Add mobile splash screen

cmd/fyne/internal/commands/data.go

@@ -9,6 +9,7 @@ type appData struct {
 	ResGoString       string
 	Release, rawIcon  bool
 	AdaptiveIcon      *metadata.AdaptiveIcon
+	Splash            *metadata.Splash
 	CustomMetadata    map[string]string
 	Migrations        map[string]bool
 	CanOpen           *metadata.CanOpen
@@ -48,6 +49,7 @@ func (a *appData) mergeMetadata(data *metadata.FyneApp) {
 		a.AppBuild = data.Details.Build
 	}
 	a.AdaptiveIcon = data.AdaptiveIcon
+	a.Splash = data.Splash
 
 	if a.Release {
 		a.appendCustomMetadata(data.Release)

cmd/fyne/internal/commands/package-mobile.go

@@ -2,18 +2,24 @@ package commands
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strconv"
+	"strings"
 
 	"fyne.io/fyne/v2"
 	"fyne.io/tools/cmd/fyne/internal/mobile"
 	"fyne.io/tools/cmd/fyne/internal/templates"
 	"fyne.io/tools/cmd/fyne/internal/util"
 )
 
+// splashIconSize is the point size of the centred launch screen icon, matching the 288dp
+// drawable size of the Android 12+ system splash so the launch looks the same on both platforms.
+const splashIconSize = 288
+
 func (p *Packager) packageAndroid(arch string, tags []string) error {
 	iconFG, iconBG, iconMono := "", "", ""
 	if p.AdaptiveIcon != nil {
@@ -23,12 +29,12 @@ func (p *Packager) packageAndroid(arch string, tags []string) error {
 	}
 
 	return mobile.RunNewBuild(arch, p.AppID, p.icon, p.Name, p.AppVersion, p.AppBuild, p.release, p.distribution,
-		"", "", tags, iconFG, iconBG, iconMono, p.verbose, p.Capabilities)
+		"", "", tags, iconFG, iconBG, iconMono, p.verbose, p.Capabilities, p.appData.Splash)
 }
 
 func (p *Packager) packageIOS(target string, tags []string) error {
 	err := mobile.RunNewBuild(target, p.AppID, p.icon, p.Name, p.AppVersion, p.AppBuild, p.release, p.distribution,
-		p.certificate, p.profile, tags, "", "", "", p.verbose, p.Capabilities)
+		p.certificate, p.profile, tags, "", "", "", p.verbose, p.Capabilities, nil)
 	if err != nil {
 		return err
 	}
@@ -60,14 +66,109 @@ func (p *Packager) packageIOS(target string, tags []string) error {
 		}
 	}
 
