Added match constraint linked list to ChainHead

Added some extra common fields into Chainhead
related to match constraint chains.

Bug: N/A
Test: Expanded ChainHeadTest
Change-Id: Ib226809bdc4ae259c8a74df5c3fbdf20cf817eb0

4 files changed, 102 insertions, 48 deletions

diff --git a/solver/src/main/java/android/support/constraint/solver/widgets/Chain.java b/solver/src/main/java/android/support/constraint/solver/widgets/Chain.java
index 6d6f12b..f992d66 100644
--- a/solver/src/main/java/android/support/constraint/solver/widgets/Chain.java
+++ b/solver/src/main/java/android/support/constraint/solver/widgets/Chain.java
@@ -85,12 +85,11 @@ class Chain {
 
         ConstraintWidget widget = first;
         ConstraintWidget next = null;
-
         boolean done = false;
-        int numMatchConstraints = 0;
-        float totalWeights = 0;
-        ConstraintWidget firstMatchConstraintsWidget = null;
-        ConstraintWidget previousMatchConstraintsWidget = null;
+
+        float totalWeights = chainHead.mTotalWeight;
+        ConstraintWidget firstMatchConstraintsWidget = chainHead.mFirstMatchConstraintWidget;
+        ConstraintWidget previousMatchConstraintsWidget = chainHead.mLastMatchConstraintWidget;
 
         boolean isWrapContent = container.mListDimensionBehaviors[orientation] == ConstraintWidget.DimensionBehaviour.WRAP_CONTENT;
         boolean isChainSpread = false;
@@ -143,26 +142,13 @@ class Chain {
                     strength);
             }
 
-            // First, let's maintain a linked list of matched widgets for the chain
-            widget.mListNextMatchConstraintsWidget[orientation] = null;
-            if (widget.getVisibility() != ConstraintWidget.GONE
-                    && widget.mListDimensionBehaviors[orientation] == ConstraintWidget.DimensionBehaviour.MATCH_CONSTRAINT) {
-                numMatchConstraints++;
-                totalWeights += widget.mWeight[orientation];
-                if (firstMatchConstraintsWidget == null) {
-                    firstMatchConstraintsWidget = widget;
-                } else {
-                    previousMatchConstraintsWidget.mListNextMatchConstraintsWidget[orientation] = widget;
-                }
-                previousMatchConstraintsWidget = widget;
-                if (isWrapContent) {
+            if (isWrapContent) {
+                if(widget.getVisibility() != ConstraintWidget.GONE
+                    && widget.mListDimensionBehaviors[orientation] == ConstraintWidget.DimensionBehaviour.MATCH_CONSTRAINT){
                     system.addGreaterThan(widget.mListAnchors[offset + 1].mSolverVariable,
                         widget.mListAnchors[offset].mSolverVariable, 0,
                         SolverVariable.STRENGTH_EQUALITY);
                 }
-            }
-
-            if (isWrapContent) {
                 system.addGreaterThan(widget.mListAnchors[offset].mSolverVariable,
                         container.mListAnchors[offset].mSolverVariable,
                         0, SolverVariable.STRENGTH_FIXED);
@@ -201,7 +187,7 @@ class Chain {
         }
 
         // Now, let's apply the centering / spreading for matched constraints widgets
-        if (numMatchConstraints > 0) {
+        if (firstMatchConstraintsWidget != null) {
             // TODO: we should not try to apply the constraints for weights = 0
             widget = firstMatchConstraintsWidget;
             while (widget != null) {
diff --git a/solver/src/main/java/android/support/constraint/solver/widgets/ChainHead.java b/solver/src/main/java/android/support/constraint/solver/widgets/ChainHead.java
index ee56b7a..70bfc38 100644
--- a/solver/src/main/java/android/support/constraint/solver/widgets/ChainHead.java
+++ b/solver/src/main/java/android/support/constraint/solver/widgets/ChainHead.java
@@ -16,6 +16,8 @@
 
 package android.support.constraint.solver.widgets;
 
+import android.support.constraint.solver.widgets.ConstraintWidget.DimensionBehaviour;
+
 /**
  * Class to represent a chain by its main elements.
  */
@@ -26,12 +28,15 @@ public class ChainHead {
     protected ConstraintWidget mLast;
     protected ConstraintWidget mLastVisibleWidget;
     protected ConstraintWidget mHead;
+    protected ConstraintWidget mFirstMatchConstraintWidget;
+    protected ConstraintWidget mLastMatchConstraintWidget;
+    protected float mTotalWeight = 0f;
     private int mOrientation;
     private boolean mIsRtl = false;
-    // TODO: Apply linked list of matched constraint widgets.
 
