added double buffering to prevent tearning

[Arduino] / Hub08_LedMatrix / LEDMatrix.cpp

diff --git a/Hub08_LedMatrix/LEDMatrix.cpp b/Hub08_LedMatrix/LEDMatrix.cpp
index 133cfb2..8cae64e 100644 (file)
--- a/Hub08_LedMatrix/LEDMatrix.cpp
+++ b/Hub08_LedMatrix/LEDMatrix.cpp
@@ -47,6 +47,7 @@ LEDMatrix::LEDMatrix(uint8_t a, uint8_t b, uint8_t c, uint8_t d, uint8_t oe, uin
 #if USE_SPI
        SPI.begin();
 #endif
+       buffer = 0;
 }
 
 void LEDMatrix::begin(uint8_t *displaybuf, uint16_t width, uint16_t height)
@@ -135,6 +136,9 @@ void LEDMatrix::scan()
     }
 
     uint8_t *head = displaybuf + row * (width / 8);
+
+    if ( buffer ) head += (width/8) * height;
+
     for (uint8_t line = 0; line < (height / 16); line++) {
         uint8_t *ptr = head;
         head += width * 2;              // width * 16 / 8
@@ -173,6 +177,18 @@ void LEDMatrix::scan()
     row = (row + 1) & 0x0F;
 }
 
+uint8_t *LEDMatrix::offscreen_buffer()
+{
+       uint8_t *buff = displaybuf;
+       if ( ! buffer ) buff += (width/8) * height;
+       return buff;
+}
+
+void LEDMatrix::swap()
+{
+    buffer = ! buffer;
+}
+
 void LEDMatrix::on()
 {
     state = 1;