Cursor control API (#500)

Let's keep as is for know, and just mention minSdk in README.

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

@@ -11,6 +11,7 @@ import kotlin.math.sin
 import kotlin.math.PI
 
 class Clocks(private val layer: SkiaLayer): SkikoView {
+    private val cursorManager = CursorManager()
     private val withFps = true
     private val fpsCounter = FPSCounter()
     private val platformYOffset = if (hostOs == OS.Ios) 50f else 5f
@@ -128,6 +129,11 @@ class Clocks(private val layer: SkiaLayer): SkikoView {
         when (event.kind) {
             SkikoPointerEventKind.DOWN,
             SkikoPointerEventKind.MOVE -> {
+                if (event.x > 200) {
+                    cursorManager.setCursor(layer.component, PredefinedCursors.HAND)
+                } else {
+                    cursorManager.setCursor(layer.component, PredefinedCursors.DEFAULT)
+                }
                 xpos = event.x
                 ypos = event.y
             }

skiko/src/androidMain/kotlin/org/jetbrains/skiko/Actuals.android.kt

@@ -4,9 +4,10 @@ import android.content.*
 import android.content.ClipboardManager
 import android.content.res.Configuration
 import android.net.Uri
+import android.view.PointerIcon.*
+import android.view.View
 import org.jetbrains.skiko.redrawer.Redrawer
 
-
 actual fun setSystemLookAndFeel(): Unit = TODO()
 
 internal class AndroidOpenGLRedrawer(
@@ -64,4 +65,28 @@ internal actual fun ClipboardManager_getText(): String? {
     val clipboard = context.getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
     val clip = clipboard.primaryClip ?: return null
     return clip.getItemAt(0)?.text?.toString()
-}
\ No newline at end of file
+}
+
+actual typealias Cursor = android.view.PointerIcon
+
+// TODO: not sure if correct.
+internal actual fun CursorManager_setCursor(component: Any, cursor: Cursor) {
+    if (component is View) {
+        component.pointerIcon = cursor
+    }
+}
+
+internal actual fun CursorManager_getCursor(component: Any): Cursor? =
+    if (component is View) {
+        component.pointerIcon
+    } else {
+        null
+    }
+
+internal actual fun getCursorById(id: PredefinedCursorsId): Cursor =
+    when (id) {
+        PredefinedCursorsId.DEFAULT -> getSystemIcon(defaultContext!!, TYPE_DEFAULT)
+        PredefinedCursorsId.CROSSHAIR -> getSystemIcon(defaultContext!!, TYPE_CROSSHAIR)
+        PredefinedCursorsId.HAND -> getSystemIcon(defaultContext!!, TYPE_HAND)
+        PredefinedCursorsId.TEXT -> getSystemIcon(defaultContext!!, TYPE_TEXT)
+    }
\ No newline at end of file

skiko/src/androidMain/kotlin/org/jetbrains/skiko/SkiaLayer.android.kt

@@ -109,5 +109,8 @@ actual open class SkiaLayer {
         }
     }
 
+    actual val component: Any?
+        get() = this.container
+
     internal actual fun draw(canvas: Canvas): Unit = TODO()
 }
\ No newline at end of file

skiko/src/awtMain/kotlin/org/jetbrains/skiko/Actuals.awt.kt

 package org.jetbrains.skiko
 
 import org.jetbrains.skiko.redrawer.*
+import java.awt.Component
 import java.awt.Desktop
 import java.awt.Toolkit
 import java.awt.datatransfer.DataFlavor
@@ -63,3 +64,27 @@ internal actual fun ClipboardManager_getText(): String? {
         null
     }
 }
+
+actual typealias Cursor = java.awt.Cursor
+
+internal actual fun CursorManager_setCursor(component: Any, cursor: Cursor) {
+    if (component is Component) {
+        component.cursor = cursor
+    }
+}
+
+internal actual fun CursorManager_getCursor(component: Any): Cursor? {
+    return if (component is Component) {
+        component.cursor
+    } else {
+        null
+    }
+}
+
+internal actual fun getCursorById(id: PredefinedCursorsId): Cursor =
+    when (id) {
+        PredefinedCursorsId.DEFAULT -> Cursor(Cursor.DEFAULT_CURSOR)
+        PredefinedCursorsId.CROSSHAIR -> Cursor(Cursor.CROSSHAIR_CURSOR)
+        PredefinedCursorsId.HAND -> Cursor(Cursor.HAND_CURSOR)
+        PredefinedCursorsId.TEXT -> Cursor(Cursor.TEXT_CURSOR)
+    }
\ No newline at end of file

