Reimplement the Canvas transformation functions via the corresponding…

… Skia functions, rather than by concatenating with a transformation matrix. (#724)

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

@@ -1080,27 +1080,47 @@ open class Canvas internal constructor(ptr: NativePointer, managed: Boolean, int
     }
 
     fun translate(dx: Float, dy: Float): Canvas {
-        return concat(Matrix33.makeTranslate(dx, dy))
+        interopScope {
+            Stats.onNativeCall()
+            _nTranslate(_ptr, dx, dy)
+        }
+        return this
     }
 
     fun scale(sx: Float, sy: Float): Canvas {
-        return concat(Matrix33.makeScale(sx, sy))
+        interopScope {
+            Stats.onNativeCall()
+            _nScale(_ptr, sx, sy)
+        }
+        return this
     }
 
     /**
      * @param deg  angle in degrees
      * @return     this
      */
     fun rotate(deg: Float): Canvas {
-        return concat(Matrix33.makeRotate(deg))
+        interopScope {
+            Stats.onNativeCall()
+            _nRotate(_ptr, deg, 0f, 0f)
+        }
+        return this
     }
 
     fun rotate(deg: Float, x: Float, y: Float): Canvas {
-        return concat(Matrix33.makeRotate(deg, x, y))
+        interopScope {
+            Stats.onNativeCall()
+            _nRotate(_ptr, deg, x, y)
+        }
+        return this
     }
 
     fun skew(sx: Float, sy: Float): Canvas {
-        return concat(Matrix33.makeSkew(sx, sy))
+        interopScope {
+            Stats.onNativeCall()
+            _nSkew(_ptr, sx, sy)
+        }
+        return this
     }
 
     fun concat(matrix: Matrix33): Canvas {
@@ -1542,14 +1562,24 @@ private external fun _nClipPath(ptr: NativePointer, nativePath: NativePointer, m
 @ExternalSymbolName("org_jetbrains_skia_Canvas__1nClipRegion")
 private external fun _nClipRegion(ptr: NativePointer, nativeRegion: NativePointer, mode: Int)
 
+@ExternalSymbolName("org_jetbrains_skia_Canvas__1nTranslate")
+private external fun _nTranslate(ptr: NativePointer, dx: Float, dy: Float)
+
+@ExternalSymbolName("org_jetbrains_skia_Canvas__1nScale")
+private external fun _nScale(ptr: NativePointer, sx: Float, sy: Float)
+
+@ExternalSymbolName("org_jetbrains_skia_Canvas__1nRotate")
+private external fun _nRotate(ptr: NativePointer, deg: Float, x: Float, y: Float)
+
+@ExternalSymbolName("org_jetbrains_skia_Canvas__1nSkew")
+private external fun _nSkew(ptr: NativePointer, sx: Float, sy: Float)
+
 @ExternalSymbolName("org_jetbrains_skia_Canvas__1nConcat")
 private external fun _nConcat(ptr: NativePointer, matrix: InteropPointer)
 
-
 @ExternalSymbolName("org_jetbrains_skia_Canvas__1nConcat44")
 private external fun _nConcat44(ptr: NativePointer, matrix: InteropPointer)
 
-
 @ExternalSymbolName("org_jetbrains_skia_Canvas__1nReadPixels")
 private external fun _nReadPixels(ptr: NativePointer, bitmapPtr: NativePointer, srcX: Int, srcY: Int): Boolean
 

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

@@ -1,16 +1,18 @@
+@file:Suppress("RemoveRedundantCallsOfConversionMethods")
+
 package org.jetbrains.skia
 
 import org.jetbrains.skia.tests.makeFromResource
 import org.jetbrains.skia.util.assertContentSame
 import org.jetbrains.skia.util.imageFromIntArray
-import org.jetbrains.skiko.tests.SkipJsTarget
-import org.jetbrains.skiko.tests.SkipNativeTarget
 import org.jetbrains.skiko.tests.runTest
 import kotlin.test.Test
 import kotlin.test.assertContentEquals
 import kotlin.test.assertTrue
 
