[androidkit] add gaussian blur filter to java ImageFilters

Change-Id: I63f3f3feaf590971633c88857105ed14dbab2bb8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/420122
Commit-Queue: Jorge Betancourt <jmbetancourt@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>

modules/androidkit/src/ImageFilter.cpp

@@ -10,6 +10,7 @@
 #include "include/core/SkImageFilter.h"
 #include "include/core/SkPoint3.h"
 #include "include/effects/SkImageFilters.h"
+#include "modules/androidkit/src/Utils.h"
 
 namespace {
 
@@ -30,12 +31,22 @@ static long ImageFilter_DistantLitDiffuse(JNIEnv* env, jobject, jfloat x, jfloat
     return reinterpret_cast<jlong>(filter.release());
 }
 
+static long ImageFilter_Blur(JNIEnv* env, jobject, jfloat sigmaX, jfloat sigmaY,
+                                                   jint jTileMode, jlong native_input) {
+    auto input = sk_ref_sp(reinterpret_cast<SkImageFilter*>(native_input));
+    auto filter = SkImageFilters::Blur(sigmaX, sigmaY,
+                                       androidkit::utils::TileMode(jTileMode),
+                                       std::move(input));
+    return reinterpret_cast<jlong>(filter.release());
+}
+
 } // namespace
 
 int register_androidkit_ImageFilter(JNIEnv* env) {
     static const JNINativeMethod methods[] = {
         {"nRelease"          , "(J)V"        , reinterpret_cast<void*>(ImageFilter_Release)},
         {"nDistantLitDiffuse", "(FFFFFFFFJ)J", reinterpret_cast<void*>(ImageFilter_DistantLitDiffuse)},
+        {"nBlur"             , "(FFIJ)J"     , reinterpret_cast<void*>(ImageFilter_Blur)},
     };
 
     const auto clazz = env->FindClass("org/skia/androidkit/ImageFilter");

platform_tools/android/apps/AndroidKit/src/main/java/org/skia/androidkit/Image.java

@@ -56,7 +56,7 @@ public class Image {
     public Shader makeShader(TileMode tmx, TileMode tmy, SamplingOptions sampling,
                              @Nullable Matrix localMatrix) {
         long nativeMatrix = localMatrix != null ? localMatrix.getNativeInstance() : 0;
-        return new Shader(nMakeShader(mNativeInstance, tmx.ordinal(), tmy.ordinal(),
+        return new Shader(nMakeShader(mNativeInstance, tmx.nativeInt, tmy.nativeInt,
                                       sampling.getNativeDesc(),
                                       sampling.getCubicCoeffB(), sampling.getCubicCoeffC(),
                                       nativeMatrix));

platform_tools/android/apps/AndroidKit/src/main/java/org/skia/androidkit/ImageFilter.java

@@ -36,6 +36,23 @@ public class ImageFilter {
         return new ImageFilter(nDistantLitDiffuse(x, y, z, c.r(), c.g(), c.b(),
                                                   surfaceScale, kd, nativeInput));
     }
+
+    /**
+     *  Create a filter that calculates the diffuse illumination from a distant light source,
+     *  interpreting the alpha channel of the input as the height profile of the surface (to
+     *  approximate normal vectors).
+     *  @param sigmaX   The Gaussian sigma value for blurring along the X axis.
+     *  @param sigmaY   The Gaussian sigma value for blurring along the Y axis.
+     *  @param tileMode The tile mode applied at edges
+     *  @param input    The input filter that is blurred, uses source bitmap if this is null.
+     */
+    public static ImageFilter blur(float sigmaX, float sigmaY, TileMode tileMode, @Nullable ImageFilter input) {
+        long nativeInput = 0;
+        if (input != null) {
+            nativeInput = input.getNativeInstance();
+        }
+        return new ImageFilter(nBlur(sigmaX, sigmaY, tileMode.nativeInt, nativeInput));
+    }
     /**
      * Releases any resources associated with this Shader.
      */
@@ -57,4 +74,5 @@ public class ImageFilter {
                                                   float r, float g, float b,
                                                   float surfaceScale, float kd,
                                                   long native_input);
+    private static native long nBlur(float sigmaX, float sigmaY, int tileMode, long native_input);
 }

platform_tools/android/apps/AndroidKit/src/main/java/org/skia/androidkit/TileMode.java

@@ -12,22 +12,27 @@ public enum TileMode {
      *  Replicate the edge color if the shader draws outside of its
      *  original bounds.
      */
-    CLAMP,
+    CLAMP(0),
 
     /**
      *  Repeat the shader's image horizontally and vertically.
      */
-    REPEAT,
+    REPEAT(1),
 
     /**
      *  Repeat the shader's image horizontally and vertically, alternating
      *  mirror images so that adjacent images always seam.
      */
-    MIRROR,
+    MIRROR(2),
 
 
     /**
      *  Only draw within the original domain, return transparent-black everywhere else.
      */
-    DECAL,
+    DECAL(3);
+
+    TileMode(int nativeInt) {
+        this.nativeInt = nativeInt;
+    }
+    final int nativeInt;
 }

platform_tools/android/apps/androidkitdemo/src/main/java/org/skia/androidkitdemo1/MainActivity.java

@@ -94,7 +94,8 @@ public class MainActivity extends Activity {
             threadedSurface = Surface.createThreadedSurface(holder.getSurface());
             Paint p = new Paint();
             p.setColor(new Color(1, 1, 0, 1));
-            ImageFilter filter = ImageFilter.distantLitDiffuse(.5f, .5f, .5f, new Color(1, 0, 0, 1), 1, 1, null);
+            //ImageFilter filter = ImageFilter.distantLitDiffuse(.5f, .5f, .5f, new Color(1, 0, 0, 1), 1, 1, null);
+            ImageFilter filter = ImageFilter.blur(10, 10, TileMode.DECAL, null);
             p.setImageFilter(filter);
             PathBuilder pathBuilder = new PathBuilder();
             pathBuilder.moveTo(20, 20);