pdfviewer: (draft, not to be checked in, just for backup online) gs implementation

experimental/PdfViewer/SkPdfBasics.h

Index: experimental/PdfViewer/SkPdfBasics.h
===================================================================
--- experimental/PdfViewer/SkPdfBasics.h	(revision 10357)
+++ experimental/PdfViewer/SkPdfBasics.h	(working copy)
@@ -20,8 +20,28 @@
 
 // TODO(edisonn): better class design.
 struct SkPdfColorOperator {
+
+    /*
+    color space   name or array     The current color space in which color values are to be interpreted
+                                    (see Section 4.5, “Color Spaces”). There are two separate color space
+                                    parameters: one for stroking and one for all other painting opera-
+                                    tions. Initial value: DeviceGray.
+     */
+
+    // TODO(edisonn): implement the array part too
     // does not own the char*
     NotOwnedString fColorSpace;
+
+
+    /*
+    color         (various)         The current color to be used during painting operations (see Section
+                                    4.5, “Color Spaces”). The type and interpretation of this parameter
+                                    depend on the current color space; for most color spaces, a color
+                                    value consists of one to four numbers. There are two separate color
+                                    parameters: one for stroking and one for all other painting opera-
+                                    tions. Initial value: black.
+     */
+
     SkColor fColor;
     double fOpacity;  // ca or CA
     // TODO(edisonn): add here other color space options.
@@ -42,10 +62,7 @@
 
 // TODO(edisonn): better class design.
 struct SkPdfGraphicsState {
-    SkMatrix            fMatrix;
-    SkMatrix            fMatrixTm;
-    SkMatrix            fMatrixTlm;
-
+    // TODO(edisonn): deprecate and remove these!
     double              fCurPosX;
     double              fCurPosY;
 
@@ -55,6 +72,35 @@
     SkPath              fPath;
     bool                fPathClosed;
 
+
+
+    double              fTextLeading;
+    double              fWordSpace;
+    double              fCharSpace;
+
+    SkPdfResourceDictionary* fResources;
+
+
+    // TODO(edisonn): move most of these in canvas/paint?
+    // we could have some in canvas (matrixes?),
+    // some in 2 paints (stroking paint and non stroking paint)
+
+//    TABLE 4.2 Device-independent graphics state parameters
+/*
+ * CTM           array             The current transformation matrix, which maps positions from user
+                                coordinates to device coordinates (see Section 4.2, “Coordinate Sys-
+                                tems”). This matrix is modified by each application of the coordi-
+                                nate transformation operator, cm. Initial value: a matrix that
+                                transforms default user coordinates to device coordinates.
+ */
+    SkMatrix fCTM;
+
+/*
+clipping path (internal)        The current clipping path, which defines the boundary against
+                                which all output is to be cropped (see Section 4.4.3, “Clipping Path
+                                Operators”). Initial value: the boundary of the entire imageable
+                                portion of the output page.
+ */
     // Clip that is applied after the drawing is done!!!
     bool                fHasClipPathToApply;
     SkPath              fClipPath;
@@ -62,21 +108,208 @@
     SkPdfColorOperator  fStroking;
     SkPdfColorOperator  fNonStroking;
 
+/*
+text state    (various)         A set of nine graphics state parameters that pertain only to the
+                                painting of text. These include parameters that select the font, scale
+                                the glyphs to an appropriate size, and accomplish other effects. The
+                                text state parameters are described in Section 5.2, “Text State
+                                Parameters and Operators.”
+ */
+
+    // TODO(edisonn): add SkPdfTextState class. remove these two existing fields
+    SkMatrix            fMatrixTm;
+    SkMatrix            fMatrixTlm;
+
+
+/*
+line width    number            The thickness, in user space units, of paths to be stroked (see “Line
+                                Width” on page 152). Initial value: 1.0.
+ */
     double              fLineWidth;
-    double              fTextLeading;
-    double              fWordSpace;
-    double              fCharSpace;
 
-    SkPdfResourceDictionary* fResources;
 