+
 class CanvasTest {
+
     @Test
     fun drawVertices() {
         val surface = Surface.makeRasterN32Premul(8, 8)
@@ -189,4 +191,104 @@ class CanvasTest {
 
         assertContentSame(expected = expected, got = surface.makeImageSnapshot(), sensitivity = 0.25)
     }
+
+
+    @Test
+    fun testTranslate() {
+        val surface = whiteSurface(4, 4)
+        surface.canvas.translate(2f, 2f)
+        surface.canvas.drawBlackPixel(0, 0)
+
+        surface.assertSingleBlackPixelAt(2, 2)
+    }
+
+
+    @Test
+    fun testScale() {
+        val surface = whiteSurface(4, 4)
+        surface.canvas.scale(2f, 2f)
+        surface.canvas.drawBlackPixel(1, 1)
+
+        surface.assertPixelsMatch(
+            IntArray(16){ index ->
+                when (index) {
+                    10, 11, 14, 15 -> 0xff000000.toInt()
+                    else -> 0xffffffff.toInt()
+                }
+            }
+        )
+    }
+
+
+    @Test
+    fun testRotate() {
+        val surface = whiteSurface(4, 4)
+        surface.canvas.rotate(deg = 90f)
+        surface.canvas.drawBlackPixel(3, -1)
+
+        surface.assertSingleBlackPixelAt(0, 3)
+    }
+
+
+    @Test
+    fun testRotateXY() {
+        val surface = whiteSurface(4, 4)
+        surface.canvas.rotate(deg = 90f, x = 2f, y=2f)
+        surface.canvas.drawBlackPixel(0, 0)
+
+        surface.assertSingleBlackPixelAt(3, 0)
+    }
+
+
+    @Test
+    fun testSkew() {
+        val surface = whiteSurface(4, 4)
+        surface.canvas.skew(sx = 0.5f, sy = 0f)
+        surface.canvas.drawBlackPixel(0, 2)
+
+        surface.assertPixelsMatch(
+            IntArray(16){ index ->
+                when (index) {
+                    // Skewing skews the shape of the pixel itself, so it becomes a parallelogram
+                    9 -> 0xff3f3f3f.toInt()
+                    10 -> 0xffbfbfbf.toInt()
+                    else -> 0xffffffff.toInt()
+                }
+            }
+        )
+    }
+
+
+    private fun whiteSurface(width: Int, height: Int): Surface {
+        val surface = Surface.makeRasterN32Premul(width, height)
+        val white = Paint().also { it.setARGB(255, 255, 255, 255) }
+        surface.canvas.drawRect(Rect(0f, 0f, width.toFloat(), height.toFloat()), white)
+        return surface
+    }
+
+
+    private fun Canvas.drawBlackPixel(x: Int, y: Int) {
+        val black = Paint().also { it.setARGB(255, 0, 0, 0) }
+        drawRect(Rect(x.toFloat(), y.toFloat(), (x + 1).toFloat(), (y + 1).toFloat()), black)
+    }
+
+
+    private fun Surface.assertPixelsMatch(pixArray: IntArray) {
+        assertContentSame(
+            expected = imageFromIntArray(
+                pixArray = pixArray,
+                imageWidth = width
+            ),
+            got = makeImageSnapshot(),
+            sensitivity = 0.0
+        )
+    }
+
+
+    private fun Surface.assertSingleBlackPixelAt(x: Int, y: Int) {
+        val pixArray = IntArray(width * height){ 0xffffffff.toInt() }
+        pixArray[y*width + x] = 0xff000000.toInt()
+
+        assertPixelsMatch(pixArray)
+    }
 }

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

@@ -278,6 +278,30 @@ extern "C" JNIEXPORT void JNICALL Java_org_jetbrains_skia_CanvasKt__1nConcat44
     canvas->concat(*m);
 }
 
