Refactor Emscripten JS issue fixes into a dedicated function for improved clarity and maintainability

1 files changed, 68 insertions, 64 deletions

diff --git a/xmake/rules/qt/build_qt_wasm_app.lua b/xmake/rules/qt/build_qt_wasm_app.lua
index 8b876ce26..dfaa54a1d 100644
--- a/xmake/rules/qt/build_qt_wasm_app.lua
+++ b/xmake/rules/qt/build_qt_wasm_app.lua
@@ -18,6 +18,73 @@
 -- @file        build_wasm_app.lua
 --
 
+import("core.base.semver")
+
+-- Fix Emscripten JS issues for Qt WASM builds
+function _fix_emscripten_js(jsfile)
+    if not os.isfile(jsfile) then
+        return
+    end
+
+    -- Remove "use strict"; to avoid issues with `this` being undefined in strict mode
+    io.gsub(jsfile, "\"use strict\";", "")
+    io.gsub(jsfile, "'use strict';", "")
+    -- Patch visualViewport access issue if present (undefined this context)
+    io.gsub(jsfile, "this%.visualViewport",
+        "(typeof window !== 'undefined' ? window.visualViewport : null)")
+    -- Guard all document.querySelector(target) calls with try-catch.
+    -- Qt WASM uses "!" prefixed selectors that are not valid CSS selectors,
+    -- and corrupted strings from SharedArrayBuffer can also cause SyntaxErrors.
+    io.gsub(jsfile, "document%.querySelector%(target%)",
+        "(function(){try{return document.querySelector(target)}catch(e){return null}})()")
+    -- Replace findCanvasEventTarget with a robust version.
+    -- Qt WASM registers canvases in Module.specialHTMLTargets with "!" prefixed
+    -- keys (e.g. "!qtwindow1", "!qtoffscreen_xxx"). With pthreads +
+    -- ALLOW_MEMORY_GROWTH, Emscripten's UTF8ToString may read corrupted strings
+    -- from SharedArrayBuffer memory, causing the specialHTMLTargets lookup to fail.
+    -- Additionally, QWasmOffscreenSurface passes an empty string when
+    -- OffscreenCanvas is unavailable. The replacement adds a fallback that
+    -- iterates specialHTMLTargets to find any Qt-registered canvas element.
+    local content = io.readfile(jsfile)
+    local marker = "var findCanvasEventTarget = target => {"
+    local pos = content:find(marker, 1, true)
+    if pos then
+        -- Find the end of the function by counting matched braces
+        local depth = 1
+        local i = pos + #marker
+        while i <= #content and depth > 0 do
+            local c = content:sub(i, i)
+            if c == "{" then depth = depth + 1
+            elseif c == "}" then depth = depth - 1 end
+            i = i + 1
+        end
+        if content:sub(i, i) == ";" then i = i + 1 end
+        local new_func = "var findCanvasEventTarget = target => {\n"
+            .. " target = maybeCStringToJsString(target);\n"
+            .. " if (specialHTMLTargets[target]) return specialHTMLTargets[target];\n"
+            .. " if (GL.offscreenCanvases[target]) return GL.offscreenCanvases[target];\n"
+            .. " if (typeof target === 'string' && target.length > 0) {\n"
+            .. "  var s = target.substr(1);\n"
+            .. "  if (GL.offscreenCanvases[s]) return GL.offscreenCanvases[s];\n"
+            .. " }\n"
+            .. " if (target === 'canvas') {\n"
+            .. "  var k = Object.keys(GL.offscreenCanvases);\n"
+            .. "  if (k.length) return GL.offscreenCanvases[k[0]];\n"
+            .. " }\n"
+            .. " for (var key in specialHTMLTargets) {\n"
+            .. "  if (typeof key === 'string' && key.charAt(0) === '!') {\n"
+            .. "   var el = specialHTMLTargets[key];\n"
+            .. "   if (el && (el.tagName === 'CANVAS' || (typeof OffscreenCanvas !== 'undefined' && el instanceof OffscreenCanvas))) return el;\n"
+            .. "  }\n"
+            .. " }\n"
+            .. " try { return typeof document !== 'undefined' ? document.querySelector(target) : undefined; }\n"
+            .. " catch(e) { return undefined; }\n"
+            .. "};\n"
+        content = content:sub(1, pos - 1) .. new_func .. content:sub(i)
+        io.writefile(jsfile, content)
+    end
+end
+
 function main(target)
     local qt = target:data("qt")
     local pluginsdir = qt and qt.pluginsdir
@@ -29,7 +96,6 @@ function main(target)
     if os.isfile(path.join(pluginsdir, "platforms/wasm_shell.html")) then
         os.vcp(path.join(pluginsdir, "platforms/wasm_shell.html"), htmlfile)
         io.gsub(htmlfile, "@APPNAME@", target:name())
-        import("core.base.semver")
         local qt_sdkver = qt.sdkver or target:data("qt_sdkver")
         if qt_sdkver and semver.new(qt_sdkver):ge("6.0") then
             io.gsub(htmlfile, "@APPEXPORTNAME@", "createQtAppInstance")
@@ -54,69 +120,7 @@ function main(target)
                 return w .. " " .. preload
             end)
             io.gsub(htmlfile, "@PRELOAD@", "")
