From 2a62f9b8ec132d49e16dd0067b87e09a329a2a09 Mon Sep 17 00:00:00 2001
From: Romain Goyet <romain.goyet@numworks.com>
Date: Wed, 27 Feb 2019 13:43:28 +0100
Subject: [PATCH] [ion/sdl] Use an areaOfInterest

---
 ion/src/sdl/layout.cpp | 63 ++++++++++++++++++++++++++++++++++--------
 ion/src/sdl/layout.h   |  9 +++---
 ion/src/sdl/main.cpp   | 35 +++++------------------
 3 files changed, 63 insertions(+), 44 deletions(-)

diff --git a/ion/src/sdl/layout.cpp b/ion/src/sdl/layout.cpp
index e6a3cbcee..e86adcbc4 100644
--- a/ion/src/sdl/layout.cpp
+++ b/ion/src/sdl/layout.cpp
@@ -7,6 +7,8 @@ namespace Layout {
 #define X(x) ((x)/(1250.0f))
 #define Y(y) ((y)/(2100.0f))
 
+constexpr SDL_FRect areaOfInterest = {X(237), Y(83), X(776), Y(1733)};
+
 static SDL_Rect sFrame;
 
 static void makeAbsolute(SDL_FRect * f, SDL_Rect * r) {
@@ -16,18 +18,50 @@ static void makeAbsolute(SDL_FRect * f, SDL_Rect * r) {
   r->h = f->h * sFrame.h;
 }
 
-void setFrame(SDL_Rect * rect) {
-  sFrame.x = rect->x;
-  sFrame.y = rect->y;
-  sFrame.w = rect->w;
-  sFrame.h = rect->h;
-}
+void recompute(int width, int height) {
+  float windowWidth = static_cast<float>(width);
+  float windowHeight = static_cast<float>(height);
 
-void getAreaOfInterest(SDL_FRect * fRect) {
-  fRect->x = X(237);
-  fRect->y = Y(83);
-  fRect->w = X(776);
-  fRect->h = Y(1733);
+  float aoiRatio = (areaOfInterest.w / areaOfInterest.h) * (1250.0f/2100.0f);
+  float windowRatio = windowWidth/windowHeight;
+
+  if (aoiRatio > windowRatio) {
+    // Area of interest is wider than the window (e.g. aoe 16:9, window 4:3)
+    // There will be "black bars" above and below
+    // We want the areaOfInterest's rect in pixels to be
+    // aoiInPixels.w = windowWidth
+    // aoiInPixels.x = 0
+    // aoiInPixels.h = windowWidth / (aoiRatio*deviceRatio)
+    // aoiInPixels.y = (windowHeight - aoiInPixels.h)/2;
+    // But we also know that
+    // aoiInPixels.x = sFrame.x + areaOfInterest.x*sFrame.w
+    // aoiInPixels.y = sFrame.y + areaOfInterest.y*sFrame.h
+    // aoiInPixels.w = sFrame.w * areaOfInterest.w
+    // aoiInPixels.h = sFrame.h * areaOfInterest*h
+
+    sFrame.w = windowWidth / areaOfInterest.w;
+    sFrame.h = (windowWidth / aoiRatio) / areaOfInterest.h;
+    sFrame.x = - areaOfInterest.x * sFrame.w;
+    sFrame.y = (windowHeight - windowWidth/aoiRatio)/2 - areaOfInterest.y * sFrame.h;
+  } else {
+    // Area of interest is taller than the window (e.g. window 16:9, aoe 4:3)
+    // There will be "black bars" on the sides
+    // We want the areaOfInterest's rect in pixels to be
+    // aoiInPixels.h = windowHeight
+    // aoiInPixels.y = 0
+    // aoiInPixels.x = windowHeight * aoiRatio
+    // aoiInPixels.w = (windowWidth - aoiInPixels.w)/2;
+    // But we also know that
+    // aoiInPixels.x = sFrame.x + areaOfInterest.x*sFrame.w
+    // aoiInPixels.y = sFrame.y + areaOfInterest.y*sFrame.h
+    // aoiInPixels.w = sFrame.w * areaOfInterest.w
+    // aoiInPixels.h = sFrame.h * areaOfInterest*h
+
+    sFrame.h = windowHeight / areaOfInterest.h;
+    sFrame.w = (windowHeight * aoiRatio) / areaOfInterest.w;
+    sFrame.y = - areaOfInterest.y * sFrame.h;
+    sFrame.x = (windowWidth - windowHeight*aoiRatio)/2 - areaOfInterest.x * sFrame.w;
+  }
 }
 
 void getScreenRect(SDL_Rect * rect) {
@@ -39,6 +73,13 @@ void getScreenRect(SDL_Rect * rect) {
   makeAbsolute(&fRect, rect);
 }
 
