Merge pull request #543 from BartInTheField/render-second-screen-seam

docs/modding.md

@@ -187,5 +187,18 @@ composited and before touch controls draw. The window-space viewport contains
 and `dpiY`, so a tool can use the letterbox margins without drawing over the
 playfield or pushing an updating game state.
 
+`render.compose` wraps the whole-window composite in `Renderer:endFrame`. It
+receives `(next, renderer, ctx)`; returning `true` without calling `next` hands
+the mod full control of the window, while calling `next` runs the engine's
+normal single-window composite so the mod can decorate around it. `ctx` carries
+the finished `worldCanvas` and `uiCanvas` with their SGB `zones` / `worldZones`,
+`worldActive`, the frame metrics (`ww`, `wh`, `pw`, `ph`, `ox`, `oy`, `vpw`,
+`vph`, `scale`, `Sx`, `Sy`, `dpiX`, `dpiY`), `renderer:blitCanvas(...)` for a
+palette-correct blit of either canvas into an arbitrary screen rect, and the
+`secondScreen` bridge (`available()` / `push(imageData, w, h)` / `setEnabled`)
+for driving a second physical display. This is what lets a mod lay the two
+passes out as two stacked Game Boy screens, or push one onto a second screen,
+without the engine knowing the layout.
+
 Developer mode also arms the mod loader's dev tripwire, which flags mods
 that reach outside their permission set.

mobile/android/love/src/jni/love/src/common/android.cpp

@@ -863,4 +863,51 @@ const char *getArg0()
 } // android
 } // love
 
+extern "C" __attribute__((visibility("default")))
+int love_android_secondary_ready()
+{
+	JNIEnv *env = (JNIEnv*) SDL_AndroidGetJNIEnv();
+	jclass activity = env->FindClass("org/love2d/android/GameActivity");
+	jmethodID m = env->GetStaticMethodID(activity, "hasSecondaryDisplay", "()Z");
+	jboolean ready = JNI_FALSE;
+	if (m)
+		ready = env->CallStaticBooleanMethod(activity, m);
+	else
+		env->ExceptionClear();
+	env->DeleteLocalRef(activity);
+	return ready ? 1 : 0;
+}
+
+extern "C" __attribute__((visibility("default")))
+void love_android_push_secondary(const void *rgba, int w, int h)
+{
+	if (!rgba || w <= 0 || h <= 0)
+		return;
+	JNIEnv *env = (JNIEnv*) SDL_AndroidGetJNIEnv();
+	jclass activity = env->FindClass("org/love2d/android/GameActivity");
+	jmethodID m = env->GetStaticMethodID(activity, "updateSecondaryFrame", "(Ljava/nio/ByteBuffer;II)V");
+	if (m)
+	{
+		jobject buf = env->NewDirectByteBuffer((void*) rgba, (jlong) w * (jlong) h * 4);
+		env->CallStaticVoidMethod(activity, m, buf, w, h);
+		env->DeleteLocalRef(buf);
+	}
+	else
+		env->ExceptionClear();
+	env->DeleteLocalRef(activity);
+}
+
+extern "C" __attribute__((visibility("default")))
+void love_android_secondary_enable(int on)
+{
+	JNIEnv *env = (JNIEnv*) SDL_AndroidGetJNIEnv();
+	jclass activity = env->FindClass("org/love2d/android/GameActivity");
+	jmethodID m = env->GetStaticMethodID(activity, "setSecondaryEnabled", "(Z)V");
+	if (m)
+		env->CallStaticVoidMethod(activity, m, on ? JNI_TRUE : JNI_FALSE);
+	else
+		env->ExceptionClear();
+	env->DeleteLocalRef(activity);
+}
+
 #endif // LOVE_ANDROID

mobile/android/love/src/main/java/org/love2d/android/GameActivity.java

@@ -331,12 +331,14 @@ public class GameActivity extends SDLActivity {
             Log.d("GameActivity", "Cancelling vibration");
             vibrator.cancel();
         }
+        teardownSecondaryDisplay();
         super.onPause();
     }
 
     @Override
     public void onResume() {
         super.onResume();
+        setupSecondaryDisplay();
     }
 
