fix

docs/content/administration/config-cheat-sheet.en-us.md

@@ -214,10 +214,9 @@ The following configuration set `Content-Type: application/vnd.android.package-a
 - `SITEMAP_PAGING_NUM`: **20**: Number of items that are displayed in a single subsitemap.
 - `GRAPH_MAX_COMMIT_NUM`: **100**: Number of maximum commits shown in the commit graph.
 - `CODE_COMMENT_LINES`: **4**: Number of line of codes shown for a code comment.
-- `DEFAULT_THEME`: **gitea-auto**: \[gitea-auto, gitea-light, gitea-dark\]: Set the default theme for the Gitea installation.
+- `DEFAULT_THEME`: **gitea-auto**: Set the default theme for the Gitea installation, custom themes could be provided by "{CustomPath}/public/assets/css/theme-*.css".
 - `SHOW_USER_EMAIL`: **true**: Whether the email of the user should be shown in the Explore Users page.
-- `THEMES`:  **gitea-auto,gitea-light,gitea-dark**: All available themes. Allow users select personalized themes.
-  regardless of the value of `DEFAULT_THEME`.
+- `THEMES`: **_empty_**: All available themes by "{CustomPath}/public/assets/css/theme-*.css". Allow users select personalized themes.
 - `MAX_DISPLAY_FILE_SIZE`: **8388608**: Max size of files to be displayed (default is 8MiB)
 - `AMBIGUOUS_UNICODE_DETECTION`: **true**: Detect ambiguous unicode characters in file contents and show warnings on the UI
 - `REACTIONS`: All available reactions users can choose on issues/prs and comments

docs/content/administration/config-cheat-sheet.zh-cn.md

@@ -212,10 +212,9 @@ menu:
 - `SITEMAP_PAGING_NUM`: **20**: 在单个子SiteMap中显示的项数。
 - `GRAPH_MAX_COMMIT_NUM`: **100**: 提交图中显示的最大commit数量。
 - `CODE_COMMENT_LINES`: **4**: 在代码评论中能够显示的最大代码行数。
-- `DEFAULT_THEME`: **gitea-auto**: \[gitea-auto, gitea-light, gitea-dark\]: 在Gitea安装时候设置的默认主题。
+- `DEFAULT_THEME`: **gitea-auto**: 在Gitea安装时候设置的默认主题，自定义的主题可以通过 "{CustomPath}/public/assets/css/theme-*.css" 提供。
 - `SHOW_USER_EMAIL`: **true**: 用户的电子邮件是否应该显示在`Explore Users`页面中。
-- `THEMES`:  **gitea-auto,gitea-light,gitea-dark**: 所有可用的主题。允许用户选择个性化的主题，
-  而不受DEFAULT_THEME 值的影响。
+- `THEMES`:  **_empty_**: 所有可用的主题（由 "{CustomPath}/public/assets/css/theme-*.css" 提供）。允许用户选择个性化的主题，
 - `MAX_DISPLAY_FILE_SIZE`: **8388608**: 能够显示文件的最大大小（默认为8MiB）。
 - `REACTIONS`: 用户可以在问题（Issue）、Pull Request（PR）以及评论中选择的所有可选的反应。
     这些值可以是表情符号别名（例如：:smile:）或Unicode表情符号。

docs/content/administration/customizing-gitea.en-us.md

@@ -381,7 +381,7 @@ To make a custom theme available to all users:
 
 1. Add a CSS file to `$GITEA_CUSTOM/public/assets/css/theme-<theme-name>.css`.
   The value of `$GITEA_CUSTOM` of your instance can be queried by calling `gitea help` and looking up the value of "CustomPath".
-2. Add `<theme-name>` to the comma-separated list of setting `THEMES` in `app.ini`
+2. Add `<theme-name>` to the comma-separated list of setting `THEMES` in `app.ini`, or leave `THEMES` empty to allow all themes.
 