skiko/src/awtMain/kotlin/org/jetbrains/skiko/SkiaLayer.awt.kt

@@ -147,6 +147,9 @@ actual open class SkiaLayer internal constructor(
             fullscreenAdapter.fullscreen = value
         }
 
+    actual val component: Any?
+        get() = backedLayer
+
     actual var skikoView: SkikoView? = null
 
     actual fun attachTo(container: Any) {

skiko/src/commonMain/kotlin/org/jetbrains/skiko/Cursor.kt

+package org.jetbrains.skiko
+
+/**
+ * Identifiers of predefined cursors.
+ */
+enum class PredefinedCursorsId {
+    DEFAULT,
+    CROSSHAIR,
+    TEXT,
+    HAND
+}
+
+/**
+ * Predefined platform cursors.
+ */
+object PredefinedCursors {
+    val DEFAULT: Cursor = getCursorById(PredefinedCursorsId.DEFAULT)
+    val CROSSHAIR: Cursor = getCursorById(PredefinedCursorsId.CROSSHAIR)
+    val TEXT: Cursor = getCursorById(PredefinedCursorsId.TEXT)
+    val HAND: Cursor = getCursorById(PredefinedCursorsId.HAND)
+}
+
+/**
+ * Pointer device cursor abstraction.
+ */
+expect class Cursor
+
+internal expect fun getCursorById(id: PredefinedCursorsId): Cursor

skiko/src/commonMain/kotlin/org/jetbrains/skiko/Platform.kt

@@ -18,10 +18,43 @@ internal expect fun URIHandler_openUri(uri: String)
  * Manager for controlling system clipboard. Is open so that platform could provide an override if default doesn't fit.
  */
 open class ClipboardManager {
+    /**
+     * Set current system clipboard content as text.
+     */
     open fun setText(text: String) = ClipboardManager_setText(text)
+    /**
+     * Get current system clipboard content as text.
+     */
     open fun getText(): String? = ClipboardManager_getText()
 }
 
 internal expect fun ClipboardManager_setText(text: String)
 internal expect fun ClipboardManager_getText(): String?
 
+/**
+ * Manager to control cursor per native component.
+ */
+open class CursorManager {
+    /**
+     * Set cursor for the given component.
+     */
+    open fun setCursor(component: Any?, cursor: Cursor) {
+        if (component != null) CursorManager_setCursor(component, cursor)
+    }
+    /**
+     * Get cursor for the given component.
+     */
+    open fun getCursor(component: Any?): Cursor? = if (component != null) {
+        CursorManager_getCursor(component)
+    } else { null }
+}
+
+/**
+ * Sets cursor for the platform component.
+ */
+internal expect fun CursorManager_setCursor(component: Any, cursor: Cursor)
+
+/**
+ * Gets current cursor for the platform component, or null if not defined or known.
+ */
+internal expect fun CursorManager_getCursor(component: Any): Cursor?

skiko/src/commonMain/kotlin/org/jetbrains/skiko/SkiaLayer.kt

@@ -3,20 +3,58 @@ package org.jetbrains.skiko
 import org.jetbrains.skia.Canvas
 import org.jetbrains.skia.Picture
 
+/**
+ * Generic layer for Skiko rendering.
+ */
 expect open class SkiaLayer {
+    /**
+     * Current graphics API used for rendering.
+     */
     var renderApi: GraphicsApi
+
+    /**
+     * Current content scale.
+     */
     val contentScale: Float
+
+    /**
+     * If rendering is full screen.
+     */
     var fullscreen: Boolean
+    /**
+     * If transparency is enabled.
+     */
     var transparency: Boolean
 
+    /**
+     * Underlying platform component.
+     */
+    val component: Any?
+
+    /**
+     * Current view used for rendering.
+     */
     var skikoView: SkikoView?
 
