add support for no Anchor onSwipe

constraintlayout/core/src/main/java/androidx/constraintlayout/core/state/Transition.java

@@ -33,6 +33,7 @@
 import androidx.constraintlayout.core.widgets.ConstraintWidgetContainer;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.HashMap;
 
 public class Transition implements TypedValues {
@@ -78,7 +79,7 @@ public boolean hasOnSwipe() {
     }
 
     static class OnSwipe {
-        private String mAnchorId;
+        String mAnchorId;
         private int mAnchorSide;
         private StopEngine mEngine;
         public static final int ANCHOR_SIDE_TOP = 0;
@@ -162,6 +163,10 @@ static class OnSwipe {
         };
         private long mStart;
 
+        float getScale() {
+            return mDragScale;
+        }
+
         float[] getDirection() {
             return TOUCH_DIRECTION[mDragDirection];
         }
@@ -362,9 +367,27 @@ public boolean isNotDone(float progress) {
      * @return the change in progress
      */
     public float dragToProgress(float currentProgress, int baseW, int baseH, float dx, float dy) {
-        if (mOnSwipe == null || mOnSwipe.mAnchorId == null) {
-            WidgetState w = mState.values().stream().findFirst().get();
-            return -dy / w.mParentHeight;
+        Collection<WidgetState> widgets = mState.values();
+        WidgetState childWidget = null;
+        for (WidgetState widget : widgets) {
+            childWidget = widget;
+            break;
+        }
+        if (mOnSwipe == null || childWidget == null) {
+            if (childWidget != null) {
+                return -dy / childWidget.mParentHeight;
+            }
+            return 1.0f;
+        }
+        if (mOnSwipe.mAnchorId == null) {
+
+            float[] dir = mOnSwipe.getDirection();
+            float motionDpDtX = childWidget.mParentHeight;
+            float motionDpDtY = childWidget.mParentHeight;
+
+            float drag = (dir[0] != 0) ? dx * Math.abs(dir[0]) / motionDpDtX
+                    : dy * Math.abs(dir[1]) / motionDpDtY;
+            return drag * mOnSwipe.getScale();
         }
         WidgetState base = mState.get(mOnSwipe.mAnchorId);
         float[] dir = mOnSwipe.getDirection();
@@ -378,7 +401,7 @@ public float dragToProgress(float currentProgress, int baseW, int baseH, float d
         if (DEBUG) {
             Utils.log(" drag " + drag);
         }
-        return drag;
+        return drag * mOnSwipe.getScale();
     }
 
     /**
@@ -412,7 +435,7 @@ public void setTouchUp(float currentProgress,
             }
 
             float drag = (dir[0] != 0) ? velocityX / motionDpDt[0] : velocityY / motionDpDt[1];
-
+            drag *= mOnSwipe.getScale();
             if (DEBUG) {
                 Utils.log(" >>> velocity        " + drag);
                 Utils.log(" >>> mDuration       " + mDuration);
@@ -825,8 +848,8 @@ static class WidgetState {
         MotionWidget mMotionWidgetEnd;
         MotionWidget mMotionWidgetInterpolated;
         KeyCache mKeyCache = new KeyCache();
-        private int mParentHeight = -1;
-        private int mParentWidth = -1;
+        int mParentHeight = -1;
+        int mParentWidth = -1;
 
         WidgetState() {
             mStart = new WidgetFrame();

projects/ComposeConstraintLayout/app/src/main/java/com/example/constraintlayout/MainActivity.kt

@@ -37,7 +37,7 @@ import com.google.accompanist.coil.rememberCoilPainter
 class MainActivity : AppCompatActivity() {
     private var mFrameLayout: FrameLayout? = null
     private var composeNum = 0
-    private val START_NUMBER = 6
+    private val START_NUMBER = 48
     private var demos:ArrayList<CompFunc> = ArrayList()
     var map = HashMap<Int, String>();
     val linkServer = LinkServer()
@@ -153,6 +153,8 @@ class MainActivity : AppCompatActivity() {
         demos.add(object : CompFunc { @Composable override fun Run() { OnSwipeExperiment() } })
         demos.add(object : CompFunc { @Composable override fun Run() { OnSwipeSample1() } })
         demos.add(object : CompFunc { @Composable override fun Run() { OnSwipeSample2() } })
+        demos.add(object : CompFunc { @Composable override fun Run() { OnSwipeSample3() } })
+
         demos.add(object : CompFunc { @Composable override fun Run() { MultiSwipe() } })
         demos.add(object : CompFunc { @Composable override fun Run() { MotionArc() } })
         demos.add(object : CompFunc { @Composable override fun Run() { MotionEasing() } })

projects/ComposeConstraintLayout/app/src/main/java/com/example/constraintlayout/OnSwipeExperiment.kt

@@ -260,6 +260,76 @@ fun OnSwipeSample2() {
                 .background(Color.White),
             motionScene = MotionScene(content = scene),
         ) {
+            Text(
+                text = "on Swipe example \n"+
+                    "  onSwipe: {\n" +
+                    "                anchor: 'box',\n" +
+                    "                direction: 'end',\n" +
+                    "                side: 'start',\n" +
+                    "                mode: 'spring'\n" +
+                    "              }"
+            )
+            Box(
+                modifier = Modifier
+                    .background(Color.Green)
+                    .layoutId("box")
+            )
+        }
+    }
+}
+
+@Preview
+@Composable
+fun OnSwipeSample3() {
+
+    var scene =
+        """
+       {
+         ConstraintSets: {
+           start: {
+             box: {
+               width: 50, height: 50,
+               bottom: ['parent', 'bottom', 70],
+               start: ['parent', 'start', 170],
+             }
+           },
+           end: {
+
+             box: {
+                width: 50, height: 50,
+                top: ['parent', 'top', 170],
+                end: ['parent', 'end', 170],
+             }
+           }
+         },
+         Transitions: {
+           default: {
+              from: 'start',
+              to: 'end',
+              onSwipe: {
+               direction: 'end',
+               mode: 'spring',
+               scale: .3,
+              }
+           }
+         }
+       }
+        """.trimIndent()
+
+    Column {
+        MotionLayout(
+            modifier = Modifier
+                .fillMaxSize()
+                .background(Color.White),
+            motionScene = MotionScene(content = scene),
+        ) {
+            Text(
+                text = "on Swipe example \n"+
+                    "  onSwipe: {\n" +
+                    "               direction: 'end',\n" +
+                    "               mode: 'spring'\n" +
+                    "              }"
+            )
             Box(
                 modifier = Modifier
                     .background(Color.Green)