Upgrade Blitz to 0.1.0-alpha.3 and add wgpu-texture example (#4286)

* Use Blitz 0.1.0-alpha.3

* Add wgpu-texture example

* Native: Support configuring wgpu Features and Limits

examples/wgpu-texture/src/demo_renderer.rs

@@ -0,0 +1,254 @@
+// Copyright © SixtyFPS GmbH <info@slint.dev>
+// SPDX-License-Identifier: MIT
+use crate::Color;
+use dioxus_native::{CustomPaintCtx, CustomPaintSource, TextureHandle};
+use std::sync::mpsc::{channel, Receiver, Sender};
+use std::time::Instant;
+use wgpu::{Device, Queue};
+
+pub struct DemoPaintSource {
+    state: DemoRendererState,
+    start_time: std::time::Instant,
+    tx: Sender<DemoMessage>,
+    rx: Receiver<DemoMessage>,
+    color: Color,
+}
+
+impl CustomPaintSource for DemoPaintSource {
+    fn resume(&mut self, device: &Device, queue: &Queue) {
+        // TODO: work out what to do about width/height
+        let active_state = ActiveDemoRenderer::new(device, queue);
+        self.state = DemoRendererState::Active(Box::new(active_state));
+    }
+
+    fn suspend(&mut self) {
+        self.state = DemoRendererState::Suspended;
+    }
+
+    fn render(
+        &mut self,
+        ctx: CustomPaintCtx<'_>,
+        width: u32,
+        height: u32,
+        _scale: f64,
+    ) -> Option<TextureHandle> {
+        self.process_messages();
+        self.render(ctx, width, height)
+    }
+}
+
+pub enum DemoMessage {
+    // Color in RGB format
+    SetColor(Color),
+}
+
+enum DemoRendererState {
+    Active(Box<ActiveDemoRenderer>),
+    Suspended,
+}
+
+#[derive(Clone)]
+struct TextureAndHandle {
+    texture: wgpu::Texture,
+    handle: TextureHandle,
+}
+
+struct ActiveDemoRenderer {
+    device: wgpu::Device,
+    queue: wgpu::Queue,
+    pipeline: wgpu::RenderPipeline,
+    displayed_texture: Option<TextureAndHandle>,
+    next_texture: Option<TextureAndHandle>,
+}
+
+impl DemoPaintSource {
+    pub fn new() -> Self {
+        let (tx, rx) = channel();
+        Self::with_channel(tx, rx)
+    }
+
+    pub fn with_channel(tx: Sender<DemoMessage>, rx: Receiver<DemoMessage>) -> Self {
+        Self {
+            state: DemoRendererState::Suspended,
+            start_time: std::time::Instant::now(),
+            tx,
+            rx,
+            color: Color::WHITE,
+        }
+    }
+
+    pub fn sender(&self) -> Sender<DemoMessage> {
+        self.tx.clone()
+    }
+
+    fn process_messages(&mut self) {
+        loop {
+            match self.rx.try_recv() {
+                Err(_) => return,
+                Ok(msg) => match msg {
+                    DemoMessage::SetColor(color) => self.color = color,
+                },
+            }
+        }
+    }
+
+    fn render(
+        &mut self,
+        ctx: CustomPaintCtx<'_>,
+        width: u32,
+        height: u32,
+    ) -> Option<TextureHandle> {
+        if width == 0 || height == 0 {
+            return None;
+        }
+        let DemoRendererState::Active(state) = &mut self.state else {
+            return None;
+        };
+
+        state.render(ctx, self.color.components, width, height, &self.start_time)
+    }
+}
+
+impl ActiveDemoRenderer {
+    pub(crate) fn new(device: &Device, queue: &Queue) -> Self {
+        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+            label: None,
+            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(include_str!(
+                "shader.wgsl"
+            ))),
+        });
+
+        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+            label: None,
+            bind_group_layouts: &[],
+            push_constant_ranges: &[wgpu::PushConstantRange {
+                stages: wgpu::ShaderStages::FRAGMENT,
+                range: 0..16, // full size in bytes, aligned
+            }],
+        });
+
+        let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+            label: None,
+            layout: Some(&pipeline_layout),
+            vertex: wgpu::VertexState {
+                module: &shader,
+                entry_point: Some("vs_main"),
+                buffers: &[],
+                compilation_options: Default::default(),
+            },
+            fragment: Some(wgpu::FragmentState {
+                module: &shader,
