ASCII sparklines generation API.

1 files changed, 172 insertions, 0 deletions

diff --git a/src/sparkline.c b/src/sparkline.c
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+++ b/src/sparkline.c
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+/* sparkline.c -- ASCII Sparklines
+ * This code is modified from http://github.com/antirez/aspark and adapted
+ * in order to return SDS strings instead of outputting directly to
+ * the terminal.
+ *
+ * ---------------------------------------------------------------------------
+ *
+ * Copyright(C) 2011-2014 Salvatore Sanfilippo <antirez@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "redis.h"
+
+#include <math.h>
+
+/* This is the charset used to display the graphs, but multiple rows are used
+ * to increase the resolution. */
+static char charset[] = "_-`";
+static char charset_fill[] = "_o#";
+static int charset_len = sizeof(charset)-1;
+static int label_margin_top = 1;
+
+/* ----------------------------------------------------------------------------
+ * Sequences are arrays of samples we use to represent data to turn
+ * into sparklines. This is the API in order to generate a sparkline:
+ *
+ * struct sequence *seq = createSparklineSequence();
+ * sparklineSequenceAddSample(seq, 10, NULL);
+ * sparklineSequenceAddSample(seq, 20, NULL);
+ * sparklineSequenceAddSample(seq, 30, "last sample label");
+ * sds output = sparklineRender(seq, 80, 4);
+ * freeSparklineSequence(seq);
+ * ------------------------------------------------------------------------- */
+
+/* Create a new sequence. */
+struct sequence *createSparklineSequence(void) {
+    struct sequence *seq = zmalloc(sizeof(*seq));
+    seq->length = 0;
+    seq->samples = NULL;
+    return seq;
+}
+
+/* Add a new sample into a sequence. */
+void sparklineSequenceAddSample(struct sequence *seq, double value, char *label) {
+    if (seq->length == 0) {
+        seq->min = seq->max = value;
+    } else {
+        if (value < seq->min) seq->min = value;
+        else if (value > seq->max) seq->max = value;
+    }
+    seq->samples = zrealloc(seq->samples,sizeof(struct sample)*(seq->length+1));
+    seq->samples[seq->length].value = value;
+    seq->samples[seq->length].label = label;
+    seq->length++;
+    if (label) seq->labels++;
+}
+
+/* Free a sequence. */
+void freeSparklineSequence(struct sequence *seq) {
+    zfree(seq->samples);
+    zfree(seq);
+}
+
+/* ----------------------------------------------------------------------------
+ * ASCII rendering of sequence
+ * ------------------------------------------------------------------------- */
+
+/* Render part of a sequence, so that render_sequence() call call this function
+ * with differnent parts in order to create the full output without overflowing
+ * the current terminal columns. */
+sds sparklineRenderRange(sds output, struct sequence *seq, int rows, int offset, int len, int flags) {
+    int j;
+    double relmax = seq->max - seq->min;
+    int steps = charset_len*rows;
+    int row = 0;
+    char *chars = zmalloc(len);
+    int loop = 1;
+    int opt_fill = flags & SPARKLINE_FILL;
+    int opt_log = flags & SPARKLINE_LOG_SCALE;
+
+    if (opt_log) {
+        relmax = log(relmax+1);
+    } else if (relmax == 0) {
+        relmax = 1;
+    }
+
+    while(loop) {
+        loop = 0;
+        memset(chars,' ',len);
+        for (j = 0; j < len; j++) {
+            struct sample *s = &seq->samples[j+offset];
+            double relval = s->value - seq->min;
+            int step;
+
+            if (opt_log) relval = log(relval+1);
+            step = (int) (relval*steps)/relmax;
+            if (step < 0) step = 0;
+            if (step >= steps) step = steps-1;
+
+            if (row < rows) {
+                /* Print the character needed to create the sparkline */
+                int charidx = step-((rows-row-1)*charset_len);
+                loop = 1;
+                if (charidx >= 0 && charidx < charset_len) {
+                    chars[j] = opt_fill ? charset_fill[charidx] :
+                                          charset[charidx];
+                } else if(opt_fill && charidx >= charset_len) {
+                    chars[j] = '|';
+                }
+            } else {
+                /* Labels spacing */
+                if (seq->labels && row-rows < label_margin_top) {
+                    loop = 1;
+                    break;
+                }
+                /* Print the label if needed. */
+                if (s->label) {
+                    int label_len = strlen(s->label);
+                    int label_char = row - rows - label_margin_top;
+
+                    if (label_len > label_char) {
+                        loop = 1;
+                        chars[j] = s->label[label_char];
+                    }
+                }
+            }
+        }
+        if (loop) {
+            row++;
+            output = sdscatlen(output,chars,len);
+            output = sdscatlen(output,"\n",1);
+        }
+    }
+    zfree(chars);
+    return output;
+}
+
+/* Turn a sequence into its ASCII representation */
+sds sparklineRender(struct sequence *seq, int columns, int rows, int flags) {
+    int j;
+    sds output = sdsempty();
+
+    for (j = 0; j < seq->length; j += columns) {
+        int sublen = (seq->length-j) < columns ? (seq->length-j) : columns;
+
+        if (j != 0) output = sdscatlen(output,"\n",1);
+        output = sparklineRenderRange(output, seq, rows, j, sublen, flags);
+    }
+    return output;
+}
+