[runtime_image] Remove stored RAMAllocator member

RAMAllocator with default flags is stateless — it's just a dispatch
wrapper over heap_caps_malloc/realloc/free. There's no need to store
it as a class member. Use stack-local instances at each call site
instead, matching the pattern used in audio_transfer_buffer and
ring_buffer.

Co-Authored-By: J. Nick Koston <nick@koston.org>

esphome/components/runtime_image/png_decoder.cpp

@@ -50,7 +50,8 @@ static void draw_callback(pngle_t *pngle, uint32_t x, uint32_t y, uint32_t w, ui
 
 PngDecoder::PngDecoder(RuntimeImage *image) : ImageDecoder(image) {
   {
-    pngle_t *pngle = this->allocator_.allocate(1, PNGLE_T_SIZE);
+    RAMAllocator<pngle_t> allocator;
+    pngle_t *pngle = allocator.allocate(1, PNGLE_T_SIZE);
     if (!pngle) {
       ESP_LOGE(TAG, "Failed to allocate memory for PNGLE engine!");
       return;
@@ -64,7 +65,8 @@ PngDecoder::PngDecoder(RuntimeImage *image) : ImageDecoder(image) {
 PngDecoder::~PngDecoder() {
   if (this->pngle_) {
     pngle_reset(this->pngle_);
-    this->allocator_.deallocate(this->pngle_, PNGLE_T_SIZE);
+    RAMAllocator<pngle_t> allocator;
+    allocator.deallocate(this->pngle_, PNGLE_T_SIZE);
   }
 }
 

esphome/components/runtime_image/png_decoder.h

@@ -29,7 +29,6 @@ class PngDecoder : public ImageDecoder {
   uint32_t get_pixels_decoded() const { return this->pixels_decoded_; }
 
  protected:
-  RAMAllocator<pngle_t> allocator_;
   pngle_t *pngle_{nullptr};
   uint32_t pixels_decoded_{0};
 };

esphome/components/runtime_image/runtime_image.cpp

@@ -230,7 +230,8 @@ void RuntimeImage::release() {
 void RuntimeImage::release_buffer_() {
   if (this->buffer_) {
     ESP_LOGV(TAG, "Releasing buffer of size %zu", this->get_buffer_size_(this->buffer_width_, this->buffer_height_));
-    this->allocator_.deallocate(this->buffer_, this->get_buffer_size_(this->buffer_width_, this->buffer_height_));
+    RAMAllocator<uint8_t> allocator;
+    allocator.deallocate(this->buffer_, this->get_buffer_size_(this->buffer_width_, this->buffer_height_));
     this->buffer_ = nullptr;
     this->data_start_ = nullptr;
     this->width_ = 0;
@@ -254,11 +255,12 @@ size_t RuntimeImage::resize_buffer_(int width, int height) {
   }
 
   ESP_LOGD(TAG, "Allocating buffer: %dx%d, %zu bytes", width, height, new_size);
-  this->buffer_ = this->allocator_.allocate(new_size);
+  RAMAllocator<uint8_t> allocator;
+  this->buffer_ = allocator.allocate(new_size);
 
   if (!this->buffer_) {
     ESP_LOGE(TAG, "Failed to allocate %zu bytes. Largest free block: %zu", new_size,
-             this->allocator_.get_max_free_block_size());
+             allocator.get_max_free_block_size());
     return 0;
   }
 

esphome/components/runtime_image/runtime_image.h

@@ -165,7 +165,6 @@ class RuntimeImage : public image::Image {
   std::unique_ptr<ImageDecoder> create_decoder_();
 
   // Memory management
-  RAMAllocator<uint8_t> allocator_{};
   uint8_t *buffer_{nullptr};
 
   // Decoder management