Refactor WASM app build logic into a separate Lua file for improved maintainability

2 files changed, 125 insertions, 107 deletions

diff --git a/xmake/rules/qt/build_qt_wasm_app.lua b/xmake/rules/qt/build_qt_wasm_app.lua
new file mode 100644
index 000000000..8b876ce26
--- /dev/null
+++ b/xmake/rules/qt/build_qt_wasm_app.lua
@@ -0,0 +1,124 @@
+--!A cross-platform build utility based on Lua
+--
+-- Licensed under the Apache License, Version 2.0 (the "License");
+-- you may not use this file except in compliance with the License.
+-- You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+-- Copyright (C) 2015-present, Xmake Open Source Community.
+--
+-- @author      ruki
+-- @file        build_wasm_app.lua
+--
+
+function main(target)
+    local qt = target:data("qt")
+    local pluginsdir = qt and qt.pluginsdir
+    if not pluginsdir then
+        return
+    end
+    local targetdir = target:targetdir()
+    local htmlfile = path.join(targetdir, target:basename() .. ".html")
+    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")
+            local preload = ""
+            -- @see https://github.com/xmake-io/xmake/issues/6182
+            local preloadfiles = target:values("wasm.preloadfiles")
+            if preloadfiles then
+                local filelist = {}
+                for _, preloadfile in ipairs(preloadfiles) do
+                    table.insert(filelist, string.format("'%s'", path.filename(preloadfile)))
+                end
+                if #filelist > 0 then
+                    preload = string.format("preload: [%s],", table.concat(filelist, ", "))
+                end
+            end
+            -- Patch old containerElements (pre-Qt 6.5)
+            io.gsub(htmlfile, "containerElements: %[screen%],", function (w)
+                return w .. " " .. preload
+            end)
+            -- Patch new qtContainerElements (Qt 6.5+)
+            io.gsub(htmlfile, "qtContainerElements: %[screen%],", function (w)
+                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
+        end
+        os.vcp(path.join(pluginsdir, "platforms/qtloader.js"), targetdir)
+        os.vcp(path.join(pluginsdir, "platforms/qtlogo.svg"), targetdir)
+    end
+end
diff --git a/xmake/rules/qt/xmake.lua b/xmake/rules/qt/xmake.lua
index eef1c9337..85eb6640c 100644
--- a/xmake/rules/qt/xmake.lua
+++ b/xmake/rules/qt/xmake.lua
@@ -18,116 +18,10 @@
 -- @file        xmake.lua
 --
 
-function _build_wasm_app(target, qt, pluginsdir)
-    local targetdir = target:targetdir()
-    local htmlfile = path.join(targetdir, target:basename() .. ".html")
-    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")
-            local preload = ""
-            -- @see https://github.com/xmake-io/xmake/issues/6182
-            local preloadfiles = target:values("wasm.preloadfiles")
-            if preloadfiles then
-                local filelist = {}
-                for _, preloadfile in ipairs(preloadfiles) do
-                    table.insert(filelist, string.format("'%s'", path.filename(preloadfile)))
-                end
-                if #filelist > 0 then
-                    preload = string.format("preload: [%s],", table.concat(filelist, ", "))
-                end
-            end
-            -- Patch old containerElements (pre-Qt 6.5)
-            io.gsub(htmlfile, "containerElements: %[screen%],", function (w)
-                return w .. " " .. preload
-            end)
-            -- Patch new qtContainerElements (Qt 6.5+)
-            io.gsub(htmlfile, "qtContainerElements: %[screen%],", function (w)
-                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
-        end
-        os.vcp(path.join(pluginsdir, "platforms/qtloader.js"), targetdir)
-        os.vcp(path.join(pluginsdir, "platforms/qtlogo.svg"), targetdir)
-    end
-end
-
 -- define rule: qt/wasm application
 rule("qt._wasm_app")
     add_deps("qt.env")
-    after_build(function (target)
-        local qt = target:data("qt")
-        local pluginsdir = qt and qt.pluginsdir
-        if pluginsdir then
-            _build_wasm_app(target, qt, pluginsdir)
-        end
-    end)
+    after_build("build_qt_wasm_app")
 
 -- define rule: qt static library
 rule("qt.static")