From 322bc57a338ec650347084ef379860c19b29d1b4 Mon Sep 17 00:00:00 2001
From: Mike Reed <reed@google.com>
Date: Tue, 20 Mar 2018 13:37:04 -0400
Subject: [PATCH] detect api version, and start respecting offsets

Test: make

Bug: 36471624
Change-Id: Ica10c557bf35e8d707fabbafab49d22109916fd3
---
 core/jni/android_graphics_Canvas.cpp       | 11 ++++++++++-
 graphics/java/android/graphics/Canvas.java |  4 ++++
 libs/hwui/hwui/Canvas.h                    |  2 ++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/core/jni/android_graphics_Canvas.cpp b/core/jni/android_graphics_Canvas.cpp
index 0017f6cd8a417..c9bfa137c7ac0 100644
--- a/core/jni/android_graphics_Canvas.cpp
+++ b/core/jni/android_graphics_Canvas.cpp
@@ -18,6 +18,7 @@
 #include "GraphicsJNI.h"
 #include "core_jni_helpers.h"
 
+#include <android/api-level.h>
 #include <androidfw/ResourceTypes.h>
 #include <hwui/Canvas.h>
 #include <hwui/Paint.h>
@@ -467,6 +468,13 @@ static void drawBitmapArray(JNIEnv* env, jobject, jlong canvasHandle,
 static void drawBitmapMesh(JNIEnv* env, jobject, jlong canvasHandle, jobject jbitmap,
                            jint meshWidth, jint meshHeight, jfloatArray jverts,
                            jint vertIndex, jintArray jcolors, jint colorIndex, jlong paintHandle) {
+    if (Canvas::GetApiLevel() < __ANDROID_API_P__) {
+        // Before P we forgot to respect these. Now that we do respect them, explicitly
+        // zero them for backward compatibility.
+        vertIndex = 0;
+        colorIndex = 0;
+    }
+
     const int ptCount = (meshWidth + 1) * (meshHeight + 1);
     AutoJavaFloatArray vertA(env, jverts, vertIndex + (ptCount << 1));
     AutoJavaIntArray colorA(env, jcolors, colorIndex + ptCount);
@@ -474,7 +482,8 @@ static void drawBitmapMesh(JNIEnv* env, jobject, jlong canvasHandle, jobject jbi
     const Paint* paint = reinterpret_cast<Paint*>(paintHandle);
     Bitmap& bitmap = android::bitmap::toBitmap(env, jbitmap);
     get_canvas(canvasHandle)->drawBitmapMesh(bitmap, meshWidth, meshHeight,
-                                             vertA.ptr(), colorA.ptr(), paint);
+                                             vertA.ptr() + vertIndex*2,
+                                             colorA.ptr() + colorIndex, paint);
 }
 
 static void drawTextChars(JNIEnv* env, jobject, jlong canvasHandle, jcharArray text,
diff --git a/graphics/java/android/graphics/Canvas.java b/graphics/java/android/graphics/Canvas.java
index d925441e36570..b0bc1029c6df8 100644
--- a/graphics/java/android/graphics/Canvas.java
+++ b/graphics/java/android/graphics/Canvas.java
@@ -1490,6 +1490,10 @@ public class Canvas extends BaseCanvas {
      * across the top of the bitmap from left to right. A more general version of this method is
      * drawVertices().
      *
+     * Prior to API level {@value Build.VERSION_CODES#P} vertOffset and colorOffset were ignored,
+     * effectively treating them as zeros. In API level {@value Build.VERSION_CODES#P} and above
+     * these parameters will be respected.
+     *
      * @param bitmap The bitmap to draw using the mesh
      * @param meshWidth The number of columns in the mesh. Nothing is drawn if this is 0
      * @param meshHeight The number of rows in the mesh. Nothing is drawn if this is 0
diff --git a/libs/hwui/hwui/Canvas.h b/libs/hwui/hwui/Canvas.h
index d04bb2e5ad034..f341cf96120da 100644
--- a/libs/hwui/hwui/Canvas.h
+++ b/libs/hwui/hwui/Canvas.h
@@ -276,6 +276,8 @@ public:
                         const SkPath& path, float hOffset, float vOffset, const Paint& paint,
                         const Typeface* typeface);
 
+    static int GetApiLevel() { return sApiLevel; }
+
 protected:
     void drawTextDecorations(float x, float y, float length, const SkPaint& paint);