lazy-foo: 6th tutorial

lazy-foo/Cargo.toml

@@ -6,8 +6,9 @@ edition = "2018"
 
 [dependencies]
 [dependencies.sdl2]
-features = ["ttf"]
 version="0.34.2"
+default-features = false
+features = ["image", "ttf"]
 
 [[bin]]
 name = "02_image_on_screen"
@@ -20,6 +21,11 @@ path = "src/03_event_driven.rs"
 [[bin]]
 name = "04_key_presses"
 path = "src/04_key_presses.rs"
+
 [[bin]]
 name = "05_optimized_loading_soft_stretching"
 path = "src/05_optimized_loading_soft_stretching.rs"
+
+[[bin]]
+name = "06_loading_pngs"
+path = "src/06_loading_pngs.rs"

lazy-foo/README.md

@@ -93,6 +93,30 @@ cargo run --bin 05_optimized_loading_soft_stretching
  - [SDL_BlitScaled](https://wiki.libsdl.org/SDL_BlitScaled)
  - [WindowSurfaceRef::update_window](https://rust-sdl2.github.io/rust-sdl2/sdl2/video/struct.WindowSurfaceRef.html#method.update_window)
 
+#### 06 Loading PNGs with SDL_image
+
+```sh
+cargo run --bin 06_loading_pngs
+```
+
+Note that I got this warning initially:
+> // libpng warning: iCCP: known incorrect sRGB profile
+
+which was easily fixed via: `convert loaded.png fixed.png` and using the
+ _fixed_ png instead which also turned out to be half the size.
+
+- [tutorials installation
+  instructions](http://lazyfoo.net/tutorials/SDL/06_extension_libraries_and_loading_other_image_formats/index.php)
+  - not needed if you followed the [main readme](../README.md) instructions
+- [tutorial](http://lazyfoo.net/tutorials/SDL/06_extension_libraries_and_loading_other_image_formats/index2.php)
+- [rust-sdl2 load_texture](https://rust-sdl2.github.io/rust-sdl2/sdl2/render
+/struct.TextureCreator.html#method.load_texture)
+- [rust-sdl2 image demo](https://github.com/Rust-SDL2/rust-sdl2/blob/master
+/examples/image-demo.rs)
+- [SDL2_Image docs](https://www.libsdl.org/projects/SDL_image/docs
+/SDL_image_frame.html)
+  - [`SDL_Surface *IMG_Load(const char *file)`](https://www.libsdl.org/projects/SDL_image/docs/SDL_image_frame.html)
+
 ## Related Projects
 
 - [rust-sdl2-lazyfoo](https://github.com/bombless/rust-sdl2-lazyfoo) from 2015 up to tutorial 18

lazy-foo/src/06_loading_pngs.rs

@@ -0,0 +1,71 @@
+use lazy_foo::init_renderer;
+use sdl2::event::Event;
+use sdl2::image;
+use sdl2::image::{LoadSurface, LoadTexture};
+use sdl2::pixels::PixelFormat;
+use sdl2::render::{Texture, TextureCreator};
+use sdl2::surface::Surface;
+use sdl2::video::WindowContext;
+use std::convert::TryFrom;
+use std::error::Error;
+
+// The way we've been loading images and converting to textures all along.
+// A bit more verbose than the `direct_texture_load` way, but allows converting
+// surface to PixelFormat
+fn load_image<'a>(
+    path: &str,
+    format: PixelFormat,
+    texture_creator: &'a TextureCreator<WindowContext>,
+) -> Result<Texture<'a>, Box<dyn Error>> {
+    let image_surface: Surface = LoadSurface::from_file(path)?;
+    let image_surface = image_surface.convert(&format)?;
+
+    let texture = image_surface.as_texture(texture_creator)?;
+    Ok(texture)
+}
+
+// Shortcut to load a texture used in rust-sdl2 image demo example.
+// Does not allow setting the PixelFormat.
+#[allow(dead_code)]
+fn direct_texture_load<'a>(
+    path: &str,
+    texture_creator: &'a TextureCreator<WindowContext>,
+) -> Result<Texture<'a>, String> {
+    texture_creator.load_texture(path)
+}
+
+fn main() {
+    let (sdl_context, mut canvas) =
+        init_renderer().expect("FATAL: failed to initialize window and canvas.");
+
+    let init_flags = image::InitFlag::PNG;
+    let _image_ctx = image::init(init_flags).expect("FATAL: failed to initialize sdl2:image");
+
+    let texture_creator = canvas.texture_creator();
+
+    // Alternative to the below 7 lines is to use the shortcut to load a texture:
+    // let texture = direct_texture_load("assets/06_loading_pngs/loaded.png", &texture_creator)
+    let window_pixel_format = PixelFormat::try_from(canvas.window().window_pixel_format())
+        .expect("FATAL: failed to obtain window pixel format");
+    let texture = load_image(
+        "assets/06_loading_pngs/fixed.png",
+        window_pixel_format,
+        &texture_creator,
+    )
+    .expect("FATAL: failed to load png texture");
+
+    let mut event_pump = sdl_context
+        .event_pump()
+        .expect("FATAL: failed to init event_pump");
+    'running: loop {
+        if let Some(Event::Quit { .. }) = event_pump.poll_event() {
+            break 'running;
+        }
+
+        canvas.clear();
+        canvas
+            .copy(&texture, None, None)
+            .expect("FATAL: failed to draw to canvas.");
+        canvas.present();
+    }
+}