Exercise: an image viewer

This exercise aims at allowing you to put together all the things we have seen in this introduction to SCTK. The goal is to write an app that loads an image from disk and displays it as the only content of its window. It should react to resizing by stretching the image so that it fills the size given to the window.

Using the image crate

Manipulating images is not the main goal of this exercise, so you can just use the image crate to do it for you. In particular:

• image::open can load an image file from disk
• image::imageops::resize can be used to resize the image accordingly

General advice

To organize your program, you'll probably find it useful to split the actual drawing code into its own function, taking as argument the &mut MemPool to use, the &WlSurface to which commit the buffer, the requested dimensions, and the image.

The xdg_shell global, used by Window, requires you to wait until you have received at least one Configure event before drawing your content. Committing a buffer before you've received it will be considered as a protocol error by the server, which will cause it to kill your connection.

Be careful about the pixel format, image provides you with the pixels in RGBA format, but the Wayland server will expect them as ARGB.

Solution

A solution to this exercise with detailed comments can be found as the image_viewer.rs example of SCTK.