/// <summary> /// Returns the Size of the given text using the specified font if not null, otherwise the font currently /// set in the dc is used. /// This method is used to get the size in points of a line of text; it uses GetTextExtentPoint32 function /// which computes the width and height of the text ignoring TAB\CR\LF characters. /// A text extent is the distance between the beginning of the space and a character that will fit in the space. /// </summary> public Size GetTextExtent(string text, WindowsFont font) { if (string.IsNullOrEmpty(text)) { return(Size.Empty); } Size size = new Size(); if (font != null) { DeviceContext.SelectFont(font); } Gdi32.GetTextExtentPoint32W(DeviceContext.Hdc, text, text.Length, ref size); // Unselect, but not from Measurement DC as it keeps the same // font selected for perf reasons. if (font != null && !MeasurementDCInfo.IsMeasurementDC(DeviceContext)) { DeviceContext.ResetFont(); } return(new Size(size.Width, size.Height)); }
/// <summary> /// Returns the Size in logical units of the given text using the given Font, and according to the formatting flags. /// The proposed size is used to create a bounding rectangle as follows: /// - If there are multiple lines of text, DrawText uses the width of the rectangle pointed to by /// the lpRect parameter and extends the base of the rectangle to bound the last line of text. /// - If the largest word is wider than the rectangle, the width is expanded. /// - If the text is less than the width of the rectangle, the width is reduced. /// - If there is only one line of text, DrawText modifies the right side of the rectangle so that /// it bounds the last character in the line. /// If the font is null, the hdc's current font will be used. /// /// Note for vertical fonts (if ever supported): DrawTextEx uses GetTextExtentPoint32 for measuring the text and this /// function has the following limitation (from MSDN): /// - This function assumes that the text is horizontal, that is, that the escapement is always 0. This is true for both /// the horizontal and vertical measurements of the text. The application must convert it explicitly. /// </summary> public Size MeasureText(string text, WindowsFont font, Size proposedSize, User32.DT flags) { Debug.Assert(((uint)flags & GdiUnsupportedFlagMask) == 0, "Some custom flags were left over and are not GDI compliant!"); if (string.IsNullOrEmpty(text)) { return(Size.Empty); } // DrawText returns a rectangle useful for aligning, but not guaranteed to encompass all // pixels (its not a FitBlackBox, if the text is italicized, it will overhang on the right.) // So we need to account for this. #if OPTIMIZED_MEASUREMENTDC User32.DRAWTEXTPARAMS dtparams; // use the cache if we've got it if (MeasurementDCInfo.IsMeasurementDC(DeviceContext)) { dtparams = MeasurementDCInfo.GetTextMargins(this, font); } else { dtparams = GetTextMargins(font); } #else User32.DRAWTEXTPARAMS dtparams = GetTextMargins(font); #endif // If Width / Height are < 0, we need to make them larger or DrawText will return // an unbounded measurement when we actually trying to make it very narrow. int minWidth = 1 + dtparams.iLeftMargin + dtparams.iRightMargin; if (proposedSize.Width <= minWidth) { proposedSize.Width = minWidth; } if (proposedSize.Height <= 0) { proposedSize.Height = 1; } var rect = new RECT(0, 0, proposedSize.Width, proposedSize.Height); if (font != null) { DeviceContext.SelectFont(font); } // If proposedSize.Height >= MaxSize.Height it is assumed bounds needed. If flags contain SINGLELINE and // VCENTER or BOTTOM options, DrawTextEx does not bind the rectangle to the actual text height since // it assumes the text is to be vertically aligned; we need to clear the VCENTER and BOTTOM flags to // get the actual text bounds. if (proposedSize.Height >= MaxSize.Height && (flags & User32.DT.SINGLELINE) != 0) { // Clear vertical-alignment flags. flags &= ~(User32.DT.BOTTOM | User32.DT.VCENTER); } if (proposedSize.Width == MaxSize.Width) { // PERF: No constraining width means no word break. // in this case, we dont care about word wrapping - there should be enough room to fit it all flags &= ~(User32.DT.WORDBREAK); } flags |= User32.DT.CALCRECT; User32.DrawTextExW(DeviceContext.Hdc, text, text.Length, ref rect, flags, ref dtparams); return(rect.Size); }
/// <summary> /// Draws the text in the given bounds, using the given Font, foreColor and backColor, and according to the specified /// TextFormatFlags flags. /// /// If font is null, the font currently selected in the hdc is used. /// /// If foreColor and/or backColor are Color.Empty, the hdc current text and/or background color are used. /// </summary> public void DrawText(string text, WindowsFont font, Rectangle bounds, Color foreColor, Color backColor, User32.DT flags) { if (string.IsNullOrEmpty(text) || foreColor == Color.Transparent) { return; } Debug.Assert(((uint)flags & GdiUnsupportedFlagMask) == 0, "Some custom flags were left over and are not GDI compliant!"); Debug.Assert((flags & User32.DT.CALCRECT) == 0, "CALCRECT flag is set, text won't be drawn"); HandleRef hdc = new HandleRef(DeviceContext, DeviceContext.Hdc); // DrawText requires default text alignment. if (DeviceContext.TextAlignment != default) { DeviceContext.TextAlignment = default; } // color empty means use the one currently selected in the dc. if (!foreColor.IsEmpty && foreColor != DeviceContext.TextColor) { DeviceContext.TextColor = foreColor; } if (font != null) { DeviceContext.SelectFont(font); } Gdi32.BKMODE newBackGndMode = (backColor.IsEmpty || backColor == Color.Transparent) ? Gdi32.BKMODE.TRANSPARENT : Gdi32.BKMODE.OPAQUE; if (DeviceContext.BackgroundMode != newBackGndMode) { DeviceContext.SetBackgroundMode(newBackGndMode); } if (newBackGndMode != Gdi32.BKMODE.TRANSPARENT && backColor != DeviceContext.BackgroundColor) { DeviceContext.BackgroundColor = backColor; } User32.DRAWTEXTPARAMS dtparams = GetTextMargins(font); bounds = AdjustForVerticalAlignment(hdc, text, bounds, flags, ref dtparams); // Adjust unbounded rect to avoid overflow since Rectangle ctr does not do param validation. if (bounds.Width == MaxSize.Width) { bounds.Width -= bounds.X; } if (bounds.Height == MaxSize.Height) { bounds.Height -= bounds.Y; } var rect = new RECT(bounds); User32.DrawTextExW(hdc, text, text.Length, ref rect, flags, ref dtparams); // No need to restore previous objects into the dc (see comments on top of the class). }