Add missing language strings in sprite properties & import sprite sheet

data/strings/en.ini

@@ -905,6 +905,10 @@ new_version_available = New {0} v{1} available!
 [import_sprite_sheet]
 title = Import Sprite Sheet
 type = Type:
+type_horz = Horizontal Strip
+type_vert = Vertical Strip
+type_rows = By Rows
+type_cols = By Columns
 tiles = Tiles:
 x = X:
 y = Y:
@@ -914,6 +918,7 @@ padding = Padding
 horizontal_padding = Horizontal:
 vertical_padding = Vertical:
 partial_tiles = Include partial tiles at bottom/right edges
+context_bar_help = Select bounds to identify sprite frames
 import = &Import
 cancel = &Cancel
 
@@ -1762,6 +1767,14 @@ double_high = Double-high Pixels (1:2)
 color_profile = Color Profile:
 assign_color_profile = Assign
 convert_color_profile = Convert
+rgb = RGB
+grayscale = Grayscale
+indexed_color = Indexed ({0} colors)
+unknown = Unknown
+indexed_image_only = (only for indexed images)
+assign_color_profile = Assign Color Profile
+convert_color_profile = Convert Color Profile
+change_sprite_props = Change Sprite Properties
 
 [sprite_size]
 title = Sprite Size

src/app/commands/cmd_import_sprite_sheet.cpp

@@ -70,10 +70,10 @@ public:
       (int)app::SpriteSheetType::Columns == 4,
       "SpriteSheetType enum changed");
 
-    sheetType()->addItem("Horizontal Strip");
-    sheetType()->addItem("Vertical Strip");
-    sheetType()->addItem("By Rows");
-    sheetType()->addItem("By Columns");
+    sheetType()->addItem(Strings::import_sprite_sheet_type_horz());
+    sheetType()->addItem(Strings::import_sprite_sheet_type_vert());
+    sheetType()->addItem(Strings::import_sprite_sheet_type_rows());
+    sheetType()->addItem(Strings::import_sprite_sheet_type_cols());
     sheetType()->setSelectedItemIndex((int)app::SpriteSheetType::Rows-1);
 
     sheetType()->Change.connect([this]{ onSheetTypeChange(); });
@@ -251,7 +251,7 @@ protected:
   }
 
   std::string onGetContextBarHelp() override {
-    return "Select bounds to identify sprite frames";
+    return Strings::import_sprite_sheet_context_bar_help();
   }
 
 private:
@@ -513,7 +513,8 @@ void ImportSpriteSheetCommand::onExecute(Context* context)
     // The following steps modify the sprite, so we wrap all
     // operations in a undo-transaction.
     ContextWriter writer(context);
-    Tx tx(writer.context(), "Import Sprite Sheet", ModifyDocument);
+    Tx tx(
+      writer.context(), Strings::import_sprite_sheet_title(), ModifyDocument);
     DocApi api = document->getApi(tx);
 
     // Add the layer in the sprite.

src/app/commands/cmd_sprite_properties.cpp

@@ -122,18 +122,18 @@ void SpritePropertiesCommand::onExecute(Context* context)
     // Update widgets values
     switch (sprite->pixelFormat()) {
       case IMAGE_RGB:
-        imgtype_text = "RGB";
+        imgtype_text = Strings::sprite_properties_rgb();
         break;
       case IMAGE_GRAYSCALE:
-        imgtype_text = "Grayscale";
+        imgtype_text = Strings::sprite_properties_grayscale();
         break;
       case IMAGE_INDEXED:
-        imgtype_text = fmt::format("Indexed ({0} colors)",
+        imgtype_text = fmt::format(Strings::sprite_properties_indexed_color(),
                                    sprite->palette(0)->size());
         break;
       default:
         ASSERT(false);
-        imgtype_text = "Unknown";
+        imgtype_text = Strings::sprite_properties_unknown();
         break;
     }
 
@@ -169,7 +169,8 @@ void SpritePropertiesCommand::onExecute(Context* context)
         LEFT);
     }
     else {
-      window.transparentColorPlaceholder()->addChild(new Label("(only for indexed images)"));
+      window.transparentColorPlaceholder()->addChild(
+        new Label(Strings::sprite_properties_indexed_image_only()));
     }
 
     // Pixel ratio
@@ -205,7 +206,7 @@ void SpritePropertiesCommand::onExecute(Context* context)
 
         ContextWriter writer(context);
         Sprite* sprite(writer.sprite());
-        Tx tx(writer.context(), "Assign Color Profile");
+        Tx tx(writer.context(), Strings::sprite_properties_assign_color_profile());
         tx(new cmd::AssignColorProfile(
              sprite, colorSpaces[selectedColorProfile]->gfxColorSpace()));
         tx.commit();
@@ -218,7 +219,7 @@ void SpritePropertiesCommand::onExecute(Context* context)
 
         ContextWriter writer(context);
         Sprite* sprite(writer.sprite());
-        Tx tx(writer.context(), "Convert Color Profile");
+        Tx tx(writer.context(), Strings::sprite_properties_convert_color_profile());
         tx(new cmd::ConvertColorProfile(
              sprite, colorSpaces[selectedColorProfile]->gfxColorSpace()));
         tx.commit();
@@ -248,7 +249,7 @@ void SpritePropertiesCommand::onExecute(Context* context)
     if (index != sprite->transparentColor() ||
         pixelRatio != sprite->pixelRatio() ||
         newUserData != sprite->userData()) {
-      Tx tx(writer.context(), "Change Sprite Properties");
+      Tx tx(writer.context(), Strings::sprite_properties_change_sprite_props());
       DocApi api = writer.document()->getApi(tx);
 
       if (index != sprite->transparentColor())