api and doc stuff, add bg image prop to container

hui/src/draw.rs

@@ -9,7 +9,7 @@ use crate::{
 
 pub(crate) mod atlas;
 use atlas::TextureAtlasManager;
-pub use atlas::{TextureHandle, TextureAtlasMeta};
+pub use atlas::{TextureHandle, TextureAtlasMeta, TextureFormat};
 
 mod corner_radius;
 pub use corner_radius::RoundedCorners;
@@ -85,7 +85,7 @@ pub struct UiVertex {
   pub uv: Vec2,
 }
 
-/// Represents a single draw call, should be handled by the render backend
+/// Represents a single draw call (vertices + indices), should be handled by the render backend
 #[derive(Default)]
 pub struct UiDrawCall {
   pub vertices: Vec<UiVertex>,

hui/src/draw/atlas.rs

@@ -5,8 +5,25 @@ use rect_packer::DensePacker;
 use crate::rectangle::Corners;
 
 const RGBA_CHANNEL_COUNT: u32 = 4;
+//TODO make this work
 const ALLOW_ROTATION: bool = false;
 
+/// Texture format of the source texture data
+#[derive(Default, Clone, Copy, PartialEq, Eq)]
+pub enum TextureFormat {
+  /// The data is stored in RGBA format, with 1 byte (8 bits) per channel
+  #[default]
+  Rgba,
+
+  /// The data is copied into the Alpha channel, with 1 byte (8 bits) per channel\
+  /// Remaining channels are set to 255 (which can be easily shaded to any color)
+  ///
+  /// This format is useful for storing grayscale textures such as icons\
+  /// (Please note that the internal representation is still RGBA, this is just a convenience feature)
+  Grayscale,
+}
+
+/// Contains a reference to the texture data, and metadata associated with it
 pub struct TextureAtlasMeta<'a> {
   /// Texture data\
   /// The data is stored in RGBA format, with 1 byte (8 bits) per channel
@@ -157,7 +174,7 @@ impl TextureAtlasManager {
 
   /// Allocate a new texture region in the atlas and copy the data into it\
   /// This function may resize the atlas as needed, and should never fail under normal circumstances.
-  pub fn add(&mut self, width: usize, data: &[u8]) -> TextureHandle {
+  pub(crate) fn add_rgba(&mut self, width: usize, data: &[u8]) -> TextureHandle {
     let size = uvec2(width as u32, (data.len() / (width * RGBA_CHANNEL_COUNT as usize)) as u32);
     let handle: TextureHandle = self.allocate(size);
     let allocation = self.allocations.get(&handle.index).unwrap();
@@ -178,7 +195,7 @@ impl TextureAtlasManager {
   /// Works the same way as [`TextureAtlasManager::add`], but the input data is assumed to be grayscale (1 channel per pixel)\
   /// The data is copied into the alpha channel of the texture, while all the other channels are set to 255\
   /// May resize the atlas as needed, and should never fail under normal circumstances.
-  pub fn add_grayscale(&mut self, width: usize, data: &[u8]) -> TextureHandle {
+  pub(crate) fn add_grayscale(&mut self, width: usize, data: &[u8]) -> TextureHandle {
     let size = uvec2(width as u32, (data.len() / width) as u32);
     let handle = self.allocate(size);
     let allocation = self.allocations.get(&handle.index).unwrap();
@@ -194,6 +211,13 @@ impl TextureAtlasManager {
     handle
   }
 
+  pub fn add(&mut self, width: usize, data: &[u8], format: TextureFormat) -> TextureHandle {
+    match format {
+      TextureFormat::Rgba => self.add_rgba(width, data),
+      TextureFormat::Grayscale => self.add_grayscale(width, data),
+    }
+  }
+
   pub fn modify(&mut self, handle: TextureHandle) {
     todo!()
   }

hui/src/element/builtin/container.rs

@@ -4,9 +4,9 @@ use derive_setters::Setters;
 use glam::{Vec2, vec2};
 use crate::{
   background::BackgroundColor,
-  draw::{RoundedCorners, UiDrawCommand},
+  draw::{RoundedCorners, TextureHandle, UiDrawCommand},
   element::{ElementList, MeasureContext, ProcessContext, UiElement},
-  layout::{Alignment, Alignment2d, LayoutInfo, UiDirection, Size, Size2d},
+  layout::{Alignment, Alignment2d, LayoutInfo, Size, Size2d, UiDirection},
   measure::{Hints, Response},
   rectangle::{Corners, Sides}
 };
@@ -55,10 +55,19 @@ pub struct Container {
   #[setters(into)]
   pub align: Alignment2d,
 
