<!--
Copyright (c) 2019 The Khronos Group Inc.
Use of this source code is governed by an MIT-style license that can be
found in the LICENSE.txt file.
-->

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>WebGL ReadPixels conformance test.</title>
<link rel="stylesheet" href="../../resources/js-test-style.css"/>
<script src="../../js/desktop-gl-constants.js"></script>
<script src="../../js/js-test-pre.js"></script>
<script src="../../js/webgl-test-utils.js"> </script>
</head>
<body>
<canvas id="example" width="200" height="200" style="width: 20px; height: 20px"></canvas>
<canvas id="example2" width="200" height="200" style="width: 20px; height: 20px"></canvas>
<div id="description"></div>
<div id="console"></div>
<script>
"use strict";
description("Checks that ReadPixels works as expected.");

var wtu = WebGLTestUtils;
let gl;

debug("<h1>antialias = false</h1>")
runTest(document.getElementById("example"), false);
debug("<h1>antialias = true</h1>")
runTest(document.getElementById("example2"), true);
finishTest();

var actual;
var expected;

function runTest(canvas, antialias) {
  gl = wtu.create3DContext(canvas, {antialias: antialias});
  var contextVersion = wtu.getDefault3DContextVersion();

  var width = 2;
  var height = 2;
  var continueTestFunc = continueTestPart1;

  gl.clearColor(1, 1, 1, 1);
  gl.clear(gl.COLOR_BUFFER_BIT);

  // Resize the canvas to 2x2. This is an attempt to get stuff in the backbuffer.
  // that shouldn't be there.
  canvas.addEventListener("webglcontextlost", function(e) { e.preventDefault(); }, false);
  canvas.addEventListener("webglcontextrestored", continueTestAfterContextRestored, false);
  canvas.width = width;
  canvas.height = height;
  if (gl.getError() != gl.CONTEXT_LOST_WEBGL) {
    continueTestPart1();
  }

  function continueTestAfterContextRestored() {
    window.gl = wtu.create3DContext(canvas);
    var func = continueTestFunc;
    window.continueTestFunc = function() { testFailed("should not be here"); };
    func();
  }

  function continueTestPart1() {
    gl.clearColor(0.2, 0.6, 0.4, 1);
    gl.clear(gl.COLOR_BUFFER_BIT);

    var innerColor = [51, 153, 102, 255]; // (0.2, 0.6, 0.4, 1)
    var outerColor = [19, 72, 0, 198]; // Random color other than [0, 0, 0, 0]

    var tests = [
      { msg: 'in range', checkColor: innerColor, x:  0, y:  0,
        oneColor: innerColor, oneX: 0, oneY: 0},
      { msg: 'off top left', checkColor: outerColor, x: -1, y: -1,
        oneColor: innerColor, oneX: 1, oneY: 1},
      { msg: 'off bottom right', checkColor: outerColor, x:  1, y:  1,
        oneColor: innerColor, oneX: 0, oneY: 0},
      { msg: 'completely off top ', checkColor: outerColor, x:  0, y: -2,
        oneColor: outerColor, oneX: 0, oneY: 0},
      { msg: 'completely off bottom', checkColor: outerColor, x:  0, y:  2,
        oneColor: outerColor, oneX: 0, oneY: 0},
      { msg: 'completely off left', checkColor: outerColor, x: -2, y:  0,
        oneColor: outerColor, oneX: 0, oneY: 0},
      { msg: 'completeley off right', checkColor: outerColor, x:  2, y:  0,
        oneColor: outerColor, oneX: 0, oneY: 0}
    ];

    for (var tt = 0; tt < tests.length; ++tt) {
      var test = tests[tt];
      debug("");
      debug("checking: " + test.msg);
      checkBuffer(test.checkColor, test.x, test.y,
                  test.oneColor, test.oneX, test.oneY);
    }

    wtu.glErrorShouldBe(gl, gl.NO_ERROR, "there should be no GL errors");

