From d975d7d207b1838ecbca936b86343767521bdf7f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrick=20Ha=C3=9Fel?= <git@patrick-hassel.de>
Date: Thu, 23 Jan 2025 11:54:10 +0100
Subject: [PATCH] DisplayMatrix::drawLine

---
 src/patrix/display/DisplayMatrix.h      |  2 ++
 src/patrix/display/DisplayMatrix_draw.h | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/patrix/display/DisplayMatrix.h b/src/patrix/display/DisplayMatrix.h
index f6335f5..afc903d 100644
--- a/src/patrix/display/DisplayMatrix.h
+++ b/src/patrix/display/DisplayMatrix.h
@@ -26,6 +26,8 @@ public:
 
   void fillRect(int w = W, int h = H) const;
 
+  void drawLine(int w = W, int h = H, int thickness = 1) const;
+
   // print ----------------------------------------------------------------------------------------
 
   void printf(const char *format, ...);
diff --git a/src/patrix/display/DisplayMatrix_draw.h b/src/patrix/display/DisplayMatrix_draw.h
index 2199b23..c50caa0 100644
--- a/src/patrix/display/DisplayMatrix_draw.h
+++ b/src/patrix/display/DisplayMatrix_draw.h
@@ -18,4 +18,27 @@ void DisplayMatrix<W, H>::fillRect(const int w, const int h) const {
   }
 }
 
+template<int W, int H>
+void DisplayMatrix<W, H>::drawLine(const int w, const int h, const int thickness) const {
+  if (w >= h) {
+    const auto m = static_cast<double>(h) / w;
+    for (auto t = 0; t < thickness; ++t) {
+      const auto offset = t % 2 == 0 ? t / 2 : -t / 2;
+      for (auto x = 0; x < w; ++x) {
+        const auto y = static_cast<int>(round(offset + x * m));
+        matrix[cursorY + y][cursorX + x].blend(foreground, alpha);
+      }
+    }
+  } else {
+    const auto m = static_cast<double>(w) / h;
+    for (auto t = 0; t < thickness; ++t) {
+      const auto offset = t % 2 == 0 ? t / 2 : -t / 2;
+      for (auto y = 0; y < w; ++y) {
+        const auto x = static_cast<int>(round(offset + y * m));
+        matrix[cursorY + y][cursorX + x].blend(foreground, alpha);
+      }
+    }
+  }
+}
+
 #endif