From: Dobrica Pavlinusic <dpavlin@rot13.org>
Date: Fri, 1 Jan 2016 20:36:26 +0000 (+0100)
Subject: added double buffering to prevent tearning
X-Git-Url: http://git.rot13.org/?p=Arduino;a=commitdiff_plain;h=6bc2030a3b0a0a4c9dc7203a325fdfacdae55be6

added double buffering to prevent tearning
---

diff --git a/Hub08_LedMatrix/Hub08_LedMatrix.ino b/Hub08_LedMatrix/Hub08_LedMatrix.ino
index 1a207f5..ce96623 100644
--- a/Hub08_LedMatrix/Hub08_LedMatrix.ino
+++ b/Hub08_LedMatrix/Hub08_LedMatrix.ino
@@ -33,7 +33,7 @@
 LEDMatrix matrix(4, 5, 6, 7, 9,  11, 10,  13);
 
 // Display Buffer 128 = 64 * 16 / 8
-uint8_t displaybuf[(WIDTH/8) * HEIGHT];
+uint8_t displaybuf[(WIDTH/8) * HEIGHT*2];
 
 uint8_t displaybuf_w[((WIDTH/8)+1) * HEIGHT];
 
@@ -146,7 +146,7 @@ void loop()
 
 	for (int o=0; o<8; o++) {
 		uint8_t *src  = displaybuf_w + pos;
-		uint8_t *dest = displaybuf;
+		uint8_t *dest = matrix.offscreen_buffer();
 
 		int i = 0;
 
@@ -168,6 +168,7 @@ void loop()
 				i++;
 			}
                 }
+                matrix.swap();
           }
     }
 
diff --git a/Hub08_LedMatrix/LEDMatrix.cpp b/Hub08_LedMatrix/LEDMatrix.cpp
index 133cfb2..8cae64e 100644
--- 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;
diff --git a/Hub08_LedMatrix/LEDMatrix.h b/Hub08_LedMatrix/LEDMatrix.h
index 34cf7da..c8feb72 100644
--- a/Hub08_LedMatrix/LEDMatrix.h
+++ b/Hub08_LedMatrix/LEDMatrix.h
@@ -25,7 +25,7 @@
  #include <stdint.h>
 
 // use hardware SPI
-#define USE_SPI 1
+#define USE_SPI 0
 
 class LEDMatrix {
 public:
@@ -72,6 +72,10 @@ public:
      */
     void scan();
 
+    void swap();
+
+    uint8_t *offscreen_buffer();
+
     void reverse();
 
     uint8_t isReversed();
@@ -87,6 +91,7 @@ private:
     uint16_t height;
     uint8_t  mask;
     uint8_t  state;
+    uint8_t  buffer;
 };
 
 #endif