     /**
-     * Initialize variables, then determine visible widgets and head.
+     * Initialize variables, then determine visible widgets, the head of chain and
+     * matched constraint widgets.
      *
      * @param first first widget in a chain
      * @param orientation orientation of the chain (either Horizontal or Vertical)
@@ -51,9 +56,32 @@ public class ChainHead {
         ConstraintWidget widget = mFirst;
         ConstraintWidget next = mFirst;
         boolean done = false;
-        widget.mListNextVisibleWidget[mOrientation] = null;
-
         while (!done) {
+            widget.mListNextVisibleWidget[mOrientation] = null;
+            widget.mListNextMatchConstraintsWidget[mOrientation] = null;
+            if(widget.getVisibility() != ConstraintWidget.GONE) {
+                // Visible widgets linked list.
+                if (mFirstVisibleWidget == null) {
+                    mFirstVisibleWidget = widget;
+                }
+                if(mLastVisibleWidget != null){
+                    mLastVisibleWidget.mListNextVisibleWidget[mOrientation] = widget;
+                }
+                mLastVisibleWidget = widget;
+
+                // Match constraint linked list.
+                if(widget.mListDimensionBehaviors[mOrientation] == DimensionBehaviour.MATCH_CONSTRAINT){
+                    mTotalWeight += widget.mWeight[mOrientation];
+                    if(mFirstMatchConstraintWidget == null){
+                        mFirstMatchConstraintWidget = widget;
+                    }
+                    if(mLastMatchConstraintWidget != null){
+                        mLastMatchConstraintWidget.mListNextMatchConstraintsWidget[mOrientation] = widget;
+                    }
+                    mLastMatchConstraintWidget = widget;
+                }
+            }
+
             // go to the next widget
             ConstraintAnchor nextAnchor = widget.mListAnchors[offset + 1].mTarget;
             if (nextAnchor != null) {
@@ -65,15 +93,6 @@ public class ChainHead {
             } else {
                 next = null;
             }
-            if(widget.getVisibility() != ConstraintWidget.GONE) {
-                if (mFirstVisibleWidget == null) {
-                    mFirstVisibleWidget = widget;
-                }
-                if(mLastVisibleWidget != null){
-                    mLastVisibleWidget.mListNextVisibleWidget[mOrientation] = widget;
-                }
-                mLastVisibleWidget = widget;
-            }
             if (next != null) {
                 widget = next;
             } else {
@@ -108,4 +127,16 @@ public class ChainHead {
     public ConstraintWidget getHead() {
         return mHead;
     }
+
+    public ConstraintWidget getFirstMatchConstraintWidget() {
+        return mFirstMatchConstraintWidget;
+    }
+
+    public ConstraintWidget getLastMatchConstraintWidget() {
+        return mLastMatchConstraintWidget;
+    }
+
+    public float getTotalWeight() {
+        return mTotalWeight;
+    }
 }
diff --git a/solver/src/main/java/android/support/constraint/solver/widgets/Optimizer.java b/solver/src/main/java/android/support/constraint/solver/widgets/Optimizer.java
index 4fb16d3..a0a3fe6 100644
--- a/solver/src/main/java/android/support/constraint/solver/widgets/Optimizer.java
+++ b/solver/src/main/java/android/support/constraint/solver/widgets/Optimizer.java
@@ -387,13 +387,12 @@ public class Optimizer {
 
         ConstraintWidget widget = first;
         ConstraintWidget next = null;
-
         boolean done = false;
 
         int numMatchConstraints = 0;
-        float totalWeights = 0;
-        ConstraintWidget firstMatchConstraintsWidget = null;
-        ConstraintWidget previousMatchConstraintsWidget = null;
+        float totalWeights = chainHead.mTotalWeight;
+        ConstraintWidget firstMatchConstraintsWidget = chainHead.mFirstMatchConstraintWidget;
+        ConstraintWidget previousMatchConstraintsWidget = chainHead.mLastMatchConstraintWidget;
 
         boolean isWrapContent = container.mListDimensionBehaviors[orientation] == DimensionBehaviour.WRAP_CONTENT;
         boolean isChainSpread = false;
@@ -436,8 +435,6 @@ public class Optimizer {
 