    function checkBuffer(checkColor, x, y, oneColor, oneX, oneY) {
      var buf = new Uint8Array(width * height * 4);
      // Initialize buf.
      for (var ii = 0; ii < width * height; ++ii) {
        buf[ii * 4] = outerColor[0];
        buf[ii * 4 + 1] = outerColor[1];
        buf[ii * 4 + 2] = outerColor[2];
        buf[ii * 4 + 3] = outerColor[3];
      }
      gl.readPixels(x, y, width, height, gl.RGBA, gl.UNSIGNED_BYTE, buf);
      for (var yy = 0; yy < height; ++yy) {
        for (var xx = 0; xx < width; ++xx) {
          var offset = (yy * width + xx) * 4;
          var expectedColors = (oneX == xx && oneY == yy) ? oneColor : checkColor;
          var mismatch = false;
          for (var cc = 0; cc < 4; ++cc) {
            var expectedColor = expectedColors[cc];
            var color = buf[offset + cc];
            var diff = Math.abs(expectedColor - color);
            if (diff >= 3) {
              mismatch = true;
              break;
            }
          }
          assertMsg(!mismatch,
                    "color pixel at " + xx + ", " + yy + " should be about " + expectedColors +
                    ", was = " + [buf[offset], buf[offset + 1], buf[offset + 2], buf[offset + 3]]);
        }
      }
    }

    continueTestPart2();
  }

  function continueTestPart2() {
    let neverValidFormats = [gl.DEPTH_COMPONENT, gl.DEPTH_STENCIL, desktopGL.R8, gl.RGBA4];
    let maybeValidFormats = [gl.LUMINANCE, gl.LUMINANCE_ALPHA];
    if (contextVersion < 2) {
    // They are valid in WebGL 2 or higher
      maybeValidFormats = maybeValidFormats.concat([desktopGL.RED, desktopGL.RG_INTEGER, desktopGL.RGBA_INTEGER]);
    }

    let neverValidTypeInfo = [
      {type: desktopGL.UNSIGNED_INT_24_8,       dest: new Uint32Array(4)}
    ];
    let maybeValidTypeInfo = [];
    if (contextVersion < 2) {
    // They are valid in WebGL 2 or Higher
      maybeValidTypeInfo = maybeValidTypeInfo.concat([
        {type: gl.UNSIGNED_SHORT,                     dest: new Uint16Array(4)},
        {type: gl.SHORT,                              dest: new Int16Array(4)},
        {type: gl.BYTE,                               dest: new Int8Array(4)},
        {type: gl.UNSIGNED_INT,                       dest: new Uint32Array(4)},
        {type: desktopGL.UNSIGNED_INT_2_10_10_10_REV, dest: new Uint32Array(4)}
      ]);
    }

    debug("");
    debug("check non-default format or type");
    for (let format of neverValidFormats) {
      var buf = new Uint8Array(4);
      gl.readPixels(0, 0, 1, 1, format, gl.UNSIGNED_BYTE, buf);
      wtu.glErrorShouldBe(gl, gl.INVALID_ENUM, "Should not be able to read as " + wtu.glEnumToString(gl, format));
    }
    for (let format of maybeValidFormats) {
      var buf = new Uint8Array(4);
      gl.readPixels(0, 0, 1, 1, format, gl.UNSIGNED_BYTE, buf);
      wtu.glErrorShouldBe(gl, [gl.INVALID_ENUM, gl.INVALID_OPERATION], "Should not be able to read as " + wtu.glEnumToString(gl, format));
    }

    for (let info of neverValidTypeInfo) {
      var type = info.type;
      var dest = info.dest;
      gl.readPixels(0, 0, 1, 1, gl.RGBA, type, dest);
      wtu.glErrorShouldBe(gl, gl.INVALID_ENUM, "Should not be able to read as " + wtu.glEnumToString(gl, type));
    }
    for (let info of maybeValidTypeInfo) {
      var type = info.type;
      var dest = info.dest;
      gl.readPixels(0, 0, 1, 1, gl.RGBA, type, dest);
      wtu.glErrorShouldBe(gl, [gl.INVALID_ENUM, gl.INVALID_OPERATION], "Should not be able to read as " + wtu.glEnumToString(gl, type));
    }


