Fix glfw3 default hints being modified

src/library_glfw.js

@@ -51,7 +51,7 @@ var LibraryGLFW = {
       this.title = title;
       this.monitor = monitor;
       this.share = share;
-      this.attributes = GLFW.hints;
+      this.attributes = Object.assign({}, GLFW.hints);
       this.inputModes = {
         0x00033001:0x00034001, // GLFW_CURSOR (GLFW_CURSOR_NORMAL)
         0x00033002:0, // GLFW_STICKY_KEYS
@@ -996,6 +996,10 @@ var LibraryGLFW = {
       }
     },
 
+    defaultWindowHints: () => {
+      GLFW.hints = Object.assign({}, GLFW.defaultHints);
+    },
+
     createWindow: (width, height, title, monitor, share) => {
       var i, id;
       for (i = 0; i < GLFW.windows.length && GLFW.windows[i] !== null; i++) {
@@ -1124,7 +1128,7 @@ var LibraryGLFW = {
     if (GLFW.windows) return 1; // GL_TRUE
 
     GLFW.initialTime = GLFW.getTime();
-    GLFW.hints = GLFW.defaultHints;
+    GLFW.defaultWindowHints();
     GLFW.windows = new Array()
     GLFW.active = null;
     GLFW.scale  = _emscripten_get_device_pixel_ratio();
@@ -1320,9 +1324,7 @@ var LibraryGLFW = {
 
   glfwSetGammaRamp: (monitor, ramp) => { throw "glfwSetGammaRamp not implemented."; },
 
-  glfwDefaultWindowHints: () => {
-    GLFW.hints = GLFW.defaultHints;
-  },
+  glfwDefaultWindowHints: () => GLFW.defaultWindowHints(),
 
   glfwWindowHint: (target, hint) => {
     GLFW.hints[target] = hint;

test/browser/test_glfw3_default_hints.c

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2023 The Emscripten Authors.  All rights reserved.
+ * Emscripten is available under two separate licenses, the MIT license and the
+ * University of Illinois/NCSA Open Source License.  Both these licenses can be
+ * found in the LICENSE file.
+ */
+
+#include <GLFW/glfw3.h>
+#include <assert.h>
+#include <emscripten/html5.h>
+
+static void checkDefaultWindowHints() {
+  int ok = EM_ASM_INT({
+    var res = 1;
+    for (var k in TEST_GLFW3_DEFAULTS_HINTS) {
+      if(GLFW.defaultHints[k] !== TEST_GLFW3_DEFAULTS_HINTS[k])
+        res = 0;
+    }
+    return res;
+  });
+  assert(ok == 1);
+}
+
+int main() {
+
+  EM_ASM(
+    TEST_GLFW3_DEFAULTS_HINTS = {};
+    TEST_GLFW3_DEFAULTS_HINTS[0x00020001] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00020002] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00020003] = 1;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00020004] = 1;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00020005] = 1;
+    TEST_GLFW3_DEFAULTS_HINTS[0x0002000A] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x0002200C] = 0;
+
+    TEST_GLFW3_DEFAULTS_HINTS[0x00021001] = 8;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00021002] = 8;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00021003] = 8;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00021004] = 8;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00021005] = 24;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00021006] = 8;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00021007] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00021008] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00021009] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x0002100A] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x0002100B] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x0002100C] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x0002100D] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x0002100E] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x0002100F] = 0;
+
+    TEST_GLFW3_DEFAULTS_HINTS[0x00022001] = 0x00030001;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00022002] = 1;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00022003] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00022004] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00022005] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00022006] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00022007] = 0;
+    TEST_GLFW3_DEFAULTS_HINTS[0x00022008] = 0;
+  );
+
+  assert(glfwInit() == GL_TRUE);
+
+  // Use case: after glfwInit, default window hints are correct
+  {
+    checkDefaultWindowHints();
+  }
+
+  // Use case: updates a window hint
+  // Expected results: window hint is properly updated
+  //                   default window hints are not affected
+  {
+    // GLFW_DEPTH_BITS
+    assert(EM_ASM_INT(return GLFW.hints[0x00021005];) == 24);
+    glfwWindowHint(GLFW_DEPTH_BITS, 16);
+    assert(EM_ASM_INT(return GLFW.hints[0x00021005];) == 16);
+    checkDefaultWindowHints();
+  }
+
+  // Use case: resets window hints to default
+  // Expected results: previously changed window hint is back to its default value
+  //                   default window hints are not affected
+  {
+    glfwDefaultWindowHints();
+    assert(EM_ASM_INT(return GLFW.hints[0x00021005];) == 24);
+    checkDefaultWindowHints();
+  }
+
+  // Use case: change window hint, create window, then change window hint
+  // Expected results: the window hint set at creation time (which is now a
+  //                   window attribute that can be read with glfwGetWindowAttrib)
+  //                   does not change
+  {
+    glfwDefaultWindowHints();
+    glfwWindowHint(GLFW_DEPTH_BITS, 16);
+    GLFWwindow* window = glfwCreateWindow(640, 480, "test_glfw3_default_hints.c", NULL, NULL);
+    assert(glfwGetWindowAttrib(window, GLFW_DEPTH_BITS) == 16);
+    glfwWindowHint(GLFW_DEPTH_BITS, 24);
+    assert(glfwGetWindowAttrib(window, GLFW_DEPTH_BITS) == 16);
+  }
+
+  glfwTerminate();
+
+  return 0;
+}

test/test_browser.py

@@ -2999,6 +2999,10 @@ def in_html(expected):
 
         in_html('200')
 
+  @requires_graphics_hardware
+  def test_glfw3_default_hints(self):
+      self.btest_exit('test_glfw3_default_hints.c', args=['-sUSE_GLFW=3', '-lglfw', '-lGL'])
+
   @requires_graphics_hardware
   @parameterized({
     'no_gl': (['-DCLIENT_API=GLFW_NO_API'],),