TextDpi.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / MS / Internal / Text / TextDpi.cs / 1305600 / TextDpi.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// Copyright (C) Microsoft Corporation.  All rights reserved.
//
// File: TextDpi.cs 
//
// Description: Helpers to handle text dpi conversions and limitations. 
// 
// History:
//  04/25/2003 : [....] - moving from Avalon branch. 
//
//---------------------------------------------------------------------------

using System;                   // Double, ... 
using System.Windows;           // DependencyObject
using System.Windows.Documents; // TextElement, ... 
using System.Windows.Media;     // FontFamily 
using MS.Internal.PtsHost.UnsafeNativeMethods;  // PTS
 
namespace MS.Internal.Text
{
    // ---------------------------------------------------------------------
    // Helpers to handle text dpi conversions and limitations. 
    // ---------------------------------------------------------------------
    internal static class TextDpi 
    { 
        // ------------------------------------------------------------------
        // Minimum width for text measurement. 
        // -----------------------------------------------------------------
        internal static double MinWidth { get { return _minSize; } }

        // ------------------------------------------------------------------ 
        // Maximum width for text measurement.
        // ------------------------------------------------------------------ 
        internal static double MaxWidth { get { return _maxSize; } } 

        // ----------------------------------------------------------------- 
        // Convert from logical measurement unit to text measurement unit.
        //
        //      d - value in logical measurement unit
        // 
        // Returns: value in text measurement unit.
        // ------------------------------------------------------------------ 
        internal static int ToTextDpi(double d) 
        {
            if (DoubleUtil.IsZero(d)) { return 0; } 
            else if (d > 0)
            {
                if (d > _maxSize) { d = _maxSize; }
                else if (d < _minSize) { d = _minSize; } 
            }
            else 
            { 
                if (d < -_maxSize) { d = -_maxSize; }
                else if (d > -_minSize) { d = -_minSize; } 
            }
            return (int)Math.Round(d * _scale);
        }
 
        // -----------------------------------------------------------------
        // Convert from text measurement unit to logical measurement unit. 
        // 
        //      i - value in text measurement unit
        // 
        // Returns: value in logical measurement unit.
        // -----------------------------------------------------------------
        internal static double FromTextDpi(int i)
        { 
            return ((double)i) / _scale;
        } 
 
        // -----------------------------------------------------------------
        // Convert point from logical measurement unit to text measurement unit. 
        // ------------------------------------------------------------------
        internal static PTS.FSPOINT ToTextPoint(Point point)
        {
            PTS.FSPOINT fspoint = new PTS.FSPOINT(); 
            fspoint.u = ToTextDpi(point.X);
            fspoint.v = ToTextDpi(point.Y); 
            return fspoint; 
        }
 
        // -----------------------------------------------------------------
        // Convert size from logical measurement unit to text measurement unit.
        // ------------------------------------------------------------------
        internal static PTS.FSVECTOR ToTextSize(Size size) 
        {
            PTS.FSVECTOR fsvector = new PTS.FSVECTOR(); 
            fsvector.du = ToTextDpi(size.Width); 
            fsvector.dv = ToTextDpi(size.Height);
            return fsvector; 
        }

        // ------------------------------------------------------------------
        // Convert rect from text measurement unit to logical measurement unit. 
        // -----------------------------------------------------------------
        internal static Rect FromTextRect(PTS.FSRECT fsrect) 
        { 
            return new Rect(
                FromTextDpi(fsrect.u), 
                FromTextDpi(fsrect.v),
                FromTextDpi(fsrect.du),
                FromTextDpi(fsrect.dv));
        } 

        // ------------------------------------------------------------------ 
        // Make sure that LS/PTS limitations are not exceeded for offset 
        // within a line.
        // ----------------------------------------------------------------- 
        internal static void EnsureValidLineOffset(ref double offset)
        {
            // Offset has to be > min allowed size && < max allowed size.
            if (offset > _maxSize) { offset = _maxSize; } 
            else if (offset < -_maxSize) { offset = -_maxSize; }
        } 
 
        // -----------------------------------------------------------------
        // Snaps the value to TextDPi, makeing sure that convertion to 
        // TextDpi and the to double produces the same value.
        // -----------------------------------------------------------------
        internal static void SnapToTextDpi(ref Size size)
        { 
            size = new Size(FromTextDpi(ToTextDpi(size.Width)), FromTextDpi(ToTextDpi(size.Height)));
        } 
 
        // ------------------------------------------------------------------
        // Make sure that LS/PTS limitations are not exceeded for line width. 
        // -----------------------------------------------------------------
        internal static void EnsureValidLineWidth(ref double width)
        {
            // Line width has to be > 0 && < max allowed size. 
            if (width > _maxSize) { width = _maxSize; }
            else if (width < _minSize) { width = _minSize; } 
        } 
        internal static void EnsureValidLineWidth(ref Size size)
        { 
            // Line width has to be > 0 && < max allowed size.
            if (size.Width > _maxSize) { size.Width = _maxSize; }
            else if (size.Width < _minSize) { size.Width = _minSize; }
        } 
        internal static void EnsureValidLineWidth(ref int width)
        { 
            // Line width has to be > 0 && < max allowed size. 
            if (width > _maxSizeInt) { width = _maxSizeInt; }
            else if (width < _minSizeInt) { width = _minSizeInt; } 
        }

