SkPDF: fall back on paths for unembeddable fonts.

src/pdf/SkPDFDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPDFDevice.h"
 
 #include "SkAnnotation.h"
@@ skipping 1213 matching lines @@
         SkASSERT(len <= 65535);
         SkString tmp(len);
         for (size_t i = 0; i < len; i++) {
             SkASSERT(0 == input[i] >> 8);
             tmp[i] = static_cast<uint8_t>(input[i]);
         }
         return SkPDFUtils::FormatString(tmp.c_str(), tmp.size());
     }
 }
 
+static void draw_transparent_text(SkPDFDevice* device,
+                                  const SkDraw& d,
+                                  const void* text, size_t len,
+                                  SkScalar x, SkScalar y,
+                                  const SkPaint& srcPaint) {
+
+    SkPaint transparent;
+    // default typeface should be embeddable
+    SkASSERT(SkPDFFont::CanEmbedTypeface(transparent.getTypeface(),

[bungeman-skia, 2015/10/12 19:05:29]

I'm not sure it's enough to just debug assert this, since if the default font
isn't embedded-able, this would be bad. Here I think it turns into an infinite
loop?

[hal.canary, 2015/10/12 19:10:25]

this:

    SK_ALWAYSBREAK(SkPDFFont::CanEmbedTypeface(transparent.getTypeface(),
                                               device->getCanon()));

or this?

    if (!SkPDFFont::CanEmbedTypeface(transparent.getTypeface(),
                                     device->getCanon())) {
        SkDEBUGFAIL("default typeface should be embeddable");
        return;
    }

+                                         device->getCanon()));
+    transparent.setTextSize(srcPaint.getTextSize());
+    transparent.setColor(SK_ColorTRANSPARENT);
+    switch (srcPaint.getTextEncoding()) {
+        case SkPaint::kGlyphID_TextEncoding: {
+            // Since a glyphId<->Unicode mapping is typeface-specific,
+            // map back to Unicode first.
+            size_t glyphCount = len / 2;
+            SkAutoTMalloc<SkUnichar> unichars(glyphCount);
+            srcPaint.glyphsToUnichars(
+                    (const uint16_t*)text, SkToInt(glyphCount), &unichars[0]);
+            transparent.setTextEncoding(SkPaint::kUTF32_TextEncoding);
+            device->drawText(d, &unichars[0],
+                             glyphCount * sizeof(SkUnichar),
+                             x, y, transparent);
+            break;
+        }
+        case SkPaint::kUTF8_TextEncoding:
+        case SkPaint::kUTF16_TextEncoding:
+        case SkPaint::kUTF32_TextEncoding:
+            transparent.setTextEncoding(srcPaint.getTextEncoding());
+            device->drawText(d, text, len, x, y, transparent);
+            break;
+        default:
+            SkFAIL("unknown text encoding");
+    }
+}
+
+
 void SkPDFDevice::drawText(const SkDraw& d, const void* text, size_t len,
                            SkScalar x, SkScalar y, const SkPaint& srcPaint) {
+    if (!SkPDFFont::CanEmbedTypeface(srcPaint.getTypeface(), fCanon)) {
+        // http://skbug.com/3866
+        SkPath path;
+        srcPaint.getTextPath(text, len, x, y, &path);
+        this->drawPath(d, path, srcPaint, &SkMatrix::I(), true);
+        // Draw text transparently to make it copyable/searchable/accessable.
+        draw_transparent_text(this, d, text, len, x, y, srcPaint);
+        return;
+    }
     SkPaint paint = srcPaint;
     replace_srcmode_on_opaque_paint(&paint);
 
     NOT_IMPLEMENTED(paint.getMaskFilter() != nullptr, false);
     if (paint.getMaskFilter() != nullptr) {
         // Don't pretend we support drawing MaskFilters, it makes for artifacts
         // making text unreadable (e.g. same text twice when using CSS shadows).
         return;
     }
     SkPaint textPaint = calculate_text_paint(paint);
@@ skipping 32 matching lines @@
         content.entry()->fContent.writeText(encodedString.c_str());
         consumedGlyphCount += availableGlyphs;
         content.entry()->fContent.writeText(" Tj\n");
     }
     content.entry()->fContent.writeText("ET\n");
 }
 
 void SkPDFDevice::drawPosText(const SkDraw& d, const void* text, size_t len,
                               const SkScalar pos[], int scalarsPerPos,
                               const SkPoint& offset, const SkPaint& srcPaint) {
+    if (!SkPDFFont::CanEmbedTypeface(srcPaint.getTypeface(), fCanon)) {
+        const SkPoint* positions = reinterpret_cast<const SkPoint*>(pos);
+        SkAutoTMalloc<SkPoint> positionsBuffer;
+        if (2 != scalarsPerPos) {
+            int glyphCount = srcPaint.textToGlyphs(text, len, NULL);
+            positionsBuffer.reset(glyphCount);
+            for (int  i = 0; i < glyphCount; ++i) {
+                positionsBuffer[i].set(pos[i], 0.0f);
+            }
+            positions = &positionsBuffer[0];
+        }
+        SkPath path;
+        srcPaint.getPosTextPath(text, len, positions, &path);
+        SkMatrix matrix;
+        matrix.setTranslate(offset);
+        this->drawPath(d, path, srcPaint, &matrix, true);
+        // Draw text transparently to make it copyable/searchable/accessable.
+        draw_transparent_text(
+                this, d, text, len, offset.x() + positions[0].x(),
+                offset.y() + positions[0].y(), srcPaint);
+        return;
+    }
+
     SkPaint paint = srcPaint;
     replace_srcmode_on_opaque_paint(&paint);
 
     NOT_IMPLEMENTED(paint.getMaskFilter() != nullptr, false);
     if (paint.getMaskFilter() != nullptr) {
         // Don't pretend we support drawing MaskFilters, it makes for artifacts
         // making text unreadable (e.g. same text twice when using CSS shadows).
         return;
     }
     SkASSERT(1 == scalarsPerPos || 2 == scalarsPerPos);
@@ skipping 993 matching lines @@
     if (!pdfimage) {
         pdfimage.reset(SkPDFCreateBitmapObject(image));
         if (!pdfimage) {
             return;
         }
         fCanon->addPDFBitmap(image->uniqueID(), pdfimage);
     }
     SkPDFUtils::DrawFormXObject(this->addXObjectResource(pdfimage.get()),
                                 &content.entry()->fContent);
 }