Add a getter and setter for ParagraphStyle.replaceTabCharacters (#1036)

This change will be used in Compose Multiplatform to fix
https://youtrack.jetbrains.com/issue/CMP-6589/wasm-can-not-render-tab-symbol

The difference can be seen here:
**Good**: https://fiddle.skia.org/c/24fb7ebc20eec08077d84b9fe37ceb4f -
`paraStyle.setReplaceTabCharacters(true);`
**Bad**: https://fiddle.skia.org/c/fbcb4a52786d63ed42a85d05d5472164 -
`paraStyle.setReplaceTabCharacters(false);`

samples/SkiaMultiplatformSample/src/commonMain/kotlin/org/jetbrains/skiko/sample/EmojiStory.kt

@@ -15,13 +15,14 @@ class EmojiStory : SkikoRenderDelegate {
     private val platformYOffset = if (hostOs == OS.Ios) 50f else 5f
 
     private val style = ParagraphStyle().apply {
+        replaceTabCharacters = true
         textStyle = TextStyle().apply {
             this.fontSize = 16.0f
         }.setColor(0xFF000000.toInt())
     }
 
     private val paragraph = ParagraphBuilder(style, fontCollection)
-        .addText("\uD83D\uDCE1 Antenna - 天线\n")
+        .addText("\uD83D\uDCE1\tAntenna\t-\t天线\t\n")
         .addText("⁉\uFE0F 〰\uFE0F ⁉\uFE0F\n")
         .addText("\uD83D\uDE32 \uD83E\uDD14 \uD83D\uDCA1\n")
         .addText("\uD83C\uDF0D Earth - 地球\n")

skiko/src/commonMain/kotlin/org/jetbrains/skia/paragraph/ParagraphStyle.kt

@@ -29,6 +29,27 @@ class ParagraphStyle : Managed(ParagraphStyle_nMake(), _FinalizerHolder.PTR) {
         }
     }
 
+    /**
+     * Controls whether tab characters are replaced with spaces in text layout.
+     *
+     * Note:
+     * All the platforms except web do not render tab characters even when this is 'false', but put a space instead.
+     * With this property we can make web behave similarly, by setting true.
+     */
+    var replaceTabCharacters: Boolean
+        get() = try {
+            Stats.onNativeCall()
+            _nGetReplaceTabCharacters(_ptr)
+        } finally {
+            reachabilityBarrier(this)
+        }
+        set(value) = try {
+            Stats.onNativeCall()
+            _nSetReplaceTabCharacters(_ptr, value)
+        } finally {
+            reachabilityBarrier(this)
+        }
+
     var strutStyle: StrutStyle
         get() = try {
             Stats.onNativeCall()
@@ -350,3 +371,11 @@ private external fun _nSetTextIndent(ptr: NativePointer, firstLine: Float, restL
 @ExternalSymbolName("org_jetbrains_skia_paragraph_ParagraphStyle__1nGetTextIndent")
 @ModuleImport("./skiko.mjs", "org_jetbrains_skia_paragraph_ParagraphStyle__1nGetTextIndent")
 private external fun _nGetTextIndent(ptr: NativePointer, result: InteropPointer)
+
+@ExternalSymbolName("org_jetbrains_skia_paragraph_ParagraphStyle__1nGetReplaceTabCharacters")
+@ModuleImport("./skiko.mjs", "org_jetbrains_skia_paragraph_ParagraphStyle__1nGetReplaceTabCharacters")
+private external fun _nGetReplaceTabCharacters(ptr: NativePointer): Boolean
+
+@ExternalSymbolName("org_jetbrains_skia_paragraph_ParagraphStyle__1nSetReplaceTabCharacters")
+@ModuleImport("./skiko.mjs", "org_jetbrains_skia_paragraph_ParagraphStyle__1nSetReplaceTabCharacters")
+private external fun _nSetReplaceTabCharacters(ptr: NativePointer, value: Boolean)
\ No newline at end of file

