From 78e8001aa8c30415b6a285132ad30f1dbf00347f Mon Sep 17 00:00:00 2001
From: Clyde Stubbs <2366188+clydebarrow@users.noreply.github.com>
Date: Tue, 15 Jul 2025 12:09:18 +1000
Subject: [PATCH] [online_image] Support `byte_order` (#9502)

---
 esphome/components/online_image/__init__.py      |  5 ++++-
 esphome/components/online_image/online_image.cpp | 16 +++++++++++-----
 esphome/components/online_image/online_image.h   |  7 ++++++-
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/esphome/components/online_image/__init__.py b/esphome/components/online_image/__init__.py
index 3f15db6e50..7a6d25bc7d 100644
--- a/esphome/components/online_image/__init__.py
+++ b/esphome/components/online_image/__init__.py
@@ -2,7 +2,7 @@ import logging
 
 from esphome import automation
 import esphome.codegen as cg
-from esphome.components.const import CONF_REQUEST_HEADERS
+from esphome.components.const import CONF_BYTE_ORDER, CONF_REQUEST_HEADERS
 from esphome.components.http_request import CONF_HTTP_REQUEST_ID, HttpRequestComponent
 from esphome.components.image import (
     CONF_INVERT_ALPHA,
@@ -11,6 +11,7 @@ from esphome.components.image import (
     Image_,
     get_image_type_enum,
     get_transparency_enum,
+    validate_settings,
 )
 import esphome.config_validation as cv
 from esphome.const import (
@@ -161,6 +162,7 @@ CONFIG_SCHEMA = cv.Schema(
             rp2040_arduino=cv.Version(0, 0, 0),
             host=cv.Version(0, 0, 0),
         ),
+        validate_settings,
     )
 )
 
@@ -213,6 +215,7 @@ async def to_code(config):
         get_image_type_enum(config[CONF_TYPE]),
         transparent,
         config[CONF_BUFFER_SIZE],
+        config.get(CONF_BYTE_ORDER) != "LITTLE_ENDIAN",
     )
     await cg.register_component(var, config)
     await cg.register_parented(var, config[CONF_HTTP_REQUEST_ID])
diff --git a/esphome/components/online_image/online_image.cpp b/esphome/components/online_image/online_image.cpp
index d0c743ef93..4e2ecc2c77 100644
--- a/esphome/components/online_image/online_image.cpp
+++ b/esphome/components/online_image/online_image.cpp
@@ -35,14 +35,15 @@ inline bool is_color_on(const Color &color) {
 }
 
 OnlineImage::OnlineImage(const std::string &url, int width, int height, ImageFormat format, ImageType type,
-                         image::Transparency transparency, uint32_t download_buffer_size)
+                         image::Transparency transparency, uint32_t download_buffer_size, bool is_big_endian)
     : Image(nullptr, 0, 0, type, transparency),
       buffer_(nullptr),
       download_buffer_(download_buffer_size),
       download_buffer_initial_size_(download_buffer_size),
       format_(format),
       fixed_width_(width),
-      fixed_height_(height) {
+      fixed_height_(height),
+      is_big_endian_(is_big_endian) {
   this->set_url(url);
 }
 
@@ -296,7 +297,7 @@ void OnlineImage::draw_pixel_(int x, int y, Color color) {
       break;
     }
     case ImageType::IMAGE_TYPE_GRAYSCALE: {
-      uint8_t gray = static_cast<uint8_t>(0.2125 * color.r + 0.7154 * color.g + 0.0721 * color.b);
+      auto gray = static_cast<uint8_t>(0.2125 * color.r + 0.7154 * color.g + 0.0721 * color.b);
       if (this->transparency_ == image::TRANSPARENCY_CHROMA_KEY) {
         if (gray == 1) {
           gray = 0;
@@ -314,8 +315,13 @@ void OnlineImage::draw_pixel_(int x, int y, Color color) {
     case ImageType::IMAGE_TYPE_RGB565: {
       this->map_chroma_key(color);
       uint16_t col565 = display::ColorUtil::color_to_565(color);
-      this->buffer_[pos + 0] = static_cast<uint8_t>((col565 >> 8) & 0xFF);
-      this->buffer_[pos + 1] = static_cast<uint8_t>(col565 & 0xFF);
+      if (this->is_big_endian_) {
+        this->buffer_[pos + 0] = static_cast<uint8_t>((col565 >> 8) & 0xFF);
+        this->buffer_[pos + 1] = static_cast<uint8_t>(col565 & 0xFF);
+      } else {
+        this->buffer_[pos + 0] = static_cast<uint8_t>(col565 & 0xFF);
+        this->buffer_[pos + 1] = static_cast<uint8_t>((col565 >> 8) & 0xFF);
+      }
       if (this->transparency_ == image::TRANSPARENCY_ALPHA_CHANNEL) {
         this->buffer_[pos + 2] = color.w;
       }
diff --git a/esphome/components/online_image/online_image.h b/esphome/components/online_image/online_image.h
index 6a2144538f..3326cbe8d6 100644
--- a/esphome/components/online_image/online_image.h
+++ b/esphome/components/online_image/online_image.h
@@ -50,7 +50,7 @@ class OnlineImage : public PollingComponent,
    * @param buffer_size Size of the buffer used to download the image.
    */
   OnlineImage(const std::string &url, int width, int height, ImageFormat format, image::ImageType type,
-              image::Transparency transparency, uint32_t buffer_size);
+              image::Transparency transparency, uint32_t buffer_size, bool is_big_endian);
 
   void draw(int x, int y, display::Display *display, Color color_on, Color color_off) override;
 
@@ -164,6 +164,11 @@ class OnlineImage : public PollingComponent,
   const int fixed_width_;
   /** height requested on configuration, or 0 if non specified. */
   const int fixed_height_;
+  /**
+   * Whether the image is stored in big-endian format.
+   * This is used to determine how to store 16 bit colors in the buffer.
+   */
+  bool is_big_endian_;
   /**
    * Actual width of the current image. If fixed_width_ is specified,
    * this will be equal to it; otherwise it will be set once the decoding