From 6d0361ae0892952fad46bc1838cfed37f9533b49 Mon Sep 17 00:00:00 2001
From: Fabrice Weinberg <Fabrice@weinberg.me>
Date: Sun, 10 Jan 2016 20:12:37 +0100
Subject: [PATCH] Improve drawStringMax performance
---
SSD1306.cpp | 50 +++++++++++++++++++++++++++++++++-----------------
SSD1306.h | 8 ++------
2 files changed, 35 insertions(+), 23 deletions(-)
diff --git a/SSD1306.cpp b/SSD1306.cpp
index 2d13709..1c23328 100644
--- a/SSD1306.cpp
+++ b/SSD1306.cpp
@@ -297,29 +297,45 @@ void SSD1306::drawString(int16_t xMove, int16_t yMove, String strUser) {
free(text);
}
-void SSD1306::drawStringMaxWidth(int16_t x, int16_t y, int16_t maxLineWidth, String text) {
- uint16_t startsAt = 0;
- uint16_t endsAt = 0;
- uint16_t lineNumber = 0;
+void SSD1306::drawStringMaxWidth(int16_t xMove, int16_t yMove, uint16_t maxLineWidth, String strUser) {
+ uint16_t firstChar = pgm_read_byte(fontData + FIRST_CHAR_POS);
uint16_t lineHeight = pgm_read_byte(fontData + HEIGHT_POS);
- String currentLine = "";
- uint16_t length = text.length();
+
+ char* text = utf8ascii(strUser);
+
+ uint16_t length = strlen(text);
+ uint16_t lastDrawnPos = 0;
+ uint16_t lineNumber = 0;
+ uint16_t strWidth = 0;
+
+ uint16_t preferredBreakpoint = 0;
+ uint16_t widthAtBreakpoint = 0;
+
for (uint16_t i = 0; i < length; i++) {
- char currentChar = text.charAt(i);
- if (currentChar == ' ' || currentChar == '-') {
- String lineCandidate = text.substring(startsAt, i);
- if (getStringWidth(lineCandidate.c_str()) <= maxLineWidth) {
- endsAt = i;
- } else {
- drawString(x, y + lineNumber * lineHeight, text.substring(startsAt, endsAt));
- lineNumber++;
- startsAt = endsAt + 1;
- }
+ strWidth += pgm_read_byte(fontData + JUMPTABLE_START + (text[i] - firstChar) * JUMPTABLE_BYTES + JUMPTABLE_WIDTH);
+
+ // Always try to break on a space or dash
+ if (text[i] == ' ' || text[i]== '-') {
+ preferredBreakpoint = i;
+ widthAtBreakpoint = strWidth;
+ }
+
+ if (strWidth >= maxLineWidth) {
+ preferredBreakpoint = preferredBreakpoint ? preferredBreakpoint : i;
+ widthAtBreakpoint = preferredBreakpoint ? widthAtBreakpoint : strWidth;
+
+ drawStringInternal(xMove, yMove + (lineNumber++) * lineHeight , &text[lastDrawnPos], preferredBreakpoint - lastDrawnPos, widthAtBreakpoint);
+
+ lastDrawnPos = preferredBreakpoint + 1; strWidth = 0; preferredBreakpoint = 0;
}
+ }
+ // Draw last part if needed
+ if (lastDrawnPos < length) {
+ drawStringInternal(xMove, yMove + lineNumber * lineHeight , &text[lastDrawnPos], length - lastDrawnPos, getStringWidth(&text[lastDrawnPos], length - lastDrawnPos));
}
- drawString(x, y + lineNumber * lineHeight, text.substring(startsAt));
+ free(text);
}
uint16_t SSD1306::getStringWidth(const char* text, uint16_t length) {
diff --git a/SSD1306.h b/SSD1306.h
index 1878f88..ee9a7b8 100644
--- a/SSD1306.h
+++ b/SSD1306.h
@@ -132,7 +132,7 @@ class SSD1306 {
byte utf8ascii(byte ascii);
char* utf8ascii(String s);
- void drawInternal(int16_t xMove, int16_t yMove, int16_t width, int16_t height, const char *data, uint16_t offset, uint16_t bytesInData);
+ void drawInternal(int16_t xMove, int16_t yMove, int16_t width, int16_t height, const char *data, uint16_t offset, uint16_t bytesInData) __attribute__((always_inline));
void drawStringInternal(int16_t xMove, int16_t yMove, char* text, uint16_t textLength, uint16_t textWidth);
public:
@@ -186,11 +186,7 @@ class SSD1306 {
// Draws a String with a maximum width at the given location.
// If the given String is wider than the specified width
// The text will be wrapped to the next line at a space or dash
- void drawStringMaxWidth(int16_t x, int16_t y, int16_t maxLineWidth, String text);
-
- // Returns the width of the const char* with the current
- // font settings
- uint16_t getStringWidth(const char* text);
+ void drawStringMaxWidth(int16_t x, int16_t y, uint16_t maxLineWidth, String text);
// Specifies relative to which anchor point
// the text is rendered. Available constants:
--
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