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comparison: gfx/src/nsBoundingMetrics.h
gfx/src/nsBoundingMetrics.h
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- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:14995942004f |
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| 1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ | |
| 2 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 3 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 5 | |
| 6 #ifndef __nsBoundingMetrics_h | |
| 7 #define __nsBoundingMetrics_h | |
| 8 | |
| 9 #include "nsCoord.h" | |
| 10 #include <algorithm> | |
| 11 | |
| 12 /* Struct used for accurate measurements of a string, in order to | |
| 13 * allow precise positioning when processing MathML. This is in its | |
| 14 * own header file because some very-widely-included headers need it | |
| 15 * but not the rest of nsFontMetrics, or vice versa. | |
| 16 */ | |
| 17 | |
| 18 struct nsBoundingMetrics { | |
| 19 | |
| 20 /////////// | |
| 21 // Metrics that _exactly_ enclose the text: | |
| 22 | |
| 23 // The character coordinate system is the one used on X Windows: | |
| 24 // 1. The origin is located at the intersection of the baseline | |
| 25 // with the left of the character's cell. | |
| 26 // 2. All horizontal bearings are oriented from left to right. | |
| 27 // 2. All horizontal bearings are oriented from left to right. | |
| 28 // 3. The ascent is oriented from bottom to top (being 0 at the orgin). | |
| 29 // 4. The descent is oriented from top to bottom (being 0 at the origin). | |
| 30 | |
| 31 // Note that Win32/Mac/PostScript use a different convention for | |
| 32 // the descent (all vertical measurements are oriented from bottom | |
| 33 // to top on these palatforms). Make sure to flip the sign of the | |
| 34 // descent on these platforms for cross-platform compatibility. | |
| 35 | |
| 36 // Any of the following member variables listed here can have | |
| 37 // positive or negative value. | |
| 38 | |
| 39 nscoord leftBearing; | |
| 40 /* The horizontal distance from the origin of the drawing | |
| 41 operation to the left-most part of the drawn string. */ | |
| 42 | |
| 43 nscoord rightBearing; | |
| 44 /* The horizontal distance from the origin of the drawing | |
| 45 operation to the right-most part of the drawn string. | |
| 46 The _exact_ width of the string is therefore: | |
| 47 rightBearing - leftBearing */ | |
| 48 | |
| 49 nscoord ascent; | |
| 50 /* The vertical distance from the origin of the drawing | |
| 51 operation to the top-most part of the drawn string. */ | |
| 52 | |
| 53 nscoord descent; | |
| 54 /* The vertical distance from the origin of the drawing | |
| 55 operation to the bottom-most part of the drawn string. | |
| 56 The _exact_ height of the string is therefore: | |
| 57 ascent + descent */ | |
| 58 | |
| 59 nscoord width; | |
| 60 /* The horizontal distance from the origin of the drawing | |
| 61 operation to the correct origin for drawing another string | |
| 62 to follow the current one. Depending on the font, this | |
| 63 could be greater than or less than the right bearing. */ | |
| 64 | |
| 65 nsBoundingMetrics() : leftBearing(0), rightBearing(0), | |
| 66 ascent(0), descent(0), width(0) | |
| 67 {} | |
| 68 | |
| 69 void | |
| 70 operator += (const nsBoundingMetrics& bm) { | |
| 71 if (ascent + descent == 0 && rightBearing - leftBearing == 0) { | |
| 72 ascent = bm.ascent; | |
| 73 descent = bm.descent; | |
| 74 leftBearing = width + bm.leftBearing; | |
| 75 rightBearing = width + bm.rightBearing; | |
| 76 } | |
| 77 else { | |
| 78 if (ascent < bm.ascent) ascent = bm.ascent; | |
| 79 if (descent < bm.descent) descent = bm.descent; | |
| 80 leftBearing = std::min(leftBearing, width + bm.leftBearing); | |
| 81 rightBearing = std::max(rightBearing, width + bm.rightBearing); | |
| 82 } | |
| 83 width += bm.width; | |
| 84 } | |
| 85 }; | |
| 86 | |
| 87 #endif // __nsBoundingMetrics_h |