             ConstraintAnchor begin = widget.mListAnchors[offset];
 
-            // First, let's maintain a linked list of matched widgets for the chain
-            widget.mListNextMatchConstraintsWidget[orientation] = null;
             if (widget.getVisibility() != ConstraintWidget.GONE
                     && widget.mListDimensionBehaviors[orientation] == MATCH_CONSTRAINT) {
                 numMatchConstraints++;
@@ -455,13 +452,6 @@ public class Optimizer {
                         return false;
                     }
                 }
-                totalWeights += widget.mWeight[orientation];
-                if (firstMatchConstraintsWidget == null) {
-                    firstMatchConstraintsWidget = widget;
-                } else {
-                    previousMatchConstraintsWidget.mListNextMatchConstraintsWidget[orientation] = widget;
-                }
-                previousMatchConstraintsWidget = widget;
             }
 
             // go to the next widget
diff --git a/solver/src/test/java/android/support/constraint/solver/ChainHeadTest.java b/solver/src/test/java/android/support/constraint/solver/ChainHeadTest.java
index 99bf0a2..f6c8e8a 100644
--- a/solver/src/test/java/android/support/constraint/solver/ChainHeadTest.java
+++ b/solver/src/test/java/android/support/constraint/solver/ChainHeadTest.java
@@ -126,4 +126,51 @@ public class ChainHeadTest {
         assertEquals(chainHead.getFirstVisibleWidget(), B);
     }
 
+    @Test
+    public void basicMatchConstraintTest(){
+        ConstraintWidgetContainer root = new ConstraintWidgetContainer(0, 0, 600, 600);
+        ConstraintWidget A = new ConstraintWidget(100, 20);
+        ConstraintWidget B = new ConstraintWidget(100, 20);
+        ConstraintWidget C = new ConstraintWidget(100, 20);
+
+        root.setDebugName("root");
+        A.setDebugName("A");
+        B.setDebugName("B");
+        C.setDebugName("C");
+
+        root.add(A);
+        root.add(B);
+        root.add(C);
+
+        A.connect(ConstraintAnchor.Type.LEFT, root, ConstraintAnchor.Type.LEFT);
+        A.connect(ConstraintAnchor.Type.RIGHT, B, ConstraintAnchor.Type.LEFT);
+        B.connect(ConstraintAnchor.Type.LEFT, A, ConstraintAnchor.Type.RIGHT);
+        B.connect(ConstraintAnchor.Type.RIGHT, C, ConstraintAnchor.Type.LEFT);
+        C.connect(ConstraintAnchor.Type.LEFT, B, ConstraintAnchor.Type.RIGHT);
+        C.connect(ConstraintAnchor.Type.RIGHT, root, ConstraintAnchor.Type.RIGHT);
+        A.connect(ConstraintAnchor.Type.TOP, root, ConstraintAnchor.Type.TOP);
+        B.connect(ConstraintAnchor.Type.TOP, root, ConstraintAnchor.Type.TOP);
+        C.connect(ConstraintAnchor.Type.TOP, root, ConstraintAnchor.Type.TOP);
+        A.setHorizontalDimensionBehaviour(ConstraintWidget.DimensionBehaviour.MATCH_CONSTRAINT);
+        B.setHorizontalDimensionBehaviour(ConstraintWidget.DimensionBehaviour.MATCH_CONSTRAINT);
+        C.setHorizontalDimensionBehaviour(ConstraintWidget.DimensionBehaviour.MATCH_CONSTRAINT);
+        A.setHorizontalWeight(1f);
+        B.setHorizontalWeight(2f);
+        C.setHorizontalWeight(3f);
+
+        ChainHead chainHead = new ChainHead(A, ConstraintWidget.HORIZONTAL, false);
+
+        assertEquals(chainHead.getFirstMatchConstraintWidget(), A);
+        assertEquals(chainHead.getLastMatchConstraintWidget(), C);
+        assertEquals(chainHead.getTotalWeight(), 6f);
+
+        C.setVisibility(ConstraintWidget.GONE);
+
+        chainHead = new ChainHead(A, ConstraintWidget.HORIZONTAL, false);
+
+        assertEquals(chainHead.getFirstMatchConstraintWidget(), A);
+        assertEquals(chainHead.getLastMatchConstraintWidget(), B);
+        assertEquals(chainHead.getTotalWeight(), 3f);
+    }
+
 }