-    // Actual type of attach container is platform-specific.
+    /**
+     * Attach this SkikoView to platform container.
+     * Actual type of attach container is platform-specific.
+     */
     fun attachTo(container: Any)
+
+    /**
+     * Detach this SkikoView from platform container.
+     */
     fun detach()
 
+    /**
+     * Force redraw.
+     */
     fun needRedraw()
 
+    /**
+     * Drawing function.
+     */
     internal fun draw(canvas: Canvas)
 }
 

skiko/src/iosMain/kotlin/org/jetbrains/skiko/Actuals.ios.kt

@@ -13,4 +13,19 @@ internal actual fun ClipboardManager_setText(text: String) {
 }
 internal actual fun ClipboardManager_getText(): String? {
     return UIPasteboard.generalPasteboard.string
-}
\ No newline at end of file
+}
+
+// TODO: not sure if correct.
+actual typealias Cursor = Any
+
+internal actual fun CursorManager_setCursor(component: Any, cursor: Cursor) {}
+
+internal actual fun CursorManager_getCursor(component: Any): Cursor? = null
+
+internal actual fun getCursorById(id: PredefinedCursorsId): Cursor =
+    when (id) {
+        PredefinedCursorsId.DEFAULT -> Any()
+        PredefinedCursorsId.CROSSHAIR -> Any()
+        PredefinedCursorsId.HAND -> Any()
+        PredefinedCursorsId.TEXT -> Any()
+    }
\ No newline at end of file

skiko/src/iosMain/kotlin/org/jetbrains/skiko/SkiaLayer.ios.kt

@@ -42,6 +42,9 @@ actual open class SkiaLayer {
         redrawer?.needRedraw()
     }
 
+    actual val component: Any?
+        get() = this.view
+
     val width: Float
        get() = view!!.frame.useContents {
            return@useContents size.width.toFloat()

skiko/src/jsMain/kotlin/org/jetbrains/skiko/Actuals.js.kt

 package org.jetbrains.skiko
 
-import kotlinx.coroutines.await
+import org.w3c.dom.HTMLElement
 
 internal actual inline fun <R> maybeSynchronized(lock: Any, block: () -> R): R =
     block()
@@ -16,6 +16,31 @@ internal actual fun ClipboardManager_setText(text: String) {
 }
 
 internal actual fun ClipboardManager_getText(): String? {
-    TODO("implement ClipboardManager_getText")
+    // TODO("implement ClipboardManager_getText")
     // kotlinx.browser.window.navigator.clipboard.readText()
-}
\ No newline at end of file
+    return null
+}
+
+actual typealias Cursor = String
+
+internal actual fun CursorManager_setCursor(component: Any, cursor: Cursor) {
+    if (component is HTMLElement) {
+        component.style.cursor = cursor
+    }
+}
+
+internal actual fun CursorManager_getCursor(component: Any): Cursor? {
+    return if (component is HTMLElement) {
+        component.style.cursor
+    } else {
+        null
+    }
+}
+
+internal actual fun getCursorById(id: PredefinedCursorsId): Cursor =
+    when (id) {
+        PredefinedCursorsId.DEFAULT -> "default"
+        PredefinedCursorsId.CROSSHAIR -> "crosshair"
+        PredefinedCursorsId.HAND -> "pointer"
+        PredefinedCursorsId.TEXT -> "text"
+    }
\ No newline at end of file

skiko/src/jsMain/kotlin/org/jetbrains/skiko/SkiaLayer.js.kt

@@ -76,11 +76,18 @@ actual open class SkiaLayer {
     private var desiredWidth = 0
     private var desiredHeight = 0
 