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

@@ -5,14 +5,11 @@ import org.jetbrains.skia.paragraph.*
 import org.jetbrains.skia.tests.assertCloseEnough
 import org.jetbrains.skia.tests.assertContentCloseEnough
 import org.jetbrains.skia.tests.makeFromResource
-import org.jetbrains.skiko.tests.*
-import kotlin.math.ceil
-import kotlin.math.floor
-import kotlin.math.truncate
-import kotlin.test.Test
-import kotlin.test.assertContentEquals
-import kotlin.test.assertEquals
-import kotlin.test.assertTrue
+import org.jetbrains.skiko.tests.SkipJsTarget
+import org.jetbrains.skiko.tests.SkipNativeTarget
+import org.jetbrains.skiko.tests.SkipWasmTarget
+import org.jetbrains.skiko.tests.runTest
+import kotlin.test.*
 
 class ParagraphTest {
     private val fontCollection = suspend {
@@ -210,4 +207,13 @@ class ParagraphTest {
         testWraps(isApplyRoundingHackEnabled = false, unexpectedWrapsPresent = false)
         testWraps(isApplyRoundingHackEnabled = true, unexpectedWrapsPresent = true)
     }
+
+    @Test
+    fun paragraphStyleCanChangeReplaceTab() {
+        ParagraphStyle().use { it ->
+            assertFalse(it.replaceTabCharacters)
+            it.replaceTabCharacters = true
+            assertTrue(it.replaceTabCharacters)
+        }
+    }
 }

skiko/src/jsWasmTest/kotlin/org/jetbrains/skia/ParagraphWebTest.kt

+package org.jetbrains.skia
+
+import org.jetbrains.skia.impl.use
+import org.jetbrains.skia.paragraph.*
+import kotlin.math.roundToInt
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+/**
+ * The tests here draw a Paragraph on canvas and check the pixels.
+ * Ideally it could be a screenshot test, but we don't have them on web yet.
+ */
+class ParagraphWebTest {
+
+    private val fontCollection = FontCollection().setDefaultFontManager(FontMgr.default)
+
+    @Test
+    fun paragraphWithTabulationReplacingTabs1() {
+        val paragraphStyle = ParagraphStyle().apply {
+            replaceTabCharacters = true
+            textStyle = TextStyle().apply {
+                this.fontSize = 32.0f
+            }.setColor(Color.BLACK)
+        }
+        val paragraph = ParagraphBuilder(paragraphStyle, fontCollection).use {
+            it.addText("\t\t\t  .")
+            it.build().layout(100.0f)
+        }
+
+        val surface = Surface.makeRasterN32Premul(100, 50)
+        surface.canvas.clear(Color.WHITE)
+        paragraph.paint(surface.canvas, 0.0f, 0.0f)
+        surface.makeImageSnapshot().use { image ->
+            val bitmap = Bitmap.makeFromImage(image)
+            assertTrue(bitmap.height == 50)
+            assertTrue(bitmap.width == 100)
+
+            val right = paragraph.lineMetrics[0].right.roundToInt()
+            val baselineY = paragraph.lineMetrics[0].baseline.roundToInt()
+
+            var notAllWhite = false
+            for (x in (right - 5)until (right + 5)) {
+                for (y in (baselineY - 5)until (baselineY + 5)) {
+                    if (bitmap.getColor(x, y) != Color.WHITE) {
+                        notAllWhite = true
+                        break
+                    }
+                }
+            }
+
+            assertTrue(notAllWhite, "Expected some non-white pixels for a dot.")
+
+            val rects = paragraph.getRectsForRange(0, 4, RectHeightMode.TIGHT, RectWidthMode.TIGHT)
+            val tabsRectRight = rects[0].rect.right.roundToInt()
+            assertTrue(tabsRectRight > paragraph.lineMetrics[0].left &&
+                    tabsRectRight < paragraph.lineMetrics[0].right
+            )
+            var countNotWhite = 0
+            for (x in 0 until tabsRectRight) {
+                for (y in 0 until bitmap.height) {
+                    if (bitmap.getColor(x, y) != Color.WHITE) {
+                        countNotWhite++
+                    }
+                }
+            }
+
+            assertEquals(0, countNotWhite, "Expected all pixels for tabs to be white.")
+        }
+    }
+
+    @Test
+    fun paragraphWithTabulationNoReplacingTabs() {
+        val paragraphStyle = ParagraphStyle().apply {
+            replaceTabCharacters = false
+            textStyle = TextStyle().apply {
+                this.fontSize = 32.0f
+            }.setColor(Color.BLACK)
+        }
+        val paragraph = ParagraphBuilder(paragraphStyle, fontCollection).use {
+            it.addText("\t\t\t  .")
+            it.build().layout(100.0f)
+        }
+
+        val surface = Surface.makeRasterN32Premul(100, 50)
+        surface.canvas.clear(Color.WHITE)
+        paragraph.paint(surface.canvas, 0.0f, 0.0f)
+        surface.makeImageSnapshot().use { image ->
+            val bitmap = Bitmap.makeFromImage(image)
+            assertTrue(bitmap.height == 50)
+            assertTrue(bitmap.width == 100)
+
+            val rects = paragraph.getRectsForRange(0, 4, RectHeightMode.TIGHT, RectWidthMode.TIGHT)
+            val tabsRect = rects[0].rect
+            val tabsRectRight = tabsRect.right.roundToInt()
+            assertTrue(tabsRectRight > paragraph.lineMetrics[0].left &&
+                    tabsRectRight < paragraph.lineMetrics[0].right
+            )
+            var countNotWhite = 0
+            for (x in 0 until tabsRectRight) {
+                for (y in 0 until bitmap.height) {
+                    if (bitmap.getColor(x, y) != Color.WHITE) {
+                        countNotWhite++
+                    }
+                }
+            }
+
+            assertTrue(countNotWhite < (tabsRect.width * tabsRect.height) / 2, "Too many non-white pixels for tabs.")
+            assertTrue(countNotWhite > 300, "Expected at least 300 non-white pixels for tabs (tofu glyphs), got $countNotWhite")
+        }
+    }
+}
\ No newline at end of file

