From ea4f2c47a2daf74a6a9e669569617f1395281e79 Mon Sep 17 00:00:00 2001
From: Romans Potasovs <justgook@gmail.com>
Date: Wed, 15 May 2019 11:25:41 +0300
Subject: [PATCH] Add WebGL.Texture.loadBytesWith

---
 elm.json                  |  1 +
 src/Elm/Kernel/Texture.js | 72 ++++++++++++++++++++++++++++++++++++++-
 src/WebGL/Texture.elm     | 52 +++++++++++++++++++++++++++-
 3 files changed, 123 insertions(+), 2 deletions(-)

diff --git a/elm.json b/elm.json
index cb1aa32..4152db2 100644
--- a/elm.json
+++ b/elm.json
@@ -14,6 +14,7 @@
     ],
     "elm-version": "0.19.0 <= v < 0.20.0",
     "dependencies": {
+        "elm/bytes": "1.0.8 <= v < 2.0.0",
         "elm/core": "1.0.0 <= v < 2.0.0",
         "elm/html": "1.0.0 <= v < 2.0.0"
     },
diff --git a/src/Elm/Kernel/Texture.js b/src/Elm/Kernel/Texture.js
index b6745d6..71063b2 100644
--- a/src/Elm/Kernel/Texture.js
+++ b/src/Elm/Kernel/Texture.js
@@ -2,7 +2,8 @@
 
 import Elm.Kernel.Utils exposing (Tuple2)
 import Elm.Kernel.Scheduler exposing (binding, succeed, fail)
-import WebGL.Texture as Texture exposing (LoadError, SizeError)
+import WebGL.Texture as Texture exposing (LoadError, SizeError, RGBA, RGB, LUMINANCE_ALPHA, LUMINANCE, ALPHA)
+import Result exposing (Err, Ok)
 
 */
 
@@ -65,3 +66,72 @@ var _Texture_load = F6(function (magnify, mininify, horizontalWrap, verticalWrap
 var _Texture_size = function (texture) {
   return __Utils_Tuple2(texture.__width, texture.__height);
 };
+
+
+//Texture Loading from Bytes
+
+
+function getFormat(gl, format) {
+  return (format == __Texture_RGBA && gl.RGBA)
+    || (format == __Texture_RGB && gl.RGB)
+    || (format == __Texture_LUMINANCE_ALPHA && gl.LUMINANCE_ALPHA)
+    || (format == __Texture_LUMINANCE && gl.LUMINANCE)
+    || (format == __Texture_ALPHA && gl.ALPHA)
+}
+
+function getByteCount(format) {
+  return (format == __Texture_RGBA && 4)
+    || (format == __Texture_RGB && 3)
+    || (format == __Texture_LUMINANCE_ALPHA && 2)
+    || (format == __Texture_LUMINANCE && 1)
+    || (format == __Texture_ALPHA && 1)
+}
+
+// eslint-disable-next-line no-unused-vars
+var _Texture_loadBytes = F9(function (magnify, mininify, horizontalWrap, verticalWrap, flipY, width, height, format, bytes) {
+  var isMipmap = mininify !== 9728 && mininify !== 9729;
+  function createTexture(gl) {
+    var pixelFormat = getFormat(gl, format);
+    var texture = gl.createTexture();
+    gl.bindTexture(gl.TEXTURE_2D, texture);
+    gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, flipY);
+    gl.texImage2D(gl.TEXTURE_2D, 0, pixelFormat, width, height, 0, pixelFormat, gl.UNSIGNED_BYTE, new Uint8Array(bytes.buffer));
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, magnify);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, mininify);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, horizontalWrap);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, verticalWrap);
+    if (isMipmap) {
+      gl.generateMipmap(gl.TEXTURE_2D);
+    }
+    gl.bindTexture(gl.TEXTURE_2D, null);
+    return texture;
+  }
+  if (bytes.byteLength < width * height * getByteCount(format)) {
+    return __Result_Err(A2(
+      __Texture_SizeError,
+      width,
+      height
+    ));
+  }
+  var widthPowerOfTwo = (width & (width - 1)) === 0;
+  var heightPowerOfTwo = (height & (height - 1)) === 0;
+  var isSizeValid = (widthPowerOfTwo && heightPowerOfTwo) || (
+    !isMipmap
+    && horizontalWrap === 33071 // clamp to edge
+    && verticalWrap === 33071
+  );
+  if (isSizeValid) {
+    return __Result_Ok({
+      $: __0_TEXTURE,
+      __$createTexture: createTexture,
+      __width: width,
+      __height: height
+    });
+  } else {
+    return __Result_Err(A2(
+      __Texture_SizeError,
+      width,
+      height
+    ));
+  }
+});
diff --git a/src/WebGL/Texture.elm b/src/WebGL/Texture.elm
index faedb12..3df1d46 100644
--- a/src/WebGL/Texture.elm
+++ b/src/WebGL/Texture.elm
@@ -21,6 +21,8 @@ module WebGL.Texture
         , nonPowerOfTwoOptions
         , repeat
         , size
+        , Format(..)
+        , loadBytesWith
         )
 
 {-|
@@ -51,10 +53,11 @@ module WebGL.Texture
 
 # Things You Shouldn’t Do
 
-@docs nonPowerOfTwoOptions
+@docs nonPowerOfTwoOptions, loadBytesWith, Format
 
 -}
 
+import Bytes exposing (Bytes)
 import Elm.Kernel.Texture
 import Task exposing (Task)
 
@@ -304,3 +307,50 @@ or other times you may want to use only a potion of a texture image.
 size : Texture -> ( Int, Int )
 size =
     Elm.Kernel.Texture.size
+
+
+{-| Building [`Texture`](#Texture) from bytes
+
+  - [`Options`](#Options) - same as for [`loadWith`](#loadWith)
+
+  - `(width, height)` - dimensions of new created texture
+
+  - [`Format`](#Format) - pixel format in bytes
+
+  - Bytes - encoded pixels, where `Bytes.width` > `width` \* `height` \* `Bytes per pixe`or you get `SizeError`
+
+Do not generate texture in `view`, [read more about this here](https://package.elm-lang.org/packages/elm-explorations/webgl/latest#making-the-most-of-the-gpu).
+
+-}
+loadBytesWith :
+    Options
+    -> ( Int, Int )
+    -> Format
+    -> Bytes
+    -> Result Error Texture
+loadBytesWith { magnify, minify, horizontalWrap, verticalWrap, flipY } ( w, h ) format b =
+    let
+        expand (Resize mag) (Resize min) (Wrap hor) (Wrap vert) =
+            Elm.Kernel.Texture.loadBytes mag min hor vert flipY w h format b
+    in
+    expand magnify minify horizontalWrap verticalWrap
+
+
+{-| How to read bytes intpo pixel
+
+        | Format          | Channels | Bytes per pixel |
+        ------------------------------------------------
+        | RGBA            |    4     |        4        |
+        | RGB             |    3     |        3        |
+        | LUMINANCE_ALPHA |    2     |        2        |
+        | LUMINANCE       |    1     |        1        |
+        | ALPHA           |    1     |        1        |
+        ------------------------------------------------
+
+-}
+type Format
+    = RGBA
+    | RGB
+    | LUMINANCE_ALPHA
+    | LUMINANCE
+    | ALPHA