+    actual val component: Any?
+        get() = this.htmlCanvas
+
+    private var htmlCanvas: HTMLCanvasElement? = null
+
     /**
      * Initializes the [CanvasRenderer] and events listeners.
      * Delegates rendering and events processing to [skikoView].
      */
     fun attachTo(htmlCanvas: HTMLCanvasElement, autoDetach: Boolean = true) {
+        this.htmlCanvas = htmlCanvas
+
         // Scale canvas to allow high DPI rendering as suggested in
         // https://www.khronos.org/webgl/wiki/HandlingHighDPI.
         desiredWidth = htmlCanvas.width

skiko/src/linuxMain/kotlin/org/jetbrains/skiko/Actuals.linux.kt

@@ -10,4 +10,22 @@ internal actual fun ClipboardManager_setText(text: String) {
 
 internal actual fun ClipboardManager_getText(): String? {
     TODO("Implement ClipboardManager_getText() on Linux")
-}
\ No newline at end of file
+}
+
+actual typealias Cursor = Any
+
+internal actual fun CursorManager_setCursor(component: Any, cursor: Cursor) {
+    TODO("Implement CursorManager_setCursor on Linux")
+}
+
+internal actual fun CursorManager_getCursor(component: Any): Cursor? {
+    TODO("Implement CursorManager_getCursor on Linux")
+}
+
+internal actual fun getCursorById(id: PredefinedCursorsId): Cursor =
+    when (id) {
+        PredefinedCursorsId.DEFAULT -> Any()
+        PredefinedCursorsId.CROSSHAIR -> Any()
+        PredefinedCursorsId.HAND -> Any()
+        PredefinedCursorsId.TEXT -> Any()
+    }
\ No newline at end of file

skiko/src/linuxMain/kotlin/org/jetbrains/skiko/SkiaLayer.linux.kt

@@ -14,6 +14,8 @@ actual open class SkiaLayer  {
     actual var transparency: Boolean
         get() = TODO("Not yet implemented")
         set(value) {}
+    actual val component: Any?
+        get() = TODO("Not yet implemented")
     actual fun needRedraw() {
         TODO("unimplemented")
     }

skiko/src/macosMain/kotlin/org/jetbrains/skiko/Actuals.macos.kt

 package org.jetbrains.skiko
 
-import platform.AppKit.NSPasteboard
-import platform.AppKit.NSPasteboardTypeString
-import platform.AppKit.NSWorkspace
+import platform.AppKit.*
 import platform.Foundation.NSURL
 
 internal actual fun URIHandler_openUri(uri: String) {
@@ -15,4 +13,31 @@ internal actual fun ClipboardManager_setText(text: String) {
 
 internal actual fun ClipboardManager_getText(): String? {
     return NSPasteboard.generalPasteboard.stringForType(dataType = NSPasteboardTypeString)
-}
\ No newline at end of file
+}
+
+actual typealias Cursor = NSCursor
+
+// TODO: not sure if it is correct.
+internal actual fun CursorManager_setCursor(component: Any, cursor: Cursor) {
+    if (component is NSView) {
+        component.resetCursorRects()
+        component.addCursorRect(component.bounds(), cursor)
+    }
+}
+
+internal actual fun CursorManager_getCursor(component: Any): Cursor? {
+    return if (component is NSView) {
+        // TODO: likely incorrect.
+        NSCursor.currentCursor
+    } else {
+        null
+    }
+}
+
+internal actual fun getCursorById(id: PredefinedCursorsId): Cursor =
+    when (id) {
+        PredefinedCursorsId.DEFAULT -> NSCursor.arrowCursor
+        PredefinedCursorsId.CROSSHAIR -> NSCursor.crosshairCursor
+        PredefinedCursorsId.HAND -> NSCursor.pointingHandCursor
+        PredefinedCursorsId.TEXT -> NSCursor.IBeamCursor
+    }
\ No newline at end of file

skiko/src/macosMain/kotlin/org/jetbrains/skiko/SkiaLayer.macos.kt

@@ -76,6 +76,9 @@ actual open class SkiaLayer {
      */
     lateinit var nsView: NSView
 
+    actual val component: Any?
+        get() = this.nsView
+
     /**
      * Implements rendering logic and events processing.
      */