Fix text spacing with vertical fonts (mozilla#6387)

According to the PDF spec, a positive value means in horizontal, that the next glyph is further to the left (so narrower), and in vertical that it is further down (so wider). This change fixes the way PDF.js has interpreted the value.
CodingFabian · Aug 28, 2015 · 55188ef · 55188ef
1 parent c6ba5ea
commit 55188ef
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Showing 4 changed files with 24 additions and 7 deletions.
diff --git a/src/core/evaluator.js b/src/core/evaluator.js
@@ -1131,17 +1131,27 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
                 if (typeof items[j] === 'string') {
                   buildTextGeometry(items[j], textChunk);
                 } else {
+                  // PDF Specification 5.3.2 states:
+                  // The number is expressed in thousandths of a unit of text
+                  // space.
+                  // This amount is subtracted from the current horizontal or
+                  // vertical coordinate, depending on the writing mode.
+                  // In the default coordinate system, a positive adjustment
+                  // has the effect of moving the next glyph painted either to
+                  // the left or down by the given amount.
                   var val = items[j] / 1000;
-                  if (!textState.font.vertical) {
-                    offset = -val * textState.fontSize * textState.textHScale *
+                  if (textState.font.vertical) {
+                    offset = val * textState.fontSize * textState.textMatrix[3];
+                    // Value needs to added to height to paint down.
+                    textState.translateTextMatrix(0, offset);
+                    textChunk.height += offset;
+                  } else {
+                    offset = val * textState.fontSize * textState.textHScale *
                       textState.textMatrix[0];
+                    // Value needs to be subtracted from width to paint left.
+                    offset = -offset;
                     textState.translateTextMatrix(offset, 0);
                     textChunk.width += offset;
-                  } else {
-                    offset = -val * textState.fontSize *
-                      textState.textMatrix[3];
-                    textState.translateTextMatrix(0, offset);
-                    textChunk.height += offset;
                   }
                   if (items[j] < 0 && textState.font.spaceWidth > 0) {
                     var fakeSpaces = -items[j] / textState.font.spaceWidth;

diff --git a/test/pdfs/.gitignore b/test/pdfs/.gitignore
@@ -96,6 +96,7 @@
 !issue5747.pdf
 !issue6099.pdf
 !issue6336.pdf
+!issue6387.pdf
 !gradientfill.pdf
 !bug903856.pdf
 !bug850854.pdf

diff --git a/test/pdfs/issue6387.pdf b/test/pdfs/issue6387.pdf
diff --git a/test/test_manifest.json b/test/test_manifest.json
@@ -1521,6 +1521,12 @@
        "lastPage": 1,
        "type": "eq"
     },
+    {  "id": "issue6387",
+       "file": "pdfs/issue6387.pdf",
+       "md5": "08c39ac6d0aab1596e6e59793eaf3ee4",
+       "rounds": 1,
+       "type": "eq"
+    },
     {  "id": "issue4890",
        "file": "pdfs/issue4890.pdf",
        "md5": "1666feb4cd26318c2bdbea6a175dce87",