private static Interop.User32.TextFormatFlags GetTextFormatFlags(TextFormatFlags flags) { if (((uint)flags & WindowsGraphics.GdiUnsupportedFlagMask) == 0) { return((Interop.User32.TextFormatFlags)flags); } // Clear TextRenderer custom flags. Interop.User32.TextFormatFlags windowsGraphicsSupportedFlags = (Interop.User32.TextFormatFlags)(((uint)flags) & ~WindowsGraphics.GdiUnsupportedFlagMask); return(windowsGraphicsSupportedFlags); }
/// <summary> /// The GDI DrawText does not do multiline alignment when Interop.User32.TextFormatFlags.DT_SINGLELINE is not set. This /// adjustment is to workaround that limitation. We don't want to duplicate SelectObject calls here, /// so put your Font in the dc before calling this. /// /// AdjustForVerticalAlignment is only used when the text is multiline and it fits inside the bounds passed in. /// In that case we want the horizontal center of the multiline text to be at the horizontal center of the bounds. /// /// If the text is multiline and it does not fit inside the bounds passed in, then return the bounds that were passed in. /// This way we paint the top of the text at the top of the bounds passed in. /// </summary> public static Rectangle AdjustForVerticalAlignment(HandleRef hdc, string text, Rectangle bounds, Interop.User32.TextFormatFlags flags, ref Interop.User32.DRAWTEXTPARAMS dtparams) { Debug.Assert(((uint)flags & GdiUnsupportedFlagMask) == 0, "Some custom flags were left over and are not GDI compliant!"); // Ok if any Top (Cannot test Interop.User32.TextFormatFlags.Top because it is 0), single line text or measuring text. bool isTop = (flags & Interop.User32.TextFormatFlags.DT_BOTTOM) == 0 && (flags & Interop.User32.TextFormatFlags.DT_VCENTER) == 0; if (isTop || ((flags & Interop.User32.TextFormatFlags.DT_SINGLELINE) != 0) || ((flags & Interop.User32.TextFormatFlags.DT_CALCRECT) != 0)) { return(bounds); } Interop.RECT rect = new Interop.RECT(bounds); // Get the text bounds. flags |= Interop.User32.TextFormatFlags.DT_CALCRECT; int textHeight = Interop.User32.DrawTextExW(hdc, text, text.Length, ref rect, flags, ref dtparams); // if the text does not fit inside the bounds then return the bounds that were passed in if (textHeight > bounds.Height) { return(bounds); } Rectangle adjustedBounds = bounds; if ((flags & Interop.User32.TextFormatFlags.DT_VCENTER) != 0) // Middle { adjustedBounds.Y = adjustedBounds.Top + adjustedBounds.Height / 2 - textHeight / 2; } else // Bottom. { adjustedBounds.Y = adjustedBounds.Bottom - textHeight; } return(adjustedBounds); }
/// <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, Interop.User32.TextFormatFlags 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 Interop.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 Interop.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 Interop.RECT(0, 0, proposedSize.Width, proposedSize.Height); if (font != null) { dc.SelectFont(font); } // If proposedSize.Height >= MaxSize.Height it is assumed bounds needed. If flags contain DT_SINGLELINE and // DT_VCENTER or DT_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 DT_VCENTER and DT_BOTTOM flags to // get the actual text bounds. if (proposedSize.Height >= MaxSize.Height && (flags & Interop.User32.TextFormatFlags.DT_SINGLELINE) != 0) { // Clear vertical-alignment flags. flags &= ~(Interop.User32.TextFormatFlags.DT_BOTTOM | Interop.User32.TextFormatFlags.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 &= ~(Interop.User32.TextFormatFlags.DT_WORDBREAK); } flags |= Interop.User32.TextFormatFlags.DT_CALCRECT; Interop.User32.DrawTextExW(dc.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, Interop.User32.TextFormatFlags 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 & Interop.User32.TextFormatFlags.DT_CALCRECT) == 0, "DT_CALCRECT flag is set, text won't be drawn"); HandleRef hdc = new HandleRef(dc, dc.Hdc); // DrawText requires default text alignment. if (dc.TextAlignment != DeviceContextTextAlignment.Default) { dc.SetTextAlignment(DeviceContextTextAlignment.Default); } // color empty means use the one currently selected in the dc. if (!foreColor.IsEmpty && foreColor != dc.TextColor) { dc.SetTextColor(foreColor); } if (font != null) { dc.SelectFont(font); } DeviceContextBackgroundMode newBackGndMode = (backColor.IsEmpty || backColor == Color.Transparent) ? DeviceContextBackgroundMode.Transparent : DeviceContextBackgroundMode.Opaque; if (dc.BackgroundMode != newBackGndMode) { dc.SetBackgroundMode(newBackGndMode); } if (newBackGndMode != DeviceContextBackgroundMode.Transparent && backColor != dc.BackgroundColor) { dc.SetBackgroundColor(backColor); } Interop.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 Interop.RECT(bounds); Interop.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). }
/// <summary> /// Draws the text in the given bounds, using the given Font and foreColor, and according to the specified flags. /// </summary> public void DrawText(string text, WindowsFont font, Rectangle bounds, Color color, Interop.User32.TextFormatFlags flags) { DrawText(text, font, bounds, color, Color.Empty, flags); }
/// <summary> /// Draws the text at the specified point, using the given Font, foreColor and backColor, and according /// to the specified flags. /// </summary> public void DrawText(string text, WindowsFont font, Point pt, Color foreColor, Color backColor, Interop.User32.TextFormatFlags flags) { Rectangle bounds = new Rectangle(pt.X, pt.Y, int.MaxValue, int.MaxValue); DrawText(text, font, bounds, foreColor, backColor, flags); }
/// <summary> /// Draws the text at the specified point, using the given Font and foreColor, and according to the /// specified flags. /// </summary> public void DrawText(string text, WindowsFont font, Point pt, Color foreColor, Interop.User32.TextFormatFlags flags) { DrawText(text, font, pt, foreColor, Color.Empty, flags); }