Fixes for IE 11 on Windows 8.1. Improved error messages for DPI scaling and browser zoom problems.

Author: jdarpinian

html/draw-pattern.js

@@ -37,7 +37,6 @@ var canvasGL = document.createElement('canvas');
 setPrefixed('position', 'absolute', canvasGL.style);
 setPrefixed('top', '0px', canvasGL.style);
 setPrefixed('left', '0px', canvasGL.style);
-setPrefixed('zIndex', '1', canvasGL.style); // IE 11 doesn't display this element without this hack.
 canvasGL.width = 500;
 canvasGL.height = 1;
 var gl = null;
@@ -86,7 +85,6 @@ rightBlocker.style.top = '0px';
 rightBlocker.style.background = 'black';
 rightBlocker.style.width = '100%';
 rightBlocker.style.height = '100%';
-rightBlocker.style.zIndex = '1'; // IE 11 doesn't draw this element without this hack.
 bottomBlocker.style.position = 'absolute';
 bottomBlocker.style.left = '0px';
 bottomBlocker.style.top = '1px';

html/latency-benchmark.js

@@ -530,7 +530,7 @@ var runNextTest = function(previousTest) {
   var test = tests[testIndex];
   test.infoCell.textContent = '';
   test.resultCell.textContent = '⋯';
-  setTimeout(function() { checkTimeout(test); }, 50000);
+  setTimeout(function() { checkTimeout(test); }, 80000);
   if (test.test) {
     setTimeout(function() {
       try {

src/latency-benchmark.c

@@ -308,7 +308,7 @@ static void init_statistic(char *name, statistic *stat, int value,
 }
 
 
-static const int64_t test_timeout_ms = 40000;
+static const int64_t test_timeout_ms = 80000;
 static const int64_t event_response_timeout_ms = 4000;
 static const int latency_measurements_to_take = 50;
 
@@ -336,7 +336,7 @@ bool measure_latency(
   bool found_pattern = find_pattern(magic_pattern, screenshot, &x, &y);
   free_screenshot(screenshot);
   if (!found_pattern) {
-    *error = "Failed to find test pattern on screen.";
+    *error = "Failed to find test pattern on screen. Ensure that your browser's zoom level is set to \"100%\", and the top-left corner of the window is visible. If you have multiple displays, try moving the browser window to the main display.";
     return false;
   }
   uint8_t full_pattern[pattern_bytes];
@@ -456,6 +456,7 @@ bool measure_latency(
           return false;
         }
         if (scroll_updated) {
+          debug_log("scroll measurements: %d", scroll_stats.measurements);
           // We saw the start of a scroll. Wait for the scroll animation to
           // finish before continuing. We assume the animation is finished if
           // it's been 100 milliseconds since we last saw the scroll position

src/win/main.cpp

@@ -182,8 +182,10 @@ int APIENTRY _tWinMain(_In_ HINSTANCE hInstance,
     HDC desktop = GetDC(NULL);
     assert(desktop);
     if (GetDeviceCaps(desktop, LOGPIXELSX) != 96) {
-      MessageBox(NULL, "Warning: The test will fail in non-DPI-aware browsers. To fix this, use Control Panel to set your DPI scaling factor to \"100%\" or \"Smaller\".",
-                 "Warning", MB_ICONWARNING | MB_OK);
+      MessageBox(NULL, "Unfortunately, due to browser bugs you must set the Windows DPI scaling factor to \"100%\" or \"Smaller\" (96 DPI) for this test to work. Please change it and reboot.",
+                 "Unsupported DPI", MB_ICONERROR | MB_OK);
+      WinExec("DpiScaling.exe", SW_NORMAL);
+      return 1;
     }
     ReleaseDC(NULL, desktop);
     run_server();