Merge pull request ThingPulse#43 from squix78/implement-print-class

Implement basic print interface

Author: squix78

OLEDDisplay.cpp

@@ -506,6 +506,111 @@ void OLEDDisplay::clear(void) {
   memset(buffer, 0, DISPLAY_BUFFER_SIZE);
 }
 
+void OLEDDisplay::drawLogBuffer(uint16_t xMove, uint16_t yMove) {
+  uint16_t lineHeight = pgm_read_byte(fontData + HEIGHT_POS);
+  // Always align left
+  setTextAlignment(TEXT_ALIGN_LEFT);
+
+  // State values
+  uint16_t length   = 0;
+  uint16_t line     = 0;
+  uint16_t lastPos  = 0;
+
+  for (uint16_t i=0;i<this->logBufferFilled;i++){
+    // Everytime we have a \n print
+    if (this->logBuffer[i] == 10) {
+      length++;
+      // Draw string on line `line` from lastPos to length
+      // Passing 0 as the lenght because we are in TEXT_ALIGN_LEFT
+      drawStringInternal(xMove, yMove + (line++) * lineHeight, &this->logBuffer[lastPos], length, 0);
+      // Remember last pos
+      lastPos = i;
+      // Reset length
+      length = 0;
+    } else {
+      // Count chars until next linebreak
+      length++;
+    }
+  }
+  // Draw the remaining string
+  if (length > 0) {
+    drawStringInternal(xMove, yMove + line * lineHeight, &this->logBuffer[lastPos], length, 0);
+  }
+}
+
+bool OLEDDisplay::setLogBuffer(uint16_t lines, uint16_t chars){
+  if (logBuffer != NULL) free(logBuffer);
+  uint16_t size = lines * chars;
+  if (size > 0) {
+    this->logBufferLine     = 0;      // Lines printed
+    this->logBufferMaxLines = lines;  // Lines max printable
+    this->logBufferSize     = size;   // Total number of characters the buffer can hold
+    this->logBuffer         = (char *) malloc(size * sizeof(uint8_t));
+    if(!this->logBuffer) {
+      DEBUG_OLEDDISPLAY("[OLEDDISPLAY][setLogBuffer] Not enough memory to create log buffer\n");
+      return false;
+    }
+  }
+  return true;
+}
+
+size_t OLEDDisplay::write(uint8_t c) {
+  if (this->logBufferSize > 0) {
+    // Don't waste space on \r\n line endings, dropping \r
+    if (c == 13) return 1;
+
+    bool maxLineNotReached = this->logBufferLine < this->logBufferMaxLines;
+    bool bufferNotFull = this->logBufferFilled < this->logBufferSize;
+
+    // Can we write to the buffer?
+    if (bufferNotFull && maxLineNotReached) {
+      this->logBuffer[logBufferFilled] = utf8ascii(c);
+      this->logBufferFilled++;
+      // Keep track of lines written
+      if (c == 10) this->logBufferLine++;
+    } else {
+      // Max line number is reached
+      if (!maxLineNotReached) this->logBufferLine--;
+
+      // Find the end of the first line
+      uint16_t firstLineEnd = 0;
+      for (uint16_t i=0;i<this->logBufferFilled;i++) {
+        if (this->logBuffer[i] == 10){
+          // Include last char too
+          firstLineEnd = i + 1;
+          break;
+        }
+      }
+      // If there was a line ending
+      if (firstLineEnd > 0) {
+        // Calculate the new logBufferFilled value
+        this->logBufferFilled = logBufferFilled - firstLineEnd;
+        // Now we move the lines infront of the buffer
+        memcpy(this->logBuffer, &this->logBuffer[firstLineEnd], logBufferFilled);
+      } else {
+        // Let's reuse the buffer if it was full
+        if (!bufferNotFull) {
+          this->logBufferFilled = 0;
+        }// else {
+        //  Nothing to do here
+        //}
+      }
+      write(c);
+    }
+  }
+  // We are always writing all uint8_t to the buffer
+  return 1;
+}
+
+size_t OLEDDisplay::write(const char* str) {
+  if (str == NULL) return 0;
+  size_t length = strlen(str);
+  for (size_t i = 0; i < length; i++) {
+    write(str[i]);
+  }
+  return length;
+}
+
 // Private functions
 void OLEDDisplay::sendInitCommands(void) {
   sendCommand(DISPLAYOFF);

OLEDDisplay.h

@@ -108,7 +108,7 @@ enum OLEDDISPLAY_TEXT_ALIGNMENT {
 };
 
 
-class OLEDDisplay {
+class OLEDDisplay : public Print {
   public:
     // Initialize the display
     bool init();
@@ -209,17 +209,39 @@ class OLEDDisplay {
     // Clear the local pixel buffer
     void clear(void);
 
+    // Log buffer implementation
+
+    // This will define the lines and characters you can
+    // print to the screen. When you exeed the buffer size (lines * chars)
+    // the output may be truncated due to the size constraint.
+    bool setLogBuffer(uint16_t lines, uint16_t chars);
+
+    // Draw the log buffer at position (x, y)
+    void drawLogBuffer(uint16_t x, uint16_t y);
+
+    // Implementent needed function to be compatible with Print class
+    size_t write(uint8_t c);
+    size_t write(const char* s);
+
     uint8_t            *buffer;
 
     #ifdef OLEDDISPLAY_DOUBLE_BUFFER
     uint8_t            *buffer_back;
     #endif
 
   protected:
+
     OLEDDISPLAY_TEXT_ALIGNMENT   textAlignment = TEXT_ALIGN_LEFT;
     OLEDDISPLAY_COLOR            color         = WHITE;
 
-    const char          *fontData          = ArialMT_Plain_10;
+    const char          *fontData              = ArialMT_Plain_10;
+
+    // State values for logBuffer
+    uint16_t   logBufferSize                   = 0;
+    uint16_t   logBufferFilled                 = 0;
+    uint16_t   logBufferLine                   = 0;
+    uint16_t   logBufferMaxLines               = 0;
+    char      *logBuffer                       = NULL;
 
     // Send a command to the display (low level function)
     virtual void sendCommand(uint8_t com);