C++ SkTDArray::rewind方法代码示例

void SkMultiPictureDraw::DrawData::Reset(SkTDArray<DrawData>& data) {
    for (int i = 0; i < data.count(); ++i) {
        data[i].fPicture->unref();
        data[i].fCanvas->unref();
        delete data[i].fPaint;
    }
    data.rewind();
}

// static
void SkPDFPage::GeneratePageTree(const SkTDArray<SkPDFPage*>& pages,
                                 SkPDFCatalog* catalog,
                                 SkTDArray<SkPDFDict*>* pageTree,
                                 SkPDFDict** rootNode) {
    // PDF wants a tree describing all the pages in the document.  We arbitrary
    // choose 8 (kNodeSize) as the number of allowed children.  The internal
    // nodes have type "Pages" with an array of children, a parent pointer, and
    // the number of leaves below the node as "Count."  The leaves are passed
    // into the method, have type "Page" and need a parent pointer. This method
    // builds the tree bottom up, skipping internal nodes that would have only
    // one child.
    static const int kNodeSize = 8;

    SkAutoTUnref<SkPDFName> kidsName(new SkPDFName("Kids"));
    SkAutoTUnref<SkPDFName> countName(new SkPDFName("Count"));
    SkAutoTUnref<SkPDFName> parentName(new SkPDFName("Parent"));

    // curNodes takes a reference to its items, which it passes to pageTree.
    SkTDArray<SkPDFDict*> curNodes;
    curNodes.setReserve(pages.count());
    for (int i = 0; i < pages.count(); i++) {
        SkSafeRef(pages[i]);
        curNodes.push(pages[i]);
    }

    // nextRoundNodes passes its references to nodes on to curNodes.
    SkTDArray<SkPDFDict*> nextRoundNodes;
    nextRoundNodes.setReserve((pages.count() + kNodeSize - 1)/kNodeSize);

    int treeCapacity = kNodeSize;
    do {
        for (int i = 0; i < curNodes.count(); ) {
            if (i > 0 && i + 1 == curNodes.count()) {
                nextRoundNodes.push(curNodes[i]);
                break;
            }

            SkPDFDict* newNode = new SkPDFDict("Pages");
            SkAutoTUnref<SkPDFObjRef> newNodeRef(new SkPDFObjRef(newNode));

            SkAutoTUnref<SkPDFArray> kids(new SkPDFArray);
            kids->reserve(kNodeSize);

            int count = 0;
            for (; i < curNodes.count() && count < kNodeSize; i++, count++) {
                curNodes[i]->insert(parentName.get(), newNodeRef.get());
                kids->append(new SkPDFObjRef(curNodes[i]))->unref();

                // TODO(vandebo): put the objects in strict access order.
                // Probably doesn't matter because they are so small.
                if (curNodes[i] != pages[0]) {
                    pageTree->push(curNodes[i]);  // Transfer reference.
                    catalog->addObject(curNodes[i], false);
                } else {
                    SkSafeUnref(curNodes[i]);
                    catalog->addObject(curNodes[i], true);
                }
            }

            // treeCapacity is the number of leaf nodes possible for the
            // current set of subtrees being generated. (i.e. 8, 64, 512, ...).
            // It is hard to count the number of leaf nodes in the current
            // subtree. However, by construction, we know that unless it's the
            // last subtree for the current depth, the leaf count will be
            // treeCapacity, otherwise it's what ever is left over after
            // consuming treeCapacity chunks.
            int pageCount = treeCapacity;
            if (i == curNodes.count()) {
                pageCount = ((pages.count() - 1) % treeCapacity) + 1;
            }
            newNode->insert(countName.get(), new SkPDFInt(pageCount))->unref();
            newNode->insert(kidsName.get(), kids.get());
            nextRoundNodes.push(newNode);  // Transfer reference.
        }

        curNodes = nextRoundNodes;
        nextRoundNodes.rewind();
        treeCapacity *= kNodeSize;
    } while (curNodes.count() > 1);

    pageTree->push(curNodes[0]);  // Transfer reference.
    catalog->addObject(curNodes[0], false);
    if (rootNode) {
        *rootNode = curNodes[0];
    }
}

void ImGuiLayer::onPaint(SkSurface* surface) {
    // This causes ImGui to rebuild vertex/index data based on all immediate-mode commands
    // (widgets, etc...) that have been issued
    ImGui::Render();

    // Then we fetch the most recent data, and convert it so we can render with Skia
    const ImDrawData* drawData = ImGui::GetDrawData();
    SkTDArray<SkPoint> pos;
    SkTDArray<SkPoint> uv;
    SkTDArray<SkColor> color;

    auto canvas = surface->getCanvas();

    for (int i = 0; i < drawData->CmdListsCount; ++i) {
        const ImDrawList* drawList = drawData->CmdLists[i];

        // De-interleave all vertex data (sigh), convert to Skia types
        pos.rewind(); uv.rewind(); color.rewind();
        for (int j = 0; j < drawList->VtxBuffer.size(); ++j) {
            const ImDrawVert& vert = drawList->VtxBuffer[j];
            pos.push_back(SkPoint::Make(vert.pos.x, vert.pos.y));
            uv.push_back(SkPoint::Make(vert.uv.x, vert.uv.y));
            color.push_back(vert.col);
        }
        // ImGui colors are RGBA
        SkSwapRB(color.begin(), color.begin(), color.count());

        int indexOffset = 0;

        // Draw everything with canvas.drawVertices...
        for (int j = 0; j < drawList->CmdBuffer.size(); ++j) {
            const ImDrawCmd* drawCmd = &drawList->CmdBuffer[j];

