EPD / OLED / LED panels: init without clear keeps the image on the panel

src/lgfx/v1/panel/Panel_GDEW0154D67.inl

@@ -185,9 +185,11 @@ epd_mode が epd_qualityか否かの変化をした場合も同様にCMD_DISPLAY
       if (_initialize_seq) {
         _initialize_seq = false;
         // リセット直後は起動シーケンス設定およびフレームバッファの転送を行う。ここではリフレッシュは行わない。
+        // Send the normal frame here: with the inverted one, the flip draw below ended inverted
+        // (white and black swapped) whenever this was the first display() after a reset.
         _bus->writeCommand(cmd_display_update_control_2, 8);
         _bus->writeData(0xF8, 8);
-        _exec_transfer(cmd_write_ram_bw, _range_mod, true);
+        _exec_transfer(cmd_write_ram_bw, _range_mod);
         _bus->writeCommand(cmd_master_activation, 8);
         _send_msec = millis();
       }
@@ -243,16 +245,23 @@ epd_mode が epd_qualityか否かの変化をした場合も同様にCMD_DISPLAY
   void Panel_GDEW0154D67::setInvert(bool invert)
   {
     if (_invert == invert && !_initialize_seq) { return; }
+    const bool changed = (_invert != invert);
     _invert = invert;
     startWrite();
     _wait_busy();
     _bus->writeCommand(cmd_display_update_control_1, 8);
     _bus->writeData((invert ^ _cfg.invert) ? 0x88 : 0x00, 8);
-    _need_flip_draw = true;
-    _range_mod.top = 0;
-    _range_mod.left = 0;
-    _range_mod.right = _width - 1;
-    _range_mod.bottom = _height - 1;
+    // Re-applying the current value right after a reset (LGFX_Device::init_impl does) must not mark
+    // the frame dirty: the first display() sends the whole frame anyway, and a refresh here would wipe
+    // the image kept on the panel (init without clear). A changed value is still shown at once.
+    if (changed || !_initialize_seq)
+    {
+      _need_flip_draw = true;
+      _range_mod.top = 0;
+      _range_mod.left = 0;
+      _range_mod.right = _width - 1;
+      _range_mod.bottom = _height - 1;
+    }
     endWrite();
   }
 

src/lgfx/v1/panel/Panel_M5UnitGLASS.inl

@@ -24,6 +24,8 @@ Contributors:
 #include "../misc/pixelcopy.hpp"
 #include "../misc/colortype.hpp"
 
+#include <string.h>
+
 namespace lgfx
 {
  inline namespace v1
@@ -36,6 +38,11 @@ namespace lgfx
     {
       return false;
     }
+    // Panel_HasBuffer::init leaves the buffer uninitialized, and the per-tile dirty flags are only
+    // ever OR-ed / cleared in display(); both must start known for the first display() after an init
+    // without clear to send just what was drawn.
+    memset(_buf, 0, _get_buffer_length());
+    memset(_modified_flags, 0, sizeof(_modified_flags));
 
     bool connected = false;
     uint8_t res = 0xFFu;

src/lgfx/v1/panel/Panel_SSD1306.inl

@@ -24,6 +24,8 @@ Contributors:
 #include "../misc/pixelcopy.hpp"
 #include "../misc/dither.hpp"
 
+#include <string.h>
+
 #ifdef min
 #undef min
 #endif
@@ -70,6 +72,10 @@ namespace lgfx
     {
       return false;
     }
+    // Panel_HasBuffer::init does not clear the allocated buffer. Nothing is pushed here, so the image
+    // on the panel survives an init without clear; the first display() then sends a known buffer
+    // (black) around the drawn area instead of whatever the allocator left in it.
+    memset(_buf, 0, _get_buffer_length());
 
     startWrite(true);
     _bus->beginRead();

src/lgfx/v1/panel/Panel_SSD1677.inl

@@ -439,6 +439,9 @@ namespace lgfx
 
   void Panel_SSD1677::setInvert(bool invert)
   {
+    // Right after a reset the first display() sends the whole frame anyway; marking it dirty here
+    // would make init() refresh the panel and wipe the image kept on it (init without clear).
+    if (_invert == invert && _initialize_seq) { return; }
     _invert = invert;
     _range_mod.top = 0;
     _range_mod.left = 0;

src/lgfx/v1/panel/Panel_TM1680.inl

@@ -38,18 +38,18 @@ namespace lgfx
     {
       return false;
     }
-    // Panel_HasBuffer::init does not clear the allocated buffer;
-    // clear it here so setInvert below does not push garbage to the LEDs.
+    // Panel_HasBuffer::init does not clear the allocated buffer.
     memset(_buf, 0, _get_buffer_length());
 
+    // The init commands do not touch the LED RAM, and nothing is pushed here, so the
+    // image on the LEDs survives init() (init without clear keeps it until the first draw).
     startWrite(true);
     for (size_t i = 0; auto cmds = getInitCommands(i); i++)
     {
       size_t idx = 0;
       while (cmds[idx] != 0xFF || cmds[idx + 1] != 0xFF) ++idx;
       if (idx) { _bus->writeBytes(cmds, idx, false, true); }
     }
-    setInvert(_invert);
     setRotation(_rotation);
     endWrite();
 
@@ -58,8 +58,11 @@ namespace lgfx
 
   void Panel_TM1680::setInvert(bool invert)
   {
-    _invert = invert;
     // The TM1680 has no display-invert command; invert while packing in display().
+    // Only a change is pushed: LGFX_Device::init_impl() re-applies the current value,
+    // and pushing the cleared buffer there would wipe the LEDs on init without clear.
+    if (_invert == invert) { return; }
+    _invert = invert;
     if (_buf)
     {
       startWrite();