Support basic text extraction, minor speedup by caching xref portion of stream object streams

Author: PerditionC

dist/CombinePDF.xlsm

@@ -1025,7 +1025,7 @@ Public Function loadPdf(ByVal pdfFilename As String) As Boolean
     ' root obj of PDF
     Set rootCatalog = GetRootObject(content, trailer, xrefTable)
     Debug.Print BytesToString(rootCatalog.serialize())
-    objectCache.Add rootCatalog.id, rootCatalog
+    'If Not objectCache.Exists(rootCatalog.ID) Then objectCache.Add rootCatalog.ID, rootCatalog
 
     loadPdf = True ' success
     Exit Function
@@ -1507,7 +1507,7 @@ Private Function GetValueType(ByRef bytes() As Byte, ByVal offset As Long, Optio
 
         Case Else
             GetValueType = PDF_ValueType.PDF_Null
-            Stop ' error! unexpected value
+            'Stop ' error! unexpected value
     End Select
 
     Exit Function

src/pdfLib.xlsm/Class Modules/pdfDocument.cls

@@ -16,6 +16,8 @@ Public stream_data As pdfValue ' PDF_StreamData
 ' stream data may be compressed, on first access we to uncompressed data we decompress and cache results
 Private m_udata() As Byte
 Private decompressed As Boolean
+' first time we extract embedded reference table, but use cache'd version on future loadObject calls
+Public embXRefTable As Dictionary
 
 
 ' returns size of data(), but warns if differs from value of meta /Length property
@@ -196,10 +198,12 @@ End Sub
 Public Sub Class_Initialize()
     Set stream_meta = New pdfValue
     stream_meta.valueType = PDF_ValueType.PDF_Null
+    Set embXRefTable = Nothing  ' indicates not yet loaded
 End Sub
 
 Public Sub Class_Terminate()
     Set stream_meta = Nothing
     Set stream_data = Nothing
     Erase m_udata
+    Set embXRefTable = Nothing
 End Sub

src/pdfLib.xlsm/Class Modules/pdfStream.cls

@@ -0,0 +1,15 @@
+VERSION 5.00
+Begin {C62A69F0-16DC-11CE-9E98-00AA00574A4F} UserForm2 
+   Caption         =   "UserForm1"
+   ClientHeight    =   9045.001
+   ClientLeft      =   120
+   ClientTop       =   465
+   ClientWidth     =   13125
+   OleObjectBlob   =   "UserForm2.frx":0000
+   StartUpPosition =   1  'CenterOwner
+End
+Attribute VB_Name = "UserForm2"
+Attribute VB_GlobalNameSpace = False
+Attribute VB_Creatable = False
+Attribute VB_PredeclaredId = True
+Attribute VB_Exposed = False

src/pdfLib.xlsm/Forms/UserForm2.frm

@@ -4,12 +4,17 @@ Option Explicit
 
 
 Sub TestReadingText()
-    Const basedir As String = "C:\Users\jeremyd\Downloads\pdf-association.pdf20examples\"
+    Const basedir As String = "C:\Users\jeremyd\Downloads\"
+    'Const fname As String = "pdf-association.pdf20examples\pdf20-utf8-test.pdf"
+    Const fname As String = "weird_spaces.pdf"
     Dim pdfDoc As pdfDocument
-    Set pdfDoc = pdfDocument.pdfDocument(basedir & "pdf20-utf8-test.pdf")
+    Set pdfDoc = pdfDocument.pdfDocument(basedir & fname)
     Dim text As String
     text = pdfDoc.GetDocumentText()
     Debug.Print text
+    Dim uf As UserForm2: Set uf = New UserForm2
+    uf.Label1.Caption = pdfDoc.Title & vbNewLine & text
+    uf.Show
 End Sub
 
 Sub TestBookmarkEditor()

src/pdfLib.xlsm/Forms/UserForm2.frx

@@ -15,17 +15,53 @@ Public Enum PdfTextOp
     opT_D = 7           ' TD Move text position and set leading
     opTm = 8            ' Tm Set text matrix
     opTStar = 9         ' T* Move to start of next line
+    
+    opTextObjectBegin   ' BT
+    opTextObjectEnd     ' ET
 End Enum
 
+
+Type Rectangle
+    Left As Double
+    Bottom As Double
+    Right As Double
+    Top As Double
+End Type
+
+Type FontState
+    FontName  As String
+    FontSize  As Double
+    IsBold    As Boolean
+    IsItalic  As Boolean
+End Type
+
+Type TextState
+    Font As FontState
+    TextMatrix(0 To 5) As Double        'Current text matrix [a b c d e f]
+    LineMatrix(0 To 5) As Double        'Text line matrix
+    CTM(0 To 5) As Double               'Current transformation matrix
+    CharSpacing As Double               'Tc
+    WordSpacing As Double               'Tw
+    HorizontalScaling As Double         'Tz (as percentage)
+    Leading As Double                   'TL
+    TextRise As Double                  'Ts
+End Type
+
 'Represents a visible text run with position & styling
 Type TextFragment
     text      As String
-    x         As Double           'User-space coordinates
-    Y         As Double
-    fontName  As String
-    fontSize  As Double
-    IsBold    As Boolean
-    IsItalic  As Boolean
+    x         As Double         ' User-space coordinates
+    y         As Double
+    state     As TextState
+    BoundingBox As Rectangle    ' of just this chunk of text, user-space coordinates
+End Type
+
+'Represents a chunk of text (quasi paragraph)
+Type TextBlock
+    text As String
+    BoundingBox As Rectangle    ' of all Fragments
+    StartState As TextState
+    Fragments() As TextFragment ' Collection of TextFragment
 End Type
 
 'Logical-structure element (see §10.7 PDF 1.7)