Rust-SDL2 Transparent Background for Texture - rust

Question

Anybody have experience with https://rust-sdl2.github.io/rust-sdl2/sdl2/index.html? I can't seem to make a texture's background be transparent. My code looks something like the following:
let mut canvas = window.into_canvas().build().unwrap();
canvas.set_blend_mode(sdl2::render::BlendMode::Blend);
let texture_creator = canvas.texture_creator();
let mut texture = texture_creator.load_texture(std::path::Path::new(
"path_to_png",
))?;
texture.set_blend_mode(sdl2::render::BlendMode::Blend);
canvas.copy_ex(&texture, None, None, 0., None, false, false)?;
canvas.present();
I've tried different permutations of blendmode without success. Help.
Edit: a reproducible example
extern crate sdl2;
use sdl2::event::Event;
use sdl2::image::LoadTexture;
use sdl2::keyboard::Keycode;
use std::time::Duration;
fn main() -> Result<(), String> {
let sdl_context = sdl2::init().unwrap();
let video_subsystem = sdl_context.video().unwrap();
let window = video_subsystem
.window("rust-sdl2 demo", 800, 600)
.position_centered()
.build()
.unwrap();
let mut canvas = window.into_canvas().build().unwrap();
canvas.default_pixel_format();
canvas.set_blend_mode(sdl2::render::BlendMode::Blend);
let texture_creator = canvas.texture_creator();
texture_creator.default_pixel_format();
let mut texture = texture_creator.load_texture(std::path::Path::new(
"someimage.png",
))?;
texture.set_blend_mode(sdl2::render::BlendMode::None);
let mut event_pump = sdl_context.event_pump().unwrap();
'running: loop {
for event in event_pump.poll_iter() {
match event {
Event::KeyDown {
keycode: Some(Keycode::Escape),
..
} => break 'running,
_ => {}
}
}
canvas.clear();
canvas.copy_ex(&texture, None, None, 0., None, false, false)?;
canvas.present();
std::thread::sleep(Duration::new(0, 1_000_000_000u32 / 60));
}
Ok(())
}