+void getBackgroundRect(SDL_Rect * rect) {
+  rect->x = sFrame.x;
+  rect->y = sFrame.y;
+  rect->w = sFrame.w;
+  rect->h = sFrame.h;
+}
+
 Keyboard::Key keyAt(SDL_Point * p) {
   for (int i=0; i<Keyboard::NumberOfValidKeys; i++) {
     SDL_Rect r;
diff --git a/ion/src/sdl/layout.h b/ion/src/sdl/layout.h
index b0c0fd783..c8a356d2b 100644
--- a/ion/src/sdl/layout.h
+++ b/ion/src/sdl/layout.h
@@ -8,15 +8,14 @@ namespace Ion {
 namespace SDL {
 namespace Layout {
 
-void setFrame(SDL_Rect * rect);
-void getAreaOfInterest(SDL_FRect * fRect);
+void recompute(int width, int height);
 
 void getScreenRect(SDL_Rect * rect);
-Ion::Keyboard::Key keyAt(SDL_Point * p);
-//Ion::Keyboard::Key keyAtF(SDL_FPoint * p);
-
+void getBackgroundRect(SDL_Rect * rect);
 void getKeyRect(int validKeyIndex, SDL_Rect * rect);
 
+Ion::Keyboard::Key keyAt(SDL_Point * p);
+
 }
 }
 }
diff --git a/ion/src/sdl/main.cpp b/ion/src/sdl/main.cpp
index f080b29f1..54b44061c 100644
--- a/ion/src/sdl/main.cpp
+++ b/ion/src/sdl/main.cpp
@@ -27,7 +27,6 @@ namespace Main {
 static SDL_Window * sWindow = nullptr;
 static SDL_Renderer * sRenderer = nullptr;
 static SDL_Texture * sBackgroundTexture = nullptr;
-static SDL_Rect sLayoutRect;
 
 void init() {
   if (SDL_Init(SDL_INIT_VIDEO) != 0) {
@@ -60,31 +59,11 @@ void relayout() {
   int windowWidth = 0;
   int windowHeight = 0;
   SDL_GetWindowSize(sWindow, &windowWidth, &windowHeight);
+  Layout::recompute(windowWidth, windowHeight);
+  SDL_Rect backgroundRect;
+  Layout::getBackgroundRect(&backgroundRect);
 
-  SDL_FRect areaOfInterest;
-  Layout::getAreaOfInterest(&areaOfInterest);
-
-  float aoiRatio = areaOfInterest.w / areaOfInterest.h;
-  float windowRatio = static_cast<float>(windowWidth)/static_cast<float>(windowHeight);
-
-  if (aoiRatio < windowRatio) {
-    // Area of interest is wider than the window (aoe is 16:9, window is 4:3)
-    // There will be "black bars" above and below
-    sLayoutRect.w = static_cast<float>(windowWidth) / areaOfInterest.w;
-    sLayoutRect.x = - areaOfInterest.x * sLayoutRect.w; // Compensate the
-    sLayoutRect.h = sLayoutRect.w / windowRatio;
-    sLayoutRect.y = - areaOfInterest.y * sLayoutRect.h / 2; // Center vertically
-  } else {
-    sLayoutRect.h = static_cast<float>(windowHeight) / areaOfInterest.h;
-    sLayoutRect.y = - areaOfInterest.y * sLayoutRect.h; // Compensate, align left
-    sLayoutRect.w = sLayoutRect.h * windowRatio;
-    sLayoutRect.x = - areaOfInterest.x * sLayoutRect.w / 2; // Center horizontally
-    // Area of interest is taller than the window
-  }
-
-  Layout::setFrame(&sLayoutRect);
-
-  SDL_RenderCopy(sRenderer, sBackgroundTexture, nullptr, &sLayoutRect);
+  SDL_RenderCopy(sRenderer, sBackgroundTexture, nullptr, &backgroundRect);
   SDL_RenderPresent(sRenderer);
 
   refresh();
@@ -95,12 +74,12 @@ void relayout() {
 void refresh() {
   SDL_Rect screenRect;
   Layout::getScreenRect(&screenRect);
+  SDL_Rect backgroundRect;
+  Layout::getBackgroundRect(&backgroundRect);
 
-  SDL_RenderCopy(sRenderer, sBackgroundTexture, nullptr, &sLayoutRect);
-
+  SDL_RenderCopy(sRenderer, sBackgroundTexture, nullptr, &backgroundRect);
   Display::draw(sRenderer, &screenRect);
   SDL_RenderPresent(sRenderer);
-  //SDL_UpdateWindowSurface(sWindow);
 }
 
 }