write basic canvas example

Author: barzamin

iui/examples/canvas.rs

@@ -0,0 +1,66 @@
+extern crate iui;
+extern crate ui_sys;
+
+use iui::controls::{
+    Area, AreaDrawParams, AreaHandler, AreaMouseEvent, HorizontalBox, LayoutStrategy,
+};
+use iui::draw::{Brush, Path, SolidBrush};
+use iui::prelude::*;
+use std::f64::consts::PI;
+use ui_sys::uiDrawFillModeWinding;
+
+struct HandleCanvas {}
+impl AreaHandler for HandleCanvas {
+    fn draw(&mut self, _area: &Area, draw_params: &AreaDrawParams) {
+        let ctx = &draw_params.context;
+
+        let path = Path::new(ctx, uiDrawFillModeWinding);
+        path.add_rectangle(ctx, 0., 0., draw_params.area_width, draw_params.area_height);
+        path.end(ctx);
+
+        let brush = Brush::Solid(SolidBrush {
+            r: 0.2,
+            g: 0.6,
+            b: 0.8,
+            a: 1.,
+        });
+
+        draw_params.context.fill(&path, &brush);
+
+        let path = Path::new(ctx, uiDrawFillModeWinding);
+        for i in 0..100 {
+            let x = i as f64 / 100.;
+            let y = ((x * PI * 2.).sin() + 1.) / 2.;
+            path.add_rectangle(
+                ctx,
+                x * draw_params.area_width,
+                0.,
+                draw_params.area_width / 100.,
+                y * draw_params.area_height,
+            );
+        }
+        path.end(ctx);
+
+        let brush = Brush::Solid(SolidBrush {
+            r: 0.2,
+            g: 0.,
+            b: 0.3,
+            a: 1.,
+        });
+
+        draw_params.context.fill(&path, &brush);
+    }
+}
+
+fn main() {
+    let ui = UI::init().expect("Couldn't initialize UI library");
+    let mut win = Window::new(&ui, "Area Canvas Example", 200, 200, WindowType::NoMenubar);
+
+    let mut hbox = HorizontalBox::new(&ui);
+    let area = Area::new(&ui, Box::new(HandleCanvas {}));
+    hbox.append(&ui, area, LayoutStrategy::Stretchy);
+
+    win.set_child(&ui, hbox);
+    win.show(&ui);
+    ui.main();
+}