C++ nsIRenderingContext::GetWidth方法代码示例

void
nsTextBoxFrame::CalculateUnderline(nsIRenderingContext& aRenderingContext)
{
    if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
         // Calculate all fields of mAccessKeyInfo which
         // are the same for both BiDi and non-BiDi frames.
         const PRUnichar *titleString = mCroppedTitle.get();
         aRenderingContext.SetTextRunRTL(PR_FALSE);
         aRenderingContext.GetWidth(titleString[mAccessKeyInfo->mAccesskeyIndex],
                                    mAccessKeyInfo->mAccessWidth);

         nscoord offset, baseline;
         nsIFontMetrics *metrics;
         aRenderingContext.GetFontMetrics(metrics);
         metrics->GetUnderline(offset, mAccessKeyInfo->mAccessUnderlineSize);
         metrics->GetMaxAscent(baseline);
         NS_RELEASE(metrics);
         mAccessKeyInfo->mAccessOffset = baseline - offset;
    }
}

void
nsTextBoxFrame::CalculateTitleForWidth(nsPresContext*      aPresContext,
                                       nsIRenderingContext& aRenderingContext,
                                       nscoord              aWidth)
{
    if (mTitle.IsEmpty())
        return;

    nsLayoutUtils::SetFontFromStyle(&aRenderingContext, GetStyleContext());

    // see if the text will completely fit in the width given
    mTitleWidth = nsLayoutUtils::GetStringWidth(this, &aRenderingContext,
                                                mTitle.get(), mTitle.Length());

    if (mTitleWidth <= aWidth) {
        mCroppedTitle = mTitle;
#ifdef IBMBIDI
        if (HasRTLChars(mTitle)) {
            mState |= NS_FRAME_IS_BIDI;
        }
#endif // IBMBIDI
        return;  // fits, done.
    }

    const nsDependentString& kEllipsis = nsContentUtils::GetLocalizedEllipsis();
    // start with an ellipsis
    mCroppedTitle.Assign(kEllipsis);

    // see if the width is even smaller than the ellipsis
    // if so, clear the text (XXX set as many '.' as we can?).
    aRenderingContext.SetTextRunRTL(PR_FALSE);
    aRenderingContext.GetWidth(kEllipsis, mTitleWidth);

    if (mTitleWidth > aWidth) {
        mCroppedTitle.SetLength(0);
        mTitleWidth = 0;
        return;
    }

    // if the ellipsis fits perfectly, no use in trying to insert
    if (mTitleWidth == aWidth)
        return;

    aWidth -= mTitleWidth;

    // XXX: This whole block should probably take surrogates into account
    // XXX and clusters!
    // ok crop things
    switch (mCropType)
    {
        case CropNone:
        case CropRight:
        {
            nscoord cwidth;
            nscoord twidth = 0;
            int length = mTitle.Length();
            int i;
            for (i = 0; i < length; ++i) {
                PRUnichar ch = mTitle.CharAt(i);
                // still in LTR mode
                aRenderingContext.GetWidth(ch,cwidth);
                if (twidth + cwidth > aWidth)
                    break;

                twidth += cwidth;
#ifdef IBMBIDI
                if (UCS2_CHAR_IS_BIDI(ch) ) {
                  mState |= NS_FRAME_IS_BIDI;
                }
#endif // IBMBIDI
            }

            if (i == 0)
                return;

            // insert what character we can in.
            nsAutoString title( mTitle );
            title.Truncate(i);
            mCroppedTitle.Insert(title, 0);
        }
        break;

        case CropLeft:
        {
            nscoord cwidth;
            nscoord twidth = 0;
            int length = mTitle.Length();
            int i;
            for (i=length-1; i >= 0; --i) {
                PRUnichar ch = mTitle.CharAt(i);
                aRenderingContext.GetWidth(ch,cwidth);
                if (twidth + cwidth > aWidth)
                    break;

                twidth += cwidth;
#ifdef IBMBIDI
                if (UCS2_CHAR_IS_BIDI(ch) ) {
                  mState |= NS_FRAME_IS_BIDI;
                }
#endif // IBMBIDI
//.........这里部分代码省略.........