     /**
@@ -1128,4 +1130,182 @@ public class GameActivity extends SDLActivity {
             return applicationInfo.sourceDir + "!/lib/" + abi + "/?.so";
         }
     }
+
+    // Dual-screen: mirror the engine's bottom-screen canvas onto a secondary
+    // physical display. Driven from the engine through love_android_secondary_*
+    // in src/jni/love/src/common/android.cpp.
+    private static volatile SecondaryPresentation secondaryPresentation;
+    private static volatile boolean secondaryEnabled = false;
+
+    @Keep
+    public static void setSecondaryEnabled(final boolean on) {
+        secondaryEnabled = on;
+        final GameActivity self = (GameActivity) mSingleton;
+        if (self == null) return;
+        self.runOnUiThread(new Runnable() {
+            @Override public void run() {
+                if (on) setupSecondaryDisplay(); else teardownSecondaryDisplay();
+            }
+        });
+    }
+
+    private static void setupSecondaryDisplay() {
+        GameActivity self = (GameActivity) mSingleton;
+        if (self == null || !secondaryEnabled || secondaryPresentation != null) return;
+        try {
+            android.hardware.display.DisplayManager dm =
+                (android.hardware.display.DisplayManager) self.getSystemService(Context.DISPLAY_SERVICE);
+            if (dm == null) return;
+            Display chosen = null;
+            for (Display d : dm.getDisplays()) {
+                android.graphics.Point size = new android.graphics.Point();
+                d.getRealSize(size);
+                Log.d("GameActivity", "display id=" + d.getDisplayId() + " name=" + d.getName()
+                    + " size=" + size.x + "x" + size.y);
+                if (chosen == null && d.getDisplayId() != Display.DEFAULT_DISPLAY) {
+                    chosen = d;
+                }
+            }
+            if (chosen == null) {
+                Display[] pres =
+                    dm.getDisplays(android.hardware.display.DisplayManager.DISPLAY_CATEGORY_PRESENTATION);
+                if (pres != null && pres.length > 0) chosen = pres[0];
+            }
+            if (chosen == null) {
+                Log.d("GameActivity", "no secondary display found");
+                return;
+            }
+            SecondaryPresentation p = new SecondaryPresentation(self, chosen);
+            p.show();
+            secondaryPresentation = p;
+            Log.d("GameActivity", "secondary display presentation started on id=" + chosen.getDisplayId());
+        } catch (Throwable t) {
+            Log.d("GameActivity", "secondary display setup failed: " + t);
+            secondaryPresentation = null;
+        }
+    }
+
+    private static void teardownSecondaryDisplay() {
+        SecondaryPresentation p = secondaryPresentation;
+        secondaryPresentation = null;
+        if (p != null) {
+            try { p.dismiss(); } catch (Throwable t) {}
+        }
+    }
+
+    @Keep
+    public static boolean hasSecondaryDisplay() {
+        return secondaryPresentation != null;
+    }
+
+    @Keep
+    public static void updateSecondaryFrame(java.nio.ByteBuffer buf, int w, int h) {
+        SecondaryPresentation p = secondaryPresentation;
+        if (p != null && buf != null && w > 0 && h > 0) {
+            p.updateFrame(buf, w, h);
+        }
+    }
+
+    private static class SecondaryPresentation extends android.app.Presentation {
+        private final FrameView frameView;
+
+        SecondaryPresentation(Context context, Display display) {
+            super(context, display);
+            frameView = new FrameView(context);
+        }
+
+        @Override
+        protected void onCreate(Bundle savedInstanceState) {
+            super.onCreate(savedInstanceState);
+            android.view.Window w = getWindow();
+            if (w != null) {
+                w.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN
+                    | WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS,
+                    WindowManager.LayoutParams.FLAG_FULLSCREEN
+                    | WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
+                w.setLayout(WindowManager.LayoutParams.MATCH_PARENT,
+                    WindowManager.LayoutParams.MATCH_PARENT);
+            }
+            setContentView(frameView);
+            applyImmersive();
+            frameView.post(new Runnable() {
+                @Override public void run() { applyImmersive(); }
+            });
+        }
+
+        @Override
+        public void onWindowFocusChanged(boolean hasFocus) {
+            super.onWindowFocusChanged(hasFocus);
+            if (hasFocus) applyImmersive();
+        }
+
+        private void applyImmersive() {
+            android.view.Window w = getWindow();
+            if (w == null) return;
+            if (android.os.Build.VERSION.SDK_INT >= 30) {
+                w.setDecorFitsSystemWindows(false);
+                android.view.WindowInsetsController c = w.getInsetsController();
+                if (c != null) {
+                    c.hide(android.view.WindowInsets.Type.systemBars());
+                    c.setSystemBarsBehavior(
+                        android.view.WindowInsetsController.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE);
+                }
+            } else {
+                w.getDecorView().setSystemUiVisibility(
+                    android.view.View.SYSTEM_UI_FLAG_LAYOUT_STABLE
+                    | android.view.View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
+                    | android.view.View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
+                    | android.view.View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
+                    | android.view.View.SYSTEM_UI_FLAG_FULLSCREEN
+                    | android.view.View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);
+            }
+        }
+
+        void updateFrame(java.nio.ByteBuffer buf, int w, int h) {
+            frameView.updateFrame(buf, w, h);
+        }
+    }
+
+    private static class FrameView extends View {
+        private android.graphics.Bitmap bitmap;
+        private final android.graphics.Rect dst = new android.graphics.Rect();
+        private final android.graphics.Paint paint = new android.graphics.Paint();
+        private final Object lock = new Object();
+        private int fw, fh;
+
+        FrameView(Context context) {
+            super(context);
+            paint.setFilterBitmap(false);
+            paint.setAntiAlias(false);
+            setBackgroundColor(0xFF000000);
+        }
+
+        void updateFrame(java.nio.ByteBuffer buf, int w, int h) {
+            synchronized (lock) {
+                if (bitmap == null || fw != w || fh != h) {
+                    if (bitmap != null) bitmap.recycle();
+                    bitmap = android.graphics.Bitmap.createBitmap(w, h, android.graphics.Bitmap.Config.ARGB_8888);
+                    fw = w; fh = h;
+                }
+                buf.rewind();
+                bitmap.copyPixelsFromBuffer(buf);
+            }
+            postInvalidate();
+        }
+
+        @Override
+        protected void onDraw(android.graphics.Canvas canvas) {
+            synchronized (lock) {
+                if (bitmap == null || fw == 0 || fh == 0) return;
+                int vw = getWidth(), vh = getHeight();
+                int s = Math.min(vw / fw, vh / fh);
+                if (s < 1) s = 1;
+                int dw = fw * s, dh = fh * s;
+                int dx = (vw - dw) / 2, dy = (vh - dh) / 2;
+                dst.set(dx, dy, dx + dw, dy + dh);
+                canvas.drawColor(0xFF000000);
+                canvas.drawBitmap(bitmap, null, dst, paint);
+            }
+        }
+    }
 }

