feat(screen): stream the display framebuffer to local clients (DisplayFrame mirroring)

src/configuration.h

@@ -673,6 +673,20 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #endif
 #endif
 
+// Display mirroring to local clients (FromRadio.display_frame).
+#if HAS_SCREEN && !(MESHTASTIC_EXCLUDE_SCREEN_MIRROR)
+#define HAS_SCREEN_MIRROR 1
+#else
+#define HAS_SCREEN_MIRROR 0
+#endif
+
+// MUI streams RGB565 dirty rects and needs a device-ui carrying DisplayMirror, so it is opt-in.
+#if HAS_SCREEN_MIRROR && HAS_TFT && defined(MESHTASTIC_MUI_MIRROR)
+#define HAS_MUI_MIRROR 1
+#else
+#define HAS_MUI_MIRROR 0
+#endif
+
 #ifndef USE_ETHERNET_DEFAULT
 #define USE_ETHERNET_DEFAULT 0
 #endif

src/graphics/HUB75Display.cpp

@@ -3,6 +3,7 @@
 #if defined(USE_HUB75)
 
 #include "HUB75Display.h"
+#include "ScreenMirror.h"
 #include "TFTColorRegions.h"
 #include "TFTPalette.h"
 #include <ESP32-HUB75-MatrixPanel-I2S-DMA.h>
@@ -121,6 +122,9 @@ void HUB75Display::display()
     firstFrame = false;
 #if GRAPHICS_TFT_COLORING_ENABLED
     lastColorSig = colorSig;
+#if HAS_SCREEN_MIRROR
+    graphics::screenMirror.capturePalette(colorSig, onBe, offBe, graphics::colorRegions, graphics::getTFTColorRegionCount());
+#endif
     // Regions are re-registered every frame by the renderers; clear so they
     // don't accumulate across frames.
     graphics::clearTFTColorRegions();

src/graphics/Screen.cpp

@@ -23,6 +23,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "Screen.h"
 #include "NodeDB.h"
 #include "PowerMon.h"
+#include "ScreenMirror.h"
 #include "Throttle.h"
 #include "UptimeClock.h"
 #include "configuration.h"
@@ -182,6 +183,15 @@ static void drawLockdownLockScreen(OLEDDisplay *display)
 }
 #endif
 
+// Hands ScreenMirror the committed framebuffer; a no-op unless a client is armed.
+static inline void screenMirrorCapture()
+{
+#if HAS_SCREEN_MIRROR
+    if (screen)
+        screenMirror.onRendered(screen->getDisplayDevice());
+#endif
+}
+
 static inline void updateUiFrame(OLEDDisplayUi *ui)
 {
 #ifdef MESHTASTIC_LOCKDOWN
@@ -209,13 +219,15 @@ static inline void updateUiFrame(OLEDDisplayUi *ui)
             NotificationRenderer::drawBannercallback(display, ui->getUiState());
         }
         display->display();
+        screenMirrorCapture(); // the locked frame, matching the panel's redaction
         return;
     }
 #endif
 #if GRAPHICS_TFT_COLORING_ENABLED
     prepareFrameColorRegions();
 #endif
     ui->update();
+    screenMirrorCapture();
 }
 // Global variables for alert banner - explicitly define with extern "C" linkage to prevent optimization
 
@@ -1230,6 +1242,11 @@ int32_t Screen::runOnce()
 
     if (!screenOn) { // If we didn't just wake and the screen is still off, then
                      // stop updating until it is on again
+#ifdef MESHTASTIC_LOCKDOWN
+        // the last committed frame may predate the lock
+        if (!meshtastic_security::shouldRedactDisplay())
+#endif
+            screenMirrorCapture(); // a request while off still gets the last committed frame
         textMessageFrameShown = false;
         enabled = false;
         return 0;

src/graphics/Screen.h

@@ -428,6 +428,9 @@ class Screen : public concurrency::OSThread
         enqueueCmd(ScreenCmd{.cmd = Cmd::NOOP});
     }
 
+    /// Runs the screen thread once without touching the display; safe from any task.
+    void kick() { enqueueCmd(ScreenCmd{.cmd = Cmd::NOOP}); }
+
     /// Overrides the default utf8 character conversion, to replace empty space with question marks
     static char customFontTableLookup(const uint8_t ch)
     {