Added onDraw plugin.

Author: khaykov

aztec/src/main/kotlin/org/wordpress/aztec/AztecText.kt

@@ -74,6 +74,7 @@ import org.wordpress.aztec.handlers.ListItemHandler
 import org.wordpress.aztec.handlers.PreformatHandler
 import org.wordpress.aztec.handlers.QuoteHandler
 import org.wordpress.aztec.plugins.IAztecPlugin
+import org.wordpress.aztec.plugins.IOnDrawPlugin
 import org.wordpress.aztec.plugins.ITextPastePlugin
 import org.wordpress.aztec.plugins.IToolbarButton
 import org.wordpress.aztec.source.Format
@@ -313,6 +314,13 @@ open class AztecText : AppCompatEditText, TextWatcher, UnknownHtmlSpan.OnUnknown
     var lastPressedXCoord: Int = 0
     var lastPressedYCoord: Int = 0
 
+    override fun onDraw(canvas: Canvas) {
+        super.onDraw(canvas)
+        plugins.filterIsInstance<IOnDrawPlugin>().forEach {
+            it.onDraw(canvas)
+        }
+    }
+
     interface OnSelectionChangedListener {
         fun onSelectionChanged(selStart: Int, selEnd: Int)
     }

aztec/src/main/kotlin/org/wordpress/aztec/plugins/IOnDrawPlugin.kt

@@ -0,0 +1,15 @@
+package org.wordpress.aztec.plugins
+
+import android.graphics.Canvas
+
+/**
+ * Use this plugin in order to get access to canvas during drawing cycle of AztecText
+ */
+interface IOnDrawPlugin : IAztecPlugin {
+    /**
+     * This method is called when onDraw method of AztecText is called.
+     * @param canvas canvas of AztecText
+     * @return html of the result
+     */
+    fun onDraw(canvas: Canvas)
+}