From ada843203ad15e18a37388c8ad8223ab56c36cbb Mon Sep 17 00:00:00 2001
From: Evan Laird <evanlaird@google.com>
Date: Thu, 1 Jun 2017 14:47:27 -0400
Subject: [PATCH] Round the corners of the mobile signal status bar icon

Add arcs of radius 0.75 dp to the drawing of the mobile signal drawble.

Test: visual
Bug: 37013523
Change-Id: I80e6e7b6888e8e35667b0df191aac7db1e2d2059
---
 packages/SystemUI/res/values/dimens.xml       |  3 +
 .../statusbar/phone/SignalDrawable.java       | 61 +++++++++++++++++--
 2 files changed, 58 insertions(+), 6 deletions(-)

diff --git a/packages/SystemUI/res/values/dimens.xml b/packages/SystemUI/res/values/dimens.xml
index 340cd79b1e793..d71bfcaecbca1 100644
--- a/packages/SystemUI/res/values/dimens.xml
+++ b/packages/SystemUI/res/values/dimens.xml
@@ -815,4 +815,7 @@
 
     <dimen name="qs_gutter_height">6dp</dimen>
 
+    <!-- Intended corner radius when drawing the mobile signal -->
+    <dimen name="stat_sys_mobile_signal_corner_radius">0.75dp</dimen>
+
 </resources>
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/SignalDrawable.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/SignalDrawable.java
index 8cd87910f945a..7633767c61816 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/SignalDrawable.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/SignalDrawable.java
@@ -31,7 +31,6 @@ import android.graphics.Rect;
 import android.graphics.drawable.Drawable;
 import android.os.Handler;
 import android.util.LayoutDirection;
-import android.util.Log;
 
 import com.android.settingslib.R;
 import com.android.settingslib.Utils;
@@ -82,6 +81,22 @@ public class SignalDrawable extends Drawable {
             {-1.9f / VIEWPORT, -1.9f / VIEWPORT},
     };
 
+    // Rounded corners are achieved by arcing a circle of radius `mCornerRadius` from its tangent
+    // points along the curve. On the top and left corners of the triangle, the tangents are as
+    // follows:
+    //      1) Along the straight lines (y = 0 and x = width):
+    //          Ps = R / tan(45)
+    //      2) Along the diagonal line (y = x):
+    //          Pd = √((Ps^2) / 2)
+    //
+    // I.e., the points where we stop the straight lines lie at (starting drawing from the bottom-
+    // right corner and counter-clockwise): (width, height - Radius), (width, Ps), (width - Pd, Pd),
+    // (Pd, height - Pd), (Ps, height), and finally (width - Radius, height).
+    private static final double TAN_THETA = Math.tan(Math.PI / 8.f);
+    private final float mCornerRadius;
+    private final float mCircleOffsetStraight;
+    private final float mCircleOffsetDiag;
+
     private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
     private final Paint mForegroundPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
     private final int mDarkModeBackgroundColor;
@@ -113,6 +128,11 @@ public class SignalDrawable extends Drawable {
         mIntrinsicSize = context.getResources().getDimensionPixelSize(R.dimen.signal_icon_size);
         mHandler = new Handler();
         setDarkIntensity(0);
+
+        mCornerRadius = context.getResources()
+                .getDimensionPixelSize(R.dimen.stat_sys_mobile_signal_corner_radius);
+        mCircleOffsetStraight = mCornerRadius / (float) TAN_THETA;
+        mCircleOffsetDiag = (float) Math.sqrt(Math.pow(mCircleOffsetStraight, 2.f) / 2.f);
     }
 
     @Override
@@ -204,11 +224,40 @@ public class SignalDrawable extends Drawable {
         mFullPath.setFillType(FillType.WINDING);
         float width = getBounds().width();
         float height = getBounds().height();
-        float padding = (PAD * width);
-        mFullPath.moveTo(width - padding, height - padding);
-        mFullPath.lineTo(width - padding, padding);
-        mFullPath.lineTo(padding, height - padding);
-        mFullPath.lineTo(width - padding, height - padding);
+        float padding = (int) (PAD * width);  // Stay on pixel boundary
+
+        // 1 - Bottom right, above corner
+        mFullPath.moveTo(width - padding, height - padding - mCornerRadius);
+        // 2 - Line to top right, below corner
+        mFullPath.lineTo(width - padding, padding + mCircleOffsetStraight);
+        // 3 - Arc to top right, on hypotenuse
+        mFullPath.arcTo(
+                width - padding - (2 * mCornerRadius),
+                padding + mCircleOffsetStraight - mCornerRadius,
+                width - padding,
+                padding + mCircleOffsetStraight + mCornerRadius,
+                0.f, -135.f, false
+        );
+        // 4 - Line to bottom left, on hypotenuse
+        mFullPath.lineTo(padding + mCircleOffsetDiag, height - padding - mCircleOffsetDiag);
+        // 5 - Arc to bottom left, on leg
+        mFullPath.arcTo(
+                padding + mCircleOffsetStraight - mCornerRadius,
+                height - padding - (2 * mCornerRadius),
+                padding + mCircleOffsetStraight + mCornerRadius,
+                height - padding,
+                -135.f, -135.f, false
+        );
+        // 6 - Line to bottom rght, before corner
+        mFullPath.lineTo(width - padding - mCornerRadius, height - padding);
+        // 7 - Arc to beginning (bottom right, above corner)
+        mFullPath.arcTo(
+                width - padding - (2 * mCornerRadius),
+                height - padding - (2 * mCornerRadius),
+                width - padding,
+                height - padding,
+                90.f, -90.f, false
+        );
 
         if (mState == STATE_CARRIER_CHANGE) {
             float cutWidth = (DOT_CUT_WIDTH * width);