//.........这里部分代码省略.........
    // itself, per http://www.w3.org/TR/CSS21/zindex.html point 7.2.1.4.1.1.
    // (We don't apply this rule to the access-key underline because we only
    // find out where that is as a side effect of drawing the text, in the
    // general case -- see below.)
    if (decorations & (NS_FONT_DECORATION_OVERLINE |
                       NS_FONT_DECORATION_UNDERLINE)) {
      fontMet->GetUnderline(offset, size);
      gfxFloat offsetPixel = presContext->AppUnitsToGfxUnits(offset);
      gfxFloat sizePixel = presContext->AppUnitsToGfxUnits(size);
      if (decorations & NS_FONT_DECORATION_UNDERLINE) {
        nsCSSRendering::PaintDecorationLine(ctx, underColor,
                          pt, gfxSize(width, sizePixel),
                          ascentPixel, offsetPixel,
                          NS_STYLE_TEXT_DECORATION_UNDERLINE,
                          nsCSSRendering::DECORATION_STYLE_SOLID);
      }
      if (decorations & NS_FONT_DECORATION_OVERLINE) {
        nsCSSRendering::PaintDecorationLine(ctx, overColor,
                          pt, gfxSize(width, sizePixel),
                          ascentPixel, ascentPixel,
                          NS_STYLE_TEXT_DECORATION_OVERLINE,
                          nsCSSRendering::DECORATION_STYLE_SOLID);
      }
    }

    aRenderingContext.SetFont(fontMet);

    CalculateUnderline(aRenderingContext);

    aRenderingContext.SetColor(aOverrideColor ? *aOverrideColor : GetStyleColor()->mColor);

#ifdef IBMBIDI
    nsresult rv = NS_ERROR_FAILURE;

    if (mState & NS_FRAME_IS_BIDI) {
      presContext->SetBidiEnabled();
      nsBidiPresUtils* bidiUtils = presContext->GetBidiUtils();

      if (bidiUtils) {
        const nsStyleVisibility* vis = GetStyleVisibility();
        nsBidiDirection direction = (NS_STYLE_DIRECTION_RTL == vis->mDirection) ? NSBIDI_RTL : NSBIDI_LTR;
        if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
           // We let the RenderText function calculate the mnemonic's
           // underline position for us.
           nsBidiPositionResolve posResolve;
           posResolve.logicalIndex = mAccessKeyInfo->mAccesskeyIndex;
           rv = bidiUtils->RenderText(mCroppedTitle.get(), mCroppedTitle.Length(), direction,
                                      presContext, aRenderingContext,
                                      aTextRect.x, baseline,
                                      &posResolve,
                                      1);
           mAccessKeyInfo->mBeforeWidth = posResolve.visualLeftTwips;
           mAccessKeyInfo->mAccessWidth = posResolve.visualWidth;
        }
        else
        {
           rv = bidiUtils->RenderText(mCroppedTitle.get(), mCroppedTitle.Length(), direction,
                                      presContext, aRenderingContext,
                                      aTextRect.x, baseline);
        }
      }
    }
    if (NS_FAILED(rv) )
#endif // IBMBIDI
    {
       aRenderingContext.SetTextRunRTL(PR_FALSE);

       if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
           // In the simple (non-BiDi) case, we calculate the mnemonic's
           // underline position by getting the text metric.
           // XXX are attribute values always two byte?
           if (mAccessKeyInfo->mAccesskeyIndex > 0)
               aRenderingContext.GetWidth(mCroppedTitle.get(), mAccessKeyInfo->mAccesskeyIndex,
                                          mAccessKeyInfo->mBeforeWidth);
           else
               mAccessKeyInfo->mBeforeWidth = 0;
       }

       aRenderingContext.DrawString(mCroppedTitle, aTextRect.x, baseline);
    }

    if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
        aRenderingContext.FillRect(aTextRect.x + mAccessKeyInfo->mBeforeWidth,
                                   aTextRect.y + mAccessKeyInfo->mAccessOffset,
                                   mAccessKeyInfo->mAccessWidth,
                                   mAccessKeyInfo->mAccessUnderlineSize);
    }

    // Strikeout is drawn on top of the text, per
    // http://www.w3.org/TR/CSS21/zindex.html point 7.2.1.4.1.1.
    if (decorations & NS_FONT_DECORATION_LINE_THROUGH) {
      fontMet->GetStrikeout(offset, size);
      gfxFloat offsetPixel = presContext->AppUnitsToGfxUnits(offset);
      gfxFloat sizePixel = presContext->AppUnitsToGfxUnits(size);
      nsCSSRendering::PaintDecorationLine(ctx, strikeColor,
                        pt, gfxSize(width, sizePixel), ascentPixel, offsetPixel,
                        NS_STYLE_TEXT_DECORATION_LINE_THROUGH,
                        nsCSSRendering::DECORATION_STYLE_SOLID);
    }
}