Introduce SkPathUtils bindings (#815)

* Introduce SkPathUtils bindings

This functionality used to exist elsewhere in Skia, but in m110 it was moved into SkPathUtils. When that change occurred, the functionality was removed from Skiko rather than moved, so this commit is to return the functionality by providing access to SkPathUtils.

* use `assertTrue` instead of `assertEquals`

to make KotlinJS happy

---------
Co-authored-by: Pavel <sergeev.pavel.al@gmail.com>

skiko/src/commonMain/kotlin/org/jetbrains/skia/PathUtils.kt

+package org.jetbrains.skia
+
+import org.jetbrains.skia.impl.*
+import org.jetbrains.skia.impl.Library.Companion.staticLoad
+import org.jetbrains.skia.impl.getPtr
+import org.jetbrains.skia.impl.reachabilityBarrier
+
+object PathUtils {
+
+    /**
+     * Returns the filled equivalent of the stroked path using the provided paint attributes.
+     *
+     * @param src       Path to create a filled version of.
+     * @param paint     Paint from which attributes such as stroke cap, width, miter, join, and
+     *                  pathEffect will be used.
+     * @param cull      Optional limit passed to the path effect.
+     * @param resScale  If > 1, increase precision, else if (0 < resScale < 1) reduce precision
+     *                  to favor speed and size.
+     * @return          A filled version of the source path.
+     */
+    fun fillPathWithPaint(src: Path, paint: Paint, cull: Rect?, resScale: Float): Path {
+        return fillPathWithPaint(src, paint, cull, Matrix33.makeScale(resScale))
+    }
+
+    /**
+     * Returns the filled equivalent of the stroked path using the provided paint attributes.
+     *
+     * @param src       Path to create a filled version of.
+     * @param paint     Paint from which attributes such as stroke cap, width, miter, join, and
+     *                  pathEffect will be used.
+     * @param cull      Optional limit passed to the path effect.
+     * @param matrix    Current transformation matrix.
+     * @return          A filled version of the source path.
+     */
+    fun fillPathWithPaint(src: Path, paint: Paint, cull: Rect?, matrix: Matrix33): Path {
+        return try {
+            Stats.onNativeCall()
+            if (cull == null) org.jetbrains.skia.Path(
+                interopScope {
+                    _nFillPathWithPaint(
+                        getPtr(src),
+                        getPtr(paint),
+                        toInterop(matrix.mat)
+                    )
+                }
+            ) else org.jetbrains.skia.Path(
+                interopScope {
+                    _nFillPathWithPaintCull(
+                        getPtr(src),
+                        getPtr(paint),
+                        cull.left,
+                        cull.top,
+                        cull.right,
+                        cull.bottom,
+                        toInterop(matrix.mat)
+                    )
+                }
+            )
+        } finally {
+            reachabilityBarrier(src)
+            reachabilityBarrier(paint)
+        }
+    }
+
+    /**
+     * Returns the filled equivalent of the stroked path using the provided paint attributes.
+     *
+     * @param src   Path to create a filled version of.
+     * @param paint Paint attributes such as stroke cap, width, miter, join, and pathEffect.
+     * @return      A filled version of the source path.
+     */
+    fun fillPathWithPaint(src: Path, paint: Paint): Path {
+        return fillPathWithPaint(src, paint, null, 1f)
+    }
+
+    init {
+        staticLoad()
+    }
+}
+
+@ExternalSymbolName("org_jetbrains_skia_PathUtils__1nFillPathWithPaint")
+private external fun _nFillPathWithPaint(
+    srcPtr: NativePointer,
+    paintPtr: NativePointer,
+    matrix: InteropPointer
+): NativePointer
+
+@ExternalSymbolName("org_jetbrains_skia_PathUtils__1nFillPathWithPaintCull")
+private external fun _nFillPathWithPaintCull(
+    srcPtr: NativePointer,
+    paintPtr: NativePointer,
+    left: Float,
+    top: Float,
+    right: Float,
+    bottom: Float,
+    matrix: InteropPointer
+): NativePointer