 Community themes are listed in [gitea/awesome-gitea#themes](https://gitea.com/gitea/awesome-gitea#themes).
 

docs/content/help/faq.en-us.md

@@ -178,17 +178,6 @@ At some point, a customer or third party needs access to a specific repo and onl
 
 Use [Fail2Ban](administration/fail2ban-setup.md) to monitor and stop automated login attempts or other malicious behavior based on log patterns
 
-## How to add/use custom themes
-
-Gitea supports three official themes right now, `gitea-light`, `gitea-dark`, and `gitea-auto` (automatically switches between the previous two depending on operating system settings).
-To add your own theme, currently the only way is to provide a complete theme (not just color overrides)
-
-As an example, let's say our theme is `arc-blue` (this is a real theme, and can be found [in this issue](https://github.com/go-gitea/gitea/issues/6011))
-
-Name the `.css` file `theme-arc-blue.css` and add it to your custom folder in `custom/public/assets/css`
-
-Allow users to use it by adding `arc-blue` to the list of `THEMES` in your `app.ini`
-
 ## SSHD vs built-in SSH
 
 SSHD is the built-in SSH server on most Unix systems.

docs/content/help/faq.zh-cn.md

@@ -182,17 +182,6 @@ Gitea不提供内置的Pages服务器。您需要一个专用的域名来提供
 
 使用 [Fail2Ban](administration/fail2ban-setup.md) 监视并阻止基于日志模式的自动登录尝试或其他恶意行为。
 
-## 如何添加/使用自定义主题
-
-Gitea 目前支持三个官方主题，分别是 `gitea-light`、`gitea-dark` 和 `gitea-auto`（根据操作系统设置自动切换前两个主题）。
-要添加自己的主题，目前唯一的方法是提供一个完整的主题（不仅仅是颜色覆盖）。
-
-假设我们的主题是 `arc-blue`（这是一个真实的主题，可以在[此问题](https://github.com/go-gitea/gitea/issues/6011)中找到）
-
-将`.css`文件命名为`theme-arc-blue.css`并将其添加到`custom/public/assets/css`文件夹中
-
-通过将`arc-blue`添加到`app.ini`中的`THEMES`列表中，允许用户使用该主题
-
 ## SSHD vs 内建SSH
 
 SSHD是大多数Unix系统上内建的SSH服务器。

modules/setting/ui.go

@@ -82,7 +82,6 @@ var UI = struct {
 	ReactionMaxUserNum:      10,
 	MaxDisplayFileSize:      8388608,
 	DefaultTheme:            `gitea-auto`,
-	Themes:                  []string{`gitea-auto`, `gitea-light`, `gitea-dark`},
 	Reactions:               []string{`+1`, `-1`, `laugh`, `hooray`, `confused`, `heart`, `rocket`, `eyes`},
 	CustomEmojis:            []string{`git`, `gitea`, `codeberg`, `gitlab`, `github`, `gogs`},
 	CustomEmojisMap:         map[string]string{"git": ":git:", "gitea": ":gitea:", "codeberg": ":codeberg:", "gitlab": ":gitlab:", "github": ":github:", "gogs": ":gogs:"},

modules/templates/helper.go

@@ -22,6 +22,7 @@ import (
 	"code.gitea.io/gitea/modules/timeutil"
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/services/gitdiff"
+	"code.gitea.io/gitea/services/webtheme"
 )
 
 // NewFuncMap returns functions for injecting to templates
@@ -137,12 +138,7 @@ func NewFuncMap() template.FuncMap {
 		"DisableImportLocal": func() bool {
 			return !setting.ImportLocalPaths
 		},
-		"ThemeName": func(user *user_model.User) string {
-			if user == nil || user.Theme == "" {
-				return setting.UI.DefaultTheme
-			}
-			return user.Theme
-		},
+		"UserThemeName": UserThemeName,
 		"NotificationSettings": func() map[string]any {
 			return map[string]any{
 				"MinTimeout":            int(setting.UI.Notification.MinTimeout / time.Millisecond),
@@ -261,3 +257,10 @@ func Eval(tokens ...any) (any, error) {
 	n, err := eval.Expr(tokens...)
 	return n.Value, err
 }
+
+func UserThemeName(user *user_model.User) string {
+	if user == nil || user.Theme == "" {
+		return setting.UI.DefaultTheme
+	}
+	return util.Iif(webtheme.IsThemeAvailable(user.Theme), user.Theme, setting.UI.DefaultTheme)
+}

routers/web/user/setting/profile.go

@@ -31,6 +31,7 @@ import (
 	"code.gitea.io/gitea/services/context"
 	"code.gitea.io/gitea/services/forms"
 	user_service "code.gitea.io/gitea/services/user"
+	"code.gitea.io/gitea/services/webtheme"
 )
 