+	if p.appData.Splash != nil {
+		splashIcon := p.appData.Splash.Icon
+		if splashIcon == "" {
+			splashIcon = p.icon
+		}
+		if err = writeSplashIconSet(assetDir, splashIcon); err != nil {
+			return err
+		}
+	}
+
 	appDir := filepath.Join(p.dir, mobile.AppOutputName(p.os, p.Name, p.release))
 	if p.verbose {
 		fmt.Println("Creating icons for", relPath(appDir))
 	}
-
-	return runCmdCaptureOutput("xcrun", "actool", "Images.xcassets", "--compile", appDir, "--platform",
+	err = runCmdCaptureOutput("xcrun", "actool", "Images.xcassets", "--compile", appDir, "--platform",
 		"iphoneos", "--target-device", "iphone", "--minimum-deployment-target", "9.0", "--app-icon", "AppIcon",
 		"--output-format", "human-readable-text", "--output-partial-info-plist", "/dev/null")
+	if err != nil {
+		return err
+	}
+
+	if p.appData.Splash != nil {
+		if err = compileLaunchScreen(p.dir, appDir, p.appData.Splash.Background); err != nil {
+			return err
+		}
+	}
+
+	if target == "iossimulator" {
+		// The build signed the bundle before the resources above were added, and iOS ignores
+		// a launch storyboard that is not sealed by the signature, so sign it again.
+		return runCmdCaptureOutput("codesign", "--force", "--sign", "-", appDir)
+	}
+	return nil
+}
+
+// writeSplashIconSet adds the launch screen icon to the asset catalog as SplashIcon, scaled for 3x displays.
+func writeSplashIconSet(assetDir, icon string) error {
+	imageDir := util.EnsureSubDir(assetDir, "SplashIcon.imageset")
+	if err := util.WriteScaledPNG(icon, filepath.Join(imageDir, "splash.png"), splashIconSize*3); err != nil {
+		return fmt.Errorf("failed to write splash icon: %w", err)
+	}
+
+	return os.WriteFile(filepath.Join(imageDir, "Contents.json"), []byte(`{
+  "images" : [
+    {
+      "filename" : "splash.png",
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}`), 0o644)
+}
+
+// compileLaunchScreen builds the LaunchScreen storyboard named in Info.plist into the app bundle,
+// with the splash background colour and the centred SplashIcon.
+func compileLaunchScreen(dir, appDir, background string) error {
+	r, g, b, err := parseHexColor(background)
+	if err != nil {
+		return fmt.Errorf("invalid splash background colour %q: %w", background, err)
+	}
+	data := struct {
+		Red, Green, Blue float64
+		IconSize         int
+	}{Red: r, Green: g, Blue: b, IconSize: splashIconSize}
+
+	storyboard := filepath.Join(dir, "LaunchScreen.storyboard")
+	out, err := os.Create(storyboard)
+	if err != nil {
+		return err
+	}
+	defer os.Remove(storyboard)
+	err = templates.LaunchScreenIOS.Execute(out, data)
+	_ = out.Close()
+	if err != nil {
+		return fmt.Errorf("failed to write launch screen storyboard: %w", err)
+	}
+
+	return runCmdCaptureOutput("xcrun", "ibtool", "--compile", filepath.Join(appDir, "LaunchScreen.storyboardc"),
+		"--target-device", "iphone", "--minimum-deployment-target", "9.0", storyboard)
+}
+
+// parseHexColor converts a "#RRGGBB" colour into 0-1 components, defaulting to white.
+func parseHexColor(hex string) (r, g, b float64, err error) {
+	if hex == "" {
+		return 1, 1, 1, nil
+	}
+	hex = strings.TrimPrefix(hex, "#")
+	if len(hex) != 6 {
+		return 0, 0, 0, errors.New("expected #RRGGBB")
+	}
+	var channels [3]float64
+	for i := range channels {
+		v, err := strconv.ParseUint(hex[i*2:i*2+2], 16, 8)
+		if err != nil {
+			return 0, 0, 0, err
+		}
+		channels[i] = float64(v) / 255
+	}
+	return channels[0], channels[1], channels[2], nil
 }
 
 func copyResizeIcon(size int, dir, source string) error {

cmd/fyne/internal/commands/package-mobile_test.go

@@ -0,0 +1,24 @@
+package commands
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_parseHexColor(t *testing.T) {
+	r, g, b, err := parseHexColor("#015952")
+	assert.Nil(t, err)
+	assert.InDelta(t, 1.0/255, r, 0.001)
+	assert.InDelta(t, 0x59/255.0, g, 0.001)
+	assert.InDelta(t, 0x52/255.0, b, 0.001)
+
+	r, g, b, err = parseHexColor("")
+	assert.Nil(t, err)
+	assert.Equal(t, []float64{1, 1, 1}, []float64{r, g, b})
+
+	_, _, _, err = parseHexColor("#0159")
+	assert.NotNil(t, err)
+	_, _, _, err = parseHexColor("#01595z")
+	assert.NotNil(t, err)
+}

cmd/fyne/internal/commands/package-util-mock_test.go

@@ -164,6 +164,10 @@ func (m mockUtil) MakePathRelativeTo(root, path string) string {
 	return utilMakePathRelativeToMock(root, path)
 }
 
