Add runtime online image support (#4710)

esphome/components/online_image/image_decoder.cpp

@@ -0,0 +1,44 @@
+#include "image_decoder.h"
+#include "online_image.h"
+
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace online_image {
+
+static const char *const TAG = "online_image.decoder";
+
+void ImageDecoder::set_size(int width, int height) {
+  this->image_->resize_(width, height);
+  this->x_scale_ = static_cast<double>(this->image_->buffer_width_) / width;
+  this->y_scale_ = static_cast<double>(this->image_->buffer_height_) / height;
+}
+
+void ImageDecoder::draw(int x, int y, int w, int h, const Color &color) {
+  auto width = std::min(this->image_->buffer_width_, static_cast<int>(std::ceil((x + w) * this->x_scale_)));
+  auto height = std::min(this->image_->buffer_height_, static_cast<int>(std::ceil((y + h) * this->y_scale_)));
+  for (int i = x * this->x_scale_; i < width; i++) {
+    for (int j = y * this->y_scale_; j < height; j++) {
+      this->image_->draw_pixel_(i, j, color);
+    }
+  }
+}
+
+uint8_t *DownloadBuffer::data(size_t offset) {
+  if (offset > this->size_) {
+    ESP_LOGE(TAG, "Tried to access beyond download buffer bounds!!!");
+    return this->buffer_;
+  }
+  return this->buffer_ + offset;
+}
+
+size_t DownloadBuffer::read(size_t len) {
+  this->unread_ -= len;
+  if (this->unread_ > 0) {
+    memmove(this->data(), this->data(len), this->unread_);
+  }
+  return this->unread_;
+}
+
+}  // namespace online_image
+}  // namespace esphome