From 5a31a60889a2f87d6b8b658690f1f1ea7adb23ae Mon Sep 17 00:00:00 2001
From: ziadb <ziadb@google.com>
Date: Fri, 13 Jul 2018 12:40:10 -0400
Subject: SkAR Java: drawing planes as paths

FREEZE.unindexed

Bug: skia:
Change-Id: Ifcb73345d7073f13bf027d79fd90bf3fbff73e5b
Reviewed-on: https://skia-review.googlesource.com/141229
Reviewed-by: Mike Reed <reed@google.com>
---
 .../core/examples/java/helloskar/DrawManager.java  | 57 ++++++++++++----------
 1 file changed, 30 insertions(+), 27 deletions(-)

diff --git a/platform_tools/android/apps/skar_java/src/main/java/com/google/ar/core/examples/java/helloskar/DrawManager.java b/platform_tools/android/apps/skar_java/src/main/java/com/google/ar/core/examples/java/helloskar/DrawManager.java
index c448ffeb42..7e5ac29384 100644
--- a/platform_tools/android/apps/skar_java/src/main/java/com/google/ar/core/examples/java/helloskar/DrawManager.java
+++ b/platform_tools/android/apps/skar_java/src/main/java/com/google/ar/core/examples/java/helloskar/DrawManager.java
@@ -39,7 +39,6 @@ public class DrawManager {
     private float viewportHeight;
     private ColorFilter lightFilter;
     private BitmapShader planeShader;
-    private Bitmap planeTexture;
     public ArrayList<float[]> modelMatrices = new ArrayList<>();
 
     public void updateViewport(float width, float height) {
@@ -178,7 +177,6 @@ public class DrawManager {
                 continue;
             }
 
-
             // Get plane model matrix
             float[] model = new float[16];
             plane.getCenterPose().toMatrix(model, 0);
@@ -186,58 +184,63 @@ public class DrawManager {
             // Initial rotation
             float[] initRot = SkARMatrix.createXYtoXZRotationMatrix();
 
-            float[] initScale = new float[16];
-            Matrix.setIdentityM(initScale, 0);
-            Matrix.scaleM(initScale, 0, 1f, 1f, 1f);
-            android.graphics.Matrix scale = SkARMatrix.createMatrixFrom4x4(SkARMatrix.multiplyMatrices4x4(new float[][] {initScale}));
-
             // Matrix = mvpv
             float[][] matrices = {initRot, model, viewMatrix, projectionMatrix, SkARMatrix.createViewportMatrix(viewportWidth, viewportHeight)};
             android.graphics.Matrix mvpv = SkARMatrix.createMatrixFrom4x4(SkARMatrix.multiplyMatrices4x4(matrices));
 
-            canvas.save();
-
-            canvas.setMatrix(mvpv);
-
-            drawPlaneAsPath(canvas, plane);
-            canvas.restore();
+            if (Build.VERSION.SDK_INT > Build.VERSION_CODES.O_MR1) {
+                // Android version P and higher
+                drawPlane(canvas, mvpv, plane);
+            } else {
+                drawPlaneAsPath(canvas, mvpv, plane);
+            }
         }
     }
 
     // Helper function that draws an AR plane using a path
-    private void drawPlaneAsPath(Canvas canvas, Plane plane) {
+    private void drawPlaneAsPath(Canvas canvas, android.graphics.Matrix mvpv, Plane plane) {
         int vertsSize = plane.getPolygon().limit() / 2;
         FloatBuffer polygon = plane.getPolygon();
         polygon.rewind();
 
-        Path path = new Path();
-        path.moveTo(polygon.get(0), polygon.get(1));
+        // Build source path from polygon data
+        Path pathSrc = new Path();
+        pathSrc.moveTo(polygon.get(0), polygon.get(1));
         for (int i = 1; i < vertsSize; i++) {
-            path.lineTo(polygon.get(i * 2), polygon.get(i * 2 + 1));
+            pathSrc.lineTo(polygon.get(i * 2), polygon.get(i * 2 + 1));
         }
-        path.close();
+        pathSrc.close();
 
+        // Set up paint
         Paint p = new Paint();
         p.setShader(planeShader);
-        p.setColorFilter(new PorterDuffColorFilter(Color.argb(0.4f, 1, 0, 0), PorterDuff.Mode.SRC_ATOP));
+        p.setColorFilter(new PorterDuffColorFilter(Color.argb(0.4f, 1, 0, 0),
+                             PorterDuff.Mode.SRC_ATOP));
         p.setAlpha(120);
 
-        //canvas.drawPath(path, p); TODO: enable this when path is drawn on GPU
+        // Build destination path by transforming source path
+        Path pathDst = new Path();
+        pathSrc.transform(mvpv, pathDst);
+
+        // Shader local matrix
+        android.graphics.Matrix lm = new android.graphics.Matrix();
+        lm.setScale(0.0005f, 0.0005f);
+        lm.postConcat(mvpv);
+        planeShader.setLocalMatrix(lm);
 
-        RectF r = new RectF();
-        path.computeBounds(r, true);
-        canvas.drawRect(r, p);
+        // Draw dest path
+        canvas.save();
+        canvas.setMatrix(new android.graphics.Matrix());
+        canvas.drawPath(pathDst, p);
+        canvas.restore();
     }
 
     public void initializePlaneShader(Context context, String gridDistanceTextureName) throws IOException {
         // Read the texture.
-        planeTexture =
+        Bitmap planeTexture =
                 BitmapFactory.decodeStream(context.getAssets().open(gridDistanceTextureName));
         // Set up the shader
         planeShader = new BitmapShader(planeTexture, Shader.TileMode.REPEAT, Shader.TileMode.REPEAT);
-        android.graphics.Matrix m = new android.graphics.Matrix();
-        m.setScale(0.0005f, 0.0005f);
-        planeShader.setLocalMatrix(m);
     }
 
     private float[] getTextScaleMatrix(float size) {
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