+func (m mockUtil) WriteScaledPNG(src, dst string, size int) error {
+	return nil
+}
+
 func (m mockUtil) RequireAndroidSDK() error {
 	return utilRequireAndroidSDKMock()
 }

cmd/fyne/internal/commands/package-util.go

@@ -15,6 +15,7 @@ type packagerUtil interface {
 	EnsureSubDir(parent, name string) string
 	EnsureAbsPath(path string) string
 	MakePathRelativeTo(root, path string) string
+	WriteScaledPNG(src, dst string, size int) error
 
 	RequireAndroidSDK() error
 	AndroidBuildToolsPath() string
@@ -54,6 +55,10 @@ func (d defaultUtil) MakePathRelativeTo(root, path string) string {
 	return util.MakePathRelativeTo(root, path)
 }
 
+func (d defaultUtil) WriteScaledPNG(src, dst string, size int) error {
+	return util.WriteScaledPNG(src, dst, size)
+}
+
 func (d defaultUtil) RequireAndroidSDK() error {
 	return util.RequireAndroidSDK()
 }

cmd/fyne/internal/commands/package.go

@@ -297,6 +297,9 @@ func (p *Packager) validate() (err error) {
 		if data.Details.Icon != "" {
 			data.Details.Icon = pkgUtil.MakePathRelativeTo(p.srcDir, data.Details.Icon)
 		}
+		if data.Splash != nil && data.Splash.Icon != "" {
+			data.Splash.Icon = util.MakePathRelativeTo(p.srcDir, data.Splash.Icon)
+		}
 
 		p.mergeMetadata(data)
 		p.sourceMetadata = data.Source

cmd/fyne/internal/metadata/data.go

@@ -6,6 +6,7 @@ type FyneApp struct {
 	Description  string `toml:",omitempty"`
 	Details      AppDetails
 	AdaptiveIcon *AdaptiveIcon `toml:",omitempty"`
+	Splash       *Splash       `toml:",omitempty"`
 
 	Development  map[string]string `toml:",omitempty"`
 	Release      map[string]string `toml:",omitempty"`
@@ -31,6 +32,14 @@ type AdaptiveIcon struct {
 	Monochrome string `toml:",omitempty"`
 }
 
+// Splash describes the native launch screen that iOS and Android show while the app loads.
+// Background is a hex colour such as "#015952" and Icon is an optional square PNG that will be centered.
+// The icon defaults to the adaptive icon foreground or the app icon.
+type Splash struct {
+	Background string `toml:",omitempty"`
+	Icon       string `toml:",omitempty"`
+}
+
 type AppSource struct {
 	Repo, Dir string `toml:",omitempty"`
 }

cmd/fyne/internal/metadata/load_test.go

@@ -29,6 +29,10 @@ func TestLoadAppMetadata(t *testing.T) {
 	assert.NotNil(t, data.Source)
 	assert.Equal(t, data.Source.Repo, "https://github.com/fyne-io/fyne")
 	assert.Equal(t, data.Source.Dir, "internal/metadata/testdata")
+
+	assert.NotNil(t, data.Splash)
+	assert.Equal(t, "#015952", data.Splash.Background)
+	assert.Equal(t, "assets/splash-icon.png", data.Splash.Icon)
 }
 
 func TestLoadAppMetadata_Permissions(t *testing.T) {

cmd/fyne/internal/metadata/testdata/FyneApp.toml

@@ -7,6 +7,10 @@ ID = "io.fyne.fyne"
 Version = "1.0.0"
 Build = 1
 
+[Splash]
+Background = "#015952"
+Icon = "assets/splash-icon.png"
+
 [Development]
 InDevelopmentOnly = "Value4"
 Test = "Value2"