1 /* 2 * Copyright (C) 2004 Red Hat, Inc. 3 * Copyright (C) 2010 Brent Fulgham <bfulgham (at) webkit.org> 4 * 5 * Based on Pango sources (see pangocairo-render.c) 6 * 7 * This library is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Library General Public 9 * License as published by the Free Software Foundation; either 10 * version 2 of the License, or (at your option) any later version. 11 * 12 * This library is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Library General Public License for more details. 16 * 17 * You should have received a copy of the GNU Library General Public 18 * License along with this library; if not, write to the 19 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 20 * Boston, MA 02111-1307, USA. 21 * 22 */ 23 24 #if USE(CAIRO) 25 26 #ifndef DrawErrorUnderline_h 27 #define DrawErrorUnderline_h 28 29 #include <cairo.h> 30 31 // 32 // Draws an error underline that looks like one of: 33 // 34 // H E H 35 // /\ /\ /\ /\ /\ - 36 // A/ \ / \ / \ A/ \ / \ | 37 // \ \ / \ / /D \ \ / \ | 38 // \ \/ C \/ / \ \/ C \ | height = heightSquares * square 39 // \ /\ F / \ F /\ \ | 40 // \ / \ / \ / \ \G | 41 // \ / \ / \ / \ / | 42 // \/ \/ \/ \/ - 43 // B B 44 // |---| 45 // unitWidth = (heightSquares - 1) * square 46 // 47 // The x, y, width, height passed in give the desired bounding box; 48 // x/width are adjusted to make the underline a integer number of units 49 // wide. 50 // 51 static inline void drawErrorUnderline(cairo_t* cr, double x, double y, double width, double height) 52 { 53 static const double heightSquares = 2.5; 54 55 double square = height / heightSquares; 56 double halfSquare = 0.5 * square; 57 58 double unitWidth = (heightSquares - 1.0) * square; 59 int widthUnits = static_cast<int>((width + 0.5 * unitWidth) / unitWidth); 60 61 x += 0.5 * (width - widthUnits * unitWidth); 62 width = widthUnits * unitWidth; 63 64 double bottom = y + height; 65 double top = y; 66 67 // Bottom of squiggle 68 cairo_move_to(cr, x - halfSquare, top + halfSquare); // A 69 70 int i = 0; 71 for (i = 0; i < widthUnits; i += 2) { 72 double middle = x + (i + 1) * unitWidth; 73 double right = x + (i + 2) * unitWidth; 74 75 cairo_line_to(cr, middle, bottom); // B 76 77 if (i + 2 == widthUnits) 78 cairo_line_to(cr, right + halfSquare, top + halfSquare); // D 79 else if (i + 1 != widthUnits) 80 cairo_line_to(cr, right, top + square); // C 81 } 82 83 // Top of squiggle 84 for (i -= 2; i >= 0; i -= 2) { 85 double left = x + i * unitWidth; 86 double middle = x + (i + 1) * unitWidth; 87 double right = x + (i + 2) * unitWidth; 88 89 if (i + 1 == widthUnits) 90 cairo_line_to(cr, middle + halfSquare, bottom - halfSquare); // G 91 else { 92 if (i + 2 == widthUnits) 93 cairo_line_to(cr, right, top); // E 94 95 cairo_line_to(cr, middle, bottom - halfSquare); // F 96 } 97 98 cairo_line_to(cr, left, top); // H 99 } 100 } 101 102 #endif // DrawErrorUnderline_h 103 104 #endif 105