From d08103168a4ee78c163f2614e5f3e8e7cede6b9d Mon Sep 17 00:00:00 2001
From: Mikael Sand <msand@abo.fi>
Date: Wed, 26 Jul 2017 03:51:57 +0300
Subject: [PATCH] Suggest adding a compatibility mid-line rendering attribute
 to textPath.

---
 .../main/java/com/horcrux/svg/TSpanShadowNode.java  | 10 +++++++++-
 .../main/java/com/horcrux/svg/TextPathMidLine.java  | 12 ++++++++++++
 .../java/com/horcrux/svg/TextPathShadowNode.java    | 11 +++++++++++
 lib/attributes.js                                   |  1 +
 lib/props.js                                        | 13 +++++++++++++
 5 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 android/src/main/java/com/horcrux/svg/TextPathMidLine.java

diff --git a/android/src/main/java/com/horcrux/svg/TSpanShadowNode.java b/android/src/main/java/com/horcrux/svg/TSpanShadowNode.java
index 77ef4cba..01e67ff8 100644
--- a/android/src/main/java/com/horcrux/svg/TSpanShadowNode.java
+++ b/android/src/main/java/com/horcrux/svg/TSpanShadowNode.java
@@ -29,6 +29,7 @@ import static android.graphics.Matrix.MTRANS_X;
 import static android.graphics.Matrix.MTRANS_Y;
 import static android.graphics.PathMeasure.POSITION_MATRIX_FLAG;
 import static android.graphics.PathMeasure.TANGENT_MATRIX_FLAG;
+import static com.horcrux.svg.TextPathMidLine.sharp;
 
 /**
  * Shadow node for virtual TSpan view
@@ -128,7 +129,9 @@ class TSpanShadowNode extends TextShadowNode {
 
         double distance = 0;
         PathMeasure pm = null;
+        boolean sharpMidline = false;
         if (textPath != null) {
+            sharpMidline = textPath.getMidLine() == sharp;
             pm = new PathMeasure(textPath.getPath(), false);
             distance = pm.getLength();
             if (distance == 0) {
@@ -368,9 +371,14 @@ class TSpanShadowNode extends TextShadowNode {
                     Position the glyph such that the glyph-midline passes through
                     the midpoint-on-the-path and is perpendicular to the line
                     through the startpoint-on-the-path and the endpoint-on-the-path.
+
+                    TODO suggest adding a compatibility mid-line rendering attribute to textPath,
+                    for a chrome/firefox/opera/safari compatible sharp text path rendering,
+                    which doesn't bend text smoothly along a right angle curve, (like Edge does)
+                    but keeps the mid-line orthogonal to the mid-point tangent at all times instead.
                 */
                 assert pm != null;
-                if (startpoint < 0 || endpoint > distance) {
+                if (startpoint < 0 || endpoint > distance || sharpMidline) {
                 /*
                     In the calculation above, if either the startpoint-on-the-path
                     or the endpoint-on-the-path is off the end of the path,
diff --git a/android/src/main/java/com/horcrux/svg/TextPathMidLine.java b/android/src/main/java/com/horcrux/svg/TextPathMidLine.java
new file mode 100644
index 00000000..764a6478
--- /dev/null
+++ b/android/src/main/java/com/horcrux/svg/TextPathMidLine.java
@@ -0,0 +1,12 @@
+package com.horcrux.svg;
+
+/*
+    TODO suggest adding a compatibility mid-line rendering attribute to textPath,
+    for a chrome/firefox/opera/safari compatible sharp text path rendering,
+    which doesn't bend text smoothly along a right angle curve, (like Edge does)
+    but keeps the mid-line orthogonal to the mid-point tangent at all times instead.
+*/
+enum TextPathMidLine {
+    sharp,
+    smooth
+}
diff --git a/android/src/main/java/com/horcrux/svg/TextPathShadowNode.java b/android/src/main/java/com/horcrux/svg/TextPathShadowNode.java
index 6223e1f7..6c976b7a 100644
--- a/android/src/main/java/com/horcrux/svg/TextPathShadowNode.java
+++ b/android/src/main/java/com/horcrux/svg/TextPathShadowNode.java
@@ -23,6 +23,7 @@ import javax.annotation.Nullable;
 class TextPathShadowNode extends TextShadowNode {
 
     private String mHref;
+    private TextPathMidLine mMidLine;
     private @Nullable String mStartOffset;
     private TextPathMethod mMethod = TextPathMethod.align;
     private TextPathSpacing mSpacing = TextPathSpacing.exact;
@@ -58,6 +59,12 @@ class TextPathShadowNode extends TextShadowNode {
         markUpdated();
     }
 
+    @ReactProp(name = "midLine")
+    public void setSharp(@Nullable String midLine) {
+        mMidLine = TextPathMidLine.valueOf(midLine);
+        markUpdated();
+    }
+
     TextPathMethod getMethod() {
         return mMethod;
     }
@@ -70,6 +77,10 @@ class TextPathShadowNode extends TextShadowNode {
         return mSide;
     }
 
+    public TextPathMidLine getMidLine() {
+        return mMidLine;
+    }
+
     String getStartOffset() {
         return mStartOffset;
     }
diff --git a/lib/attributes.js b/lib/attributes.js
index 8854e66b..9865a069 100644
--- a/lib/attributes.js
+++ b/lib/attributes.js
@@ -134,6 +134,7 @@ const TextPathAttributes = {
     method: true,
     spacing: true,
     side: true,
+    midLine: true,
 };
 
 const TSpanAttibutes = {
diff --git a/lib/props.js b/lib/props.js
index 0c14884f..51fda003 100644
--- a/lib/props.js
+++ b/lib/props.js
@@ -263,6 +263,18 @@ const method = PropTypes.oneOf(['align', 'stretch']);
  */
 const spacing = PropTypes.oneOf(['auto', 'exact']);
 
+/*
+ Name
+ mid-line
+ Value
+ sharp | smooth
+ initial value
+ smooth
+ Animatable
+ yes
+ */
+const midLine = PropTypes.oneOf(['sharp', 'smooth']);
+
 // https://svgwg.org/svg2-draft/text.html#TextPathAttributes
 // https://developer.mozilla.org/en/docs/Web/SVG/Element/textPath
 const textPathProps = {
@@ -272,6 +284,7 @@ const textPathProps = {
     method,
     spacing,
     side,
+    midLine,
 };
 
 export {