+                entry_point: Some("fs_main"),
+                compilation_options: Default::default(),
+                targets: &[Some(wgpu::TextureFormat::Rgba8Unorm.into())],
+            }),
+            primitive: wgpu::PrimitiveState::default(),
+            depth_stencil: None,
+            multisample: wgpu::MultisampleState::default(),
+            multiview: None,
+            cache: None,
+        });
+
+        Self {
+            device: device.clone(),
+            queue: queue.clone(),
+            pipeline,
+            displayed_texture: None,
+            next_texture: None,
+        }
+    }
+
+    pub(crate) fn render(
+        &mut self,
+        mut ctx: CustomPaintCtx<'_>,
+        light: [f32; 3],
+        width: u32,
+        height: u32,
+        start_time: &Instant,
+    ) -> Option<TextureHandle> {
+        // If "next texture" size doesn't match specified size then unregister and drop texture
+        if let Some(next) = &self.next_texture {
+            if next.texture.width() != width || next.texture.height() != height {
+                ctx.unregister_texture(next.handle);
+                self.next_texture = None;
+            }
+        }
+
+        // If there is no "next texture" then create one and register it.
+        let texture_and_handle = match &self.next_texture {
+            Some(next) => next,
+            None => {
+                let texture = create_texture(&self.device, width, height);
+                let handle = ctx.register_texture(texture.clone());
+                self.next_texture = Some(TextureAndHandle { texture, handle });
+                self.next_texture.as_ref().unwrap()
+            }
+        };
+
+        let next_texture = &texture_and_handle.texture;
+        let next_texture_handle = texture_and_handle.handle;
+
+        let elapsed: f32 = start_time.elapsed().as_millis() as f32 / 500.;
+        let [light_red, light_green, light_blue] = light;
+        let push_constants = PushConstants {
+            light_color_and_time: [light_red, light_green, light_blue, elapsed],
+        };
+
+        let mut encoder = self
+            .device
+            .create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
+        {
+            let mut rpass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+                label: None,
+                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                    view: &next_texture.create_view(&wgpu::TextureViewDescriptor::default()),
+                    resolve_target: None,
+                    ops: wgpu::Operations {
+                        load: wgpu::LoadOp::Clear(wgpu::Color::GREEN),
+                        store: wgpu::StoreOp::Store,
+                    },
+                })],
+                depth_stencil_attachment: None,
+                timestamp_writes: None,
+                occlusion_query_set: None,
+            });
+            rpass.set_pipeline(&self.pipeline);
+            rpass.set_push_constants(
+                wgpu::ShaderStages::FRAGMENT, // Stage (your constants are for fragment shader)
+                0,                            // Offset in bytes (start at 0)
+                bytemuck::bytes_of(&push_constants),
+            );
+            rpass.draw(0..3, 0..1);
+        }
+
+        self.queue.submit(Some(encoder.finish()));
+
+        std::mem::swap(&mut self.next_texture, &mut self.displayed_texture);
+        Some(next_texture_handle)
+    }
+}
+
+#[repr(C)]
+#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
+struct PushConstants {
+    light_color_and_time: [f32; 4],
+}
+
+fn create_texture(device: &wgpu::Device, width: u32, height: u32) -> wgpu::Texture {
+    device.create_texture(&wgpu::TextureDescriptor {
+        label: None,
+        size: wgpu::Extent3d {
+            width,
+            height,
+            depth_or_array_layers: 1,
+        },
+        mip_level_count: 1,
+        sample_count: 1,
+        dimension: wgpu::TextureDimension::D2,
+        format: wgpu::TextureFormat::Rgba8Unorm,
+        usage: wgpu::TextureUsages::RENDER_ATTACHMENT
+            | wgpu::TextureUsages::TEXTURE_BINDING
+            | wgpu::TextureUsages::COPY_SRC,
+        view_formats: &[],
+    })
+}