draw and write on FlxSprites relative to their boundaries

src/hollywoo_flixel/FlxMovie.hx

@@ -6,6 +6,7 @@ import flixel.system.FlxSound;
 import hollywoo.Movie;
 import hollywoo_flixel.ActorFlxSprite;
 import hollywoo_flixel.SceneFlxState;
+import hollywoo_flixel.SpriteTools;
 
 enum FlxStagePosition {
     Left;

src/hollywoo_flixel/SpriteTools.hx

@@ -0,0 +1,24 @@
+package hollywoo_flixel;
+
+import kiss.Prelude;
+import kiss.List;
+import flixel.FlxSprite;
+import flixel.util.FlxColor;
+import flixel.text.FlxText;
+import flixel.math.FlxPoint;
+
+enum RelativeCoordinate {
+    // Negative means to count back from the far edge
+    Pixels(p:Int); // Pixels from an edge.
+    Percent(p:Float); // Percent from an edge. -1 to 1
+}
+
+typedef RelativePosition = {
+    x:RelativeCoordinate, 
+    y:RelativeCoordinate,
+    ?anchorX:RelativeCoordinate, // default Percent(0.5)
+    ?anchorY:RelativeCoordinate, // default Percent(0.5)
+};
+
+@:build(kiss.Kiss.build())
+class SpriteTools {}

src/hollywoo_flixel/SpriteTools.kiss

@@ -0,0 +1,31 @@
+// Calculate where to draw the given stamp sprite on the given canvas sprite, as percentages or pixels from edge
+(function :Array<Int> positionOn [:FlxSprite stamp :FlxSprite canvas :RelativePosition pos]
+    (unless pos.anchorX (set pos.anchorX (Percent 0.5)))
+    (unless pos.anchorY (set pos.anchorY (Percent 0.5)))
+    (let [&mut x (coordIn pos.x (/ canvas.width canvas.scale.x))
+            &mut y (coordIn pos.y (/ canvas.height canvas.scale.y))]
+        (-= x (coordIn pos.anchorX (/ stamp.width stamp.scale.x)))
+        (-= y (coordIn pos.anchorY (/ stamp.height stamp.scale.y)))
+        [x y]))
+
+(function :Int coordIn [:RelativeCoordinate coord :Int range]
+    (Math.round
+        (case coord
+            ((when (and (>= p -1) (< p 0)) (Percent p))
+                (+ range (* p range)))
+            ((when (and (>= p -range) (< p 0)) (Pixels p))
+                (+ range p))
+            ((when (<= p 1) (Percent p))
+                (* range p))
+            ((when (<= p range) (Pixels p))
+                p)
+            (otherwise (throw "$coord is out of range $range")))))
+
+// TODO allow specifying size relative to canvas
+(function :Void drawOnSprite [:FlxSprite stamp :FlxSprite canvas :RelativePosition pos]
+    (let [[x y] (positionOn stamp canvas pos)]
+        (canvas.stamp stamp x y)))
+
+// TODO allow specifying size relative to canvas
+(function :Void writeOnSprite [:String text :Int size :FlxSprite canvas :RelativePosition pos]
+    (drawOnSprite (new FlxText 0 0 0 text size) canvas pos))