C++ InlineFlowBox::topVisibleOverflow方法代码示例

void RenderLineBoxList::paint(RenderBoxModelObject* renderer, RenderObject::PaintInfo& paintInfo, int tx, int ty) const
{
    // Only paint during the foreground/selection phases.(只有画前景和选择才会跑到这里)
    if (paintInfo.phase != PaintPhaseForeground && paintInfo.phase != PaintPhaseSelection && paintInfo.phase != PaintPhaseOutline 
        && paintInfo.phase != PaintPhaseSelfOutline && paintInfo.phase != PaintPhaseChildOutlines && paintInfo.phase != PaintPhaseTextClip
        && paintInfo.phase != PaintPhaseMask)
        return;

    ASSERT(renderer->isRenderBlock() || (renderer->isRenderInline() && renderer->hasLayer())); // The only way an inline could paint like this is if it has a layer.

    // If we have no lines then we have no work to do.
    if (!firstLineBox())
        return;

    // We can check the first box and last box and avoid painting if we don't
    // intersect.  This is a quick short-circuit that we can take to avoid walking any lines.
    // FIXME: This check is flawed in the following extremely obscure way:
    // if some line in the middle has a huge overflow, it might actually extend below the last line.
    int yPos = firstLineBox()->topVisibleOverflow() - renderer->maximalOutlineSize(paintInfo.phase);
    int h = renderer->maximalOutlineSize(paintInfo.phase) + lastLineBox()->bottomVisibleOverflow() - yPos; // 要画的inline块(从第一行到最后一行的)整个高度
    yPos += ty;	// 起始高度
    if (yPos >= paintInfo.rect.bottom() || yPos + h <= paintInfo.rect.y())
        return;

    RenderObject::PaintInfo info(paintInfo);
    ListHashSet<RenderInline*> outlineObjects;
    info.outlineObjects = &outlineObjects;

    // See if our root lines intersect with the dirty rect.  If so, then we paint
    // them.  Note that boxes can easily overlap, so we can't make any assumptions
    // based off positions of our first line box or our last line box.
    RenderView* v = renderer->view();
    bool usePrintRect = !v->printRect().isEmpty();
    for (InlineFlowBox* curr = firstLineBox(); curr; curr = curr->nextLineBox()) { // 开始对每行进行绘制
        if (usePrintRect) {
            // FIXME: This is a feeble effort to avoid splitting a line across two pages.
            // It is utterly inadequate, and this should not be done at paint time at all.
            // The whole way objects break across pages needs to be redone.
            // Try to avoid splitting a line vertically, but only if it's less than the height
            // of the entire page.
            if (curr->bottomVisibleOverflow() - curr->topVisibleOverflow() <= v->printRect().height()) {
                if (ty + curr->bottomVisibleOverflow() > v->printRect().bottom()) {
                    if (ty + curr->topVisibleOverflow() < v->truncatedAt())
                        v->setBestTruncatedAt(ty + curr->root()->topVisibleOverflow(), renderer);
                    // If we were able to truncate, don't paint.
                    if (ty + curr->topVisibleOverflow() >= v->truncatedAt())
                        break;
                }
            }
        }

        int top = min(curr->topVisibleOverflow(), curr->root()->selectionTop()) - renderer->maximalOutlineSize(info.phase); // 高点
        int bottom = curr->bottomVisibleOverflow() + renderer->maximalOutlineSize(info.phase); // 底点
        h = bottom - top;	// 高度
        yPos = ty + top;	// 开始绘制点
        v->setMinimumColumnHeight(h);
        if (yPos < info.rect.bottom() && yPos + h > info.rect.y()) 
            curr->paint(info, tx, ty); // 开始绘制该行
    }

    if (info.phase == PaintPhaseOutline || info.phase == PaintPhaseSelfOutline || info.phase == PaintPhaseChildOutlines) {
        ListHashSet<RenderInline*>::iterator end = info.outlineObjects->end();
        for (ListHashSet<RenderInline*>::iterator it = info.outlineObjects->begin(); it != end; ++it) {
            RenderInline* flow = *it;
            flow->paintOutline(info.context, tx, ty);
        }
        info.outlineObjects->clear();
    }
}