SkAR Java: smooth finger painting, planes draw with outlines

Bug: skia:
Change-Id: I0e6f3c00f030f7a03c3829cd4ff22ac7459dc132
Reviewed-on: https://skia-review.googlesource.com/142685
Reviewed-by: Mike Reed <reed@google.com>

1 files changed, 57 insertions, 10 deletions

diff --git a/platform_tools/android/apps/skar_java/src/main/java/com/google/skar/SkARFingerPainting.java b/platform_tools/android/apps/skar_java/src/main/java/com/google/skar/SkARFingerPainting.java
index 5fc31e7ff8..c93a900f58 100644
--- a/platform_tools/android/apps/skar_java/src/main/java/com/google/skar/SkARFingerPainting.java
+++ b/platform_tools/android/apps/skar_java/src/main/java/com/google/skar/SkARFingerPainting.java
@@ -3,33 +3,80 @@ package com.google.skar;
 import android.graphics.Path;
 import android.graphics.PointF;
 
+import java.util.ArrayList;
+
 public class SkARFingerPainting {
+    // Points obtained by touching the screen. The first point is always brough to (0,0).
+    // All subsequent points are translated by the same amount.
+    public ArrayList<PointF> points = new ArrayList<>();
+
     public Path path = new Path();
 
     // Previous point added to the path. This points belongs to the path in local space.
     public PointF previousPoint;
 
-    private int numberOfPoints = 0;
-
     // Holds the model matrix of the first point added to such that the path can be drawn at the
     // model location (i.e on the Plane)
     private float[] modelMatrix;
 
-    public SkARFingerPainting() {}
+    private boolean isSmooth;
+
+    public SkARFingerPainting(boolean smooth) {
+        this.isSmooth = smooth;
+    }
+
+    public boolean getSmoothness() {
+        return isSmooth;
+    }
+
+    public void setSmoothness(boolean smooth) {
+        isSmooth = smooth;
+    }
 
     // Adds another point to the path in Local space
     public void addPoint(PointF p) {
-        if (numberOfPoints == 0) {
-            path.moveTo(p.x, p.y);
+        points.add(p);
+        previousPoint = p;
+    }
+
+    // Used to build a path before rendering it
+    public void buildPath() {
+        if (points.size() < 1) {
+            return;
+        }
+
+        path = new Path();
+        if (isSmooth) {
+            // If less than 3 points, than draw a line between the two points
+            if (points.size() <= 2 && points.size() > 0) {
+                path.moveTo(points.get(0).x, points.get(0).y);
+                path.lineTo(points.get(1).x, points.get(1).y);
+            } else if (points.size() >= 3){
+                // Else, essentially run deCasteljau
+                path.moveTo(points.get(0).x, points.get(0).y);
+                PointF mid = new PointF((points.get(0).x + points.get(1).x) / 2,
+                                        (points.get(0).y + points.get(1).y) / 2);
+                path.lineTo(mid.x, mid.y);
+
+                for (int i = 1; i < points.size() - 1; i++) {
+                    PointF p1 = points.get(i);
+                    PointF p2 = points.get(i + 1);
+                    PointF midP = new PointF((p1.x + p2.x) / 2,(p1.y + p2.y) / 2);
+                    path.quadTo(p1.x, p1.y, midP.x, midP.y);
+                }
+
+                path.lineTo(points.get(points.size() - 1).x, points.get(points.size() - 1).y);
+            }
         } else {
-            path.lineTo(p.x, p.y);
+            path.moveTo(points.get(0).x, points.get(0).y);
+            for (int i = 1; i < points.size(); i++) {
+                path.lineTo(points.get(i).x, points.get(i).y);
+            }
         }
-        previousPoint = p;
-        numberOfPoints++;
     }
 
     public boolean isEmpty() {
-        return numberOfPoints == 0;
+        return path.isEmpty();
     }
 
     public float[] getModelMatrix() {
@@ -41,7 +88,7 @@ public class SkARFingerPainting {
     }
 
     public void reset() {
+        points = new ArrayList<>();
         path = new Path();
-        numberOfPoints = 0;
     }
 }