Use write_buffer_with for buffer uploads

examples/hello-world.rs

@@ -2,6 +2,7 @@ use glyphon::{
     Attrs, Buffer, Cache, Color, Family, FontSystem, Metrics, Resolution, Shaping, SwashCache,
     TextArea, TextAtlas, TextBounds, TextRenderer, Viewport,
 };
+use std::sync::Arc;
 use wgpu::{
     CommandEncoderDescriptor, CompositeAlphaMode, DeviceDescriptor, Features, Instance,
     InstanceDescriptor, Limits, LoadOp, MultisampleState, Operations, PresentMode,
@@ -15,8 +16,6 @@ use winit::{
     window::WindowBuilder,
 };
 
-use std::sync::Arc;
-
 fn main() {
     pollster::block_on(run());
 }

src/lib.rs

@@ -10,6 +10,8 @@ mod text_atlas;
 mod text_render;
 mod viewport;
 
+use std::{mem, num::NonZeroU64};
+
 pub use cache::Cache;
 pub use error::{PrepareError, RenderError};
 pub use text_atlas::{ColorMode, TextAtlas};
@@ -76,6 +78,10 @@ pub(crate) struct Params {
     _pad: [u32; 2],
 }
 
+pub(crate) const PARAMS_LEN: usize = mem::size_of::<Params>();
+pub(crate) const PARAMS_LEN_NONZERO: NonZeroU64 =
+    unsafe { NonZeroU64::new_unchecked(PARAMS_LEN as u64) };
+
 /// Controls the visible area of the text. Any text outside of the visible area will be clipped.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct TextBounds {

src/text_render.rs

@@ -2,7 +2,7 @@ use crate::{
     ColorMode, FontSystem, GlyphDetails, GlyphToRender, GpuCacheStatus, PrepareError, RenderError,
     SwashCache, SwashContent, TextArea, TextAtlas, Viewport,
 };
-use std::{slice, sync::Arc};
+use std::{num::NonZeroU64, slice, sync::Arc};
 use wgpu::{
     Buffer, BufferDescriptor, BufferUsages, DepthStencilState, Device, Extent3d, ImageCopyTexture,
     ImageDataLayout, MultisampleState, Origin3d, Queue, RenderPass, RenderPipeline, TextureAspect,
@@ -269,9 +269,16 @@ impl TextRenderer {
                 std::mem::size_of_val(vertices),
             )
         };
-
-        if self.vertex_buffer_size >= vertices_raw.len() as u64 {
-            queue.write_buffer(&self.vertex_buffer, 0, vertices_raw);
+        let vertices_size = vertices_raw.len() as u64;
+
+        if self.vertex_buffer_size >= vertices_size {
+            if let Some(mut view) = queue.write_buffer_with(
+                &self.vertex_buffer,
+                0,
+                NonZeroU64::new(vertices_size).expect("buffer size of 0"),
+            ) {
+                view.copy_from_slice(vertices_raw);
+            }
         } else {
             self.vertex_buffer.destroy();
 

src/viewport.rs

@@ -1,10 +1,7 @@
-use crate::{Cache, Params, Resolution};
-
+use crate::{Cache, Params, Resolution, PARAMS_LEN, PARAMS_LEN_NONZERO};
+use std::{mem, slice};
 use wgpu::{BindGroup, Buffer, BufferDescriptor, BufferUsages, Device, Queue};
 
-use std::mem;
-use std::slice;
-
 #[derive(Debug)]
 pub struct Viewport {
     params: Params,
@@ -39,15 +36,19 @@ impl Viewport {
     }
 
     pub fn update(&mut self, queue: &Queue, resolution: Resolution) {
-        if self.params.screen_resolution != resolution {
-            self.params.screen_resolution = resolution;
-
-            queue.write_buffer(&self.params_buffer, 0, unsafe {
-                slice::from_raw_parts(
-                    &self.params as *const Params as *const u8,
-                    mem::size_of::<Params>(),
-                )
-            });
+        if self.params.screen_resolution == resolution {
+            return;
+        }
+
+        self.params.screen_resolution = resolution;
+
+        if let Some(mut view) = queue.write_buffer_with(&self.params_buffer, 0, PARAMS_LEN_NONZERO)
+        {
+            let params_raw = unsafe {
+                slice::from_raw_parts(&self.params as *const Params as *const u8, PARAMS_LEN)
+            };
+
+            view.copy_from_slice(params_raw);
         }
     }