src/render/Renderer.lua

@@ -474,6 +474,41 @@ local function withTrueColor(zoneList, pass)
   return merged
 end
 
+-- Palette-correct blit of `canvas` at (sx, sy) LOVE-unit scales into origin
+-- (bx, by), scissored to the (boxX, boxY, boxW, boxH) screen rect.  zoneSx/
+-- zoneSy convert zone coords (canvas-space) into screen units.  Public so a
+-- render.compose mod can composite the world/UI canvases into its own layout.
+function Renderer:blitCanvas(canvas, sx, sy, zoneList, zoneSx, zoneSy,
+                             bx, by, boxX, boxY, boxW, boxH, dpiX, dpiY)
+  local shader = zoneList and zoneList[1] and PaletteFX.shader() or nil
+  if not shader then
+    love.graphics.setScissor(boxX, boxY, boxW, boxH)
+    love.graphics.draw(canvas, bx, by, 0, sx, sy)
+    love.graphics.setScissor()
+    return
+  end
+  love.graphics.setShader(shader)
+  -- a colors == false zone is the trueColor opt-out: its rect draws with
+  -- no shader at all.  Nothing sets one without a mod, so a vanilla zone
+  -- list never toggles and issues exactly the calls it always did.
+  local bare = false
+  for _, z in ipairs(zoneList) do
+    local plain = z.colors == false
+    if plain ~= bare then
+      bare = plain
+      love.graphics.setShader(not plain and shader or nil)
+    end
+    if not plain then PaletteFX.sendColors(shader, z.colors) end
+    if scissorClamped(bx + z.x * zoneSx, by + z.y * zoneSy,
+                      z.w * zoneSx, z.h * zoneSy,
+                      boxX, boxY, boxW, boxH, dpiX, dpiY) then
+      love.graphics.draw(canvas, bx, by, 0, sx, sy)
+    end
+  end
+  love.graphics.setScissor()
+  love.graphics.setShader()
+end
+
 -- zones: optional list of SGB palette regions (see PaletteFX) in
 -- 160x144 UI space, applied to the UI pass.  worldZones: optional
 -- regions in world-canvas pixels (overworld survey zoom colors each
@@ -506,6 +541,36 @@ function Renderer:endFrame(zones, worldZones)
   zones = withTrueColor(zones, "ui")
   worldZones = withTrueColor(worldZones, "world")
 
