New simple HTML5 canvas component

1 files changed, 91 insertions, 0 deletions

diff --git a/src/main/kotlin/pl/treksoft/kvision/html/Canvas.kt b/src/main/kotlin/pl/treksoft/kvision/html/Canvas.kt
new file mode 100644
index 00000000..450042a2
--- /dev/null
+++ b/src/main/kotlin/pl/treksoft/kvision/html/Canvas.kt
@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2017-present Robert Jaros
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package pl.treksoft.kvision.html
+
+import com.github.snabbdom.VNode
+import org.w3c.dom.CanvasRenderingContext2D
+import org.w3c.dom.HTMLCanvasElement
+import pl.treksoft.kvision.core.Container
+import pl.treksoft.kvision.core.StringPair
+import pl.treksoft.kvision.core.Widget
+
+/**
+ * Canvas component.
+ *
+ * @constructor
+ * @param canvasWidth the width of the canvas
+ * @param canvasHeight the height of the canvas
+ * @param classes a set of CSS class names
+ */
+open class Canvas(
+    canvasWidth: Int? = null, canvasHeight: Int? = null, classes: Set<String> = setOf()
+) : Widget(classes) {
+    /**
+     * The width of the canvas.
+     */
+    var canvasWidth by refreshOnUpdate(canvasWidth)
+    /**
+     * The height of the canvas.
+     */
+    var canvasHeight by refreshOnUpdate(canvasHeight)
+
+    /**
+     * The canvas rendering context.
+     */
+    lateinit var context2D: CanvasRenderingContext2D
+
+    override fun render(): VNode {
+        return render("canvas")
+    }
+
+    override fun getSnAttrs(): List<StringPair> {
+        val pr = super.getSnAttrs().toMutableList()
+        canvasWidth?.let {
+            pr.add("width" to it.toString())
+        }
+        canvasHeight?.let {
+            pr.add("height" to it.toString())
+        }
+        return pr
+    }
+
+    override fun afterInsert(node: VNode) {
+        context2D = (node.elm as HTMLCanvasElement).getContext("2d") as CanvasRenderingContext2D
+    }
+
+    companion object {
+        /**
+         * DSL builder extension function.
+         *
+         * It takes the same parameters as the constructor of the built component.
+         */
+        fun Container.canvas(
+            canvasWidth: Int? = null, canvasHeight: Int? = null, classes: Set<String> = setOf(),
+            init: (Canvas.() -> Unit)? = null
+        ): Canvas {
+            val canvas =
+                Canvas(canvasWidth, canvasHeight, classes).apply { init?.invoke(this) }
+            this.add(canvas)
+            return canvas
+        }
+    }
+}