From 329bf692e668e5c3d0a9b24c5e53415021b2064a Mon Sep 17 00:00:00 2001
From: Sergio Valor <jaildesigner@gmail.com>
Date: Thu, 23 Apr 2026 11:58:58 +0200
Subject: [PATCH] =?UTF-8?q?feat(editor):=20Screen::windowToCanvas()=20per?=
 =?UTF-8?q?=20a=20input=20de=20rat=C3=B2li?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 source/core/rendering/screen.cpp | 29 +++++++++++++++++++++++++++++
 source/core/rendering/screen.hpp | 10 ++++++++++
 2 files changed, 39 insertions(+)

diff --git a/source/core/rendering/screen.cpp b/source/core/rendering/screen.cpp
index 69248fb..6953fd1 100644
--- a/source/core/rendering/screen.cpp
+++ b/source/core/rendering/screen.cpp
@@ -11,6 +11,7 @@
 #include <ranges>
 
 #include "core/rendering/canvas.hpp"
+#include "core/rendering/sdl3gpu/viewport.hpp"
 #include "utils/defines.hpp"
 
 namespace {
@@ -265,6 +266,34 @@ void Screen::blendRect(int x, int y, int w, int h, std::uint32_t argb, std::uint
     }
 }
 
+auto Screen::windowToCanvas(float window_x, float window_y) const -> SDL_FPoint {
+    // Path fallback: SDL ja porta un helper que desfà el
+    // logical_presentation automàticament. Evita que haguem de replicar
+    // les regles de letterbox/integer/etc.
+    if (renderer_ != nullptr) {
+        float cx = 0.0F;
+        float cy = 0.0F;
+        SDL_RenderCoordinatesFromWindow(renderer_, window_x, window_y, &cx, &cy);
+        return {cx, cy};
+    }
+    // Path GPU: el canvas es pinta al viewport que calcula
+    // `computeViewport` a partir del mode d'escalat i la mida del
+    // swapchain. Fem el mateix càlcul aquí per trobar la inversa.
+    int win_w = 0;
+    int win_h = 0;
+    SDL_GetWindowSize(window_, &win_w, &win_h);
+    if (win_w <= 0 || win_h <= 0) { return {-1.0F, -1.0F}; }
+    const auto VP = Rendering::computeViewport(config_.scaling_mode,
+        static_cast<std::uint32_t>(win_w),
+        static_cast<std::uint32_t>(win_h),
+        canvas_width_,
+        canvas_height_);
+    if (VP.w <= 0.0F || VP.h <= 0.0F) { return {-1.0F, -1.0F}; }
+    const float NX = (window_x - VP.x) / VP.w;
+    const float NY = (window_y - VP.y) / VP.h;
+    return {NX * static_cast<float>(canvas_width_), NY * static_cast<float>(canvas_height_)};
+}
+
 void Screen::setOverlayRenderer(std::function<void()> callback) {
     overlay_renderer_ = std::move(callback);
 }
diff --git a/source/core/rendering/screen.hpp b/source/core/rendering/screen.hpp
index 763460a..2bb8726 100644
--- a/source/core/rendering/screen.hpp
+++ b/source/core/rendering/screen.hpp
@@ -86,6 +86,16 @@ class Screen {
     [[nodiscard]] auto getCanvasWidth() const -> int { return canvas_width_; }
     [[nodiscard]] auto getCanvasHeight() const -> int { return canvas_height_; }
 
+    // Transforma una coordenada en espai finestra (tal com venen als
+    // esdeveniments SDL de ratolí) a espai canvas (0..canvas_w, 0..canvas_h).
+    // Reverteix el zoom de la finestra i el mode d'escalat actiu: al path
+    // fallback SDL_Renderer es delega a `SDL_RenderCoordinatesFromWindow`;
+    // al path GPU es recalcula a partir del viewport actual. Si el punt
+    // cau fora de la zona del canvas (letterbox/integer), els valors
+    // retornats queden fora del rang `[0, canvas_w/h)` — el caller ha de
+    // fer el bounds-check i ignorar el clic en eixe cas.
+    [[nodiscard]] auto windowToCanvas(float window_x, float window_y) const -> SDL_FPoint;
+
     // Mètriques per a overlays de debug (RenderInfo).
     [[nodiscard]] auto getLastFPS() const -> int { return fps_.last_value; }
     [[nodiscard]] auto getGPUDriver() const -> const std::string& { return gpu_driver_; }