        // ------------------------------------------------------------------
        // Make sure that PTS limitations are not exceeded for page size. 
        // ------------------------------------------------------------------
        internal static void EnsureValidPageSize(ref Size size) 
        { 
            // Page size has to be > 0 && < max allowed size.
            if (size.Width > _maxSize) { size.Width = _maxSize; } 
            else if (size.Width < _minSize) { size.Width = _minSize; }
            if (size.Height > _maxSize) { size.Height = _maxSize; }
            else if (size.Height < _minSize) { size.Height = _minSize; }
        } 
        internal static void EnsureValidPageWidth(ref double width)
        { 
            // Page size has to be > 0 && < max allowed size. 
            if (width > _maxSize) { width = _maxSize; }
            else if (width < _minSize) { width = _minSize; } 
        }
        internal static void EnsureValidPageMargin(ref Thickness pageMargin, Size pageSize)
        {
            if (pageMargin.Left >= pageSize.Width) { pageMargin.Right = 0.0; } 
            if (pageMargin.Left + pageMargin.Right >= pageSize.Width)
            { 
                pageMargin.Right = Math.Max(0.0, pageSize.Width - pageMargin.Left - _minSize); 
                if (pageMargin.Left + pageMargin.Right >= pageSize.Width)
                { 
                    pageMargin.Left = pageSize.Width - _minSize;
                }
            }
            if (pageMargin.Top >= pageSize.Height) { pageMargin.Bottom = 0.0; } 
            if (pageMargin.Top + pageMargin.Bottom >= pageSize.Height)
            { 
                pageMargin.Bottom = Math.Max(0.0, pageSize.Height - pageMargin.Top - _minSize);; 
                if (pageMargin.Top + pageMargin.Bottom >= pageSize.Height)
                { 
                    pageMargin.Top = pageSize.Height - _minSize;
                }
            }
        } 

        // ----------------------------------------------------------------- 
        // Make sure that LS/PTS limitations are not exceeded for object's size. 
        // ------------------------------------------------------------------
        internal static void EnsureValidObjSize(ref Size size) 
        {
            // Embedded object can have size == 0, but its width and height
            // have to be less than max allowed size.
            if (size.Width > _maxObjSize) { size.Width = _maxObjSize; } 
            if (size.Height > _maxObjSize) { size.Height = _maxObjSize; }
        } 
 
        // -----------------------------------------------------------------
        // Make sure that LS/PTS limitations are not exceeded. 
        // -----------------------------------------------------------------
        static TextDpi()
        {
            _scale = 300.0; 
            _maxSizeInt = 0x3ffffffe;
            _minSizeInt = 0x00000001; 
            _maxSize = ((double)_maxSizeInt) / _scale; // = 3,579,139.40 pixels 
            _minSize = ((double)_minSizeInt) / _scale; // > 0
            _maxObjSize = _maxSize / 3;                // = 1,193,046.46 pixels 
        }

        // -----------------------------------------------------------------
        // Measuring unit for PTS presenters is int, but logical measuring 
        // for the rest of the system is is double.
        // Logical measuring dpi        = 96 
        // PTS presenters measuring dpi = 28800 
        // ------------------------------------------------------------------
        private static double _scale; 

        // -----------------------------------------------------------------
        // PTS/LS limitation for max size.
        // ------------------------------------------------------------------ 
        private static int _maxSizeInt;
        private static double _maxSize; 
 
        // ------------------------------------------------------------------
        // PTS/LS limitation for min size. 
        // -----------------------------------------------------------------
        private static int _minSizeInt;
        private static double _minSize;
 
        // ------------------------------------------------------------------
        // Embedded object size is limited to 1/3 of max size accepted by LS/PTS. 
        // ----------------------------------------------------------------- 
        private static double _maxObjSize;
    } 

#if TEXTLAYOUTDEBUG
    // ---------------------------------------------------------------------
    // Pefrormance debugging helpers. 
    // ---------------------------------------------------------------------
    internal static class TextDebug 
    { 
        // ------------------------------------------------------------------
        // Enter the scope and log the message. 
        // -----------------------------------------------------------------
        internal static void BeginScope(string name)
        {
            Log(name); 
            ++_indent;
        } 
 
        // ------------------------------------------------------------------
        // Exit the current scope. 
        // ------------------------------------------------------------------
        internal static void EndScope()
        {
            --_indent; 
        }
 
        // ----------------------------------------------------------------- 
        // Log message.
        // ------------------------------------------------------------------ 
        internal static void Log(string msg)
        {
            Console.WriteLine("> " + CurrentIndent + msg);
        } 

        // ----------------------------------------------------------------- 
        // String representing current indent. 
        // -----------------------------------------------------------------
        private static string CurrentIndent { get { return new string(' ', _indent * 2); } } 

        // -----------------------------------------------------------------
        // Current indent.
        // ------------------------------------------------------------------ 
        private static int _indent;
    } 
#endif // TEXTLAYOUTDEBUG 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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