layout/generic/nsHTMLReflowMetrics.h

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  37
  38 /* struct containing the output from nsIFrame::Reflow */
  39
  40 #ifndef nsHTMLReflowMetrics_h___
  41 #define nsHTMLReflowMetrics_h___
  42
  43 #include <stdio.h>
  44 #include "nsISupports.h"
  45 #include "nsMargin.h"
  46 #include "nsRect.h"
  47 // for MOZ_MATHML
  48 #include "nsIRenderingContext.h" //to get struct nsBoundingMetrics
  49
  50 //----------------------------------------------------------------------
  51
  52 // Option flags
  53 #ifdef MOZ_MATHML
  54 #define NS_REFLOW_CALC_BOUNDING_METRICS  0x0001
  55 #endif
  56
  57 /**
  58  * An nsCollapsingMargin represents a vertical collapsing margin between
  59  * blocks as described in section 8.3.1 of CSS2,
  60  * <URL: http://www.w3.org/TR/REC-CSS2/box.html#collapsing-margins >.
  61  *
  62  * All adjacent vertical margins collapse, and the resulting margin is
  63  * the sum of the largest positive margin included and the smallest (most
  64  * negative) negative margin included.
  65  */
  66 struct nsCollapsingMargin {
  67   private:
  68     nscoord mMostPos;  // the largest positive margin included
  69     nscoord mMostNeg;  // the smallest negative margin included
  70
  71   public:
  72     nsCollapsingMargin()
  73         : mMostPos(0),
  74           mMostNeg(0)
  75       {
  76       }
  77
  78     nsCollapsingMargin(const nsCollapsingMargin& aOther)
  79         : mMostPos(aOther.mMostPos),
  80           mMostNeg(aOther.mMostNeg)
  81       {
  82       }
  83
  84     PRBool operator==(const nsCollapsingMargin& aOther)
  85       {
  86         return mMostPos == aOther.mMostPos &&
  87           mMostNeg == aOther.mMostNeg;
  88       }
  89
  90     PRBool operator!=(const nsCollapsingMargin& aOther)
  91       {
  92         return !(*this == aOther);
  93       }
  94
  95     nsCollapsingMargin& operator=(const nsCollapsingMargin& aOther)
  96       {
  97         mMostPos = aOther.mMostPos;
  98         mMostNeg = aOther.mMostNeg;
  99         return *this;
 100       }
 101
 102     void Include(nscoord aCoord)
 103       {
 104         if (aCoord > mMostPos)
 105           mMostPos = aCoord;
 106         else if (aCoord < mMostNeg)
 107           mMostNeg = aCoord;
 108       }
 109
 110     void Include(const nsCollapsingMargin& aOther)
 111       {
 112         if (aOther.mMostPos > mMostPos)
 113           mMostPos = aOther.mMostPos;
 114         if (aOther.mMostNeg < mMostNeg)
 115           mMostNeg = aOther.mMostNeg;
 116       }
 117
 118     void Zero()
 119       {
 120         mMostPos = 0;
 121         mMostNeg = 0;
 122       }
 123
 124     PRBool IsZero() const
 125       {
 126         return (mMostPos == 0) && (mMostNeg == 0);
 127       }
 128
 129     nscoord get() const
 130       {
 131         return mMostPos + mMostNeg;
 132       }
 133 };
 134
 135 /**
 136  * Reflow metrics used to return the frame's desired size and alignment
 137  * information.
 138  *
 139  * @see #Reflow()
 140  */
 141 struct nsHTMLReflowMetrics {
 142   nscoord width, height;    // [OUT] desired width and height (border-box)
 143   nscoord ascent;           // [OUT] baseline (from top), or ASK_FOR_BASELINE
 144
 145   enum { ASK_FOR_BASELINE = nscoord_MAX };
 146
 147 #ifdef MOZ_MATHML
 148   // Metrics that _exactly_ enclose the text to allow precise MathML placements.
 149   // If the NS_REFLOW_CALC_BOUNDING_METRICS flag is set, then the caller is
 150   // requesting that you also compute additional details about your inner
 151   // bounding box and italic correction. For example, the bounding box of
 152   // msup is the smallest rectangle that _exactly_ encloses both the text
 153   // of the base and the text of the superscript.
 154   nsBoundingMetrics mBoundingMetrics;  // [OUT]
 155 #endif
 156
 157   // Carried out bottom margin values. This is the collapsed
 158   // (generational) bottom margin value.
 159   nsCollapsingMargin mCarriedOutBottomMargin;
 160
 161   // For frames that have content that overflow their content area
 162   // (NS_FRAME_OUTSIDE_CHILDREN) this rectangle represents the total area
 163   // of the frame including visible overflow, i.e., don't include overflowing
 164   // content that is hidden.
 165   // The rect is in the local coordinate space of the frame, and should be at
 166   // least as big as the desired size. If there is no content that overflows,
 167   // then the overflow area is identical to the desired size and should be
 168   // {0, 0, mWidth, mHeight}.
 169   nsRect mOverflowArea;
 170
 171   PRUint32 mFlags;
 172
 173   // XXXldb Should |aFlags| generally be passed from parent to child?
 174   // Some places do it, and some don't.  |aFlags| should perhaps go away
 175   // entirely.
 176   nsHTMLReflowMetrics(PRUint32 aFlags = 0) {
 177     mFlags = aFlags;
 178     mOverflowArea.x = 0;
 179     mOverflowArea.y = 0;
 180     mOverflowArea.width = 0;
 181     mOverflowArea.height = 0;
 182 #ifdef MOZ_MATHML
 183     mBoundingMetrics.Clear();
 184 #endif
 185
 186     // XXX These are OUT parameters and so they shouldn't have to be
 187     // initialized, but there are some bad frame classes that aren't
 188     // properly setting them when returning from Reflow()...
 189     width = height = 0;
 190     ascent = ASK_FOR_BASELINE;
 191   }
 192
 193   nsHTMLReflowMetrics& operator=(const nsHTMLReflowMetrics& aOther)
 194   {
 195     mFlags = aOther.mFlags;
 196     mCarriedOutBottomMargin = aOther.mCarriedOutBottomMargin;
 197     mOverflowArea.x = aOther.mOverflowArea.x;
 198     mOverflowArea.y = aOther.mOverflowArea.y;
 199     mOverflowArea.width = aOther.mOverflowArea.width;
 200     mOverflowArea.height = aOther.mOverflowArea.height;
 201 #ifdef MOZ_MATHML
 202     mBoundingMetrics = aOther.mBoundingMetrics;
 203 #endif
 204
 205     width = aOther.width;
 206     height = aOther.height;
 207     ascent = aOther.ascent;
 208     return *this;
 209   }
 210
 211 };
 212
 213 #endif /* nsHTMLReflowMetrics_h___ */