simpler + out of bounds color for image blur

src/pixie/images.nim

@@ -317,7 +317,7 @@ proc invert*(target: Image | Mask) =
     for j in i ..< target.data.len:
       target.data[j] = (255 - target.data[j]).uint8
 
-proc blur*(image: Image, radius: float32) =
+proc blur*(image: Image, radius: float32, outOfBounds = ColorRGBX()) =
   ## Applies Gaussian blur to the image given a radius.
   let radius = round(radius).int
   if radius == 0:
@@ -354,18 +354,23 @@ proc blur*(image: Image, radius: float32) =
   for y in 0 ..< image.height:
     for x in 0 ..< image.width:
       var values: array[4, uint32]
-      if image.inside(x - radius, y) and image.inside(x + radius, y):
-        for step in -radius .. radius:
-          let
-            sample = image.getRgbaUnsafe(x + step, y)
-            a = lookup[step + radius].uint32
-          values += sample * a
-      else:
-        for step in -radius .. radius:
-          let
-            sample = image[x + step, y]
-            a = lookup[step + radius].uint32
-          values += sample * a
+      for xx in x - radius ..< min(x + radius, 0):
+        let
+          sample = outOfBounds
+          a = lookup[xx - x + radius].uint32
+        values += sample * a
+
+      for xx in max(x - radius, 0) ..< min(x + radius, image.width):
+        let
+          sample = image.getRgbaUnsafe(xx, y)
+          a = lookup[xx - x + radius].uint32
+        values += sample * a
+
+      for xx in max(x - radius, image.width) ..< x + radius:
+        let
+          sample = outOfBounds
+          a = lookup[xx - x + radius].uint32
+        values += sample * a
 
       blurX.setRgbaUnsafe(x, y, values.rgbx())
 
@@ -373,18 +378,23 @@ proc blur*(image: Image, radius: float32) =
   for y in 0 ..< image.height:
     for x in 0 ..< image.width:
       var values: array[4, uint32]
-      if image.inside(x, y - radius) and image.inside(x, y + radius):
-        for step in -radius .. radius:
-          let
-            sample = blurX.getRgbaUnsafe(x, y + step)
-            a = lookup[step + radius].uint32
-          values += sample * a
-      else:
-        for step in -radius .. radius:
-          let
-            sample = blurX[x, y + step]
-            a = lookup[step + radius].uint32
-          values += sample * a
+      for yy in y - radius ..< min(y + radius, 0):
+        let
+          sample = outOfBounds
+          a = lookup[yy - y + radius].uint32
+        values += sample * a
+
+      for yy in max(y - radius, 0) ..< min(y + radius, image.height):
+        let
+          sample = blurX.getRgbaUnsafe(x, yy)
+          a = lookup[yy - y + radius].uint32
+        values += sample * a
+
+      for yy in max(y - radius, image.height) ..< y + radius:
+        let
+          sample = outOfBounds
+          a = lookup[yy - y + radius].uint32
+        values += sample * a
 
       image.setRgbaUnsafe(x, y, values.rgbx())
 

src/pixie/masks.nim

@@ -167,18 +167,17 @@ proc blur*(mask: Mask, radius: float32, outOfBounds: uint8 = 0) =
   for y in 0 ..< mask.height:
     for x in 0 ..< mask.width:
       var value: uint32
-      if mask.inside(x - radius, y) and mask.inside(x + radius, y):
-        for step in -radius .. radius:
-          let sample = mask.getValueUnsafe(x + step, y)
-          value += sample * lookup[step + radius].uint32
-      else:
-        for step in -radius .. radius:
-          var sample: uint32
-          if mask.inside(x + step, y):
-            sample = mask.getValueUnsafe(x + step, y)
-          else:
-            sample = outOfBounds
-          value += sample * lookup[step + radius].uint32
+      for xx in x - radius ..< min(x + radius, 0):
+        let sample = outOfBounds
+        value += sample * lookup[xx - x + radius].uint32
+
+      for xx in max(x - radius, 0) ..< min(x + radius, mask.width):
+        let sample = mask.getValueUnsafe(xx, y)
+        value += sample * lookup[xx - x + radius].uint32
+
+      for xx in max(x - radius, mask.width) ..< x + radius:
+        let sample = outOfBounds
+        value += sample * lookup[xx - x + radius].uint32
 
       blurX.setValueUnsafe(x, y, (value div 1024 div 255).uint8)
 
@@ -186,19 +185,17 @@ proc blur*(mask: Mask, radius: float32, outOfBounds: uint8 = 0) =
   for y in 0 ..< mask.height:
     for x in 0 ..< mask.width:
       var value: uint32
-      if mask.inside(x, y - radius) and mask.inside(x, y + radius):
-        for step in -radius .. radius:
-          let sample = blurX.getValueUnsafe(x, y + step)
-          value += sample * lookup[step + radius].uint32
-      else:
-        for step in -radius .. radius:
-          var sample: uint32
-          if blurX.inside(x, y + step):
-            sample = blurX.getValueUnsafe(x, y + step)
-          else:
-            sample = outOfBounds
-          let a = lookup[step + radius].uint32
-          value += sample * a
+      for yy in y - radius ..< min(y + radius, 0):
+        let sample = outOfBounds
+        value += sample * lookup[yy - y + radius].uint32
+
+      for yy in max(y - radius, 0) ..< min(y + radius, mask.height):
+        let sample = blurX.getValueUnsafe(x, yy)
+        value += sample * lookup[yy - y + radius].uint32
+
+      for yy in max(y - radius, mask.height) ..< y + radius:
+        let sample = outOfBounds
+        value += sample * lookup[yy - y + radius].uint32
 
       mask.setValueUnsafe(x, y, (value div 1024 div 255).uint8)
 

tests/test_images.nim

@@ -111,3 +111,10 @@ block:
   image.fillRect(rect(25, 25, 50, 50), rgba(255, 255, 255, 255))
   image.blur(20)
   image.writeFile("tests/images/imageblur20.png")
+
+block:
+  let image = newImage(100, 100)
+  image.fill(rgba(0, 0, 0, 255))
+  image.fillRect(rect(25, 25, 50, 50), rgba(255, 255, 255, 255))
+  image.blur(20, rgba(0, 0, 0, 255))
+  image.writeFile("tests/images/imageblur20oob.png")