skiko/src/jvmMain/cpp/common/paragraph/ParagraphStyle.cc

@@ -23,6 +23,19 @@ extern "C" JNIEXPORT jlong JNICALL Java_org_jetbrains_skia_paragraph_ParagraphSt
     return reinterpret_cast<jlong>(instance);
 }
 
+extern "C" JNIEXPORT jboolean JNICALL Java_org_jetbrains_skia_paragraph_ParagraphStyleKt__1nGetReplaceTabCharacters
+    (JNIEnv* env, jclass jclass, jlong ptr) {
+  ParagraphStyle* instance = reinterpret_cast<ParagraphStyle*>(static_cast<uintptr_t>(ptr));
+  return instance->getReplaceTabCharacters();
+}
+
+
+extern "C" JNIEXPORT void JNICALL Java_org_jetbrains_skia_paragraph_ParagraphStyleKt__1nSetReplaceTabCharacters
+    (JNIEnv* env, jclass jclass, jlong ptr, jboolean value) {
+  ParagraphStyle* instance = reinterpret_cast<ParagraphStyle*>(static_cast<uintptr_t>(ptr));
+  instance->setReplaceTabCharacters(value);
+}
+
 extern "C" JNIEXPORT jboolean JNICALL Java_org_jetbrains_skia_paragraph_ParagraphStyleKt__1nEquals
   (JNIEnv* env, jclass jclass, jlong ptr, jlong otherPtr) {
     ParagraphStyle* instance = reinterpret_cast<ParagraphStyle*>(static_cast<uintptr_t>(ptr));

skiko/src/nativeJsMain/cpp/paragraph/ParagraphStyle.cc

@@ -20,6 +20,19 @@ SKIKO_EXPORT KNativePointer org_jetbrains_skia_paragraph_ParagraphStyle__1nMake
     return reinterpret_cast<KNativePointer>(instance);
 }
 
+SKIKO_EXPORT KBoolean org_jetbrains_skia_paragraph_ParagraphStyle__1nGetReplaceTabCharacters
+    (KNativePointer ptr) {
+  ParagraphStyle* instance = reinterpret_cast<ParagraphStyle*>((ptr));
+  return instance->getReplaceTabCharacters();
+}
+
+
+SKIKO_EXPORT void org_jetbrains_skia_paragraph_ParagraphStyle__1nSetReplaceTabCharacters
+    (KNativePointer ptr, KBoolean value) {
+  ParagraphStyle* instance = reinterpret_cast<ParagraphStyle*>((ptr));
+  instance->setReplaceTabCharacters(value);
+}
+
 SKIKO_EXPORT KBoolean org_jetbrains_skia_paragraph_ParagraphStyle__1nEquals
   (KNativePointer ptr, KNativePointer otherPtr) {
     ParagraphStyle* instance = reinterpret_cast<ParagraphStyle*>((ptr));