+extern "C" JNIEXPORT void JNICALL Java_org_jetbrains_skia_CanvasKt__1nTranslate
+  (JNIEnv* env, jclass jclass, jlong ptr, jfloat dx, jfloat dy) {
+    SkCanvas* canvas = reinterpret_cast<SkCanvas*>(static_cast<uintptr_t>(ptr));
+    canvas->translate(dx, dy);
+}
+
+extern "C" JNIEXPORT void JNICALL Java_org_jetbrains_skia_CanvasKt__1nScale
+  (JNIEnv* env, jclass jclass, jlong ptr, jfloat sx, jfloat sy) {
+    SkCanvas* canvas = reinterpret_cast<SkCanvas*>(static_cast<uintptr_t>(ptr));
+    canvas->scale(sx, sy);
+}
+
+extern "C" JNIEXPORT void JNICALL Java_org_jetbrains_skia_CanvasKt__1nRotate
+  (JNIEnv* env, jclass jclass, jlong ptr, jfloat deg, jfloat x, jfloat y) {
+    SkCanvas* canvas = reinterpret_cast<SkCanvas*>(static_cast<uintptr_t>(ptr));
+    canvas->rotate(deg, x, y);
+}
+
+extern "C" JNIEXPORT void JNICALL Java_org_jetbrains_skia_CanvasKt__1nSkew
+  (JNIEnv* env, jclass jclass, jlong ptr, jfloat sx, jfloat sy) {
+    SkCanvas* canvas = reinterpret_cast<SkCanvas*>(static_cast<uintptr_t>(ptr));
+    canvas->skew(sx, sy);
+}
+
 extern "C" JNIEXPORT jint JNICALL Java_org_jetbrains_skia_CanvasKt__1nReadPixels
   (JNIEnv* env, jclass jclass, jlong ptr, jlong bitmapPtr, jint srcX, jint srcY) {
     SkCanvas* canvas = reinterpret_cast<SkCanvas*>(static_cast<uintptr_t>(ptr));

skiko/src/nativeJsMain/cpp/Canvas.cc

@@ -269,6 +269,34 @@ SKIKO_EXPORT void org_jetbrains_skia_Canvas__1nConcat44
 }
 
 
+SKIKO_EXPORT void org_jetbrains_skia_Canvas__1nTranslate
+  (KNativePointer canvasPtr, KFloat dx, KFloat dy) {
+    SkCanvas* canvas = reinterpret_cast<SkCanvas*>((canvasPtr));
+    canvas->translate(dx, dy);
+}
+
+
+SKIKO_EXPORT void org_jetbrains_skia_Canvas__1nScale
+  (KNativePointer canvasPtr, KFloat sx, KFloat sy) {
+    SkCanvas* canvas = reinterpret_cast<SkCanvas*>((canvasPtr));
+    canvas->scale(sx, sy);
+}
+
+
+SKIKO_EXPORT void org_jetbrains_skia_Canvas__1nRotate
+  (KNativePointer canvasPtr, KFloat deg, KFloat x, KFloat y) {
+    SkCanvas* canvas = reinterpret_cast<SkCanvas*>((canvasPtr));
+    canvas->rotate(deg, x, y);
+}
+
+
+SKIKO_EXPORT void org_jetbrains_skia_Canvas__1nSkew
+  (KNativePointer canvasPtr, KFloat sx, KFloat sy) {
+    SkCanvas* canvas = reinterpret_cast<SkCanvas*>((canvasPtr));
+    canvas->skew(sx, sy);
+}
+
+
 SKIKO_EXPORT KInt org_jetbrains_skia_Canvas__1nReadPixels
   (KNativePointer ptr, KNativePointer bitmapPtr, KInt srcX, KInt srcY) {
     SkCanvas* canvas = reinterpret_cast<SkCanvas*>((ptr));