            SkAutoCanvasRestore acr(canvas, true);

            // TODO: Find min/max index for each draw, so we know how many vertices (sigh)
            if (drawCmd->UserCallback) {
                drawCmd->UserCallback(drawList, drawCmd);
            } else {
                intptr_t idIndex = (intptr_t)drawCmd->TextureId;
                if (idIndex < fSkiaWidgetFuncs.count()) {
                    // Small image IDs are actually indices into a list of callbacks. We directly
                    // examing the vertex data to deduce the image rectangle, then reconfigure the
                    // canvas to be clipped and translated so that the callback code gets to use
                    // Skia to render a widget in the middle of an ImGui panel.
                    ImDrawIdx rectIndex = drawList->IdxBuffer[indexOffset];
                    SkPoint tl = pos[rectIndex], br = pos[rectIndex + 2];
                    canvas->clipRect(SkRect::MakeLTRB(tl.fX, tl.fY, br.fX, br.fY));
                    canvas->translate(tl.fX, tl.fY);
                    fSkiaWidgetFuncs[idIndex](canvas);
                } else {
                    SkPaint* paint = static_cast<SkPaint*>(drawCmd->TextureId);
                    SkASSERT(paint);

                    canvas->clipRect(SkRect::MakeLTRB(drawCmd->ClipRect.x, drawCmd->ClipRect.y,
                                                      drawCmd->ClipRect.z, drawCmd->ClipRect.w));
                    auto vertices = SkVertices::MakeCopy(SkVertices::kTriangles_VertexMode,
                                                         drawList->VtxBuffer.size(),
                                                         pos.begin(), uv.begin(), color.begin(),
                                                         drawCmd->ElemCount,
                                                         drawList->IdxBuffer.begin() + indexOffset);
                    canvas->drawVertices(vertices, SkBlendMode::kModulate, *paint);
                }
                indexOffset += drawCmd->ElemCount;
            }
        }
    }

    fSkiaWidgetFuncs.reset();
}

// static
void SkPDFPage::GeneratePageTree(const SkTDArray<SkPDFPage*>& pages,
                                 SkPDFCatalog* catalog,
                                 SkTDArray<SkPDFDict*>* pageTree,
                                 SkPDFDict** rootNode) {
    // PDF wants a tree describing all the pages in the document.  We arbitrary
    // choose 8 (kNodeSize) as the number of allowed children.  The internal
    // nodes have type "Pages" with an array of children, a parent pointer, and
    // the number of leaves below the node as "Count."  The leaves are passed
    // into the method, have type "Page" and need a parent pointer. This method
    // builds the tree bottom up, skipping internal nodes that would have only
    // one child.
    static const int kNodeSize = 8;

    SkRefPtr<SkPDFName> kidsName = new SkPDFName("Kids");
    kidsName->unref();  // SkRefPtr and new both took a reference.
    SkRefPtr<SkPDFName> countName = new SkPDFName("Count");
    countName->unref();  // SkRefPtr and new both took a reference.
    SkRefPtr<SkPDFName> parentName = new SkPDFName("Parent");
    parentName->unref();  // SkRefPtr and new both took a reference.

    // curNodes takes a reference to its items, which it passes to pageTree.
    SkTDArray<SkPDFDict*> curNodes;
    curNodes.setReserve(pages.count());
    for (int i = 0; i < pages.count(); i++) {
        SkSafeRef(pages[i]);
        curNodes.push(pages[i]);
    }

    // nextRoundNodes passes its references to nodes on to curNodes.
    SkTDArray<SkPDFDict*> nextRoundNodes;
    nextRoundNodes.setReserve((pages.count() + kNodeSize - 1)/kNodeSize);

    int treeCapacity = kNodeSize;
    do {
        for (int i = 0; i < curNodes.count(); ) {
            if (i > 0 && i + 1 == curNodes.count()) {
                nextRoundNodes.push(curNodes[i]);
                break;
            }

            SkPDFDict* newNode = new SkPDFDict("Pages");
            SkRefPtr<SkPDFObjRef> newNodeRef = new SkPDFObjRef(newNode);
            newNodeRef->unref();  // SkRefPtr and new both took a reference.

            SkRefPtr<SkPDFArray> kids = new SkPDFArray;
            kids->unref();  // SkRefPtr and new both took a reference.
            kids->reserve(kNodeSize);

            int count = 0;
            for (; i < curNodes.count() && count < kNodeSize; i++, count++) {
                curNodes[i]->insert(parentName.get(), newNodeRef.get());
                kids->append(new SkPDFObjRef(curNodes[i]))->unref();

                // TODO(vandebo): put the objects in strict access order.
                // Probably doesn't matter because they are so small.
                if (curNodes[i] != pages[0]) {
                    pageTree->push(curNodes[i]);  // Transfer reference.
                    catalog->addObject(curNodes[i], false);
                } else {
                    SkSafeUnref(curNodes[i]);
                    catalog->addObject(curNodes[i], true);
                }
            }

            newNode->insert(kidsName.get(), kids.get());
            int pageCount = treeCapacity;
            if (count < kNodeSize) {
                pageCount = pages.count() % treeCapacity;
            }
            newNode->insert(countName.get(), new SkPDFInt(pageCount))->unref();
            nextRoundNodes.push(newNode);  // Transfer reference.
        }

        curNodes = nextRoundNodes;
        nextRoundNodes.rewind();
        treeCapacity *= kNodeSize;
    } while (curNodes.count() > 1);

    pageTree->push(curNodes[0]);  // Transfer reference.
    catalog->addObject(curNodes[0], false);
    if (rootNode) {
        *rootNode = curNodes[0];
    }
}