1 files changed, 123 insertions, 6 deletions

diff --git a/src/utils/SkMultiPictureDocument.cpp b/src/utils/SkMultiPictureDocument.cpp
index d987818f86..4251442fcf 100644
--- a/src/utils/SkMultiPictureDocument.cpp
+++ b/src/utils/SkMultiPictureDocument.cpp
@@ -7,11 +7,14 @@
 
 #include "SkMultiPictureDocument.h"
 #include "SkMultiPictureDocumentPriv.h"
+#include "SkNWayCanvas.h"
 #include "SkPicture.h"
 #include "SkPictureRecorder.h"
 #include "SkStream.h"
 #include "SkTArray.h"
 
+#include <limits.h>
+
 /*
   File format:
       BEGINNING_OF_FILE:
@@ -26,6 +29,22 @@
 */
 
 namespace {
+// The unique file signature for this file type.
+static constexpr char kMagic[] = "Skia Multi-Picture Doc\n\n";
+
+static constexpr char kEndPage[] = "SkMultiPictureEndPage";
+
+const uint32_t kVersion = 2;
+
+static SkSize join(const SkTArray<SkSize>& sizes) {
+    SkSize joined = SkSize::Make(0, 0);
+    for (SkSize s : sizes) {
+        joined = SkSize::Make(SkTMax(joined.width(), s.width()),
+                              SkTMax(joined.height(), s.height()));
+    }
+    return joined;
+}
+
 static SkCanvas* trim(SkCanvas* canvas,
                       SkScalar w, SkScalar h,
                       const SkRect& trimBox) {
@@ -59,19 +78,17 @@ struct MultiPictureDocument final : public SkDocument {
     void onClose(SkWStream* wStream) override {
         SkASSERT(wStream);
         SkASSERT(wStream->bytesWritten() == 0);
-        wStream->writeText(SkMultiPictureDocumentProtocol::kMagic);
-        wStream->write32(SkMultiPictureDocumentProtocol::kVersion);
+        wStream->writeText(kMagic);
+        wStream->write32(kVersion);
         wStream->write32(SkToU32(fPages.count()));
         for (SkSize s : fSizes) {
             wStream->write(&s, sizeof(s));
         }
-        SkSize bigsize = SkMultiPictureDocumentProtocol::Join(fSizes);
+        SkSize bigsize = join(fSizes);
         SkCanvas* c = fPictureRecorder.beginRecording(SkRect::MakeSize(bigsize));
         for (const sk_sp<SkPicture>& page : fPages) {
             c->drawPicture(page);
-            c->drawAnnotation(SkRect::MakeEmpty(),
-                              SkMultiPictureDocumentProtocol::kEndPage,
-                              nullptr);
+            c->drawAnnotation(SkRect::MakeEmpty(), kEndPage, nullptr);
         }
         sk_sp<SkPicture> p = fPictureRecorder.finishRecordingAsPicture();
         p->serialize(wStream);
@@ -89,3 +106,103 @@ struct MultiPictureDocument final : public SkDocument {
 sk_sp<SkDocument> SkMakeMultiPictureDocument(SkWStream* wStream) {
     return sk_make_sp<MultiPictureDocument>(wStream, nullptr);
 }
+
+////////////////////////////////////////////////////////////////////////////////
+
+int SkMultiPictureDocumentReadPageCount(SkStreamSeekable* stream) {
+    if (!stream) {
+        return 0;
+    }
+    stream->seek(0);
+    const size_t size = sizeof(kMagic) - 1;
+    char buffer[size];
+    if (size != stream->read(buffer, size) || 0 != memcmp(kMagic, buffer, size)) {
+        stream = nullptr;
+        return 0;
+    }
+    uint32_t versionNumber = stream->readU32();
+    if (versionNumber != kVersion) {
+        return 0;
+    }
+    uint32_t pageCount = stream->readU32();
+    if (pageCount > INT_MAX) {
+        return 0;
+    }
+    // leave stream position right here.
+    return (int)pageCount;
+}
+
+bool SkMultiPictureDocumentReadPageSizes(SkStreamSeekable* stream,
+                                         SkDocumentPage* dstArray,
+                                         int dstArrayCount) {
+    if (!dstArray || dstArrayCount < 1) {
+        return false;
+    }
+    int pageCount = SkMultiPictureDocumentReadPageCount(stream);
+    if (pageCount < 1 || pageCount != dstArrayCount) {
+        return false;
+    }
+    for (int i = 0; i < pageCount; ++i) {
+        SkSize& s = dstArray[i].fSize;
+        if (sizeof(s) != stream->read(&s, sizeof(s))) {
+            return false;
+        }
+    }
+    // leave stream position right here.
+    return true;
+}
+
+namespace {
+struct PagerCanvas : public SkNWayCanvas {
+    SkPictureRecorder fRecorder;
+    SkDocumentPage* fDst;
+    int fCount;
+    int fIndex = 0;
+    PagerCanvas(SkISize wh, SkDocumentPage* dst, int count)
+            : SkNWayCanvas(wh.width(), wh.height()), fDst(dst), fCount(count) {
+        this->nextCanvas();
+    }
+    void nextCanvas() {
+        if (fIndex < fCount) {
+            SkRect bounds = SkRect::MakeSize(fDst[fIndex].fSize);
+            this->addCanvas(fRecorder.beginRecording(bounds));
+        }
+    }
+    void onDrawAnnotation(const SkRect& r, const char* key, SkData* d) override {
+        if (0 == strcmp(key, kEndPage)) {
+            this->removeAll();
+            if (fIndex < fCount) {
+                fDst[fIndex].fPicture = fRecorder.finishRecordingAsPicture();
+                ++fIndex;
+            }
+            this->nextCanvas();
+        } else {
+            this->SkNWayCanvas::onDrawAnnotation(r, key, d);
+        }
+    }
+};
+}  // namespace
+
+bool SkMultiPictureDocumentRead(SkStreamSeekable* stream,
+                                SkDocumentPage* dstArray,
+                                int dstArrayCount) {
+    if (!SkMultiPictureDocumentReadPageSizes(stream, dstArray, dstArrayCount)) {
+        return false;
+    }
+    SkSize joined = SkSize::Make(0.0f, 0.0f);
+    for (int i = 0; i < dstArrayCount; ++i) {
+        joined = SkSize::Make(SkTMax(joined.width(), dstArray[i].fSize.width()),
+                              SkTMax(joined.height(), dstArray[i].fSize.height()));
+    }
+
+    auto picture = SkPicture::MakeFromStream(stream);
+
+    PagerCanvas canvas(joined.toCeil(), dstArray, dstArrayCount);
+    // Must call playback(), not drawPicture() to reach
+    // PagerCanvas::onDrawAnnotation().
+    picture->playback(&canvas);
+    if (canvas.fIndex != dstArrayCount) {
+        SkDEBUGF(("Malformed SkMultiPictureDocument\n"));
+    }
+    return true;
+}