-  /// Background color of the container
+  /// Background color of the container\
+  ///
+  /// If the container has a background texture, it will be multiplied by this color
   #[setters(into)]
   pub background: BackgroundColor,
 
+  /// Background texture of the container
+  ///
+  /// Can be used in conjunction with the background color\
+  /// In this case, the texture will be shaded by the color
+  #[setters(into)]
+  pub background_image: Option<TextureHandle>,
+
   /// Corner radius of the background rectangle
   #[setters(into)]
   pub corner_radius: Corners<f32>,
@@ -88,6 +97,7 @@ impl Default for Container {
       padding: Sides::all(0.),
       align: Alignment2d::default(),
       background: Default::default(),
+      background_image: None,
       children: ElementList(Vec::new()),
       wrap: false,
       corner_radius: Corners::all(0.),

hui/src/instance.rs

@@ -1,8 +1,7 @@
 use glam::Vec2;
 use crate::{
   draw::{
-    atlas::{TextureAtlasManager, TextureAtlasMeta},
+    atlas::{TextureAtlasManager, TextureAtlasMeta}, TextureFormat, TextureHandle, UiDrawCall, UiDrawCommandList
-    UiDrawCall, UiDrawCommandList,
   }, element::{MeasureContext, ProcessContext, UiElement}, event::{EventQueue, UiEvent}, input::UiInputState, layout::{LayoutInfo, UiDirection}, state::StateRepo, text::{FontHandle, TextRenderer}
 };
 
@@ -45,7 +44,7 @@ impl UiInstance {
       atlas: {
         let mut atlas = TextureAtlasManager::default();
         //HACK: Ensure that vec(0, 0) uv is white square
-        atlas.add(1, &[255, 255, 255, 255]);
+        atlas.add_rgba(1, &[255, 255, 255, 255]);
         atlas
       },
       events: EventQueue::new(),
@@ -58,10 +57,23 @@ impl UiInstance {
   /// TrueType (`.ttf`/`.ttc`) and OpenType (`.otf`) fonts are supported\
   ///
   /// Returns a font handle ([`FontHandle`]).
+  ///
+  /// ## Panics:
+  /// If the font data is invalid or corrupt
   pub fn add_font(&mut self, font: &[u8]) -> FontHandle {
     self.text_renderer.add_font_from_bytes(font)
   }
 
+  /// Add an image to the texture atlas\
+  /// Accepted texture formats are `Rgba` and `Grayscale`
+  ///
+  /// Returns a texture handle ([`TextureHandle`])\
+  /// This handle can be used to reference the texture in draw commands\
+  /// It's a light reference and can be cloned/copied freely, but will not be cleaned up even when dropped
+  pub fn add_image(&mut self, format: TextureFormat, data: &[u8], width: usize) -> TextureHandle {
+    self.atlas.add(width, data, format)
+  }
+
   /// Push a font to the font stack\
   /// The font will be used for all text rendering until it is popped
   ///
@@ -88,6 +100,9 @@ impl UiInstance {
   ///
   /// Use the `max_size` parameter to specify the maximum size of the element\
   /// (usually, the size of the window/screen)
+  ///
+  /// ## Panics:
+  /// If called while the UI is not active (call [`UiInstance::begin`] first)
   pub fn add<T: UiElement>(&mut self, element: T, max_size: Vec2) {
     assert!(self.state, "must call UiInstance::begin before adding elements");
     let layout = LayoutInfo {
@@ -114,7 +129,7 @@ impl UiInstance {
   /// Prepare the UI for layout and processing\
   /// You must call this function at the beginning of the frame, before adding any elements\
   ///
-  /// # Panics
+  /// ## Panics:
   /// If called twice in a row (for example, if you forget to call [`UiInstance::end`])\
   /// This is an indication of a bug in your code and should be fixed.
   pub fn begin(&mut self) {
@@ -137,7 +152,7 @@ impl UiInstance {
   /// End the frame and prepare the UI for rendering\
   /// You must call this function at the end of the frame, before rendering the UI
   ///
-  /// # Panics
+  /// ## Panics:
   /// If called without calling [`UiInstance::begin`] first. (or if called twice)\
   /// This is an indication of a bug in your code and should be fixed.
   pub fn end(&mut self) {