adjust CssLength

CssLength now stores px and mm values as pure integers similar to
what dw::core::style::Length does.

1 files changed, 53 insertions, 6 deletions

diff --git a/src/css.hh b/src/css.hh
index ac9620dc..f948632f 100644
--- a/src/css.hh
+++ b/src/css.hh
@@ -51,14 +51,20 @@ typedef enum {
 /*
  * Lengths are represented as int in the following way:
  *
+ *    | <------   integer value   ------> |
+ *
+ *    +---+ - - - +---+---+- - - - - -+---+---+---+---+
+ *    |          integer part             |   type    |
  *    +---+ - - - +---+---+- - - - - -+---+---+---+---+
  *    | integer part  | decimal fraction  |   type    |
  *    +---+ - - - +---+---+- - - - - -+---+---+---+---+
- *     n-1          19  18              3   2  1   0
+ *     n-1          15  14              3   2  1   0
  *
  *    | <------ fixed point value ------> |
  *
  * where type is one of the CSS_LENGTH_TYPE_* values.
+ * CSS_LENGTH_TYPE_PX and CSS_LENGTH_TYPE_MM are stored as
+ * 29 bit signed integer, all other types as fixed point values.
  */
 
 typedef int CssLength;
@@ -76,17 +82,58 @@ typedef enum {
 } CssLengthType;
 
 inline CssLength CSS_CREATE_LENGTH (float v, CssLengthType t) {
-   return ((int) (v * (1 << 19)) & ~7 ) | t;
-}
-
-inline float CSS_LENGTH_VALUE (CssLength l) {
-   return  ((float)(l & ~7)) / (1 << 19);
+   static const int CSS_LENGTH_FRAC_MAX = (1 << (32 - 15 - 1)) - 1;
+   static const int CSS_LENGTH_INT_MAX = 1 << (32 - 4) - 1;
+   int iv;
+
+   switch (t) {
+   case CSS_LENGTH_TYPE_PX:
+   case CSS_LENGTH_TYPE_MM:
+      iv = (int) (v + 0.5);
+      if (iv > CSS_LENGTH_INT_MAX)
+         iv = CSS_LENGTH_INT_MAX;
+      else if (iv < -CSS_LENGTH_INT_MAX)
+         iv = -CSS_LENGTH_INT_MAX;
+      return iv << 3 | t;
+   case CSS_LENGTH_TYPE_EM:
+   case CSS_LENGTH_TYPE_EX:
+   case CSS_LENGTH_TYPE_PERCENTAGE:
+   case CSS_LENGTH_TYPE_RELATIVE:
+      if (v > CSS_LENGTH_FRAC_MAX)
+         v = CSS_LENGTH_FRAC_MAX;
+      else if (v < -CSS_LENGTH_FRAC_MAX)
+         v = -CSS_LENGTH_FRAC_MAX;
+      return ((int) (v * (1 << 15)) & ~7 ) | t;
+   case CSS_LENGTH_TYPE_AUTO:
+      return t;
+   default:
+      assert(false);
+      return CSS_LENGTH_TYPE_AUTO;
+   }
 }
 
 inline CssLengthType CSS_LENGTH_TYPE (CssLength l) {
    return (CssLengthType) (l & 7);
 }
 
+inline float CSS_LENGTH_VALUE (CssLength l) {
+   switch (CSS_LENGTH_TYPE(l)) {
+   case CSS_LENGTH_TYPE_PX:
+   case CSS_LENGTH_TYPE_MM:
+      return (float) (l >> 3);
+   case CSS_LENGTH_TYPE_EM:
+   case CSS_LENGTH_TYPE_EX:
+   case CSS_LENGTH_TYPE_PERCENTAGE:
+   case CSS_LENGTH_TYPE_RELATIVE:
+      return  ((float)(l & ~7)) / (1 << 15);
+   case CSS_LENGTH_TYPE_AUTO:
+      return 0.0;
+   default:
+      assert(false);
+      return 0.0;
+   }
+}
+
 typedef enum {
    CSS_PROPERTY_BACKGROUND_ATTACHMENT,
    CSS_PROPERTY_BACKGROUND_COLOR,