Add the Ability to Specify Egui Texture Filters (#1636)

Only works for egui_glow

epaint/src/image.rs

@@ -1,4 +1,4 @@
-use crate::Color32;
+use crate::{textures::TextureFilter, Color32};
 
 /// An image stored in RAM.
 ///
@@ -272,6 +272,8 @@ pub struct ImageDelta {
     /// If [`Self::pos`] is `Some`, this describes a patch of the whole image starting at [`Self::pos`].
     pub image: ImageData,
 
+    pub filter: TextureFilter,
+
     /// If `None`, set the whole texture to [`Self::image`].
     ///
     /// If `Some(pos)`, update a sub-region of an already allocated texture with the patch in [`Self::image`].
@@ -280,17 +282,19 @@ pub struct ImageDelta {
 
 impl ImageDelta {
     /// Update the whole texture.
-    pub fn full(image: impl Into<ImageData>) -> Self {
+    pub fn full(image: impl Into<ImageData>, filter: TextureFilter) -> Self {
         Self {
             image: image.into(),
+            filter,
             pos: None,
         }
     }
 
     /// Update a sub-region of an existing texture.
-    pub fn partial(pos: [usize; 2], image: impl Into<ImageData>) -> Self {
+    pub fn partial(pos: [usize; 2], image: impl Into<ImageData>, filter: TextureFilter) -> Self {
         Self {
             image: image.into(),
+            filter,
             pos: Some(pos),
         }
     }

epaint/src/texture_atlas.rs

@@ -1,6 +1,6 @@
 use emath::{remap_clamp, Rect};
 
-use crate::{FontImage, ImageDelta};
+use crate::{textures::TextureFilter, FontImage, ImageDelta};
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 struct Rectu {
@@ -176,12 +176,12 @@ impl TextureAtlas {
         if dirty == Rectu::NOTHING {
             None
         } else if dirty == Rectu::EVERYTHING {
-            Some(ImageDelta::full(self.image.clone()))
+            Some(ImageDelta::full(self.image.clone(), TextureFilter::Linear))
         } else {
             let pos = [dirty.min_x, dirty.min_y];
             let size = [dirty.max_x - dirty.min_x, dirty.max_y - dirty.min_y];
             let region = self.image.region(pos, size);
-            Some(ImageDelta::partial(pos, region))
+            Some(ImageDelta::partial(pos, region, TextureFilter::Linear))
         }
     }
 

epaint/src/texture_handle.rs

@@ -1,6 +1,9 @@
 use std::sync::Arc;
 
-use crate::{emath::NumExt, mutex::RwLock, ImageData, ImageDelta, TextureId, TextureManager};
+use crate::{
+    emath::NumExt, mutex::RwLock, textures::TextureFilter, ImageData, ImageDelta, TextureId,
+    TextureManager,
+};
 
 /// Used to paint images.
 ///
@@ -63,17 +66,22 @@ impl TextureHandle {
     }
 
     /// Assign a new image to an existing texture.
-    pub fn set(&mut self, image: impl Into<ImageData>) {
+    pub fn set(&mut self, image: impl Into<ImageData>, filter: TextureFilter) {
         self.tex_mngr
             .write()
-            .set(self.id, ImageDelta::full(image.into()));
+            .set(self.id, ImageDelta::full(image.into(), filter));
     }
 
     /// Assign a new image to a subregion of the whole texture.
-    pub fn set_partial(&mut self, pos: [usize; 2], image: impl Into<ImageData>) {
+    pub fn set_partial(
+        &mut self,
+        pos: [usize; 2],
+        image: impl Into<ImageData>,
+        filter: TextureFilter,
+    ) {
         self.tex_mngr
             .write()
-            .set(self.id, ImageDelta::partial(pos, image.into()));
+            .set(self.id, ImageDelta::partial(pos, image.into(), filter));
     }
 
     /// width x height

epaint/src/textures.rs

@@ -27,7 +27,7 @@ impl TextureManager {
     /// MUST have a white pixel at (0,0) ([`crate::WHITE_UV`]).
     ///
     /// The texture is given a retain-count of `1`, requiring one call to [`Self::free`] to free it.
-    pub fn alloc(&mut self, name: String, image: ImageData) -> TextureId {
+    pub fn alloc(&mut self, name: String, image: ImageData, filter: TextureFilter) -> TextureId {
         let id = TextureId::Managed(self.next_id);
         self.next_id += 1;
 
@@ -36,9 +36,10 @@ impl TextureManager {
             size: image.size(),
             bytes_per_pixel: image.bytes_per_pixel(),
             retain_count: 1,
+            filter,
         });
 
-        self.delta.set.insert(id, ImageDelta::full(image));
+        self.delta.set.insert(id, ImageDelta::full(image, filter));
         id
     }
 
@@ -130,6 +131,22 @@ pub struct TextureMeta {
 
     /// Free when this reaches zero.
     pub retain_count: usize,
+
+    /// The texture filtering mode to use when rendering
+    pub filter: TextureFilter,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub enum TextureFilter {
+    Linear,
+    Nearest,
+}
+
+impl Default for TextureFilter {
+    fn default() -> Self {
+        Self::Linear
+    }
 }
 
 impl TextureMeta {