 const (
@@ -318,6 +319,7 @@ func Repos(ctx *context.Context) {
 func Appearance(ctx *context.Context) {
 	ctx.Data["Title"] = ctx.Tr("settings.appearance")
 	ctx.Data["PageIsSettingsAppearance"] = true
+	ctx.Data["AllThemes"] = webtheme.GetAvailableThemes()
 
 	var hiddenCommentTypes *big.Int
 	val, err := user_model.GetUserSetting(ctx, ctx.Doer.ID, user_model.SettingsKeyHiddenCommentTypes)
@@ -341,11 +343,12 @@ func UpdateUIThemePost(ctx *context.Context) {
 	ctx.Data["PageIsSettingsAppearance"] = true
 
 	if ctx.HasError() {
+		ctx.Flash.Error(ctx.GetErrMsg())
 		ctx.Redirect(setting.AppSubURL + "/user/settings/appearance")
 		return
 	}
 
-	if !form.IsThemeExists() {
+	if !webtheme.IsThemeAvailable(form.Theme) {
 		ctx.Flash.Error(ctx.Tr("settings.theme_update_error"))
 		ctx.Redirect(setting.AppSubURL + "/user/settings/appearance")
 		return

routers/web/web.go

@@ -652,7 +652,7 @@ func registerRoutes(m *web.Route) {
 			m.Get("", user_setting.BlockedUsers)
 			m.Post("", web.Bind(forms.BlockUserForm{}), user_setting.BlockedUsersPost)
 		})
-	}, reqSignIn, ctxDataSet("PageIsUserSettings", true, "AllThemes", setting.UI.Themes, "EnablePackages", setting.Packages.Enabled))
+	}, reqSignIn, ctxDataSet("PageIsUserSettings", true, "EnablePackages", setting.Packages.Enabled))
 
 	m.Group("/user", func() {
 		m.Get("/activate", auth.Activate)

services/context/context.go

@@ -230,6 +230,7 @@ func Contexter() func(next http.Handler) http.Handler {
 
 // HasError returns true if error occurs in form validation.
 // Attention: this function changes ctx.Data and ctx.Flash
+// If HasError is called, then before Redirect, the error message should be stored by ctx.Flash.Error(ctx.GetErrMsg()) again.
 func (ctx *Context) HasError() bool {
 	hasErr, ok := ctx.Data["HasError"]
 	if !ok {

services/forms/user_form.go

@@ -11,7 +11,6 @@ import (
 
 	auth_model "code.gitea.io/gitea/models/auth"
 	user_model "code.gitea.io/gitea/models/user"
-	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/web/middleware"
 	"code.gitea.io/gitea/services/context"
@@ -273,7 +272,7 @@ func (f *AddEmailForm) Validate(req *http.Request, errs binding.Errors) binding.
 
 // UpdateThemeForm form for updating a users' theme
 type UpdateThemeForm struct {
-	Theme string `binding:"Required;MaxSize(30)"`
+	Theme string `binding:"Required;MaxSize(255)"`
 }
 
 // Validate validates the field
@@ -282,20 +281,6 @@ func (f *UpdateThemeForm) Validate(req *http.Request, errs binding.Errors) bindi
 	return middleware.Validate(errs, ctx.Data, f, ctx.Locale)
 }
 
-// IsThemeExists checks if the theme is a theme available in the config.
-func (f UpdateThemeForm) IsThemeExists() bool {
-	var exists bool
-
-	for _, v := range setting.UI.Themes {
-		if strings.EqualFold(v, f.Theme) {
-			exists = true
-			break
-		}
-	}
-
-	return exists
-}
-
 // ChangePasswordForm form for changing password
 type ChangePasswordForm struct {
 	OldPassword string `form:"old_password" binding:"MaxSize(255)"`