    // -

    const combinations = [
      {
        format: gl.RGB,
        type: gl.UNSIGNED_SHORT_5_6_5,
        dest: new Uint8Array(3),
      },
      {
        format: gl.RGBA,
        type: gl.UNSIGNED_SHORT_5_5_5_1,
        dest: new Uint16Array(1),
      },
      {
        format: gl.RGBA,
        type: gl.UNSIGNED_SHORT_4_4_4_4,
        dest: new Uint16Array(1),
      },
    ];

    const FORMATS = [
      {
        format: gl.RGBA,
        channels: 4,
      }, {
        format: gl.RGB,
        channels: 3,
      }, {
        format: gl.LUMINANCE_ALPHA,
        channels: 2,
      }, {
        format: gl.ALPHA,
        channels: 1,
      }, {
        format: gl.LUMINANCE,
        channels: 3,
      },
    ];
    if (contextVersion >= 2) {
      FORMATS.push(
        {
          format: gl.RED,
          channels: 1,
        }, {
          format: gl.RG,
          channels: 1,
        }, {
          format: gl.RGBA_INTEGER,
          channels: 4,
        }, {
          format: gl.RGB_INTEGER,
          channels: 3,
        }, {
          format: gl.RG_INTEGER,
          channels: 2,
        }, {
          format: gl.RED_INTEGER,
          channels: 1,
        }
      );
    }

    // -

    const TYPES = [
      {
        type: gl.UNSIGNED_BYTE,
        ctor: Uint8Array,
      }, {
        type: gl.BYTE,
        ctor: Int8Array,
      }, {
        type: gl.UNSIGNED_SHORT,
        ctor: Uint16Array,
      }, {
        type: gl.SHORT,
        ctor: Int16Array,
      }, {
        type: gl.UNSIGNED_INT,
        ctor: Uint32Array,
      }, {
        type: gl.INT,
        ctor: Int32Array,
      }, {
        type: gl.FLOAT,
        ctor: Float32Array,
      }
    ];

    if (contextVersion >= 2) {
      TYPES.push(
        {
          type: gl.HALF_FLOAT,
          ctor: Uint16Array,
        }
      );
    }

    const ext = gl.getExtension('OES_texture_half_float');
    if (ext) {
      TYPES.push(
        {
          type: ext.HALF_FLOAT_OES,
          ctor: Uint16Array,
        }
      );
    }

    for (const t of TYPES) {
      for (const f of FORMATS) {
        const desc = Object.assign({}, f, t);
        desc.dest = new desc.ctor(desc.channels);
        combinations.push(desc);
      }
    }

    // -

    debug("");
    debug("check invalid combinations of format/type");

    var implFormat = gl.getParameter(gl.IMPLEMENTATION_COLOR_READ_FORMAT);
    var implType = gl.getParameter(gl.IMPLEMENTATION_COLOR_READ_TYPE);
    debug("IMPLEMENTATION_COLOR_READ_FORMAT: " + wtu.glEnumToString(gl, implFormat));
    debug("IMPLEMENTATION_COLOR_READ_TYPE: " + wtu.glEnumToString(gl, implType));

    for (var tt = 0; tt < combinations.length; ++ tt) {
      var info = combinations[tt];
      var format = info.format;
      var type = info.type;
      var dest = info.dest;
      gl.readPixels(0, 0, 1, 1, format, type, dest);
      // Only two format/type parameter pairs are accepted. GL_RGBA/GL_UNSIGNED_BYTE is always
      // accepted on default readbuffer. The other acceptable pair can be discovered by querying
      // GL_IMPLEMENTATION_COLOR_READ_FORMAT and GL_IMPLEMENTATION_COLOR_READ_TYPE.
      if ((format == gl.RGBA && type == gl.UNSIGNED_BYTE) || (format == implFormat && type == implType)) {
        wtu.glErrorShouldBe(
            gl, gl.NO_ERROR,
            "Should be able to read as " + wtu.glEnumToString(gl, format) +
            " / " + wtu.glEnumToString(gl, type));
      } else {
        wtu.glErrorShouldBe(
            gl, [gl.INVALID_OPERATION, gl.INVALID_ENUM],
            "Should not be able to read as " + wtu.glEnumToString(gl, format) +
            " / " + wtu.glEnumToString(gl, type));
      }
    }

