Switch text examples to use SVG output

This should give both better looking output and output with the correct
font. I really don't feel like debugging why the build doesn't have a
serif font.

docs/src/pages/pictures/text.md

@@ -18,10 +18,7 @@ val hello =
 
 The output is shown below.
 
-@:image(hello.png) {
-  alt = A picture showing the text "Hello from Doodle!"
-  title = "Hello from Doodle!"
-}
+@:doodle("hello-example", "SvgTextExamples.drawHello") 
 
 In addition to creating pictures containing text, it also allows specifying the @:api(doodle.core.Font) used for the text, via the `font` method.
 In this example we use the default serif font, in bold weight and 24 point size.
@@ -37,10 +34,7 @@ val font =
 
 This produces the picture below.
 
-@:image(font.png) {
-  alt = A picture showing the text "Change the font"
-  title = "Change the font"
-}
+@:doodle("font-example", "SvgTextExamples.drawFont") 
 
 
 ## Implementation

examples/js/src/main/scala/doodle/examples/TextExamples.scala

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2015 Creative Scala
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package doodle.examples
+
+import doodle.algebra.*
+import doodle.core.*
+import doodle.core.font.*
+import doodle.syntax.all.*
+
+/** All the examples from the Text documentation page, written in a backend
+  * independent style.
+  */
+trait TextExamples[Alg <: Layout & Text] extends BaseExamples[Alg] {
+  val hello =
+    text("Hello from Doodle!")
+
+  val font =
+    text("Change the font")
+      .font(Font.defaultSerif.bold.size(FontSize.points(24)))
+  //
+  // If you add a new example, also add it in here
+  val allPictures =
+    List(
+      hello,
+      font
+    )
+}

examples/js/src/main/scala/doodle/examples/svg/SvgTextExamples.scala

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2015 Creative Scala
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package doodle.examples.svg
+
+import cats.effect.unsafe.implicits.global
+import doodle.examples.TextExamples
+import doodle.svg.*
+import doodle.syntax.all.*
+
+import scala.scalajs.js.annotation.*
+
+@JSExportTopLevel("SvgTextExamples")
+object SvgTextExamples extends TextExamples[Algebra] {
+  @JSExport
+  def drawHello(id: String): Unit = hello.drawWithFrame(Frame(id))
+
+  @JSExport
+  def drawfont(id: String): Unit = font.drawWithFrame(Frame(id))
+}