feat(zoom): add FitToWidthZoom mode

BREAKING CHANGE: ZoomMode config key type got changed, the program will
not start with an old config file

config.go

@@ -36,7 +36,7 @@ const (
 )
 
 type Config struct {
-	ZoomMode             string
+	ZoomMode             ZoomMode
 	Enlarge              bool
 	Shrink               bool
 	LastDirectory        string
@@ -95,7 +95,7 @@ func (app *App) saveConfig() {
 }
 
 func (c *Config) setDefaults() {
-	c.ZoomMode = "FitToWidth"
+	c.ZoomMode = FitToWidth
 	c.Shrink = true
 	c.Enlarge = true
 	c.WindowWidth = 640
@@ -152,17 +152,29 @@ func (c *Config) save(path string) error {
 	return err
 }
 
-func (app *App) setZoomMode(mode string) {
+type ZoomMode int
+
+const (
+	FitToWidth ZoomMode = iota
+	FitToHalfWidth
+	FitToHeight
+	BestFit
+	Original
+)
+
+func (app *App) setZoomMode(mode ZoomMode) {
 	switch mode {
-	case "FitToWidth":
+	case FitToWidth:
 		app.W.MenuItemFitToWidth.SetActive(true)
-	case "FitToHeight":
+	case FitToHalfWidth:
+		app.W.MenuItemFitToHalfWidth.SetActive(true)
+	case FitToHeight:
 		app.W.MenuItemFitToHeight.SetActive(true)
-	case "BestFit":
+	case BestFit:
 		app.W.MenuItemBestFit.SetActive(true)
 	default:
 		app.W.MenuItemOriginal.SetActive(true)
-		mode = "Original"
+		mode = Original
 	}
 
 	app.Config.ZoomMode = mode

gomicsv.ui

@@ -217,6 +217,16 @@
                             <property name="group">MenuItemBestFit</property>
                           </object>
                         </child>
+                        <child>
+                          <object class="GtkRadioMenuItem" id="MenuItemFitToHalfWidth">
+                            <property name="visible">true</property>
+                            <property name="can-focus">false</property>
+                            <property name="label" translatable="yes">Fit to half-width</property>
+                            <property name="use-underline">true</property>
+                            <property name="draw-as-radio">true</property>
+                            <property name="group">MenuItemBestFit</property>
+                          </object>
+                        </child>
                         <child>
                           <object class="GtkRadioMenuItem" id="MenuItemFitToHeight">
                             <property name="visible">true</property>

image.go

@@ -117,14 +117,19 @@ func (app *App) getScaledSize() (scale float64) {
 
 	w, h := app.pixbufSize()
 	switch app.Config.ZoomMode {
-	case "FitToWidth":
+	case FitToWidth:
 		needscale := (app.Config.Enlarge && w < scrw) || (app.Config.Shrink && w > scrw)
 		if needscale {
 			return float64(scrw) / float64(w)
 		}
-	case "FitToHeight":
+	case FitToHalfWidth:
+		needscale := (app.Config.Enlarge && w/2 < scrw) || (app.Config.Shrink && w/2 > scrw)
+		if needscale {
+			return float64(scrw) / float64(w/2)
+		}
+	case FitToHeight:
 		return float64(scrh) / float64(h)
-	case "BestFit":
+	case BestFit:
 		needscale := (app.Config.Enlarge && (w < scrw && h < scrh)) || (app.Config.Shrink && (w > scrw || h > scrh))
 		if needscale {
 			fw, _ := util.Fit(w, h, scrw, scrh)

menu.go

@@ -89,25 +89,31 @@ func (app *App) menuInit() {
 
 	app.W.MenuItemOriginal.Connect("toggled", func() {
 		if app.W.MenuItemOriginal.GetActive() {
-			app.setZoomMode("Original")
+			app.setZoomMode(Original)
 		}
 	})
 
 	app.W.MenuItemBestFit.Connect("toggled", func() {
 		if app.W.MenuItemBestFit.GetActive() {
-			app.setZoomMode("BestFit")
+			app.setZoomMode(BestFit)
 		}
 	})
 
 	app.W.MenuItemFitToWidth.Connect("toggled", func() {
 		if app.W.MenuItemFitToWidth.GetActive() {
-			app.setZoomMode("FitToWidth")
+			app.setZoomMode(FitToWidth)
+		}
+	})
+
+	app.W.MenuItemFitToHalfWidth.Connect("toggled", func() {
+		if app.W.MenuItemFitToHalfWidth.GetActive() {
+			app.setZoomMode(FitToHalfWidth)
 		}
 	})
 
 	app.W.MenuItemFitToHeight.Connect("toggled", func() {
 		if app.W.MenuItemFitToHeight.GetActive() {
-			app.setZoomMode("FitToHeight")
+			app.setZoomMode(FitToHeight)
 		}
 	})
 
@@ -290,6 +296,7 @@ func (app *App) menuSetupAccels() {
 				{&app.W.MenuItemBestFit.MenuItem, Accel{gdk.KEY_B, 0}},
 				{&app.W.MenuItemOriginal.MenuItem, Accel{gdk.KEY_O, 0}},
 				{&app.W.MenuItemFitToWidth.MenuItem, Accel{gdk.KEY_W, 0}},
+				{&app.W.MenuItemFitToHalfWidth.MenuItem, Accel{gdk.KEY_W, gdk.MOD1_MASK}},
 				{&app.W.MenuItemFitToHeight.MenuItem, Accel{gdk.KEY_H, 0}},
 				{&app.W.MenuItemFullscreen.MenuItem, Accel{gdk.KEY_F, 0}},
 				{&app.W.MenuItemRandom.MenuItem, Accel{gdk.KEY_R, 0}},

ui.go

@@ -92,11 +92,13 @@ func (app *App) syncWidgetsToConfig() {
 	app.W.MenuItemMangaMode.SetActive(app.Config.MangaMode)
 
 	switch app.Config.ZoomMode {
-	case "FitToWidth":
+	case FitToWidth:
 		app.W.MenuItemFitToWidth.SetActive(true)
-	case "FitToHeight":
+	case FitToHalfWidth:
+		app.W.MenuItemFitToHalfWidth.SetActive(true)
+	case FitToHeight:
 		app.W.MenuItemFitToHeight.SetActive(true)
-	case "BestFit":
+	case BestFit:
 		app.W.MenuItemBestFit.SetActive(true)
 	default:
 		app.W.MenuItemOriginal.SetActive(true)

widgets.go

@@ -89,6 +89,7 @@ type Widgets struct {
 	MenuItemBestFit                    *gtk.RadioMenuItem     `build:"MenuItemBestFit"`
 	MenuItemOriginal                   *gtk.RadioMenuItem     `build:"MenuItemOriginal"`
 	MenuItemFitToWidth                 *gtk.RadioMenuItem     `build:"MenuItemFitToWidth"`
+	MenuItemFitToHalfWidth             *gtk.RadioMenuItem     `build:"MenuItemFitToHalfWidth"`
 	MenuItemFitToHeight                *gtk.RadioMenuItem     `build:"MenuItemFitToHeight"`
 	MenuItemAbout                      *gtk.MenuItem          `build:"MenuItemAbout"`
 	GoToThumbnailImage                 *gtk.Image             `build:"GoToThumbnailImage"`