Add baseline for pretty printing.

Change-Id: I77e76cb4b6191992137dd83f366006115ae65661

poincare/include/poincare/expression_layout.h

@@ -13,12 +13,14 @@ class ExpressionLayout {
     void draw(KDPoint point);
     KDPoint origin();
     KDSize size();
+    KDCoordinate baseline();
     void setParent(ExpressionLayout* parent);
   protected:
     virtual void render(KDPoint point) = 0;
     virtual KDSize computeSize() = 0;
     virtual ExpressionLayout * child(uint16_t index) = 0;
     virtual KDPoint positionOfChild(ExpressionLayout * child) = 0;
+    KDCoordinate m_baseline;
   private:
     KDPoint absoluteOrigin();
     //void computeLayout();//ExpressionLayout * parent, uint16_t childIndex);

poincare/src/layout/exponent_layout.cpp

@@ -9,6 +9,7 @@ ExponentLayout::ExponentLayout(ExpressionLayout * base_layout, ExpressionLayout
 ExpressionLayout(), m_base_layout(base_layout), m_exponent_layout(exponent_layout) {
   m_base_layout->setParent(this);
   m_exponent_layout->setParent(this);
+  m_baseline = m_exponent_layout->baseline() + m_base_layout->baseline() - EXPONENT_HEIGHT;
 }
 
 ExponentLayout::~ExponentLayout() {
@@ -44,7 +45,7 @@ KDPoint ExponentLayout::positionOfChild(ExpressionLayout * child) {
   KDPoint p;
   if (child == m_base_layout) {
     p.x = 0;
-    p.y = m_exponent_layout->size().height - EXPONENT_HEIGHT;
+    p.y = m_exponent_layout->baseline() - EXPONENT_HEIGHT;
   } else if (child == m_exponent_layout) {
     p.x = m_base_layout->size().width;
     p.y = 0;

poincare/src/layout/expression_layout.cpp

@@ -3,6 +3,7 @@
 #include "string_layout.h"
 
 ExpressionLayout::ExpressionLayout() :
+  m_baseline(0),
   m_parent(nullptr),
   m_sized(false),
   m_positioned(false),
@@ -12,6 +13,10 @@ ExpressionLayout::ExpressionLayout() :
 ExpressionLayout::~ExpressionLayout() {
 }
 
+KDCoordinate ExpressionLayout::baseline() {
+  return m_baseline;
+}
+
 KDPoint ExpressionLayout::origin() {
   if (m_parent == nullptr) {
     return absoluteOrigin();
@@ -26,11 +31,6 @@ void ExpressionLayout::draw(KDPoint point) {
     c->draw(point);
   }
   render(KDPointTranslate(absoluteOrigin(), point));
-#if 0
-  KDPoint topLeft = KDPointTranslate(absoluteOrigin(), point);
-  KDPoint bottomRight = KDPointTranslate(KDPointTranslate(absoluteOrigin(), KDPOINT(size().width, 0 /*size().height*/)), point);
-  KDDrawLine(topLeft, bottomRight);
-#endif
 }
 
 KDPoint ExpressionLayout::absoluteOrigin() {

poincare/src/layout/fraction_layout.cpp

@@ -14,6 +14,7 @@ FractionLayout::FractionLayout(ExpressionLayout * numerator_layout, ExpressionLa
 ExpressionLayout(), m_numerator_layout(numerator_layout), m_denominator_layout(denominator_layout) {
   m_numerator_layout->setParent(this);
   m_denominator_layout->setParent(this);
+  m_baseline = m_numerator_layout->size().height + FRACTION_LINE_MARGIN + KDStringSize(" ").height/2;
 }
 
 FractionLayout::~FractionLayout() {

poincare/src/layout/horizontal_layout.cpp

@@ -11,6 +11,9 @@ HorizontalLayout::HorizontalLayout(ExpressionLayout ** children_layouts, int num
   assert(number_of_children > 0);
   for (int i=0; i<m_number_of_children; i++) {
     m_children_layouts[i]->setParent(this);
+    if (m_children_layouts[i]->baseline() > m_baseline) {
+      m_baseline = m_children_layouts[i]->baseline();
+    }
   }
 }
 
@@ -26,13 +29,18 @@ void HorizontalLayout::render(KDPoint point) { }
 KDSize HorizontalLayout::computeSize() {
   KDSize size = (KDSize){.width = 0, .height = 0};
   int i = 0;
+  KDCoordinate max_under_baseline, max_above_baseline;
   while (ExpressionLayout * c = child(i++)) {
     KDSize childSize = c->size();
     size.width += childSize.width;
-    if (childSize.height > size.height) {
-      size.height = childSize.height;
+    if (childSize.height - c->baseline() > max_under_baseline) {
+      max_under_baseline = childSize.height - c->baseline() ;
+    }
+    if (c->baseline() > max_above_baseline) {
+      max_above_baseline = c->baseline();
     }
   }
+  size.height = max_under_baseline + max_above_baseline;
   return size;
 }
 
@@ -59,6 +67,6 @@ KDPoint HorizontalLayout::positionOfChild(ExpressionLayout * child) {
     assert(previousChild != nullptr);
     position.x = previousChild->origin().x + previousChild->size().width;
   }
-  position.y = (size().height - child->size().height)/2;
+  position.y = m_baseline - child->baseline();
   return position;
 }

poincare/src/layout/string_layout.cpp

@@ -8,6 +8,8 @@ ExpressionLayout() {
   m_string = (char *)malloc(sizeof(char)*(length+1));
   memcpy(m_string, string, (length+1));
   m_inverse = inverse;
+  // Height of the font.
+  m_baseline = KDStringSize(" ").height;
 }
 
 StringLayout::~StringLayout() {