From 92f56445fe5238056123b24df2f438ce758cf2d6 Mon Sep 17 00:00:00 2001
From: Arthur Camouseigt <arthur.camouseigt@numworks.com>
Date: Wed, 6 May 2020 18:04:42 +0200
Subject: [PATCH] [poincare/sum_layout] Modified the way to draw sigma

New way of drawing sigma sign. Only a single branch is stored. The full
symbol is created by mirroring half a symbol.

Change-Id: I0fc32393203e51578c88b01125a907d402291534
---
 poincare/src/sum_layout.cpp | 93 +++++++++++++++++++++++--------------
 1 file changed, 58 insertions(+), 35 deletions(-)

diff --git a/poincare/src/sum_layout.cpp b/poincare/src/sum_layout.cpp
index 25244ae71..0c1051955 100644
--- a/poincare/src/sum_layout.cpp
+++ b/poincare/src/sum_layout.cpp
@@ -3,48 +3,72 @@
 #include <poincare/horizontal_layout.h>
 #include <algorithm>
 
+
+
 namespace Poincare {
-
-const uint8_t symbolPixel[SumLayoutNode::k_symbolHeight][SumLayoutNode::k_symbolWidth] = {
-  {0x70, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-  {0xF8, 0x2E, 0x9E, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xD5, 0x15, 0xDB, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0x95, 0x35, 0xFA, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFE, 0x4C, 0x7A, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xE9, 0x1B, 0xC0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xB7, 0x1F, 0xEE, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x6F, 0x56, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xF7, 0x2E, 0x9F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xD3, 0x16, 0xDB, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x93, 0x37, 0xFA, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE, 0x4B, 0x7B, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xE8, 0x1A, 0xC0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xB6, 0x20, 0xEF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x6D, 0x57, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x6D, 0x57, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xB6, 0x20, 0xEE, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xE8, 0x1A, 0xC0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE, 0x4B, 0x7A, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x93, 0x36, 0xFA, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xD3, 0x15, 0xDB, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xF7, 0x2E, 0x9F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x6F, 0x55, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xFF, 0xB7, 0x1E, 0xEE, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFF, 0xE9, 0x1B, 0xC0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0xFE, 0x4C, 0x79, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xFF, 0x95, 0x35, 0xFA, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xFF, 0xD5, 0x15, 0xDA, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0xF8, 0x2E, 0x9D, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
-  {0x71, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+// Stores a single branch of the sigma symbol
+// Data is stored so that every two line a white pixel must be added. This way the branch's slope is respected
+constexpr static int k_significantPixelWidth = 6;
+const uint8_t symbolPixelOneBranch[(SumLayoutNode::k_symbolHeight/2-1)*k_significantPixelWidth] = {
+  0xF8, 0x2E, 0x9E, 0xFF, 0xFF, 0xFF,
+  0xFF, 0xD5, 0x15, 0xDB, 0xFF, 0xFF,
+  0xFF, 0x95, 0x35, 0xFA, 0xFF, 0xFF,
+  0xFF, 0xFE, 0x4C, 0x7A, 0xFF, 0xFF,
+  0xFF, 0xE9, 0x1B, 0xC0, 0xFF, 0xFF,
+  0xFF, 0xFF, 0xB7, 0x1F, 0xEE, 0xFF,
+  0xFF, 0xFF, 0x6F, 0x56, 0xFF, 0xFF,
+  0xFF, 0xFF, 0xF7, 0x2E, 0x9F, 0xFF,
+  0xFF, 0xFF, 0xD3, 0x16, 0xDB, 0xFF,
+  0xFF, 0xFF, 0xFF, 0x93, 0x37, 0xFA,
+  0xFF, 0xFF, 0xFE, 0x4B, 0x7B, 0xFF,
+  0xFF, 0xFF, 0xFF, 0xE8, 0x1A, 0xC0,
+  0xFF, 0xFF, 0xFF, 0xB6, 0x20, 0xEF,
+  0xFF, 0xFF, 0xFF, 0xFF, 0x6D, 0x57,
 };
 
-
 int SumLayoutNode::serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const {
   return SequenceLayoutNode::writeDerivedClassInBuffer("sum", buffer, bufferSize, floatDisplayMode, numberOfSignificantDigits);
 }
 
 void SumLayoutNode::render(KDContext * ctx, KDPoint p, KDColor expressionColor, KDColor backgroundColor, Layout * selectionStart, Layout * selectionEnd, KDColor selectionColor) {
-  // Computes sizes.
+  // Creates half size sigma symbol from one branch
+  uint8_t symbolPixel[k_symbolHeight * k_symbolWidth];
+  int whiteOffset;
+
+  // Taking care of the first line which is a straight line
+  // First pixel is antialized
+  symbolPixel[0] = 0x70;
+  // The rest of the bar is black
+  for (int j = 1; j < k_symbolWidth; j++) {
+    symbolPixel[j] = 0x00;
+  }
+  static_assert(k_symbolHeight%2 == 0, "sum_layout : k_symbolHeight is not even");
+  for (int i = 1; i < k_symbolHeight/2; i++) {
+    // Adding the white offset
+    whiteOffset = (i-1)/2;
+    for (int j = 0; j < whiteOffset; j++) {
+      symbolPixel[i*k_symbolWidth + j] = 0xFF;
+    }
+
+    // Adding the actual pixels of the branch
+    for (int j = 0; j < k_significantPixelWidth; j++) {
+      symbolPixel[i*k_symbolWidth + whiteOffset + j] = symbolPixelOneBranch[(i-1)*k_significantPixelWidth + j];
+    }
+
+    // Filling the gap with white
+    for (int j = whiteOffset + k_significantPixelWidth  ; j < k_symbolWidth; j++) {
+      symbolPixel[i*k_symbolWidth + j] = 0xFF;
+    }
+  }
+
+  // Create real size sigma symbol by flipping the previous array
+  for (int i = k_symbolHeight/2; i < k_symbolHeight; i++) {
+    for (int j = 0; j < k_symbolWidth; j++) {
+      symbolPixel[i*k_symbolWidth + j] = symbolPixel[(k_symbolHeight-i-1)*k_symbolWidth +j];
+    }
+  }
+
+  // Compute sizes.
   KDSize upperBoundSize = upperBoundLayout()->layoutSize();
   KDSize lowerBoundNEqualsSize = lowerBoundSizeWithVariableEquals();
 
@@ -58,5 +82,4 @@ void SumLayoutNode::render(KDContext * ctx, KDPoint p, KDColor expressionColor,
   // Render the "n=" and the parentheses.
   SequenceLayoutNode::render(ctx, p, expressionColor, backgroundColor);
 }
-
 }