-            -- Fix Emscripten JS issues for Qt WASM builds
-            local jsfile = path.join(targetdir, target:basename() .. ".js")
-            if os.isfile(jsfile) then
-                -- Remove "use strict"; to avoid issues with `this` being undefined in strict mode
-                io.gsub(jsfile, "\"use strict\";", "")
-                io.gsub(jsfile, "'use strict';", "")
-                -- Patch visualViewport access issue if present (undefined this context)
-                io.gsub(jsfile, "this%.visualViewport",
-                    "(typeof window !== 'undefined' ? window.visualViewport : null)")
-                -- Guard all document.querySelector(target) calls with try-catch.
-                -- Qt WASM uses "!" prefixed selectors that are not valid CSS selectors,
-                -- and corrupted strings from SharedArrayBuffer can also cause SyntaxErrors.
-                io.gsub(jsfile, "document%.querySelector%(target%)",
-                    "(function(){try{return document.querySelector(target)}catch(e){return null}})()")
-                -- Replace findCanvasEventTarget with a robust version.
-                -- Qt WASM registers canvases in Module.specialHTMLTargets with "!" prefixed
-                -- keys (e.g. "!qtwindow1", "!qtoffscreen_xxx"). With pthreads +
-                -- ALLOW_MEMORY_GROWTH, Emscripten's UTF8ToString may read corrupted strings
-                -- from SharedArrayBuffer memory, causing the specialHTMLTargets lookup to fail.
-                -- Additionally, QWasmOffscreenSurface passes an empty string when
-                -- OffscreenCanvas is unavailable. The replacement adds a fallback that
-                -- iterates specialHTMLTargets to find any Qt-registered canvas element.
-                -- @see https://code.qt.io/cgit/qt/qtbase.git/tree/src/plugins/platforms/wasm/qwasmwindow.cpp
-                -- @see https://code.qt.io/cgit/qt/qtbase.git/tree/src/plugins/platforms/wasm/qwasmoffscreensurface.cpp
-                local content = io.readfile(jsfile)
-                local marker = "var findCanvasEventTarget = target => {"
-                local pos = content:find(marker, 1, true)
-                if pos then
-                    -- Find the end of the function by counting matched braces
-                    local depth = 1
-                    local i = pos + #marker
-                    while i <= #content and depth > 0 do
-                        local c = content:sub(i, i)
-                        if c == "{" then depth = depth + 1
-                        elseif c == "}" then depth = depth - 1 end
-                        i = i + 1
-                    end
-                    if content:sub(i, i) == ";" then i = i + 1 end
-                    local new_func = "var findCanvasEventTarget = target => {\n"
-                        .. " target = maybeCStringToJsString(target);\n"
-                        .. " if (specialHTMLTargets[target]) return specialHTMLTargets[target];\n"
-                        .. " if (GL.offscreenCanvases[target]) return GL.offscreenCanvases[target];\n"
-                        .. " if (typeof target === 'string' && target.length > 0) {\n"
-                        .. "  var s = target.substr(1);\n"
-                        .. "  if (GL.offscreenCanvases[s]) return GL.offscreenCanvases[s];\n"
-                        .. " }\n"
-                        .. " if (target === 'canvas') {\n"
-                        .. "  var k = Object.keys(GL.offscreenCanvases);\n"
-                        .. "  if (k.length) return GL.offscreenCanvases[k[0]];\n"
-                        .. " }\n"
-                        .. " for (var key in specialHTMLTargets) {\n"
-                        .. "  if (typeof key === 'string' && key.charAt(0) === '!') {\n"
-                        .. "   var el = specialHTMLTargets[key];\n"
-                        .. "   if (el && (el.tagName === 'CANVAS' || (typeof OffscreenCanvas !== 'undefined' && el instanceof OffscreenCanvas))) return el;\n"
-                        .. "  }\n"
-                        .. " }\n"
-                        .. " try { return typeof document !== 'undefined' ? document.querySelector(target) : undefined; }\n"
-                        .. " catch(e) { return undefined; }\n"
-                        .. "};\n"
-                    content = content:sub(1, pos - 1) .. new_func .. content:sub(i)
-                    io.writefile(jsfile, content)
-                end
-            end
+            _fix_emscripten_js(path.join(targetdir, target:basename() .. ".js"))
         end
         os.vcp(path.join(pluginsdir, "platforms/qtloader.js"), targetdir)
         os.vcp(path.join(pluginsdir, "platforms/qtlogo.svg"), targetdir)