skiko/src/commonTest/kotlin/org/jetbrains/skia/PathUtilsTest.kt

+package org.jetbrains.skia
+
+import org.jetbrains.skiko.tests.runTest
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+class PathUtilsTest {
+
+    @Test
+    fun fillPathWithPaint() = runTest {
+        val paint = Paint().apply {
+            color = 0xff000000.toInt()
+            strokeWidth = 10f
+            mode = PaintMode.STROKE
+        }
+        val path = Path().lineTo(40f, 40f)
+
+        val fillPath = PathUtils.fillPathWithPaint(path, paint)
+
+        assertTrue(fillPath.isLastContourClosed)
+        assertTrue(fillPath.pointsCount > path.pointsCount)
+        assertTrue(fillPath.verbsCount > path.verbsCount)
+    }
+
+    @Test
+    fun fillPathWithPaintScale() = runTest {
+        val paint = Paint().apply {
+            color = 0xff000000.toInt()
+            strokeWidth = 10f
+            mode = PaintMode.STROKE
+        }
+        val path = Path().arcTo(Rect(0f, 0f, 40f, 40f), 0f, 90f, false)
+
+        val fillPath1 = PathUtils.fillPathWithPaint(path, paint,null, 1f)
+        val fillPath001 = PathUtils.fillPathWithPaint(path, paint,null, 0.01f)
+
+        // assert 1f scale has higher precision (more points) than 0.01f
+        assertTrue(fillPath1.pointsCount > fillPath001.pointsCount)
+    }
+
+}

skiko/src/jvmMain/cpp/common/PathUtils.cc

+#include <jni.h>
+#include "SkPathUtils.h"
+#include "SkPath.h"
+#include "SkPaint.h"
+#include "interop.hh"
+
+extern "C" JNIEXPORT jlong JNICALL Java_org_jetbrains_skia_PathUtilsKt__1nFillPathWithPaint
+  (JNIEnv* env, jclass jclass, jlong srcPtr, jlong paintPtr, jfloatArray matrixArr) {
+    std::unique_ptr<SkMatrix> matrix = skMatrix(env, matrixArr);
+    SkPath* src = reinterpret_cast<SkPath*>(static_cast<uintptr_t>(srcPtr));
+    SkPaint* paint = reinterpret_cast<SkPaint*>(static_cast<uintptr_t>(paintPtr));
+    SkPath* dst = new SkPath();
+    skpathutils::FillPathWithPaint(*src, *paint, dst, nullptr, *matrix);
+    return reinterpret_cast<jlong>(dst);
+}
+
+extern "C" JNIEXPORT jlong JNICALL Java_org_jetbrains_skia_PathUtilsKt__1nFillPathWithPaintCull
+  (JNIEnv* env, jclass jclass, jlong srcPtr, jlong paintPtr, jfloat left, jfloat top, jfloat right, jfloat bottom, jfloatArray matrixArr) {
+    std::unique_ptr<SkMatrix> matrix = skMatrix(env, matrixArr);
+    SkPath* src = reinterpret_cast<SkPath*>(static_cast<uintptr_t>(srcPtr));
+    SkPaint* paint = reinterpret_cast<SkPaint*>(static_cast<uintptr_t>(paintPtr));
+    SkPath* dst = new SkPath();
+    SkRect cull {left, top, right, bottom};
+    skpathutils::FillPathWithPaint(*src, *paint, dst, &cull, *matrix);
+    return reinterpret_cast<jlong>(dst);
+}

skiko/src/nativeJsMain/cpp/PathUtils.cc

+#include "SkPathUtils.h"
+#include "SkPath.h"
+#include "SkPaint.h"
+#include "common.h"
+
+SKIKO_EXPORT KNativePointer org_jetbrains_skia_PathUtils__1nFillPathWithPaint
+  (KNativePointer srcPtr, KNativePointer paintPtr, KFloat* matrixArr) {
+    std::unique_ptr<SkMatrix> matrix = skMatrix(matrixArr);
+    SkPath* src = reinterpret_cast<SkPath*>((srcPtr));
+    SkPaint* paint = reinterpret_cast<SkPaint*>((paintPtr));
+    SkPath* dst = new SkPath();
+    skpathutils::FillPathWithPaint(*src, *paint, dst, nullptr, *matrix);
+    return reinterpret_cast<KNativePointer>(dst);
+}
+
+SKIKO_EXPORT KNativePointer org_jetbrains_skia_PathUtils__1nFillPathWithPaintCull
+  (KNativePointer srcPtr, KNativePointer paintPtr, KFloat left, KFloat top, KFloat right, KFloat bottom, KFloat* matrixArr) {
+    std::unique_ptr<SkMatrix> matrix = skMatrix(matrixArr);
+    SkPath* src = reinterpret_cast<SkPath*>((srcPtr));
+    SkPaint* paint = reinterpret_cast<SkPaint*>((paintPtr));
+    SkPath* dst = new SkPath();
+    SkRect cull {left, top, right, bottom};
+    skpathutils::FillPathWithPaint(*src, *paint, dst, &cull, *matrix);
+    return reinterpret_cast<KNativePointer>(dst);
+}