From fb7ea044e204e9cc8a700720b91ea8438adefc63 Mon Sep 17 00:00:00 2001
From: Tad Hardesty <tad@platymuus.com>
Date: Mon, 10 Sep 2018 00:54:00 -0700
Subject: [PATCH] Split the ImTexture allocator into a generic struct

---
 imgui-gfx-renderer/src/lib.rs | 24 ++++++++---------------
 src/image.rs                  | 36 +++++++++++++++++++++++++++++++++++
 src/lib.rs                    |  2 +-
 3 files changed, 45 insertions(+), 17 deletions(-)

diff --git a/imgui-gfx-renderer/src/lib.rs b/imgui-gfx-renderer/src/lib.rs
index c6c135e..d3aa98a 100644
--- a/imgui-gfx-renderer/src/lib.rs
+++ b/imgui-gfx-renderer/src/lib.rs
@@ -7,9 +7,7 @@ use gfx::memory::Bind;
 use gfx::texture::{FilterMethod, SamplerInfo, WrapMode};
 use gfx::traits::FactoryExt;
 use gfx::{Bundle, CommandBuffer, Encoder, Factory, IntoIndexBuffer, Rect, Resources, Slice};
-use imgui::{DrawList, FrameSize, ImDrawIdx, ImDrawVert, ImGui, Ui, ImTexture};
-
-use std::collections::HashMap;
+use imgui::{DrawList, FrameSize, ImDrawIdx, ImDrawVert, ImGui, Ui, Textures};
 
 pub type RendererResult<T> = Result<T, RendererError>;
 
@@ -101,8 +99,7 @@ pub type Texture<R> = (gfx::handle::ShaderResourceView<R, [f32; 4]>, gfx::handle
 pub struct Renderer<R: Resources> {
     bundle: Bundle<R, pipe::Data<R>>,
     index_buffer: Buffer<R, u16>,
-    textures: HashMap<usize, Texture<R>>,
-    next_texture: usize,
+    textures: Textures<Texture<R>>,
 }
 
 impl<R: Resources> Renderer<R> {
@@ -140,9 +137,8 @@ impl<R: Resources> Renderer<R> {
         let sampler =
             factory.create_sampler(SamplerInfo::new(FilterMethod::Trilinear, WrapMode::Clamp));
         let pair = (texture, sampler);
-        let mut textures = HashMap::new();
-        textures.insert(0, pair.clone());
-        imgui.set_texture_id(0);
+        let mut textures = Textures::new();
+        imgui.set_texture_id(textures.insert(pair.clone()));
 
         let data = pipe::Data {
             vertex_buffer: vertex_buffer,
@@ -171,8 +167,7 @@ impl<R: Resources> Renderer<R> {
         Ok(Renderer {
             bundle: Bundle::new(slice, pso, data),
             index_buffer: index_buffer,
-            textures,
-            next_texture: 1,
+            textures: textures,
         })
     }
 
@@ -180,11 +175,8 @@ impl<R: Resources> Renderer<R> {
         self.bundle.data.out = out;
     }
 
-    pub fn add_texture(&mut self, texture: Texture<R>) -> ImTexture {
-        let id = self.next_texture;
-        self.textures.insert(id, texture);
-        self.next_texture += 1;
-        id
+    pub fn textures(&mut self) -> &mut Textures<Texture<R>> {
+        &mut self.textures
     }
 
     pub fn render<'a, F: Factory<R>, C: CommandBuffer<R>>(
@@ -235,7 +227,7 @@ impl<R: Resources> Renderer<R> {
 
         self.bundle.slice.start = 0;
         for cmd in draw_list.cmd_buffer {
-            if let Some(tex) = self.textures.get(&(cmd.texture_id as usize)) {
+            if let Some(tex) = self.textures.get(cmd.texture_id as usize) {
                 // cloning handles is okay, since they're Arcs internally
                 self.bundle.data.tex = tex.clone();
             }
diff --git a/src/image.rs b/src/image.rs
index b8cf978..2326ef4 100644
--- a/src/image.rs
+++ b/src/image.rs
@@ -1,5 +1,6 @@
 use super::{ImVec2, ImVec4, Ui};
 use std::marker::PhantomData;
+use std::collections::HashMap;
 use std::os::raw::c_void;
 use sys;
 
@@ -88,3 +89,38 @@ impl<'ui> Image<'ui> {
         }
     }
 }
+
+/// Generic texture mapping for use by renderers.
+pub struct Textures<T> {
+    textures: HashMap<usize, T>,
+    next: usize,
+}
+
+impl<T> Textures<T> {
+    pub fn new() -> Self {
+        Textures {
+            textures: HashMap::new(),
+            next: 0,
+        }
+    }
+
+    pub fn insert(&mut self, texture: T) -> ImTexture {
+        let id = self.next;
+        self.textures.insert(id, texture);
+        self.next += 1;
+        id
+    }
+
+    pub fn replace(&mut self, id: ImTexture, texture: T) {
+        assert!(self.textures.contains_key(&id));
+        self.textures.insert(id, texture);
+    }
+
+    pub fn remove(&mut self, id: ImTexture) {
+        self.textures.remove(&id);
+    }
+
+    pub fn get(&self, id: ImTexture) -> Option<&T> {
+        self.textures.get(&id)
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 4e9688f..55aa8e8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -18,7 +18,7 @@ pub use drag::{
     DragInt4, DragIntRange2,
 };
 pub use fonts::{FontGlyphRange, ImFont, ImFontAtlas, ImFontConfig};
-pub use image::{ImTexture, Image};
+pub use image::{ImTexture, Image, Textures};
 pub use input::{
     InputFloat, InputFloat2, InputFloat3, InputFloat4, InputInt, InputInt2, InputInt3, InputInt4,
     InputText, InputTextMultiline,