services/webtheme/webtheme.go

@@ -0,0 +1,69 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package webtheme
+
+import (
+	"strings"
+	"sync"
+
+	"code.gitea.io/gitea/modules/container"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/public"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+var (
+	availableThemes    []string
+	availableThemesSet container.Set[string]
+	themeOnce          sync.Once
+)
+
+func initThemes() {
+	availableThemes = nil
+	defer func() {
+		availableThemesSet = container.SetOf(availableThemes...)
+	}()
+	cssFiles, err := public.AssetFS().ListFiles("/assets/css")
+	if err != nil {
+		log.Error("Failed to list themes: %v", err)
+		availableThemes = []string{setting.UI.DefaultTheme}
+		return
+	}
+	var foundThemes []string
+	for _, name := range cssFiles {
+		name, ok := strings.CutPrefix(name, "theme-")
+		if !ok {
+			continue
+		}
+		name, ok = strings.CutSuffix(name, ".css")
+		if !ok {
+			continue
+		}
+		foundThemes = append(foundThemes, name)
+	}
+	if len(setting.UI.Themes) > 0 {
+		allowedThemes := container.SetOf(setting.UI.Themes...)
+		for _, theme := range foundThemes {
+			if allowedThemes.Contains(theme) {
+				availableThemes = append(availableThemes, theme)
+			}
+		}
+	} else {
+		availableThemes = foundThemes
+	}
+	if len(availableThemes) == 0 {
+		log.Error("No theme candidate, but gitea requires there should be at least one usable theme")
+		availableThemes = []string{setting.UI.DefaultTheme}
+	}
+}
+
+func GetAvailableThemes() []string {
+	themeOnce.Do(initThemes)
+	return availableThemes
+}
+
+func IsThemeAvailable(name string) bool {
+	themeOnce.Do(initThemes)
+	return availableThemesSet.Contains(name)
+}

templates/base/head.tmpl

@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<html lang="{{ctx.Locale.Lang}}" data-theme="{{ThemeName .SignedUser}}">
+<html lang="{{ctx.Locale.Lang}}" data-theme="{{UserThemeName .SignedUser}}">
 <head>
 	<meta name="viewport" content="width=device-width, initial-scale=1">
 	<title>{{if .Title}}{{.Title}} - {{end}}{{if .Repository.Name}}{{.Repository.Name}} - {{end}}{{AppName}}</title>

templates/base/head_style.tmpl

@@ -1,2 +1,2 @@
 <link rel="stylesheet" href="{{AssetUrlPrefix}}/css/index.css?v={{AssetVersion}}">
-<link rel="stylesheet" href="{{AssetUrlPrefix}}/css/theme-{{ThemeName .SignedUser | PathEscape}}.css?v={{AssetVersion}}">
+<link rel="stylesheet" href="{{AssetUrlPrefix}}/css/theme-{{UserThemeName .SignedUser | PathEscape}}.css?v={{AssetVersion}}">

templates/status/500.tmpl

@@ -1,12 +1,12 @@
 {{/* This page should only depend the minimal template functions/variables, to avoid triggering new panics.
-* base template functions: AppName, AssetUrlPrefix, AssetVersion, AppSubUrl, ThemeName
+* base template functions: AppName, AssetUrlPrefix, AssetVersion, AppSubUrl, UserThemeName
 * ctx.Locale
 * .Flash
 * .ErrorMsg
 * .SignedUser (optional)
 */}}
 <!DOCTYPE html>
-<html lang="{{ctx.Locale.Lang}}" data-theme="{{ThemeName .SignedUser}}">
+<html lang="{{ctx.Locale.Lang}}" data-theme="{{UserThemeName .SignedUser}}">
 <head>
 	<meta name="viewport" content="width=device-width, initial-scale=1">
 	<title>Internal Server Error - {{AppName}}</title>

web_src/css/themes/theme-gitea-dark-protanopia-deuteranopia.css

@@ -0,0 +1,11 @@
+@import "./theme-gitea-dark.css";
+
+/* red/green colorblind-friendly colors */
+/* from GitHub: --diffBlob-addition-*, --diffBlob-deletion-*, etc */
+:root {
+  --color-diff-added-word-bg: #388bfd66;
+  --color-diff-added-row-bg: #388bfd26;
+
+  --color-diff-removed-word-bg: #db6d2866;
+  --color-diff-removed-row-bg: #db6d2826;
+}

web_src/css/themes/theme-gitea-light-protanopia-deuteranopia.css

@@ -0,0 +1,11 @@
+@import "./theme-gitea-light.css";
+
+/* red/green colorblind-friendly colors */
+/* from GitHub: --diffBlob-addition-*, --diffBlob-deletion-*, etc */
+:root {
+  --color-diff-added-word-bg: #54aeff66;
+  --color-diff-added-row-bg: #ddf4ff80;
+
+  --color-diff-removed-word-bg: #ffb77c80;
+  --color-diff-removed-row-bg: #fff1e580;
+}