File Loading

Introduction

A typical Gum project references many file types. Aside from the XML files created by the Gum tool (such as a .gumx file), a Gum project also references .png files and .fnt files.

Files referenced by your Gum project (as created in the Gum UI tool) automatically load their necessary dependencies assuming the files are part of the built file system. Usually your project game project should copy all Gum XML, PNG, and FNT files to the output folder. Gum does not use the MonoGame content pipeline.

Files in Gum Projects

When a file is added to a Gum project, the Gum UI tool checks the location of the file. If the file is not relative to the Gum project file (.gumx), the Gum UI tool warns you about the file being located outside of the project's folder. The tool recommends that the file should be copied so that your project remains portable.

If all of your project files are located relative to the .gumx root project file, then your project should be portable, and all referenced files will be automatically resolved for you when instantiating Screens and Components from your Gum project.

The Gum runtime library performs all of its loading from-file, so all of your files must be present in the destination directory. As explained in the Loading .gumx page, all of your files should be set to Copy if newer in Visual Studio.

Loading Files Through Runtime Objects

Gum runtime objects can reference files. For example both SpriteRuntime and NineSliceRuntime can reference a Texture2D. Similarly, the TextRuntime type can reference BitmapFonts which are loaded from .fnt and .png files.

All runtime types support the assignment of these files by direct assignment of their appropriate type, or by string name.

For example, a Sprite's texture could be assigned either through the SourceFileName property or the Texture property:

SpriteRuntimeInstance.SourceFile = "bear.png";
// or
SpriteRuntimeInstance.Texture = MyTexture;

In the case of the SourceFile assignment, the SpriteRuntime loads the Texture2D from disk. By default the file is loaded relative to the Content folder.

Example - Loading a Font File

You can explicitly load font files if you would like to change fonts in custom code, or if you are using the GumBatch class to do your own Gum rendering.

To load a file, first make sure that your font is added to Visual Studio, usually in the Content folder. In the case of fonts, you should have at least 2 files:

1. A .png file

2. A .fnt file

Usually both files are added to the same directory. Be sure to mark both files as Copy if Newer.

The file can be loaded using the BitmapFont constructor:

// RelativeDirectory defaults to "Content/" so we leave that off
var bitmapFont = new BitmapFont("Fonts/Font18Arial.fnt", SystemManagers.Default);

Setting FileManager.RelativeDirectory

Whenever a file is assigned on a runtime object, Gum looks for the file in the ToolsUtilities.FileManager.RelativeDirectory directory. This directory defaults to your game's Content folder.

If you call GumService.Default.Initialize and pass a .gumx file, then RelativeDirectory is set to the directory containing the Gum project.

If your Gum project (.gumx) is located in the Content folder, RelativeDirectory is set to "Content/".

If your project is located in a subfolder of Content, then RelativeDirectory is set to the folder containing the Gum project. In this case, RelativeDirectory would be set to "Content/gum/"

RelativeDirectory is used whenever files are loaded. These operations include:

• Calling ToGraphicalUiElement

• Assigning SourceFileName

• Setting custom or cached fonts on a Text object

• Setting states (which may assign variables)

It's recommended practice to set the RelativeDirectory to your Gum project's location and to leave it there so you never have to consider subfolders in any code that accesses files directly or indirectly.

File Caching

By default Gum caches loaded textures. In other words, the following code only results in a single file IO operation:

Sprite1.SourceFile = "MyFile.png";
Sprite2.SourceFile = "MyFile.png";

File caching can be disabled by setting the LoaderManager's CacheTextures property to false as shown in the following code:

LoaderManager.Self.CacheTextures = false;

Of course, doing so means that Gum will go to disk for every file which can increase load times and result in significantly more video memory usage.

Note that setting CacheTextures to false flushes the cache and disposes all cached content, so you can force the reload of all files by calling setting CacheTextures to false, then back to true as shown in the following code:

Sprite1.SourceFile = "MyFile.png"; // This loads the file from disk
Sprite2.SourceFile = "MyFile.png"; // This uses the cached Texture2D

LoaderManager.Self.CacheTextures = false; // This clears the cache:
LoaderManager.Self.CacheTextures = true;
Sprite1.SourceFile = "MyFile.png"; // This once-again goes to disk to load the file
Sprite2.SourceFile = "MyFile.png"; // This uses the cached Texture2D 

LoaderManager.Self.CacheTextures = false; // This clears the cache
Sprite1.SourceFile = "MyFile.png"; // This once-again goes to disk to load the file
Sprite2.SourceFile = "MyFile.png"; // This also goes to disk to load the file

Be careful setting CacheTextures to false since all existing textures will be disposed. This means that if you have loaded textures which are still being referenced by runtime objects, you will get an exception if those are still being drawn after setting CacheTextures to false.