    debug("");
    debug("check reading with lots of drawing");
    continueTestFunc = continueTestPart3;
    width = 1024;
    height = 1024;
    canvas.width = width;
    canvas.height = height;
    if (gl.getError() != gl.CONTEXT_LOST_WEBGL) {
      continueTestPart3();
    }
  }

  function continueTestPart3() {
    gl.viewport(0, 0, 1024, 1024);
    var program = wtu.setupTexturedQuad(gl);
    var loc = gl.getUniformLocation(program, "tex");
    gl.disable(gl.BLEND);
    gl.disable(gl.DEPTH_TEST);
    var colors = [[255, 0, 0, 255], [0, 255, 0, 255], [0, 0, 255, 255]];
    var textures = [];
    var results = [];
    for (var ii = 0; ii < colors.length; ++ii) {
      gl.activeTexture(gl.TEXTURE0 + ii);
      var tex = gl.createTexture();
      wtu.fillTexture(gl, tex, 1, 1, colors[ii]);
      textures.push(tex);
    }
    for (var ii = 0; ii < colors.length; ++ii) {
      for (var jj = 0; jj < 300 + ii + 1; ++jj) {
        gl.uniform1i(loc, jj % 3);
        gl.drawArrays(gl.TRIANGLES, 0, 6);
      }
      var buf = new Uint8Array(4);
      gl.readPixels(512, 512, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, buf);
      results.push(buf);
      for (var kk = 0; kk < 99; ++kk) {
        gl.uniform1i(loc, (jj + kk) % 3);
        gl.drawArrays(gl.TRIANGLES, 0, 6);
      }
    }
    for (var ii = 0; ii < colors.length; ++ii) {
      var buf = results[ii];
      var color = colors[ii];
      actual = [buf[0], buf[1], buf[2], buf[3]];
      expected = [color[0], color[1], color[2], color[3]];
      shouldBe("actual", "expected");
    }
    wtu.glErrorShouldBe(gl, gl.NO_ERROR, "there should be no GL errors");

    debug("");
    debug("check readback into Uint8ClampedArray");
    continueTestFunc = continueTestPart4;
    const kSize = 32;
    canvas.width = kSize;
    canvas.height = kSize;
    if (gl.getError() != gl.CONTEXT_LOST_WEBGL) {
      continueTestPart4();
    }
  }

  function continueTestPart4() {
    const kSize = 32;
    gl.viewport(0, 0, kSize, kSize);
    gl.clearColor(0.0, 1.0, 0.0, 1.0);
    gl.clear(gl.COLOR_BUFFER_BIT);

    var buf = new Uint8ClampedArray(4);
    gl.readPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, buf);
    wtu.glErrorShouldBe(gl, gl.NO_ERROR, "there should be no GL errors reading back into a Uint8ClampedArray");
    if (buf[0] == 0 && buf[1] == 255 && buf[2] == 0 && buf[3] == 255) {
      testPassed("Readback into Uint8ClampedArray worked successfully");
    } else {
      assertMsg(false,
                "color pixel at 0, 0 should be [0, 255, 0, 255], was " +
                [buf[0], buf[1], buf[2], buf[3]]);
    }

    const validDatas = [
      `new Uint8Array(4)`,
      `new Uint8Array(new ArrayBuffer(4))`,
      `new Uint8ClampedArray(4)`,
      `new Uint8ClampedArray(new ArrayBuffer(4))`,
    ];
    if (window.SharedArrayBuffer) {
      validDatas.push(
        `new Uint8Array(new SharedArrayBuffer(4))`,
        `new Uint8ClampedArray(new SharedArrayBuffer(4))`
      );
    }
    for (const x of validDatas) {
      shouldNotThrow(`gl.readPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, ${x});`);
    }
  }
}
</script>
</body>
</html>