1/*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "SkTextBox.h"
9#include "SkUtils.h"
10
11static inline int is_ws(int c)
12{
13    return !((c - 1) >> 5);
14}
15
16static size_t linebreak(const char text[], const char stop[],
17                        const SkPaint& paint, SkScalar margin,
18                        size_t* trailing = NULL)
19{
20    size_t lengthBreak = paint.breakText(text, stop - text, margin);
21
22    //Check for white space or line breakers before the lengthBreak
23    const char* start = text;
24    const char* word_start = text;
25    int prevWS = true;
26    if (trailing) {
27        *trailing = 0;
28    }
29
30    while (text < stop) {
31        const char* prevText = text;
32        SkUnichar uni = SkUTF8_NextUnichar(&text);
33        int currWS = is_ws(uni);
34
35        if (!currWS && prevWS) {
36            word_start = prevText;
37        }
38        prevWS = currWS;
39
40        if (text > start + lengthBreak) {
41            if (currWS) {
42                // eat the rest of the whitespace
43                while (text < stop && is_ws(SkUTF8_ToUnichar(text))) {
44                    text += SkUTF8_CountUTF8Bytes(text);
45                }
46                if (trailing) {
47                    *trailing = text - prevText;
48                }
49            } else {
50                // backup until a whitespace (or 1 char)
51                if (word_start == start) {
52                    if (prevText > start) {
53                        text = prevText;
54                    }
55                } else {
56                    text = word_start;
57                }
58            }
59            break;
60        }
61
62        if ('\n' == uni) {
63            size_t ret = text - start;
64            size_t lineBreakSize = 1;
65            if (text < stop) {
66                uni = SkUTF8_NextUnichar(&text);
67                if ('\r' == uni) {
68                    ret = text - start;
69                    ++lineBreakSize;
70                }
71            }
72            if (trailing) {
73                *trailing = lineBreakSize;
74            }
75            return ret;
76        }
77
78        if ('\r' == uni) {
79            size_t ret = text - start;
80            size_t lineBreakSize = 1;
81            if (text < stop) {
82                uni = SkUTF8_NextUnichar(&text);
83                if ('\n' == uni) {
84                    ret = text - start;
85                    ++lineBreakSize;
86                }
87            }
88            if (trailing) {
89                *trailing = lineBreakSize;
90            }
91            return ret;
92        }
93    }
94
95    return text - start;
96}
97
98int SkTextLineBreaker::CountLines(const char text[], size_t len, const SkPaint& paint, SkScalar width)
99{
100    const char* stop = text + len;
101    int         count = 0;
102
103    if (width > 0)
104    {
105        do {
106            count += 1;
107            text += linebreak(text, stop, paint, width);
108        } while (text < stop);
109    }
110    return count;
111}
112
113//////////////////////////////////////////////////////////////////////////////
114
115SkTextBox::SkTextBox()
116{
117    fBox.setEmpty();
118    fSpacingMul = SK_Scalar1;
119    fSpacingAdd = 0;
120    fMode = kLineBreak_Mode;
121    fSpacingAlign = kStart_SpacingAlign;
122}
123
124void SkTextBox::setMode(Mode mode)
125{
126    SkASSERT((unsigned)mode < kModeCount);
127    fMode = SkToU8(mode);
128}
129
130void SkTextBox::setSpacingAlign(SpacingAlign align)
131{
132    SkASSERT((unsigned)align < kSpacingAlignCount);
133    fSpacingAlign = SkToU8(align);
134}
135
136void SkTextBox::getBox(SkRect* box) const
137{
138    if (box)
139        *box = fBox;
140}
141
142void SkTextBox::setBox(const SkRect& box)
143{
144    fBox = box;
145}
146
147void SkTextBox::setBox(SkScalar left, SkScalar top, SkScalar right, SkScalar bottom)
148{
149    fBox.set(left, top, right, bottom);
150}
151
152void SkTextBox::getSpacing(SkScalar* mul, SkScalar* add) const
153{
154    if (mul)
155        *mul = fSpacingMul;
156    if (add)
157        *add = fSpacingAdd;
158}
159
160void SkTextBox::setSpacing(SkScalar mul, SkScalar add)
161{
162    fSpacingMul = mul;
163    fSpacingAdd = add;
164}
165
166/////////////////////////////////////////////////////////////////////////////////////////////
167
168void SkTextBox::draw(SkCanvas* canvas, const char text[], size_t len, const SkPaint& paint)
169{
170    SkASSERT(canvas && &paint && (text || len == 0));
171
172    SkScalar marginWidth = fBox.width();
173
174    if (marginWidth <= 0 || len == 0)
175        return;
176
177    const char* textStop = text + len;
178
179    SkScalar                x, y, scaledSpacing, height, fontHeight;
180    SkPaint::FontMetrics    metrics;
181
182    switch (paint.getTextAlign()) {
183    case SkPaint::kLeft_Align:
184        x = 0;
185        break;
186    case SkPaint::kCenter_Align:
187        x = SkScalarHalf(marginWidth);
188        break;
189    default:
190        x = marginWidth;
191        break;
192    }
193    x += fBox.fLeft;
194
195    fontHeight = paint.getFontMetrics(&metrics);
196    scaledSpacing = SkScalarMul(fontHeight, fSpacingMul) + fSpacingAdd;
197    height = fBox.height();
198
199    //  compute Y position for first line
200    {
201        SkScalar textHeight = fontHeight;
202
203        if (fMode == kLineBreak_Mode && fSpacingAlign != kStart_SpacingAlign)
204        {
205            int count = SkTextLineBreaker::CountLines(text, textStop - text, paint, marginWidth);
206            SkASSERT(count > 0);
207            textHeight += scaledSpacing * (count - 1);
208        }
209
210        switch (fSpacingAlign) {
211        case kStart_SpacingAlign:
212            y = 0;
213            break;
214        case kCenter_SpacingAlign:
215            y = SkScalarHalf(height - textHeight);
216            break;
217        default:
218            SkASSERT(fSpacingAlign == kEnd_SpacingAlign);
219            y = height - textHeight;
220            break;
221        }
222        y += fBox.fTop - metrics.fAscent;
223    }
224
225    for (;;)
226    {
227        size_t trailing;
228        len = linebreak(text, textStop, paint, marginWidth, &trailing);
229        if (y + metrics.fDescent + metrics.fLeading > 0)
230            canvas->drawText(text, len - trailing, x, y, paint);
231        text += len;
232        if (text >= textStop)
233            break;
234        y += scaledSpacing;
235        if (y + metrics.fAscent >= fBox.fBottom)
236            break;
237    }
238}
239
240///////////////////////////////////////////////////////////////////////////////
241
242void SkTextBox::setText(const char text[], size_t len, const SkPaint& paint) {
243    fText = text;
244    fLen = len;
245    fPaint = &paint;
246}
247
248void SkTextBox::draw(SkCanvas* canvas) {
249    this->draw(canvas, fText, fLen, *fPaint);
250}
251
252int SkTextBox::countLines() const {
253    return SkTextLineBreaker::CountLines(fText, fLen, *fPaint, fBox.width());
254}
255
256SkScalar SkTextBox::getTextHeight() const {
257    SkScalar spacing = SkScalarMul(fPaint->getTextSize(), fSpacingMul) + fSpacingAdd;
258    return this->countLines() * spacing;
259}
260