From 43f14444fa6f4756aaac255e9c1b47b756d0ecd5 Mon Sep 17 00:00:00 2001
From: natrixaeria <janng@gmx.de>
Date: Thu, 30 May 2019 00:13:18 +0200
Subject: Initialise WebGl2 context

---
 WebInterface/wasm/webhogg/src/app.rs               | 11 ++++--
 WebInterface/wasm/webhogg/src/canvas.rs            | 42 ++++++++++++++++++++++
 WebInterface/wasm/webhogg/src/lib.rs               |  4 ++-
 WebInterface/wasm/webhogg/src/page.rs              | 26 ++++++++++++++
 WebInterface/wasm/webhogg/src/webhogg_exception.rs | 18 ++++++++--
 5 files changed, 96 insertions(+), 5 deletions(-)
 create mode 100644 WebInterface/wasm/webhogg/src/canvas.rs
 create mode 100644 WebInterface/wasm/webhogg/src/page.rs

diff --git a/WebInterface/wasm/webhogg/src/app.rs b/WebInterface/wasm/webhogg/src/app.rs
index bee7c08..7931418 100644
--- a/WebInterface/wasm/webhogg/src/app.rs
+++ b/WebInterface/wasm/webhogg/src/app.rs
@@ -1,15 +1,22 @@
 use crate::webhogg_exception::WebhoggException;
+use crate::page::Page;
+use crate::canvas::Canvas;
 
-pub struct WebhoggApplication {
+pub(crate) struct WebhoggApplication {
+    page: Page,
+    canvas: Canvas,
 }
 
 impl WebhoggApplication {
     pub fn new() -> Result<Self, WebhoggException> {
+        let page = Page::obtain()?;
+        let canvas = Canvas::from_existing("canvas", &page)?;
         Ok(Self {
+            page, canvas,
         })
     }
 
-    pub fn run(&mut self) -> Result<(), WebhoggException> {
+    pub fn run(self) -> Result<(), WebhoggException> {
         Ok(())
     }
 }
diff --git a/WebInterface/wasm/webhogg/src/canvas.rs b/WebInterface/wasm/webhogg/src/canvas.rs
new file mode 100644
index 0000000..a0ef7d1
--- /dev/null
+++ b/WebInterface/wasm/webhogg/src/canvas.rs
@@ -0,0 +1,42 @@
+use web_sys::WebGl2RenderingContext as WebGl2;
+use wasm_bindgen::JsCast;
+use crate::webhogg_exception::WebhoggException;
+use crate::page::Page;
+
+pub struct Canvas {
+    ctx: WebGl2,
+}
+
+impl Canvas {
+    pub fn from_existing(id: &str, page: &Page) -> Result<Self, WebhoggException> {
+        let canvas_element = page.get_element(id)
+            .ok_or(WebhoggException::DomError(
+                    "could not obtain canvas element (id=canvas)"
+                    .to_string()))?;
+        let canvas_element = canvas_element
+            .dyn_into::<web_sys::HtmlCanvasElement>()
+            .map_err(|_| WebhoggException::DomError(
+                    "id=canvas is not a canvas element".to_string()))?;
+        debug!("successfully obtained canvas element");
+        let ctx = canvas_element.get_context("webgl2")
+            .map_err(|_| WebhoggException::WebGlContextError(
+                    "obtained invalid webgl2 context js value".to_string()))?
+            .ok_or(WebhoggException::WebGlContextError(
+                    "could not obtaine webgl2 context".to_string()))?
+            .dyn_into::<WebGl2>()
+            .map_err(|_| WebhoggException::WebGlContextError(
+                    "obtained invalid webgl2 context js object".to_string()))?;
+        debug!("successfully obtained webgl2 context");
+        Ok(Self {
+            ctx,
+        })
+    }
+
+    pub fn gl<'a>(&'a self) -> &'a WebGl2 {
+        &self.ctx
+    }
+
+    pub fn gl_mut<'a>(&'a mut self) -> &'a mut WebGl2 {
+        &mut self.ctx
+    }
+}
diff --git a/WebInterface/wasm/webhogg/src/lib.rs b/WebInterface/wasm/webhogg/src/lib.rs
index 8b75ee1..81a3237 100644
--- a/WebInterface/wasm/webhogg/src/lib.rs
+++ b/WebInterface/wasm/webhogg/src/lib.rs
@@ -1,5 +1,7 @@
 mod client_logger;
 mod webhogg_exception;
+mod page;
+mod canvas;
 mod app;
 
 use wasm_bindgen::prelude::*;
@@ -9,7 +11,7 @@ use app::WebhoggApplication as App;
 extern crate log;
 
 fn run_application() {
-    match App::new().and_then(|mut app| app.run()) {
+    match App::new().and_then(|app| app.run()) {
         Ok(_) => info!("program terminated successfully"),
         Err(e) => error!("program terminated with failure > {}", e)
     }
diff --git a/WebInterface/wasm/webhogg/src/page.rs b/WebInterface/wasm/webhogg/src/page.rs
new file mode 100644
index 0000000..cb9ee3f
--- /dev/null
+++ b/WebInterface/wasm/webhogg/src/page.rs
@@ -0,0 +1,26 @@
+use web_sys;
+
+use crate::webhogg_exception::WebhoggException;
+
+pub struct Page {
+    window: web_sys::Window,
+    document: web_sys::Document,
+}
+
+impl Page {
+    pub fn obtain() -> Result<Self, WebhoggException> {
+        let window = web_sys::window()
+            .ok_or(WebhoggException::DomError("could not obtain window".to_string()))?;
+        let document = window.document()
+            .ok_or(WebhoggException::DomError("could not obtain document".to_string()))?;
+        debug!("initialised page");
+        Ok(Self {
+            window,
+            document,
+        })
+    }
+
+    pub fn get_element(&self, id: &str) -> Option<web_sys::Element> {
+        self.document.get_element_by_id(id)
+    }
+}
diff --git a/WebInterface/wasm/webhogg/src/webhogg_exception.rs b/WebInterface/wasm/webhogg/src/webhogg_exception.rs
index eac67c7..46eedd6 100644
--- a/WebInterface/wasm/webhogg/src/webhogg_exception.rs
+++ b/WebInterface/wasm/webhogg/src/webhogg_exception.rs
@@ -2,11 +2,25 @@ use std::error::Error;
 
 #[derive(Debug)]
 pub enum WebhoggException {
+    DomError(String),
+    WebGlContextError(String),
+}
+
+impl WebhoggException {
+    fn err_name(&self) -> &str {
+        match self {
+            WebhoggException::DomError(_) => "DomError",
+            WebhoggException::WebGlContextError(_) => "WebGlContextError",
+        }
+    }
 }
 
 impl Error for WebhoggException {
     fn description(&self) -> &str {
-        "webhogg exception"
+        match self {
+            WebhoggException::DomError(desc) => desc,
+            WebhoggException::WebGlContextError(desc) => desc,
+        }
     }
 
     fn cause(&self) -> Option<&dyn Error> {
@@ -20,6 +34,6 @@ impl Error for WebhoggException {
 
 impl std::fmt::Display for WebhoggException {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        write!(f, "WebhoggException: {}", self.description())
+        write!(f, "WebhoggException::{} {}", self.err_name(), self.description())
     }
 }
-- 
cgit v1.2.3-54-g00ecf