From ed5679787d17257a0a21ba90c8e57cf1dd43a094 Mon Sep 17 00:00:00 2001
From: treeform <starplant@gmail.com>
Date: Sat, 5 Dec 2020 00:28:42 -0800
Subject: [PATCH] Fix flip.

---
 src/pixie/images.nim      |  20 ++++++++++++++------
 tests/images/flipped1.png | Bin 0 -> 356 bytes
 tests/images/flipped2.png | Bin 0 -> 351 bytes
 tests/images/flipped3.png | Bin 0 -> 343 bytes
 tests/test_flips.nim      |  16 ++++++++++++++++
 5 files changed, 30 insertions(+), 6 deletions(-)
 create mode 100644 tests/images/flipped1.png
 create mode 100644 tests/images/flipped2.png
 create mode 100644 tests/images/flipped3.png
 create mode 100644 tests/test_flips.nim

diff --git a/src/pixie/images.nim b/src/pixie/images.nim
index d230c30..b3080ce 100644
--- a/src/pixie/images.nim
+++ b/src/pixie/images.nim
@@ -126,17 +126,25 @@ proc magnifyBy2*(image: Image): Image =
 
 proc flipHorizontal*(image: Image) =
   ## Flips the image around the Y axis.
+  let w = image.width div 2
   for y in 0 ..< image.height:
-    for x in 0 ..< image.width:
-      let rgba = image.getRgbaUnsafe(x, y)
-      image.setRgbaUnsafe(image.width - x - 1, y, rgba)
+    for x in 0 ..< w:
+      let
+        rgba1 = image.getRgbaUnsafe(x, y)
+        rgba2 = image.getRgbaUnsafe(image.width - x - 1, y)
+      image.setRgbaUnsafe(image.width - x - 1, y, rgba1)
+      image.setRgbaUnsafe(x, y, rgba2)
 
 proc flipVertical*(image: Image) =
   ## Flips the image around the X axis.
-  for y in 0 ..< image.height:
+  let h = image.height div 2
+  for y in 0 ..< h:
     for x in 0 ..< image.width:
-      let rgba = image.getRgbaUnsafe(x, y)
-      image.setRgbaUnsafe(x, image.height - y - 1, rgba)
+      let
+        rgba1 = image.getRgbaUnsafe(x, y)
+        rgba2 = image.getRgbaUnsafe(x, image.height - y - 1)
+      image.setRgbaUnsafe(x, image.height - y - 1, rgba1)
+      image.setRgbaUnsafe(x, y, rgba2)
 
 func lerp(a, b: Color, v: float32): Color {.inline.} =
   result.r = lerp(a.r, b.r, v)
diff --git a/tests/images/flipped1.png b/tests/images/flipped1.png
new file mode 100644
index 0000000000000000000000000000000000000000..2fa1421b35acf9df7154353f806e3d0916ec61b3
GIT binary patch
literal 356
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literal 0
HcmV?d00001

diff --git a/tests/images/flipped2.png b/tests/images/flipped2.png
new file mode 100644
index 0000000000000000000000000000000000000000..442446e3adb7831bdde0a4dd25432a3e021f345d
GIT binary patch
literal 351
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DBz;|K

literal 0
HcmV?d00001

diff --git a/tests/images/flipped3.png b/tests/images/flipped3.png
new file mode 100644
index 0000000000000000000000000000000000000000..344d92338d6420efc3c52d933efcadbf37860094
GIT binary patch
literal 343
zcmeAS@N?(olHy`uVBq!ia0vp^sUXb31|&mjbk8#|Fv@wlIEGX(zP-4Sv%x{Y^`NM<
zy>|GU10M5?nC)*rdH44DnVo6VO8+J7Pv+5F#L_9G;x$3TkuHqCTBpj+$-MskJ9LWm
w3Hc6+Y~GVS@5c2rRYgBokNd|d5$}aq=39F64^)+900WG{)78&qol`;+00R$jTmS$7

literal 0
HcmV?d00001

diff --git a/tests/test_flips.nim b/tests/test_flips.nim
new file mode 100644
index 0000000..ae23dfb
--- /dev/null
+++ b/tests/test_flips.nim
@@ -0,0 +1,16 @@
+import pixie, chroma, vmath
+
+block:
+
+  var a = newImage(101, 101)
+  a.fill(rgba(255, 0, 0, 255))
+  var b = newImage(50, 50)
+  b.fill(rgba(0, 255, 0, 255))
+
+  a.draw(b, vec2(0, 0))
+
+  a.writeFile("tests/images/flipped1.png")
+  a.flipVertical()
+  a.writeFile("tests/images/flipped2.png")
+  a.flipHorizontal()
+  a.writeFile("tests/images/flipped3.png")