+/*
+line cap      integer           A code specifying the shape of the endpoints for any open path that
+                                is stroked (see “Line Cap Style” on page 153). Initial value: 0, for
+                                square butt caps.
+ */
+    // TODO (edisonn): implement defaults - page 153
+    int fLineCap;
+
+/*
+line join     integer           A code specifying the shape of joints between connected segments
+                                of a stroked path (see “Line Join Style” on page 153). Initial value: 0,
+                                for mitered joins.
+ */
+    // TODO (edisonn): implement defaults - page 153
+    int fLineJoin;
+
+/*
+miter limit   number            The maximum length of mitered line joins for stroked paths (see
+                                “Miter Limit” on page 153). This parameter limits the length of
+                                “spikes” produced when line segments join at sharp angles. Initial
+                                value: 10.0, for a miter cutoff below approximately 11.5 degrees.
+ */
+    // TODO (edisonn): implement defaults - page 153
+    double fMiterLimit;
+
+/*
+dash pattern      array and     A description of the dash pattern to be used when paths are
+                  number        stroked (see “Line Dash Pattern” on page 155). Initial value: a solid
+                                line.
+ */
+    SkScalar fDashArray[256]; // TODO(edisonn): allocate array?
+    int fDashArrayLength;
+    SkScalar fDashPhase;
+
+
+/*
+rendering intent  name          The rendering intent to be used when converting CIE-based colors
+                                to device colors (see “Rendering Intents” on page 197). Default
+                                value: RelativeColorimetric.
+ */
+    // TODO(edisonn): seems paper only. Verify.
+
+/*
+stroke adjustment boolean       (PDF 1.2) A flag specifying whether to compensate for possible ras-
+                                terization effects when stroking a path with a line width that is
+                                small relative to the pixel resolution of the output device (see Sec-
+                                tion 6.5.4, “Automatic Stroke Adjustment”). Note that this is con-
+                                sidered a device-independent parameter, even though the details of
+                                its effects are device-dependent. Initial value: false.
+ */
+    // TODO(edisonn): stroke adjustment low priority.
+
+
+/*
+blend mode        name or array (PDF 1.4) The current blend mode to be used in the transparent
+                                imaging model (see Sections 7.2.4, “Blend Mode,” and 7.5.2, “Spec-
+                                ifying Blending Color Space and Blend Mode”). This parameter is
+                                implicitly reset to its initial value at the beginning of execution of a
+                                transparency group XObject (see Section 7.5.5, “Transparency
+                                Group XObjects”). Initial value: Normal.
+ */
+    SkXfermode::Mode fBlendMode;
+
+/*
+soft mask         dictionary    (PDF 1.4) A soft-mask dictionary (see “Soft-Mask Dictionaries” on
+                  or name       page 445) specifying the mask shape or mask opacity values to be
+                                used in the transparent imaging model (see “Source Shape and
+                                Opacity” on page 421 and “Mask Shape and Opacity” on page 443),
+                                or the name None if no such mask is specified. This parameter is
+                                implicitly reset to its initial value at the beginning of execution of a
+                                transparency group XObject (see Section 7.5.5, “Transparency
+                                Group XObjects”). Initial value: None.
+ */
     SkBitmap            fSMask;
 