+  -- render.compose: hand a mod the finished world + UI canvases (and their
+  -- SGB zones), the frame metrics, Renderer:blitCanvas and the SecondScreen
+  -- bridge, letting it lay the two passes out however it likes -- e.g. as two
+  -- stacked Game Boy screens, or driving one onto a second physical display.
+  -- The mod returns true to take over the whole window; anything else (or no
+  -- mod wrapping the hook) falls through to the normal composite below.
+  if Runtime.wantsHook("render.compose") then
+    local ctx = {
+      renderer = self,
+      worldCanvas = self.worldCanvas, uiCanvas = self.canvas,
+      worldOverride = self.worldOverride,
+      worldActive = self.worldActive and true or false,
+      zones = zones, worldZones = worldZones,
+      ww = ww, wh = wh, pw = pw, ph = ph, ox = ox, oy = oy,
+      vpw = vpw, vph = vph, uiw = uiw, uih = uih,
+      scale = Sp, Sx = Sx, Sy = Sy, dpiX = dpiX, dpiY = dpiY,
+      secondScreen = require("src.render.SecondScreen"),
+    }
+    if Runtime.call("render.compose", function() return false end, self, ctx) == true then
+      self.worldActive = false
+      self.uprightActive = false
+      self.worldOverride = nil
+      PaletteFX.setPass(nil)
+      return {
+        width = ww, height = wh, gameX = ox, gameY = oy,
+        gameWidth = vpw, gameHeight = vph, scale = Sp, dpiX = dpiX, dpiY = dpiY,
+      }
+    end
+  end
+
   -- A post-process pipeline needs the whole composite in a canvas for the
   -- same reason GBC FX does, so either one alone is enough to take the
   -- present path; with neither, the frame draws straight to the screen
@@ -560,38 +625,12 @@ function Renderer:endFrame(zones, worldZones)
     })
   end
 
-  -- blit `canvas` at (sx, sy) LOVE-unit scales into origin (bx, by),
-  -- scissored to the (boxX, boxY, boxW, boxH) screen rect.  zoneSx/zoneSy
-  -- convert zone coords (canvas-space) into screen units.
+  -- see Renderer:blitCanvas; bound here to the frame's dpi so the composite
+  -- call sites below stay unchanged.
   local function blit(canvas, sx, sy, zoneList, zoneSx, zoneSy,
                       bx, by, boxX, boxY, boxW, boxH)
-    local shader = zoneList and zoneList[1] and PaletteFX.shader() or nil
-    if not shader then
-      love.graphics.setScissor(boxX, boxY, boxW, boxH)
-      love.graphics.draw(canvas, bx, by, 0, sx, sy)
-      love.graphics.setScissor()
-      return
-    end
-    love.graphics.setShader(shader)
-    -- a colors == false zone is the trueColor opt-out: its rect draws with
-    -- no shader at all.  Nothing sets one without a mod, so a vanilla zone
-    -- list never toggles and issues exactly the calls it always did.
-    local bare = false
-    for _, z in ipairs(zoneList) do
-      local plain = z.colors == false
-      if plain ~= bare then
-        bare = plain
-        love.graphics.setShader(not plain and shader or nil)
-      end
-      if not plain then PaletteFX.sendColors(shader, z.colors) end
-      if scissorClamped(bx + z.x * zoneSx, by + z.y * zoneSy,
-                        z.w * zoneSx, z.h * zoneSy,
-                        boxX, boxY, boxW, boxH, dpiX, dpiY) then
-        love.graphics.draw(canvas, bx, by, 0, sx, sy)
-      end
-    end
-    love.graphics.setScissor()
-    love.graphics.setShader()
+    return self:blitCanvas(canvas, sx, sy, zoneList, zoneSx, zoneSy,
+                           bx, by, boxX, boxY, boxW, boxH, dpiX, dpiY)
   end
 
