Add a local coordinate system

This introduces a local coordinate system to the display component. This is useful for nested/localised drawing without having to do repeated and error prone coordinate maths

esphome/components/display/display.cpp

@@ -579,6 +579,31 @@ bool Display::clip(int x, int y) {
     return false;
   return true;
 }
+void Display::set_local_coordinates_relative_to_current(int x_offset, int y_offset) {
+  Point p(0, 0);
+  if (!this->local_coordinate_.empty()) {
+    p = this->local_coordinate_.back();
+  }
+  p.x += x_offset;
+  p.y += y_offset;
+
+  this->local_coordinate_.push_back(p);
+}
+void Display::pop_local_coordinates() {
+  if (this->local_coordinate_.empty()) {
+    ESP_LOGE(TAG, "pop_local_coordinates: No local coordinates set");
+  } else {
+    this->local_coordinate_.pop_back();
+  }
+}
+Point Display::get_local_coordinates() {
+  Point p(0, 0);
+  if (!this->local_coordinate_.empty()) {
+    p = this->local_coordinate_.back();
+  }
+
+  return p;
+}
 bool Display::clamp_x_(int x, int w, int &min_x, int &max_x) {
   min_x = std::max(x, 0);
   max_x = std::min(x + w, this->get_width());

esphome/components/display/display.h

@@ -4,10 +4,12 @@
 #include <vector>
 
 #include "rect.h"
+#include "point.h"
 
 #include "esphome/core/color.h"
 #include "esphome/core/automation.h"
 #include "esphome/core/time.h"
+#include "esphome/core/log.h"
 #include "display_color_utils.h"
 
 #ifdef USE_GRAPH
@@ -631,6 +633,36 @@ class Display : public PollingComponent {
    */
   bool clip(int x, int y);
 
+  /** Changes the local coordinates to be relative to (x, y). After calling a pixel
+   *  drawn at (10, 20) would be drawn to the screen at (x + 10, y + 20)
+   *
+   * @param[in] x: x coordinate as the new local. Absolute to the displays underlying 0
+   * @param[in] y: y coordinate as the new local. Absolute to the displays underlying 0
+   */
+  void set_local_coordinate(int x, int y) { this->local_coordinate_.emplace_back(x, y); };
+
+  /** Changes the local coordinates to be to be (x_local + x_offset, y_local + y_offset)
+   *  After calling a pixel drawn at (10, 20) would be drawn to the screen at
+   *  (x_local + x_offset + 10, y_local + y_offset + 20)
+   *
+   * @param[in] x_offset: x offset from the current local. Relative to the local x
+   * @param[in] y_offset: y offset from the current local. Relative to the local y
+   */
+  void set_local_coordinates_relative_to_current(int x_offset, int y_offset);
+
+  /** Removes the most recent local coordinate system from use
+   */
+  void pop_local_coordinates();
+
+  /** Gets the current local coordinates in the displays absolute coordinate system
+   */
+  Point get_local_coordinates();
+
+  /** Clears all the local coordinate systems and revers to the displays absolute coordinate
+   *  system
+   */
+  void clear_local_coordinates() { this->local_coordinate_.clear(); };
+
   void test_card();
   void show_test_card() { this->show_test_card_ = true; }
 
@@ -662,6 +694,7 @@ class Display : public PollingComponent {
   std::vector<DisplayOnPageChangeTrigger *> on_page_change_triggers_;
   bool auto_clear_enabled_{true};
   std::vector<Rect> clipping_rectangle_;
+  std::vector<Point> local_coordinate_;
   bool show_test_card_{false};
 };
 
@@ -737,5 +770,7 @@ class DisplayOnPageChangeTrigger : public Trigger<DisplayPage *, DisplayPage *>
   DisplayPage *to_{nullptr};
 };
 
+const LogString *text_align_to_string(TextAlign textalign);
+
 }  // namespace display
 }  // namespace esphome

esphome/components/display/display_buffer.cpp

@@ -4,6 +4,7 @@
 
 #include "esphome/core/application.h"
 #include "esphome/core/log.h"
+#include "point.h"
 
 namespace esphome {
 namespace display {
@@ -45,6 +46,11 @@ int DisplayBuffer::get_height() {
 }
 
 void HOT DisplayBuffer::draw_pixel_at(int x, int y, Color color) {
+  // Convert (x, y) from the local coordinate system to the display absolute coordinate system
+  Point local_coord = this->get_local_coordinates();
+  x += local_coord.x;
+  y += local_coord.y;
+
   if (!this->get_clipping().inside(x, y))
     return;  // NOLINT
 

esphome/components/display/point.h

@@ -0,0 +1,19 @@
+
+#pragma once
+
+#include "esphome/core/helpers.h"
+
+namespace esphome {
+namespace display {
+
+class Point {
+ public:
+  int16_t x;
+  int16_t y;
+
+  Point() : x(VALUE_NO_SET), y(VALUE_NO_SET){};
+  inline Point(int16_t x, int16_t y) ESPHOME_ALWAYS_INLINE : x(x), y(y){};
+};
+
+}  // namespace display
+}  // namespace esphome