+
+/*
+alpha constant    number        (PDF 1.4) The constant shape or constant opacity value to be used
+                                in the transparent imaging model (see “Source Shape and Opacity”
+                                on page 421 and “Constant Shape and Opacity” on page 444).
+                                There are two separate alpha constant parameters: one for stroking
+                                and one for all other painting operations. This parameter is implic-
+                                itly reset to its initial value at the beginning of execution of a trans-
+                                parency group XObject (see Section 7.5.5, “Transparency Group
+                                XObjects”). Initial value: 1.0.
+ */
+    double fAphaConstant;
+
+/*
+alpha source      boolean       (PDF 1.4) A flag specifying whether the current soft mask and alpha
+                                constant parameters are to be interpreted as shape values (true) or
+                                opacity values (false). This flag also governs the interpretation of
+                                the SMask entry, if any, in an image dictionary (see Section 4.8.4,
+                                “Image Dictionaries”). Initial value: false.
+ */
+    bool fAlphaSource;
+
+
+// TODO(edisonn): Device-dependent seem to be required only on the actual physical printer?
+//                       TABLE 4.3 Device-dependent graphics state parameters
+/*
+overprint          boolean            (PDF 1.2) A flag specifying (on output devices that support the
+                                      overprint control feature) whether painting in one set of colorants
+                                      should cause the corresponding areas of other colorants to be
+                                      erased (false) or left unchanged (true); see Section 4.5.6, “Over-
+                                      print Control.” In PDF 1.3, there are two separate overprint param-
+                                      eters: one for stroking and one for all other painting operations.
+                                      Initial value: false.
+ */
+
+
+/*
+overprint mode     number             (PDF 1.3) A code specifying whether a color component value of 0
+                                      in a DeviceCMYK color space should erase that component (0) or
+                                      leave it unchanged (1) when overprinting (see Section 4.5.6, “Over-
+                                      print Control”). Initial value: 0.
+ */
+
+
+/*
+black generation   function           (PDF 1.2) A function that calculates the level of the black color
+                   or name            component to use when converting RGB colors to CMYK (see Sec-
+                                      tion 6.2.3, “Conversion from DeviceRGB to DeviceCMYK”). Initial
+                                      value: installation-dependent.
+ */
+
+
+/*
+undercolor removal function           (PDF 1.2) A function that calculates the reduction in the levels of
+                   or name            the cyan, magenta, and yellow color components to compensate for
+                                      the amount of black added by black generation (see Section 6.2.3,
+                                      “Conversion from DeviceRGB to DeviceCMYK”). Initial value: in-
+                                      stallation-dependent.
+ */
+
+
+/*
+transfer           function,          (PDF 1.2) A function that adjusts device gray or color component
+                   array, or name     levels to compensate for nonlinear response in a particular out-
+                                      put device (see Section 6.3, “Transfer Functions”). Initial value:
+                                      installation-dependent.
+ */
+
+
+/*
+halftone           dictionary,        (PDF 1.2) A halftone screen for gray and color rendering, specified
+                   stream, or name    as a halftone dictionary or stream (see Section 6.4, “Halftones”).
+                                      Initial value: installation-dependent.
+ */
+
+
+/*
+flatness            number             The precision with which curves are to be rendered on the output
+                                      device (see Section 6.5.1, “Flatness Tolerance”). The value of this
+                                      parameter gives the maximum error tolerance, measured in output
+                                      device pixels; smaller numbers give smoother curves at the expense
+                                      of more computation and memory use. Initial value: 1.0.
+ */
+
+
+/*
+smoothness             number             (PDF 1.3) The precision with which color gradients are to be ren-
+                                          dered on the output device (see Section 6.5.2, “Smoothness Toler-
+                                          ance”). The value of this parameter gives the maximum error
+                                          tolerance, expressed as a fraction of the range of each color compo-
+                                          nent; smaller numbers give smoother color transitions at the
+                                          expense of more computation and memory use. Initial value:
+                                          installation-dependent.
+ */
+
+
+
+
+
+
+
     SkPdfGraphicsState() {
         fCurPosX      = 0.0;
         fCurPosY      = 0.0;
         fCurFontSize  = 0.0;
         fTextBlock    = false;
-        fMatrix       = SkMatrix::I();
+        fCTM          = SkMatrix::I();
         fMatrixTm     = SkMatrix::I();
         fMatrixTlm    = SkMatrix::I();
         fPathClosed   = true;
@@ -87,22 +320,18 @@
         fHasClipPathToApply = false;
         fResources    = NULL;
         fSkFont       = NULL;
+        fLineCap      = 0;
+        fLineJoin     = 0;
+        fMiterLimit   = 10.0;
+        fAphaConstant = 1.0;
+        fAlphaSource  = false;
+        fDashArrayLength = 0;
+        fDashPhase    = 0;
+        fBlendMode    = SkXfermode::kSrc_Mode;  // PDF: Normal Blend mode
     }
 
-    void applyGraphicsState(SkPaint* paint, bool stroking) {
-        if (stroking) {
-            fStroking.applyGraphicsState(paint);
-        } else {
-            fNonStroking.applyGraphicsState(paint);
-        }
-
-        // TODO(edisonn): get this from pdfContext->options,
-        // or pdfContext->addPaintOptions(&paint);
-        paint->setAntiAlias(true);
-
-        // TODO(edisonn): dashing, miter, ...
-        paint->setStrokeWidth(SkDoubleToScalar(fLineWidth));
-    }
+    // TODO(edisonn): make two functons instead, stroking and non stoking, avoid branching
+    void applyGraphicsState(SkPaint* paint, bool stroking);
 };
 
 // TODO(edisonn): better class design.