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
168SkScalar SkTextBox::visit(Visitor& visitor, const char text[], size_t len,
169                          const SkPaint& paint) const {
170    SkScalar marginWidth = fBox.width();
171
172    if (marginWidth <= 0 || len == 0) {
173        return fBox.top();
174    }
175
176    const char* textStop = text + len;
177
178    SkScalar                x, y, scaledSpacing, height, fontHeight;
179    SkPaint::FontMetrics    metrics;
180
181    switch (paint.getTextAlign()) {
182    case SkPaint::kLeft_Align:
183        x = 0;
184        break;
185    case SkPaint::kCenter_Align:
186        x = SkScalarHalf(marginWidth);
187        break;
188    default:
189        x = marginWidth;
190        break;
191    }
192    x += fBox.fLeft;
193
194    fontHeight = paint.getFontMetrics(&metrics);
195    scaledSpacing = SkScalarMul(fontHeight, fSpacingMul) + fSpacingAdd;
196    height = fBox.height();
197
198    //  compute Y position for first line
199    {
200        SkScalar textHeight = fontHeight;
201
202        if (fMode == kLineBreak_Mode && fSpacingAlign != kStart_SpacingAlign) {
203            int count = SkTextLineBreaker::CountLines(text, textStop - text, paint, marginWidth);
204            SkASSERT(count > 0);
205            textHeight += scaledSpacing * (count - 1);
206        }
207
208        switch (fSpacingAlign) {
209        case kStart_SpacingAlign:
210            y = 0;
211            break;
212        case kCenter_SpacingAlign:
213            y = SkScalarHalf(height - textHeight);
214            break;
215        default:
216            SkASSERT(fSpacingAlign == kEnd_SpacingAlign);
217            y = height - textHeight;
218            break;
219        }
220        y += fBox.fTop - metrics.fAscent;
221    }
222
223    for (;;) {
224        size_t trailing;
225        len = linebreak(text, textStop, paint, marginWidth, &trailing);
226        if (y + metrics.fDescent + metrics.fLeading > 0) {
227            visitor(text, len - trailing, x, y, paint);
228        }
229        text += len;
230        if (text >= textStop) {
231            break;
232        }
233        y += scaledSpacing;
234        if (y + metrics.fAscent >= fBox.fBottom) {
235            break;
236        }
237    }
238    return y + metrics.fDescent + metrics.fLeading;
239}
240
241///////////////////////////////////////////////////////////////////////////////
242
243class CanvasVisitor : public SkTextBox::Visitor {
244    SkCanvas* fCanvas;
245public:
246    CanvasVisitor(SkCanvas* canvas) : fCanvas(canvas) {}
247
248    void operator()(const char text[], size_t length, SkScalar x, SkScalar y,
249                    const SkPaint& paint) override {
250        fCanvas->drawText(text, length, x, y, paint);
251    }
252};
253
254void SkTextBox::setText(const char text[], size_t len, const SkPaint& paint) {
255    fText = text;
256    fLen = len;
257    fPaint = &paint;
258}
259
260void SkTextBox::draw(SkCanvas* canvas, const char text[], size_t len, const SkPaint& paint) {
261    CanvasVisitor sink(canvas);
262    this->visit(sink, text, len, paint);
263}
264
265void SkTextBox::draw(SkCanvas* canvas) {
266    this->draw(canvas, fText, fLen, *fPaint);
267}
268
269int SkTextBox::countLines() const {
270    return SkTextLineBreaker::CountLines(fText, fLen, *fPaint, fBox.width());
271}
272
273SkScalar SkTextBox::getTextHeight() const {
274    SkScalar spacing = SkScalarMul(fPaint->getTextSize(), fSpacingMul) + fSpacingAdd;
275    return this->countLines() * spacing;
276}
277
278///////////////////////////////////////////////////////////////////////////////
279
280#include "SkTextBlob.h"
281
282class TextBlobVisitor : public SkTextBox::Visitor {
283public:
284    SkTextBlobBuilder fBuilder;
285
286    void operator()(const char text[], size_t length, SkScalar x, SkScalar y,
287                    const SkPaint& paint) override {
288        SkPaint p(paint);
289        p.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
290        const int count = paint.countText(text, length);
291        paint.textToGlyphs(text, length, fBuilder.allocRun(p, count, x, y).glyphs);
292    }
293};
294
295SkTextBlob* SkTextBox::snapshotTextBlob(SkScalar* computedBottom) const {
296    TextBlobVisitor visitor;
297    SkScalar newB = this->visit(visitor, fText, fLen, *fPaint);
298    if (computedBottom) {
299        *computedBottom = newB;
300    }
301    return (SkTextBlob*)visitor.fBuilder.build();
302}
303
304