOST_EQUAL(mRotation, 0)) {
+            if (mRotation == 0.0f) {
                 mMatrixFlags &= ~ROTATION;
             } else {
                 mMatrixFlags |= ROTATION;
@@ -220,7 +221,7 @@ public:
         if (rotationX != mRotationX) {
             mRotationX = rotationX;
             mMatrixDirty = true;
-            if (ALMOST_EQUAL(mRotationX, 0) && ALMOST_EQUAL(mRotationY, 0)) {
+            if (mRotationX == 0.0f && mRotationY == 0.0f) {
                 mMatrixFlags &= ~ROTATION_3D;
             } else {
                 mMatrixFlags |= ROTATION_3D;
@@ -232,7 +233,7 @@ public:
         if (rotationY != mRotationY) {
             mRotationY = rotationY;
             mMatrixDirty = true;
-            if (ALMOST_EQUAL(mRotationX, 0) && ALMOST_EQUAL(mRotationY, 0)) {
+            if (mRotationX == 0.0f && mRotationY == 0.0f) {
                 mMatrixFlags &= ~ROTATION_3D;
             } else {
                 mMatrixFlags |= ROTATION_3D;
@@ -244,7 +245,7 @@ public:
         if (scaleX != mScaleX) {
             mScaleX = scaleX;
             mMatrixDirty = true;
-            if (ALMOST_EQUAL(mScaleX, 1) && ALMOST_EQUAL(mScaleY, 1)) {
+            if (mScaleX == 1.0f && mScaleY == 1.0f) {
                 mMatrixFlags &= ~SCALE;
             } else {
                 mMatrixFlags |= SCALE;
@@ -267,7 +268,7 @@ public:
     void setPivotX(float pivotX) {
         mPivotX = pivotX;
         mMatrixDirty = true;
-        if (ALMOST_EQUAL(mPivotX, 0) && ALMOST_EQUAL(mPivotY, 0)) {
+        if (mPivotX == 0.0f && mPivotY == 0.0f) {
             mMatrixFlags &= ~PIVOT;
         } else {
             mMatrixFlags |= PIVOT;
@@ -278,7 +279,7 @@ public:
     void setPivotY(float pivotY) {
         mPivotY = pivotY;
         mMatrixDirty = true;
-        if (ALMOST_EQUAL(mPivotX, 0) && ALMOST_EQUAL(mPivotY, 0)) {
+        if (mPivotX == 0.0f && mPivotY == 0.0f) {
             mMatrixFlags &= ~PIVOT;
         } else {
             mMatrixFlags |= PIVOT;
diff --git a/libs/hwui/OpenGLRenderer.h b/libs/hwui/OpenGLRenderer.h
index ab324ff..bf136ad 100644
--- a/libs/hwui/OpenGLRenderer.h
+++ b/libs/hwui/OpenGLRenderer.h
@@ -90,7 +90,7 @@ public:
     virtual int saveLayerAlpha(float left, float top, float right, float bottom,
             int alpha, int flags);
 
-    virtual void setAlpha(float alpha) {
+    void setAlpha(float alpha) {
         mSnapshot->alpha = alpha;
     }
 
diff --git a/libs/hwui/utils/Compare.h b/libs/hwui/utils/Compare.h
index f079a7b..fdd9acf 100644
--- a/libs/hwui/utils/Compare.h
+++ b/libs/hwui/utils/Compare.h
@@ -19,10 +19,6 @@
 
 #include <cmath>
 
-#define EPSILON 0.00001f
-
-#define ALMOST_EQUAL(u, v) (fabs((u) - (v)) < EPSILON)
-
 /**
  * Compare floats.
  */