   if self.worldOverride then

src/render/SecondScreen.lua

@@ -0,0 +1,59 @@
+-- Bridge to native secondary-display output (Android Presentation). The C
+-- functions live in mobile/android/love/src/jni/love/src/common/android.cpp.
+-- Everything is guarded: off Android, or if the symbols cannot be resolved,
+-- this stays inert and the renderer keeps the in-window stacked layout.
+
+local SecondScreen = {}
+local C = nil
+
+local function log(msg)
+  pcall(function() require("src.core.Logger").info("SecondScreen: %s", msg) end)
+end
+
+do
+  local ok, ffi = pcall(require, "ffi")
+  if not (ok and ffi) then
+    log("ffi unavailable (not LuaJIT); second display disabled")
+  else
+    pcall(ffi.cdef, [[
+      int love_android_secondary_ready();
+      void love_android_push_secondary(const void *rgba, int w, int h);
+      void love_android_secondary_enable(int on);
+    ]])
+    local okLib, lib = pcall(ffi.load, "love")
+    if okLib and lib and pcall(function() return lib.love_android_secondary_ready end) then
+      C = lib
+      log("bridge linked via ffi.load('love')")
+    elseif pcall(function() return ffi.C.love_android_secondary_ready end) then
+      C = ffi.C
+      log("bridge linked via default namespace")
+    else
+      log(("bridge symbols not found (ffi.load ok=%s); second display disabled")
+        :format(tostring(okLib)))
+    end
+  end
+end
+
+function SecondScreen.usable()
+  return C ~= nil
+end
+
+function SecondScreen.available()
+  if not C then return false end
+  local ok, r = pcall(C.love_android_secondary_ready)
+  return ok and r ~= 0
+end
+
+function SecondScreen.push(imageData, w, h)
+  if not C or not imageData then return false end
+  return pcall(function()
+    C.love_android_push_secondary(imageData:getFFIPointer(), w, h)
+  end)
+end
+
+function SecondScreen.setEnabled(on)
+  if not C then return end
+  pcall(function() C.love_android_secondary_enable(on and 1 or 0) end)
+end
+
+return SecondScreen

tests/engine/render_compose_seam.lua

@@ -0,0 +1,62 @@
+-- Unit coverage for the render.compose seam (D14: a public-API test names
+-- the hook, gate_hooks supplies the no-mod parity, docs/modding.md documents
+-- it).  render.compose lets a mod take over window composition: a wrap that
+-- returns true without calling next owns the whole window; a wrap that calls
+-- next lets the engine's normal single-window composite run and decorates it.
+
+package.path = "./?.lua;./?/init.lua;" .. package.path
+
+local T = require("tests.modkit")
+local Runtime = require("src.mods.Runtime")
+local Hooks = require("src.mods.Hooks")
+
+local savedEvents, savedHooks = Runtime.events, Runtime.hooks
+local bus = Hooks.new()
+Runtime.hooks = bus
+
+-- the shape Renderer:endFrame hands the hook
+local function fakeCtx()
+  return {
+    renderer = {}, worldCanvas = {}, uiCanvas = {},
+    worldActive = true, zones = {}, worldZones = nil,
+    ww = 480, wh = 432, ox = 0, oy = 12, scale = 3,
+    dpiX = 1, dpiY = 1, secondScreen = {},
+  }
+end
+
+-- takeover: a mod drawing its own layout returns true and never calls next,
+-- so the engine's vanilla composite is skipped entirely
+do
+  local vanillaRan, gotCtx = false, nil
+  bus:wrap("render.compose", function(next, renderer, ctx)
+    gotCtx = ctx
+    return true
+  end, 0, "ds-mod")
+  local handled = Runtime.call("render.compose",
+    function() vanillaRan = true; return false end,
+    { tag = "renderer" }, fakeCtx())
+  T.eq(handled, true, "a mod returning true signals full window takeover")
+  T.eq(vanillaRan, false, "takeover skips the engine composite (vanilla not run)")
+  T.check(gotCtx ~= nil and gotCtx.ww == 480 and gotCtx.secondScreen ~= nil,
+    "the hook receives the frame ctx (metrics, canvases, secondScreen)")
+  bus.chains["render.compose"] = nil
+end
+
+-- decorate: a mod calling next lets the engine composite run, and the
+-- engine's not-handled return (false) flows back through the chain
+do
+  local vanillaRan = false
+  bus:wrap("render.compose", function(next, renderer, ctx)
+    return next()
+  end, 0, "ds-mod")
+  local handled = Runtime.call("render.compose",
+    function() vanillaRan = true; return false end,
+    { tag = "renderer" }, fakeCtx())
+  T.eq(vanillaRan, true, "calling next runs the engine composite")
+  T.eq(handled, false, "the engine's not-handled return flows back through next")
+  bus.chains["render.compose"] = nil
+end
+
+Runtime.events, Runtime.hooks = savedEvents, savedHooks
+
+T.finish("render_compose_seam")